Seabirds: strategic ornithological compensatory measures: review

Annex 1: Systematic literature reviews

1 Comprehensive overview of the steps taken during the systematic literature reviews

Following Foo et al. (2021) and Higgins et al. (2022), for each systematic literature review we undertook the steps shown in Figure 4 (Figure 3 within main document).

1. Defining and identifying the research questions and keywords: Overall, research questions had the following structure: ‘Would ‘conservation action/s’ benefit species?’ Appropriate research questions should be sufficiently general to address the topic of interest, but not so broad that the search becomes impractical. Therefore, while in most cases a single research question was used for a single systematic review, in some instances, several research questions were tackled within a single systematic review. Keywords varied depending on the scope of the research questions. In most instances, however, keywords included synonyms of the conservation actions, the species, Genus and English name of the focal seabirds, and other relevant key words.

2. Conducting the literature search:

a. Search engines: We chose to undertake the literature search using two complementary search engines: Web of Science (WoS) and Google Scholar (GS). Although both are widely used academic search engines, they have different strengths and limitations. WoS is a platform that provides access to multiple databases and collections (e.g. Web of Science Core Collection and Zoological Record), which in turn provide access to peer-reviewed journals, conference proceedings, books, and other scholarly material. WoS also offers more advanced search features, such as Boolean operators, which allow for more precise searching, making it one of the most frequently used search engines in the natural sciences, especially within the ecology and evolution fields (Gusenbauer and Haddaway, 2020). On the other hand, GS is subject to limitations that make it unsuitable as the principal search engine (e.g. limited Boolean search functionality that may not allow for precise searching, results are influenced by stored research histories/geographic locations; (Gusenbauer and Haddaway, 2020)). However, here we use GS as a tool, with the specific benefit of finding relevant grey literature (unpublished research or those published outside of traditional academic publishing) that would otherwise not be found using WoS. We believed that, by using both search engines, we would find different, but often equally important and relevant literature. Although we did consider using other search engines, we are confident that the combination of WoS and GS substantially minimises the possibility of overlooking key literature.

b. Search strings: We used a selection of the previously identified keywords to produce appropriate search strings. In WoS we used longer search strings using Boolean operators (e.g. AND, OR). We used the Advanced Search options to search all databases and collections, and to search by Topic, which included searching titles, abstract, and indexing. We performed WoS searches with the ‘Exact Search’ option off. With this option disabled, WoS uses stemming and lemmatisation to expand search terms to include closely related words, though not all synonyms (e.g. searching for mouse would also include mice). For GS we used shorter and broader search strings. We searched any type of reference and did not set a publication date limit. In both engines, references were sorted by relevance. For each review, we formulated a set of different search strings and refined them through a pilot screening. The goal was to provide a key string broad enough to provide all relevant literature, but not broad enough as to make the search impractical. The selection of the number of references varied according to the review and the search engine. When five consecutive articles were not relevant to the topic, we stopped and all references up to that point, were saved for screening. We anticipated that most search results would be in English, since the search terms were based on English keywords but studies in other languages that are comprehensible to the authors (e.g. Spanish, French, Portuguese) were also considered. Information on the time and date that search strings were used, as well as the number of records retained for screening can be found in Annex 2.

3. Screening and selection of relevant literature: References obtained from WoS and GS were uploaded and screened in CADIMA (Kohl et al., 2018), a free web tool that facilitates the execution and documentation of systematic literature reviews. After eliminating duplicated records, we screened all references following a pre-defined set of inclusion criteria (see Table A 2 within main document). References were first screened at a title and abstract level, and those that advanced to the next stage were then screened at a full-text level. Inclusion criteria depended on the scope of the topic, but overall, we were looking for studies that tested, either indirectly or directly, the effect of the conservation action on seabirds. In some instances, when several annual results of the same species at the same colony was found, we kept the most recent study and excluded the rest (e.g. Annual species status reports). While we primarily focussed on studies conducted within Scotland and the UK and on focal species, relevant information collected elsewhere or from closely related species were also included. Information on the complete reference list obtained during the literature search, and the level at which each reference was eliminated can be found in Annex 3.

4. Data extraction: In a Microsoft Office Excel spreadsheet, we recorded details of all references screened at a full-text level (this information can be found in Annex 4):

a. Initials of whoever undertook the screening: Tom Evans (TE), Claudia Tapia Harris (CTH)

b. Title

c. Authors

d. Publication year

e. Type of document: research article, review paper, report, thesis (PhD or Master’s), conference proceedings, book, or book chapter

f. Access to full text: yes or no

g. A brief summary of the reference, including reasons for exclusion

5. For those references that were deemed relevant for the final assessment, we also recorded the following information (note that additional information specific to the actions was extracted if deemed relevant. This information can be found in Annex 4):

a. Study species

b. Duration of study

c. Location of study

d. Region of study: OSS (Orkney and Shetland), NWS (Northwest Scotland), NES (North and Northeast Scotland), Southwest Scotland (SWS), Southeast Scotland (SES), NEE (Northeast England), EE (East England), SEE (Southeast England), SWE (Southwest England), or name of the country if not within the UK. Regional definitions followed those previously defined for the Seabird Monitoring Programme (see Figure 2.3 in Cook and Robinson (2010)), though with the Orkney Islands and Shetland Islands combined as one region and the North and Northeast Scotland regions combined (Moray Firth and Aberdeenshire coasts).

e. What seabird demographic parameters were being tested plus any potential drivers of demographic parameters: e.g. productivity, survival, diet, abundance

f. Age class of studied individuals: adults, chicks, fledglings, breeding pairs

g. How conservation action was tested: directly, indirectly

h. Sample size: in terms of location, years, individuals, pairs

i. Study design: methods, statistical analysis

j. A brief summary of the methods

k. Whether the action had an impact on the species: yes, no

l. If yes, the direction of impact: beneficial, detrimental

m. A brief summary of the results

6. Additional literature: We are aware that relevant studies could have been missed during this literature search. Therefore, we also made use of expert judgment and subject knowledge of the authors, to identify highly relevant key studies (from publications both identified and not identified by the literature search). All references within these studies were scanned to identify any additional relevant references. All newly identified references were screened at full-text level, repeating steps 4 and 5.

Steps 3–5 were performed by one of the authors (either TE or CTH). The inclusion/exclusion criteria, however, were agreed on prior to these steps. Early in this process, we met regularly to refine the inclusion and exclusion criteria, standardise data extraction methods, and to jointly screen several examples. In instances where there was uncertainty regarding whether a study should progress to the following stage, the other author assisted in its evaluation.

2. Methods of the systematic literature review on ‘Sandeel fishery closure’

2.1 Research questions, keywords, and search strings

The corresponding research question to this conservation action is: ‘Would Kittiwake populations benefit from widening the spatial extent of the closure of the sandeel fishery?’

We identified the following keywords: ‘sandeel’ and any variation thereof (‘Sand eel’, ‘sandlance’, ‘sand lance’, ‘prey’), main sandeel genera (‘Hyperoplus’, ‘Gymnammodytes’, ‘Ammodytes’), ‘fishery’ and any variation thereof (‘industrial fishery’, ‘fishery management’), closure synonyms (‘closure’, ‘termination’, ‘cessation’), and the species, genus, and English name of ‘Kittiwake’ (‘Rissa’, ‘Rissa tridactyla’, ‘Kittiwake’).

We identified the most relevant keywords and undertook a pilot screening with several search strings in Web of Science (WoS) and Google Scholar (GS). The search strings and corresponding number of records for each search engine are listed below. The option highlighted in bold indicates the search string that was used for the systematic literature review. Note that “TS” means “topic search”, and it is an operator used in Web of Science.

1. Web of Science (WoS)

Option 1: TS = (sandeel fishery closure) = 19 results

Option 2: ((TS=(kittiwake)) AND TS=(sandeel)) AND TS=(fishery) = 42 results

Option 3: (TS=(sandeel OR sand eel or Hyperoplus OR Gymnammodytes OR Ammodytes)) AND TS=(Fishery OR Industrial* fishery) = 609 results

Option 4: (((TS=(sandeel OR sand eel or Hyperoplus OR Gymnammodytes OR Ammodytes)) AND TS=(Fishery OR Industrial* fishery)) AND TS=(Closure)) AND TS=(Kittiwake OR Rissa) = 14 results

Option 5: ((TS=(kittiwake* OR Rissa)) AND TS=(prey OR sandeel* OR sand eel* OR sand lance* OR Hyperoplus OR Gymnammodytes OR Ammodytes)) AND TS=(fisher*) = 106 results

2. Google Scholar (GS)

Option 1: Sandeel fishery = 12,000 results

Option 2: Sandeel fishery closure = 2,400 results

Option 3; Sandeel fishery and kittiwake = 1,350 results

Option 4: Sandeel fisher* and kittiwakes Rissa = 872 results

Information on the time and date that search strings were used, as well as the number of records retained for screening can be found in Annex 2.

2.2 Study selection

On 23 February 2023 we conducted a literature search on WoS and GS (Figure 7; Figure 6 within main document). A total of 978 references were identified; 106 in WoS, of which all were exported for screening, and 872 in GS, of which the first 100 records were exported. This first search yielded a total of 206 records, of which 32 were duplicates (i.e. included by both WoS and GS) and were automatically removed prior to screening. All 174 unique records were screened at title and abstract level to identify and exclude studies outside the review’s scope, such as those studies unrelated to sandeels, sandeel fisheries, fishery management and Kittiwakes, and those from which the abstract could not be assessed (see Table A 2 within the main document). Studies where this criterion was unclear, were kept for full-text screening. At this stage, we excluded 79% (137) of the records. All 37 remaining records were screened in their entirety and relevant information was recorded. At this stage, we excluded studies that did not test the effect, directly or indirectly, of a sandeel fishery closure, or a similar type of sandeel fishery management, on any demographic parameter of Kittiwakes, those that did not focus on sandeels and Kittiwakes, and those that did not provide new evidence on the matter. We retained 15 records for final assessment.

Additionally, we identified five key articles and reports that explored the effect of sandeel fishery closure on Kittiwakes: Furness et al. (2013a), Furness (2021), Pearce-Higgins et al. (2021), McGregor et al. (2022), and Searle et al. (2023), and searched references within to identify additional relevant literature that may have been overlooked. We identified, read the full text, and extracted relevant information from seven references. From this process, we retained three additional records for final assessment. Overall, 18 references were included for the final review.

Information on the complete reference list obtained during the literature search, and the level at which each reference was eliminated can be found in Annex 3.

3. Methods of the systematic literature review on ‘Fishery closure or enhanced management on prey fisheries’

3.1 Research questions, keywords, and search strings

The corresponding research question to this conservation action is: ‘Would the focal seabird species benefit from enhanced management of fisheries that target seabird prey fish species in Scotland?’ In addition to the key question, we also sought to identify which prey species may be most impacted by fisheries and which seabird species could most benefit from any changes in management.

We identified the following keywords: Fishery/management related: Fishery/fishery management/sustainable management/sustainability/sustainable fishing

Prey: sprat, herring, mackerel; Sprattus sprattus, Atlantic herring, Clupea harengus, Atlantic mackerel, Scomber scombrus

Seabirds (focal): Seabirds/Marine birds; Kittiwake/Rissa/Rissa tridactyla; Larus/Great Black-backed Gull/Larus marinus/Herring Gull/Larus argentatus/Lesser Black-backed Gull/Larus fuscus; Auk/alcid; Guillemot/Common Murre/Uria aalge; Razorbill/Alca torda; Atlantic Puffin/Puffin/Fratercula arctica; Gannet/Morus/Morus bassanus/Sula bassana

We identified the most relevant keywords and conducted a pilot screening by using multiple search strings in Web of Science (WoS) and Google Scholar (GS). The search strings and corresponding number of records for each search engine are listed below. The bolded options denote the search strings used for the systematic literature review. All have a brief explanation as to why they were or were not used.

1. Web of Science (WoS)

Option 1: ((TS=(Fisher* OR "fishery management" OR (sustain* AND fisher*) OR ("ecosystem based" AND fisher*))) AND TS=(sprat OR herring OR mackerel OR "Sprattus sprattus" OR "Atlantic herring" OR "Clupea harengus" OR "Atlantic mackerel" OR "Scomber scombrus")) AND TS=(Kittiwake OR Rissa OR "Rissa tridactyla" OR Larus OR "Great Black-backed Gull" OR "Larus marinus" OR "Herring Gull" OR "Larus argentatus" OR "Lesser Black-backed Gull" OR "Larus fuscus" OR Auk OR alcide OR "Common Guillemot" OR "Common Murre" OR "Uria aalge" OR "Razorbill" OR "Alca torda" OR "Atlantic Puffin" OR "Fratercula arctica" OR "Northern Gannet" OR "Morus bassanus" OR "Sula bassana") = 113 results. First page of results generally not relevant, more diet focused than relating to fisheries

Option 2: ((TS=(Fisher* OR "fishery management" OR (sustain* AND fisher*) OR ("ecosystem based" AND fisher*))) AND TS=(sprat OR herring OR mackerel OR "Sprattus sprattus" OR "Atlantic herring" OR "Clupea harengus" OR "Atlantic mackerel" OR "Scomber scombrus")) AND TS=(seabird OR "marine bird" OR Kittiwake OR Rissa OR "Rissa tridactyla" OR Larus OR "Great Black-backed Gull" OR "Larus marinus" OR "Herring Gull" OR "Larus argentatus" OR "Lesser Black-backed Gull" OR "Larus fuscus" OR Auk OR alcid OR "Common Guillemot" OR "Common Murre" OR "Uria aalge" OR "Razorbill" OR "Alca torda" OR "Atlantic Puffin" OR "Fratercula arctica" OR "Northern Gannet" OR "Morus bassanus" OR "Sula bassana") = 192 results. Results relevance low.

Option 3: ((TS=(Fisher* OR "fishery management" OR (sustain* AND fisher*) OR ("ecosystem based" AND fisher*) OR "prey depletion")) AND TS=(sprat OR herring OR mackerel OR "Sprattus sprattus" OR "Atlantic herring" OR "Clupea harengus" OR "Atlantic mackerel" OR "Scomber scombrus")) AND TS=(seabird OR "marine bird") = 154 results. Results ordered better in terms of relevance – first page of results generally relevant in terms of fisheries impacting prey availability.

Option 4: (TS=(Fisher* OR "fishery management" OR (sustain* AND fisher*) OR ("ecosystem based" AND fisher*) OR "prey depletion" OR "prey availability")) AND TS=(sprat OR herring OR mackerel OR "Sprattus sprattus" OR "Atlantic herring" OR "Clupea harengus" OR "Atlantic mackerel" OR "Scomber scombrus")) AND TS=(seabird OR "marine bird") = 179 results. Results generally relevant, though some less specifically related to fisheries.

Option 5: ((TS=(fisher* AND (management OR sustainable OR "ecosystem based"))) AND TS=(sprat OR herring OR mackerel OR "Sprattus sprattus" OR "Atlantic herring" OR "Clupea harengus" OR "Atlantic mackerel" OR "Scomber scombrus")) AND TS=(seabird OR "marine bird") = 56 results. Mostly relevant, though quite a few non NE Atlantic.

Option 6: ((TS=("prey depletion" OR overfish* OR (fisher* AND (management OR sustainable OR "ecosystem based")))) AND TS=(sprat OR herring OR mackerel OR "Sprattus sprattus" OR "Atlantic herring" OR "Clupea harengus" OR "Atlantic mackerel" OR "Scomber scombrus")) AND TS=(seabird OR "marine bird") = 61 results. Similar level of relevance to above

Option 7: (((TS=(fisher*)) AND TS=("prey depletion" OR overfish* OR "prey availability" OR "prey abundance" OR "diet")) AND TS=(sprat OR herring OR mackerel OR "Sprattus sprattus" OR "Atlantic herring" OR "Clupea harengus" OR "Atlantic mackerel" OR "Scomber scombrus")) AND TS=(seabird OR "marine bird" OR Kittiwake OR Rissa OR "Rissa tridactyla" OR Larus OR "Great Black-backed Gull" OR "Larus marinus" OR "Herring Gull" OR "Larus argentatus" OR "Lesser Black-backed Gull" OR "Larus fuscus" OR Auk OR alcide OR "Common Guillemot" OR "Common Murre" OR "Uria aalge" OR "Razorbill" OR "Alca torda" OR "Atlantic Puffin" OR "Fratercula arctica" OR "Northern Gannet" OR "Morus bassanus" OR "Sula bassana") = 99 results. Results partially relevant though doesn’t seem that well ordered in terms of relevancy.

Option 8: ((TS=(Fisher* OR "fishery management" OR (sustain* AND fisher*) OR ("ecosystem based" AND fisher*) OR "prey depletion")) AND TS=(sprat OR herring OR mackerel OR "Sprattus sprattus" OR "Atlantic herring" OR "Clupea harengus" OR "Atlantic mackerel" OR "Scomber scombrus")) AND TS=(seabird OR "marine bird"OR Kittiwake OR Rissa OR "Rissa tridactyla" OR Larus OR "Great Black-backed Gull" OR "Larus marinus" OR "Herring Gull" OR "Larus argentatus" OR "Lesser Black-backed Gull" OR "Larus fuscus" OR Auk OR alcide OR "Common Guillemot" OR "Common Murre" OR "Uria aalge" OR "Razorbill" OR "Alca torda" OR "Atlantic Puffin" OR "Fratercula arctica" OR "Northern Gannet" OR "Morus bassanus" OR "Sula bassana") = 192 results. Fairly relevant and ok order, though still quite a few not relevant results on first page.

Option 9: ((TS=(Fisher* OR "fishery management" OR (sustain* AND fisher*) OR ("ecosystem based" AND fisher*) OR "prey depletion")) AND TS=(sprat OR herring OR mackerel OR "Sprattus sprattus" OR "Atlantic herring" OR "Clupea harengus" OR "Atlantic mackerel" OR "Scomber scombrus")) AND TS=(Kittiwake OR Rissa OR "Rissa tridactyla" OR Larus OR "Great Black-backed Gull" OR "Larus marinus" OR "Herring Gull" OR "Larus argentatus" OR "Lesser Black-backed Gull" OR "Larus fuscus" OR Auk OR alcide OR "Common Guillemot" OR "Common Murre" OR "Uria aalge" OR "Razorbill" OR "Alca torda" OR "Atlantic Puffin" OR "Fratercula arctica" OR "Northern Gannet" OR "Morus bassanus" OR "Sula bassana") = 113 results. Better than #8 being more specific to the seabird species of interest.

Option 10: ((TS=(Fisher* OR "fishery management" OR (sustain* AND fisher*) OR ("ecosystem based" AND fisher*) OR "prey depletion" OR "prey abundance" OR "prey availability")) AND TS=(sprat OR herring OR mackerel OR "Sprattus sprattus" OR "Atlantic herring" OR "Clupea harengus" OR "Atlantic mackerel" OR "Scomber scombrus")) AND TS=(Kittiwake OR Rissa OR "Rissa tridactyla" OR Larus OR "Great Black-backed Gull" OR "Larus marinus" OR "Herring Gull" OR "Larus argentatus" OR "Lesser Black-backed Gull" OR "Larus fuscus" OR Auk OR alcide OR "Common Guillemot" OR "Common Murre" OR "Uria aalge" OR "Razorbill" OR "Alca torda" OR "Atlantic Puffin" OR "Fratercula arctica" OR "Northern Gannet" OR "Morus bassanus" OR "Sula bassana") = 137 results. Better than #9 as appears to include more studies related to prey abundance/availability.

2. Google Scholar (GS)

Option 1: seabird fishery prey availability abundance = 25,300 results. First results relevant though very large number of results.

Option 2-4: As for Option 1 with addition of the prey species (i.e. a separate search for each prey species):

• seabird "Sprattus sprattus" fishery prey availability abundance = 1,490 results
• seabird "Clupea harengus" fishery prey availability abundance = 4,880 results
• seabird "Scomber scombrus" fishery prey availability abundance = 1,930 results

Information on the time and date that search strings were used, as well as the number of records retained for screening can be found in Annex 2.

3.2 Study selection

On 11 April 2023 we conducted a literature search on WoS and three literature searches in GS (Figure 10; Figure 9 within main document). With this review having three target prey fish species, for the GS searches we used a separate search for each prey species, otherwise there were insufficient relevant results for each prey species. In total, 8,630 references were identified; 340 in WoS, of which 110 were exported for screening. Then for the GS searches, there were 1490 results for the Sprat specific search, of which the first 50 records were exported. For Herring, 4870 results, with the first 74 results exported for screening. Then finally for Mackerel, 1930 results, of which the first 52 results were exported for screening. Together all searches yielded a total of 286 records, of which 81 were duplicates (i.e. included at least twice) and were automatically removed prior to screening. All 205 unique records were screened at title and abstract level to identify and exclude studies outside the review's scope. Excluded studies included those where the seabird and prey target species were not researched, the geographic region was not North Atlantic/Europe, where fisheries were only considered in terms of bycatch or discards (rather than in terms of prey depletion) and those where the abstract could not be assessed (see Table A 2 within the main document). Studies where it was unclear whether they met the inclusion criterion were retained for full-text screening. At this stage, we excluded 75% (153) of the records.

The remaining 52 records were screened in their entirety and relevant information was recorded. We, additionally, recorded information on the prey fish species included, what type of fisheries management was used, and the seabird season that studies occurred in. At this stage, we were looking for studies that measured, directly or indirectly, empirically, or theoretically, the effect that changes in the management of fisheries that target seabird prey fish species could have on seabird population (see Table A 2 within the main document). Our ideal studies would have been those where any seabird demographic parameter was researched and compared under different fishery management regimes, but due to the nature of this topic, few studies addressed this directly. Therefore, we included studies that provided any type of measure (empirically or theoretically) of the impact to seabirds of fisheries targeting fish species that were also seabird prey fish. We excluded studies that mentioned fisheries but only in a more speculative or contextual way (e.g. a brief mention in the introduction or discussion sections), those that did not include the relevant region (North Atlantic/Europe), and those where the full texts were not available. We retained 8 records for final assessment.

Additionally, we identified 7 key articles and reports that included consideration of fishery impacts on seabirds in terms of prey depletion (Furness et al., 2013a; Heath et al., 2017; Furness, 2021; Pearce-Higgins et al., 2021; Cunningham et al., 2022; McGregor et al., 2022; Montevecchi, 2023). Cited literature within these were checked to identify relevant literature that may have been overlooked during the systematic literature search. We identified, read the full text, and extracted relevant information from five references. From this process, we retained four records for final assessment. Overall, 12 references were included for the final review.

Information on the complete reference list obtained during the literature search, and the level at which each reference was eliminated can be found in Annex 3.

4. Methods of the systematic literature review on ‘End of the Gannet harvest at Sula Sgeir’

4.1 Research questions, keywords, and search strings

The corresponding research question to this conservation action is: ‘Would the Gannet population at Sula Sgeir and/or in the wider SPA network benefit from ending the harvest of Gannet chicks at Sula Sgeir?’

We identified the following keywords: ‘harvest’, its synonyms and related activities (‘cessation’, ‘termination’, ‘poach’, ‘hunt’), the objects subject to harvest (‘chicks’, ‘eggs’, ‘young’, ‘adults’) and the species, genus, previous genus, closely related species, and the English and Scottish Gaelic name of ‘Gannet (‘Morus’, ‘bassanus’, ‘Sula’, ‘booby’, ‘guga’, ‘seabird’), ‘conservation’, ‘population’, ‘Sula Sgeir’, and ‘Scotland’.

We identified the most relevant keywords and conducted a pilot screening by using multiple search strings in Web of Science (WoS) and Google Scholar (GS). The search strings and corresponding number of records for each search engine are listed below. The bolded options denote the search strings used for the systematic literature review. All have a brief explanation as to why they were or were not used.

1. Web of Science (WoS)

Option 1: (TS=(‘chick harvest*’ OR ‘egg harvest*’ OR ‘guga harvest*’ OR ‘harvest*’ OR ‘poach’)) AND TS=(Gannet OR Morus OR Sula OR booby OR guga) = 359 results. Too broad.

Option 2: (TS=(chick* OR egg*) AND TS=(Gannet OR Morus OR Sula OR booby OR guga) AND TS=(harvest* OR poach*)) = 21 results. Restricted.

Options 3 and 4: (TS=(‘harvest*’ OR ‘poach’)) AND TS=(Gannet OR Morus OR Sula OR booby OR guga) AND TS=(Sula Sgeir) = 4 results and (TS=(‘harvest*’ OR ‘poach’)) AND TS=(Gannet OR Morus OR Sula OR booby OR guga) AND TS=(Scotland) = 6 results. Both extremely restricted.

Option 5: ((TS=(chick* or egg*)) AND TS=(Gannet OR Morus OR Sula OR boob* OR guga OR seabird)) AND TS=(harvest* OR poach* OR hunt*) = 157 results. Many results were not pertinent, as they mostly investigated prey-related activities (e.g. food web processes, influence of diet on reproductive success).

Option 6: (TS=(Gannet OR Morus OR Sula OR boob* OR guga OR seabird)) AND TS=(harvest* OR poach* OR hunt*) AND TS=(chick* OR egg* OR young*) AND TS=(conservation OR population) = 135 results. This search excluded all prey-related studies, expanded the search to consider all seabirds, and narrowed the searches to studies considering the conservation and population effect of harvests.

2. Google Scholar (GS)

Option 1: egg and chick harvest of Gannets = 1900 results. Too broad.

Option 2: pause of seabird egg and chick harvest = 9510 results. Too broad.

Option 3: effect of ending seabird harvests = 18,200 results. Too broad.

Option 4: harvest of Gannet egg and chick in Sula Sgeir = 72 results. Too narrow.

Option 5: harvest and hunt of Gannet Sula egg and chick = 490 results. Did not provide many relevant studies.

Option 6: effect of ending seabird harvest = 19,300 results. Broad search to obtain a comprehensive understanding of the most relevant studies regarding the effect of ending seabird harvests around the world.

Option 7: harvest of Gannets in ‘Sula Sgeir’ = 115 results. Additional search term to retrieve all relevant information relating to Gannets in Sula Sgeir.

Information on the time and date that search strings were used, as well as the number of records retained for screening can be found in Annex 2.

4.2 Study selection

On 4 April 2023 we conducted a literature search on WoS and two literature searches in GS (Figure 13; Figure 12 within main document). Due to the nature of the conservation action, we aimed to understand the effect of ending harvests on seabird populations, and to identify all available information regarding Gannets on Sula Sgeir, the colony specifically referred to in this action. Because we could not produce a single search string in GS that could provide all this information, we undertook two different searches. In total, 19,550 references were identified; 135 in WoS, of which all were exported for screening, 19,300 in the broader GS search, of which the first 50, most relevant, records were exported, and 115 in the limited GS search, of which the first 50 records were exported. We selected the first 50 records from both GS searches because studies from the 6^th page onwards (i.e. results 50+) did not seem relevant. All searches yielded a total of 235 records, of which 16 were duplicates (i.e. included at least twice) and were automatically removed prior to screening. All 219 unique records were screened at title and abstract level to identify and exclude studies outside the review’s scope, such as those records where the harvest was unrelated to seabird chicks or eggs (e.g. harvest of adults, shorebirds or marine mammals, prey-related studies, guano harvest, seabird harvest by fisheries), where chick or egg harvest was mentioned as a potential threat, but was not tested, where harvest at Sula Sgeir was briefly mentioned, and those from which the abstract could not be assessed. Studies where this criterion was unclear, were kept for full-text screening. At this stage, we excluded 71% (156) of the records.

All remaining 63 records were screened in their entirety and relevant information was recorded. We, additionally, recorded information on whether eggs or chicks were being harvested, as well as the proportion of the population that was harvested at each study site. At this stage, we were looking for studies that measured, directly or indirectly, empirically, or theoretically, the effect that egg and/or chick harvest had on seabird populations (see Table A 2 within the main document). Our ideal studies would have been those where any seabird demographic parameter was researched and compared before the period when harvest started, during the harvest, and once the harvest was stopped completely, but due to the nature of this activity, these studies were difficult to come by. Therefore, we included studies that provided any type of measure (empirically or theoretically) of the impact of the harvest on seabirds, including studies that modelled or simulated population trends under different levels of harvest intensities and those that provided a threshold for a sustainable harvest. We excluded studies that briefly mentioned harvest as a potential threat, but was not measured or tested in any way, those that did not provide new evidence on the matter, and those where the full texts were not available. We retained 11 records for final assessment.

Additionally, we identified six key articles and reports that explored the effect of harvest or end of harvest on seabirds or that could provide references related to the Gannet harvest at Sula Sgeir: Furness et al. (2013a), Trinder (2016), Lewis et al. (2017), Furness (2021), Pearce-Higgins et al. (2021), and Naves and Rothe (2023), and searched references within to identify relevant literature that may have been overlooked during the systematic literature search. We identified, read the full text, and extracted relevant information from six references. From this process, we retained two records for final assessment. Overall, 13 references were included for the final review.

Information on the complete reference list obtained during the literature search, and the level at which each reference was eliminated can be found in Annex 3.

5. Methods of the systematic literature review on ‘Mammalian predator eradication and/or management’

5.1 Research questions, keywords, and search strings

This conservation action was associated with two research questions. The first, ‘What is the potential for seabirds to have increased productivity or survival from mammalian predator eradication/control?’ explores the effect of eradication and/or control of mammalian predators on seabird populations. Then the second question, ‘Among mammalian predators, which ones offer the most potential for effective eradication and/or control?’, aims to identify the mammalian species with higher probabilities of eradication and/or management success.

We identified the following keywords: ‘Eradication’ and synonyms (‘extermination’, ‘annihilation’, ‘elimination’, ‘management’, ‘control’, ‘lethal control’, ‘removal’), ‘predator’ and related terms (‘invasive species’, ‘non-native species’, ‘alien’, ‘exotic’), the English, scientific, and species group names of the focal species (‘Gull’, ‘Larus’, ‘Great Black-backed Gull’, ‘Larus marinus’, ‘Herring Gull’, ‘Larus argentatus’, ‘Lesser Black-backed Gull’, ‘Larus fuscus’, ‘Guillemot’, ‘Common Murre’, ‘Uria aalge’, ‘Razorbill’, ‘Alca torda’, ‘Atlantic Puffin’, ‘Puffin’, ‘Fratercula arctica’, ‘Auk’, ‘Alcid’, ‘seabird’), the most common mammalian predators in the UK ^[1] (‘mammal’, ‘Black rat’, ‘Rattus rattus’, ‘Brown rat’, ‘Rattus norvegicus’, ‘Polynesian rat’, ‘Rattus exulans’, ‘rodent’, ‘House Mice’, ‘Mus musculus’, ‘fox’, ‘Vulpes vulpes’, ‘American Mink’, ‘Neogale vison’, ‘cat’, ‘Felis catus’, ‘stoat’, ‘Mustela erminea’, ‘mustelids’), and a Scottish-related geographic scope (‘UK’, ‘British Isles’, ‘Scotland’, ‘Scottish islands’). Hedgehogs were also identified as potential mammalian predators of seabirds in the UK, however, we excluded them as focal predators because their eradication would mostly benefit ground-nesting waders rather than seabird species (Thompson and Ferguson, 2019).

We identified the most relevant keywords and conducted a pilot screening by using multiple search strings in Web of Science (WoS) and Google Scholar (GS). The search strings and corresponding number of records for each search engine are listed below. The bolded options denote the search strings used for the systematic literature review. All have a brief explanation as to why they were or were not used.

1. Web of Science (WoS)

Option 1: ((TS=(“mammal*” OR “Black rat*” OR “Rattus rattus” OR “Brown rat*” OR “Rattus norvegicus” OR “Polynesian rat*” OR “Rattus exulans” OR “Rodent*” OR “House Mice” OR “House Mouse” OR “Mus musculus” OR “Fox*” OR “Vulpes vulpes” OR “American Mink*” OR “Neogale vison” OR “Cat*” OR “Felis catus” OR “Stoat*” OR “Mustela erminea” OR “Mustelid*” OR “mammal* predator*” OR “invasive non-native mammal*” OR “mammal* alien species”)) AND TS=(“eradicate” OR “control” OR “management” OR “removal”)) AND TS=(“Seabird*” OR “Gull*” OR “Larus” OR “Great Black-backed Gull*” OR “Larus marinus” OR “Herring Gull*” OR “Larus argentatus” OR “Lesser Black-backed Gull*” OR “Larus fuscus” OR “Guillemot*” OR “Common Murre*” OR “Uria aalge” OR “Razorbill*” OR “Alca torda” OR “Atlantic Puffin*” OR “Puffin*” OR “Fratercula arctica” OR “Auk*” OR “alcid*”) = 6,394 results. List of all identified mammalian predators, synonyms for eradication, and all focus species. Too broad.

Option 2: ((TS=(“mammal*” OR “Black rat*” OR “Rattus rattus” OR “Brown rat*” OR “Rattus norvegicus” OR “Polynesian rat*” OR “Rattus exulans” OR “Rodent*” OR “House Mice” OR “House Mouse” OR “Mus musculus” OR “Fox*” OR “Vulpes vulpes” OR “American Mink*” OR “Neogale vison” OR “Cat*” OR “Felis catus” OR “Stoat*” OR “Mustela erminea” OR “Mustelid*” OR “mammal* predator*” OR “invasive non-native mammal*” OR “mammal* alien species”)) AND TS=(“eradication” OR “control” OR “management” OR “removal”)) AND TS=(“Gull*” OR “Larus” OR “Great Black-backed Gull*” OR “Larus marinus” OR “Herring Gull*” OR “Larus argentatus” OR “Lesser Black-backed Gull*” OR “Larus fuscus” OR “Guillemot*” OR “Common Murre*” OR “Uria aalge” OR “Razorbill*” OR “Alca torda” OR “Atlantic Puffin*” OR “Puffin*” OR “Fratercula arctica” OR “Auk*” OR “alcid*”) = 4,462 results. Like Option 1 but without ‘seabird*’. Still too broad.

Option 3: ((TS=(“mammal*” OR “Black rat*” OR “Rattus rattus” OR “Brown rat*” OR “Rattus norvegicus” OR “Polynesian rat*” OR “Rattus exulans” OR “Rodent*” OR “House Mice” OR “House Mouse” OR “Mus musculus” OR “Fox*” OR “Vulpes vulpes” OR “American Mink*” OR “Neogale vison” OR “Cat*” OR “Felis catus” OR “Stoat*” OR “Mustela erminea” OR “Mustelid*” OR “mammal* predator*” OR “invasive non-native mammal*” OR “mammal* alien species”)) AND TS=(“eradication” OR “control” OR “management” OR “removal”)) AND TS=(“Seabird*” OR “Gull*” OR “Larus” OR “Great Black-backed Gull*” OR “Larus marinus” OR “Herring Gull*” OR “Larus argentatus” OR “Lesser Black-backed Gull*” OR “Larus fuscus” OR “Guillemot*” OR “Common Murre*” OR “Uria aalge” OR “Razorbill*” OR “Alca torda” OR “Atlantic Puffin*” OR “Puffin*” OR “Fratercula arctica” OR “Auk*” OR “alcid*”) AND TS=("UK" OR “Brit*” OR “Ireland” OR “Scotland” OR “Scott*”) = 506 results. Like Option 1 but added a string regarding geographic scope.

Option 4: (((TS=(“mammal*” OR “Rat*” OR “Rattus” OR “Rodent*” OR “Mice” OR “Mouse” OR “Mus” OR “Fox*” OR “Vulpes” OR “Mink*” OR “Neogale” OR “Cat*” OR “Felis” OR “Stoat*” OR “Mustela” OR “Mustelid*” OR “mammal* predator*” OR “invasive non-native mammal*” OR “mammal* alien species”)) AND TS=(“eradication” OR “control” OR “management” OR “removal”)) AND TS=(“Seabird*” OR “Gull*” OR “Larus” OR “Great Black-backed Gull*” OR “Larus marinus” OR “Herring Gull*” OR “Larus argentatus” OR “Lesser Black-backed Gull*” OR “Larus fuscus” OR “Guillemot*” OR “Common Murre*” OR “Uria aalge” OR “Razorbill*” OR “Alca torda” OR “Atlantic Puffin*” OR “Puffin*” OR “Fratercula arctica” OR “Auk*” OR “alcid*”)) AND TS=("UK" OR “Brit*” OR “Ireland” OR “Scotland” OR “Scott*”) = 737 results. Like Option 3 but changed mammalian predators to broader terms. Results did not seem to be relevant. Most references focussed on research on avian (gull) as predators, seabird population status, or effects of mammal predation on seabirds.

Option 5: ((TS=(“mammal*” OR “Black rat*” OR “Rattus” OR “Brown rat*” OR “Polynesian rat*” OR “Rodent*” OR “House Mice” OR “House Mouse” OR “Mus” OR “Fox*” OR “Vulpes” OR “Mink*” OR “Neogale” OR “Cat*” OR “Felis” OR “Stoat*” OR “Mustela” OR “Mustelid*” OR “mammal* predator*” OR “invasive non-native mammal*” OR “mammal* alien species”)) AND TS=(“eradication” OR “control” OR “management” OR “removal”)) AND TS=(“Seabird*” OR “Gull*” OR “Larus” OR “Great Black-backed Gull*” OR “Larus marinus” OR “Herring Gull*” OR “Larus argentatus” OR “Lesser Black-backed Gull*” OR “Larus fuscus” OR “Guillemot*” OR “Common Murre*” OR “Uria aalge” OR “Razorbill*” OR “Alca torda” OR “Atlantic Puffin*” OR “Puffin*” OR “Fratercula arctica” OR “Auk*” OR “alcid*”) AND TS=("UK" OR “Brit*” OR “Ireland” OR “Scotland” OR “Scott*”) = 511 results. Like Option 4 but removing the species of mammalian predators. This search excluded all avian predator studies, expanded the search to consider all seabirds, and narrowed the searches to provide studies undertaken within the British Isles and Ireland.

Option 6: ((TS=(“mammal*” OR “Black rat*” OR “Rattus” OR “Brown rat*” OR “Polynesian rat*” OR “Rodent*” OR “House Mice” OR “House Mouse” OR “Mus” OR “Fox*” OR “Vulpes” OR “Mink*” OR “Neogale” OR “Cat*” OR “Felis” OR “Stoat*” OR “Mustela” OR “Mustelid*” OR “mammal* predator*” OR “invasive non-native mammal*” OR “mammal* alien species”)) AND TS=(“eradication” OR “control” OR “management” OR “removal”)) AND TS=(“Seabird*” OR “Gull*” OR “Larus” OR “Great Black-backed Gull*” OR “Larus marinus” OR “Herring Gull*” OR “Larus argentatus” OR “Lesser Black-backed Gull*” OR “Larus fuscus” OR “Guillemot*” OR “Common Murre*” OR “Uria aalge” OR “Razorbill*” OR “Alca torda” OR “Atlantic Puffin*” OR “Puffin*” OR “Fratercula arctica” OR “Auk*” OR “alcid*”) = 6,416 results. Like Option 5 but without the geographic scope aspect. This search expanded the search to consider mammalian eradication and/or management on all seabirds around the world.

2. Google Scholar (GS)

Option 1: Mammal predator eradication for seabirds = 20,000 results.

Option 2: Mammal predator eradication for seabird in UK or Britain = 18,800 results.

Option 3: Rat, Mouse, Fox, Mink, Cat eradication to protect Gulls, Razorbills, Guillemots, and Puffins = 97 results.

Option 5: Mammal predator eradication to protect UK seabird colonies = 17,200 results.

Option 6: Mammal predator eradication, control, or management to protect UK, British, Scottish seabird colonies = 1,300 results. Broad search to obtain a comprehensive understanding of the most relevant studies regarding the effect of mammalian predator eradication and management on UK seabird colonies.

Information on the time and date that search strings were used, as well as the number of records retained for screening can be found in Annex 2.

5.2 Study selection

On 26 April 2023 we conducted two literature searches on WoS and a literature search in GS (Figure 16; Figure 15 within main document). This conservation action is well studied around the world and within the UK. Therefore, we aimed to retrieve the most relevant studies on the effect of mammalian predator eradication and/or control efforts on seabird colonies within the British Isles and Ireland (results from first search in WoS), as well as at a global scale (results from second search in WoS).

In total, 8,227 references were identified; 511 in the first WoS search, of which the first 50, most relevant, records were exported, 6,416 in the second WoS search, of which the first 50, most relevant, records were exported, and 1,300 in the GS search, of which the first 80 records were exported. We selected the first 50 – 80 records after identifying a string of five consecutive less-relevant studies. The searches yielded a total of 180 records, of which 18 were duplicates (i.e. included by both WoS and GS) and were automatically removed prior to screening. All 162 unique records were screened at a title and abstract level to identify and exclude studies outside the review’s scope, such as those records where the effect of the eradication and/or control of mammalian predators on seabirds was not tested, studies that only mentioned the effect of invasive species on seabirds (and not of the eradication/control), those that researched avian predators, and those from which the abstract could not be accessed (see Table A 2 within the main document). Studies where this criterion was unclear were kept for full text screening. At this stage, we excluded 79% (128) of the records.

The remaining 34 records were screened in their entirety (i.e. full text) and relevant information was recorded. We additionally recorded information on the mammalian predators, the year of eradication, whether study sites were islands or on mainland, if the prior, then the distance to the mainland, the eradication/control method, whether the eradication/control efforts were successful, the effect seen on each seabird species population, a list of species that benefitted or that were negatively affected from the eradication/control, any observation regarding other wildlife changes, and comments that authors mentioned relating to biosecurity measures. At this stage, our aim was to identify studies that assessed the impact of mammalian predator eradication and/or control projects on seabird populations. We excluded studies that described the eradication/management procedure but that did not test its effect on seabirds, those that did not provide new evidence on the matter, and those where the full texts were not available. We retained 18 records for final assessment.

Additionally, we identified four key articles and reports that were highly relevant to this topic, Furness et al. (2013a), Veitch et al. (2019), Furness (2021), and Holmes et al. (2023), and searched references within to identify relevant literature that may have been overlooked during the systematic literature search. We identified, read the full text, and extracted relevant information from nine references. From this process, we retained five records for final assessment. Overall, 23 references were included for the final review. While searching for additional references, we came across two studies, Jones et al. (2016) and Brooke et al. (2018), which explored the impact of successful eradication projects on seabirds and animals worldwide. Despite the high relevance of these studies to the review, we decided to exclude them from our ecological efficacy scoring. This choice was based on their broad nature and the challenges associated with extracting the specific information required for our analysis. Nonetheless, in the results section, we provide a brief mention of the overall findings from Brooke et al. (2018) due to its greater relevance to our study, specifically in relation to seabirds.

Information on the complete reference list obtained during the literature search, and the level at which each reference was eliminated can be found in Annex 3.

6. Methods of the systematic literature review on ‘Avian predator management’

6.1 Research questions, keywords, and search strings

The conservation action, the management of avian predators, involves a set of different management actions and was, therefore, associated with three research questions. The first research question, ‘What is the potential for seabirds to experience increased productivity or survival through avian predator management?’, investigates the impact of avian predator management actions on seabird populations. The second question, ‘Which management action is more effective?’ aims to identify the management action that has the strongest beneficial effect on seabird populations. The third question, ‘For which avian predator is there the most potential for effective management?’, aims to identify the avian species with higher probabilities of management success.

We identified the following keywords: ‘Management’ and related terms (‘eradication’, ‘avian predator management’, ‘removal’, ‘avian population control’, ‘control’, ‘deter’, ‘removal’, ‘exclude’, ‘top-down control’), ‘avian predator’ and related terms (‘birds of prey’, ‘raptors’, ‘corvids’, ‘apex predators’, ‘eagles’, ‘falcons’, ‘skuas’, ‘gulls’), the English, scientific, and species group names of the focal species (‘Gull’, ‘Larus’, ‘Great Black-backed Gull’, ‘Larus marinus’, ‘Herring Gull’, ‘Larus argentatus’, ‘Lesser Black-backed Gull’, ‘Larus fuscus’, ‘Guillemot’, ‘Common Murre’, ‘Uria aalge’, ‘Razorbill’, ‘Alca torda’, ‘Atlantic Puffin’, ‘Puffin’, ‘Fratercula arctica’, ‘Auk’, ‘Alcid’, ‘seabird’), the most common avian predators that are likely to affect UK seabird colonies (‘Carrion Crow’, ‘Corvus corone’, Raven, ‘Corvus corax’, ‘Hooded Crow’, ‘Corvus cornix’, ‘White-tailed eagle’, ‘Haliaeetus albicilla’, ‘Golden eagle, ‘Aquila chrysaetos, ‘Peregrine falcon’, ‘Falco peregrinus’, ‘Gulls’, ‘Great skua’, ‘Stercorarius skua’), and a Scottish-related geographic scope (‘UK’, ‘British Isles’, ‘Scotland’, ‘Scottish islands’, ‘NE Atlantic’).

We identified the most relevant keywords and conducted a pilot screening in both search engines, Web of Science (WoS) and Google Scholar (GS). We first generated a set of search string which compiled all keywords associated with ‘management’, avian predators and a list of the focal seabird species (example: ((TS=("avian predator" OR "bird* of prey" OR raptor* OR corvid* OR eagle* OR falcon* OR gull* OR skua*)) AND TS=(management OR removal OR control* OR deter* OR remov* OR exclud* OR "avian management")) AND TS=(seabird* OR Gull* OR Auk* OR alcid*)). Although these searches produced significant number of results, most studies were not deemed relevant, as they mostly focussed on deterring avian predators from non-seabird colonies, or focussed on gull ecology or on contaminants and toxicity in birds of prey, and other unrelated topics. Therefore, we decided to generate more specific search strings. To do so, we searched for examples of avian predator management actions that could be undertaken at seabird colonies within the UK. During this time, we realised that evidence on the topic was going to be limited. However, we identified three management actions: (1) diversionary feeding (Smart and Amar, 2018), (2) deterrence of avian predators with bioacoustics or physical objects (Boothby et al., 2019; Sutherland et al., 2021), and (3) targeted nest and/or individual removal or translocation (Donehower et al., 2007). We proceeded to generate search strings for each management action for both search engines. A selection of the search strings (including all those retained for the final review) and corresponding number of records for each management action and search engine are listed below. The bolded options denote the search strings used for the systematic literature review. All have a brief explanation as to why they were or were not used.

1. Web of Science (WoS) – diversionary feeding

Option 1: TS=(“Diversionary feeding” OR “Supplementary feeding” OR “artificial feeding”) AND TS=("avian predator" OR "bird* of prey" OR raptor* OR corvid* OR eagle* OR falcon* OR skua* OR Crow OR “Carrion Crow” OR “Corvus corone” OR Raven OR “Corvus corax” OR “Hooded Crow” OR “Corvus cornix” OR “White-tailed eagle” OR “Haliaeetus albicilla” OR “Golden eagle” OR “Aquila chrysaetos” OR “Peregrine falcon” OR “Falco peregrinus” OR “Great skua” OR “Stercorarius skua” OR “Larus”) AND TS=(“Seabird*” OR “Gull*” OR “Larus” OR “Great Black-backed Gull*” OR “Larus marinus” OR “Herring Gull*” OR “Larus argentatus” OR “Lesser Black-backed Gull*” OR “Larus fuscus” OR “Guillemot*” OR “Common Murre*” OR “Uria aalge” OR “Razorbill*” OR “Alca torda” OR “Atlantic Puffin*” OR “Puffin*” OR “Fratercula arctica” OR “Auk*” OR “alcid*”) = 22 results. Diversionary feeding and list of identified avian predators and focal species. Studies not relevant. They mostly focus on diversionary feeding and the effect it has on survival of the species. No mention of seabird colonies.

Option 2: TS=(“Diversionary feeding” OR “Supplementary feeding” OR “artificial feeding”) AND TS=("avian predator" OR "bird* of prey" OR raptor* OR corvid* OR eagle* OR falcon* OR skua* OR Crow*) = 352 results. Eliminated focal seabird species. Although many records appeared, studies were focussed on diversionary and supplementary feeding at non-seabird colonies, and therefore were not in the scope of this review.

Option 3: TS=(“Diversionary feeding” OR “Supplementary feeding” OR “artificial feeding”) AND TS=("avian predator" OR "bird* of prey" OR raptor* OR corvid* OR eagle* OR falcon* OR skua* OR crow*) AND TS=(“Seabird*” OR “Seabird colon*” OR “Gull*” OR “Auk*” OR “alcid*”) = 11 results. Retained diversionary feeding, groups of avian predators, and seabirds. Although results are limited, they are more relevant to the topic than results from other searches. Note that gulls were removed from the avian predator list because, when kept, most studies focussed on their ecology or movement on non-seabird colonies.

2. Google Scholar (GS) – diversionary feeding

Option 1: Diversionary feeding of avian predators = 1,450 results. Many results about diversionary feeding of mammals rather than avian predators, not many relevant to our aims.

Option 2: Diversionary or supplementary feeding of avian predators at seabird colonies = 78 results. Broad search to obtain all evidence related to diversionary feeding at seabird colonies.

3. WoS – deterrence of avian predators

Option 1: TS=(“Deterrence” OR deterr* OR “bioacoustic deter*” OR scarecrow* OR cane* OR laser* OR scare* OR exclud*) AND TS=("avian predator" OR "bird* of prey" OR raptor* OR corvid* OR eagle* OR falcon* OR skua* OR Crow OR “Carrion Crow” OR “Corvus corone” OR Raven OR “Corvus corax” OR “Hooded Crow” OR “Corvus cornix” OR “White-tailed eagle” OR “Haliaeetus albicilla” OR “Golden eagle” OR “Aquila chrysaetos” OR “Peregrine falcon” OR “Falco peregrinus” OR “Great skua” OR “Stercorarius skua”) AND TS=(“Seabird*” OR “Gull*” OR “Larus” OR “Great Black-backed Gull*” OR “Larus marinus” OR “Herring Gull*” OR “Larus argentatus” OR “Lesser Black-backed Gull*” OR “Larus fuscus” OR “Guillemot*” OR “Common Murre*” OR “Uria aalge” OR “Razorbill*” OR “Alca torda” OR “Atlantic Puffin*” OR “Puffin*” OR “Fratercula arctica” OR “Auk*” OR “alcid*”) = 132 results. Many examples of deterring gulls but most not from seabird colonies (so out of the scope of this review). Few examples of this on seabird colonies.

Option 2: TS=(“Deterrence” OR deterr* OR “bioacoustic deter*” OR scarecrow* OR cane* OR laser* OR scare* OR exclud*) AND TS=("avian predator" OR "bird* of prey" OR raptor* OR corvid* OR eagle* OR falcon* OR skua* OR Crow OR “Carrion Crow” OR “Corvus corone” OR Raven OR “Corvus corax” OR “Hooded Crow” OR “Corvus cornix” OR “White-tailed eagle” OR “Haliaeetus albicilla” OR “Golden eagle” OR “Aquila chrysaetos” OR “Peregrine falcon” OR “Falco peregrinus” OR “Great skua” OR “Stercorarius skua”) AND TS=(“Seabird*” OR “seabird colon*” OR “Auk*” OR “alcid*” OR “gull*”) = 122 results. Most relevant, but still few studies that tackled the topic.

Option 3: TS=(avian predator deterrence) = 55 results. Studies mainly focussed on deterring mammals.

4. GS – deterrence of avian predators

Option 1: Deterrence of avian predators at seabird colonies = 6,800 results. Most results focus on mammalian predators. A few studies mention the impact of avian predation on seabirds.

Option 2: Impact of deterring "avian predators" at seabird colonies = 1,060. By using quotes, we eliminate studies focussed on mammalian predators. Overall, more studies on the evidence of avian predation and not the action of deterring of them.

Option 3: Impact of deterring "avian predators" at European seabird colonies = 672. Added a geographic scope within Europe. More relevant studies.

5. WoS – targeted removal and translocation

Option 1. TS=(translocat* OR remov* OR nest removal OR targeted removal OR culling OR management) AND TS=("avian predator" OR "bird* of prey" OR raptor* OR corvid* OR eagle* OR falcon* OR skua* OR Crow OR “Carrion Crow” OR “Corvus corone” OR Raven OR “Corvus corax” OR “Hooded Crow” OR “Corvus cornix” OR “White-tailed eagle” OR “Haliaeetus albicilla” OR “Golden eagle” OR “Aquila chrysaetos” OR “Peregrine falcon” OR “Falco peregrinus” OR “Great skua” OR “Stercorarius skua”) AND TS=(“Seabird*” OR “Gull*” OR “Larus” OR “Great Black-backed Gull*” OR “Larus marinus” OR “Herring Gull*” OR “Larus argentatus” OR “Lesser Black-backed Gull*” OR “Larus fuscus” OR “Guillemot*” OR “Common Murre*” OR “Uria aalge” OR “Razorbill*” OR “Alca torda” OR “Atlantic Puffin*” OR “Puffin*” OR “Fratercula arctica” OR “Auk*” OR “alcid*”) = 1154 results. Results are mainly on Gull ecology and behaviour and not on avian predator management. Many studies focussed on toxicity and contaminants in raptors.

Option 2. TS=(translocat* OR remov* OR nest removal OR targeted removal OR culling) AND TS=("avian predator" OR "bird* of prey" OR raptor* OR corvid* OR eagle* OR falcon* OR skua* OR Crow OR “Carrion Crow” OR “Corvus corone” OR Raven OR “Corvus corax” OR “Hooded Crow” OR “Corvus cornix” OR “White-tailed eagle” OR “Haliaeetus albicilla” OR “Golden eagle” OR “Aquila chrysaetos” OR “Peregrine falcon” OR “Falco peregrinus” OR “Great skua” OR “Stercorarius skua”) AND TS=(“Seabird*” OR “Gull*” OR “Larus” OR “Auk*” OR “alcid*”) = 178 results. Reduced list of focal seabird species. Most results are irrelevant. Many studies on toxicity in raptors.

Option 3. TS=(translocat* OR remov* OR nest removal OR targeted removal OR culling) AND TS=("avian predator" OR "bird* of prey" OR raptor* OR corvid* OR eagle* OR falcon* OR skua*) AND TS=(“Seabird*” OR “Gull*” OR “Larus” OR “Auk*” OR “alcid*”) = 160 results. More relevant results.

6. GS – targeted removal and translocation

Option 1: Management, removal and translocation of avian predators on seabird colonies = 2,840. Too broad. Studies focussed mainly on translocation and restoration projects.

Option 2: Management, removal, and translocation of "avian predators" on seabird colonies = 237 results. Did not improve much.

Option 3: Effectiveness of management and removal of "avian predators" on European seabird colonies = 960 results. Most relevant.

Information on the time and date that search strings were used, as well as the number of records retained for screening can be found in Annex 2.

6.2 Study selection

On 2 June 2023 we conducted three literature searches in WoS and three literature searches in GS (Figure 19; Figure 18 within main document), two for each identified management action (i.e. diversionary feeding, deterrence, and targeted removal and translocation).

In total, 2,003 references were identified. For each search, we selected the first 20 – 40 records after identifying a string of five consecutive less-relevant studies. In WoS, 11 records were obtained from the first search, of which all were exported, 122 from the second search, of which the first 20, most relevant, records were exported, and 160 from the third search, of which the first 40 records were exported. In GS, 78 records were obtained from the first search, of which the first 20, most relevant, records were exported, 672 from the second search, of which the first 40, most relevant, records were exported, and 960 from the third search, of which the first 40 records were exported. The searches yielded a total of 181 records, of which 25 were duplicates (i.e. identified in more than one search) and were automatically removed prior to screening. All 156 unique records were screened at a title and abstract level to identify and exclude studies outside the review's scope. Excluded studies were those records that: did not research the effect of the avian predator management action at seabird or waterbird colonies, only provided evidence of avian predation on seabirds but did not measure the effect, researched mammalian predators, focused on toxicity, pollutants or contaminants in birds of prey, studies where diversionary feeding was for the benefit of the species being fed (i.e. supplementary feeding) and not to avoid predation on seabird colonies, when avian predator was a small passerine, and when the abstract could not be accessed (see Table A 2 within the main document). Studies where the inclusion criteria was unclear were kept for full-text screening. We decided to retain studies where the management action was also tested on waterbirds within the Charadriiformes order (same order as gulls and auks), as results from these could be relevant and could be applied to seabird colonies (but note that we did not expand the search strings or undertook further, more directed searches to include them). At this stage, we excluded 84% (131) of the records.

The remaining 25 records were screened in their entirety (i.e. full text) and relevant information was recorded. Similar to the ‘eradication and/or control of mammalian predators’ review, we recorded additional information: avian predator species, year that management occurred, whether study sites were islands or on mainland, if the first, then the distance to the mainland, management action and a brief description of it, effect seen on each focal seabird species, a list of species that benefitted or that were negatively affected from the management, observations regarding other changes in wildlife, and comments that authors mentioned relating to biosecurity or recuring measures. At this stage, our aim was to identify studies that assessed the impact of avian predator management on seabird or waterbird colonies. We excluded studies that described the management procedure but that did not test its effect on seabirds or waterbirds, those that did not provide new evidence on the matter, broad reviews on the subject, and those where the full texts were not available. We retained 8 records for final assessment.

Additionally, we identified three key references that were highly relevant to this topic: Lavers et al. (2010), Laidlaw et al. (2021), and Sutherland et al. (2021), and searched references within to identify relevant literature that may have been overlooked during the systematic literature search. We identified, read the full-text, and extracted relevant information from seven references. From this process, we retained three records for final assessment. Overall, 11 references were included for the final review.

Information on the complete reference list obtained during the literature search, and the level at which each reference was eliminated can be found in Annex 3.

7. Methods of the systematic literature review on ‘Reduction of disturbance (at colony)’

7.1 Research questions, keywords, and search strings

This conservation action was associated with two research questions. The first research question, ‘What are the potential population level benefits from reducing on-land and coastal disturbance at seabird colonies?’, investigates the impact of disturbance management measures on seabirds when present at the colonies. The second question, ‘What types of disturbance management measures will provide the strongest benefit?’ aims to identify the measure/s that could have the strongest beneficial effect on seabirds. Note that this review focusses solely on disturbance occurring during the breeding season, and management actions will focus on reducing disturbance directly on land, or at sea, but close to shore, enough to disturb birds breeding on land.

We identified the following keywords: ‘Regulation and related terms (‘management action’, ‘reduction, ‘mitigation’, ‘management’), examples of regulations on land (‘paths’, ‘signage, ‘access restriction’, ‘education’, ‘warden’), examples of regulations at sea but near the colony (‘buffer area’, ‘speed limit’, ‘closure’), the different type of vessels that could cause disturbance (‘boat’, ‘kayak’, ‘canoe’, ‘water sports’, ‘jet ski’, ‘sailboat’, ‘kite surf’, ‘yacht’, ‘motorboat’, ‘recreational boat’, ‘tourist boat’, ‘wildlife watching boat’), activities on land which could cause disturbance (‘tourist’, ‘visitor’, ‘photographer’, ‘dog’, ‘farm’, ‘ecotourism’, ‘fishing on shore’), and the English, scientific, and species group names of the focal species (‘Gull’, ‘Larus’, ‘Great Black-backed Gull’, ‘Larus marinus’, ‘Herring Gull’, ‘Larus argentatus’, ‘Lesser Black-backed Gull’, ‘Larus fuscus’, ‘Guillemot’, ‘Common Murre’, ‘Uria aalge’, ‘Razorbill’, ‘Alca torda’, ‘Atlantic Puffin’, ‘Puffin’, ‘Fratercula arctica’, ‘Auk’, ‘Alcid’, ‘seabird’).

We identified the most relevant keywords and undertook a pilot screening with several search strings in Web of Science (WoS) and Google Scholar (GS). We decided to conduct separate searches, one focussed on land-based management measures and another one focussed on management measures at sea, but close to the colonies (disturbance away from land is considered in the ‘reduction of disturbance (at sea)’ review). The search strings and corresponding number of records for each search engine are listed below. The option highlighted in bold indicates the search string that was used for the systematic literature review.

7. Web of Science (WoS) – land-based measures

Option 1: ((TS=(colony OR nest* OR breeding site)) AND TS=(seabird*)) AND TS=(path OR signage OR access restrict*) = 125 results. The first few results were relevant, but subsequently results were not.

Option 2: ((TS=(colony OR nest* OR breeding site)) AND TS=(seabird*)) AND TS=(path OR signage OR access restrict* OR visitor OR tourist) = 215 results. Many references were broadly relevant, but most measured the impacts of disturbance rather than management interventions.

Option 3: ((TS=(colony OR nest* OR breeding site)) AND TS=(seabird* OR guillemot OR murre OR uria aalge OR razorbill OR alca torda OR puffin OR fratercula arctica OR larus OR gull*)) AND TS=(path OR signage OR access restrict* OR visitor OR tourist) = 330 results. Most relevant results.

8. Google Scholar (GS) – land-based disturbance

Option 1: Reducing or mitigating disturbance by visitors at seabird colonies = 8,040 results. Too broad.

Option 2: Reducing or mitigating disturbance by visitors at seabird colonies auks or gulls = 1,030 results.

9. WoS – sea-based management measures near colonies

Option 1: (((TS=(colony OR nest* OR breeding site)) AND TS=(seabird*)) AND TS=("speed restrict*" OR "exclusion" OR "closure")) AND TS=(boat* OR kayak* OR canoe* OR "water sport*" OR "jet ski*" OR "sailing" OR "sailboat" OR "tourist boat" OR "wildlife watching boat") = 2 results. Too specific.

Option 2: ((TS=(colony OR nest* OR breeding site)) AND TS=(seabird* OR guillemot OR murre OR uria aalge OR razorbill OR alca torda OR puffin OR fratercula arctica OR larus OR gull*)) AND TS=(boats OR kayaks OR canoes OR jetskis OR “sailing boats” OR surfing OR “recreational fishing” OR angling OR sailboat OR yacht OR motorboat OR tourist boat OR wildlife watching boat) = 224 results. Not many top results were relevant.

Option 3: (((TS=(colony OR nest* OR breeding site)) AND TS=(seabird*)) AND TS=(boats OR kayaks OR canoes OR jetskis OR “sailing boats” OR surfing OR “recreational fishing” OR angling OR sailboat OR yacht OR motorboat OR tourist boat OR wildlife watching boat)) AND TS=(mitigat* OR reduc* OR management) = 67 results. Results mostly not relevant.

Option 4: (((TS=(colony OR nest* OR breeding site OR inshore OR coast)) AND TS=(seabird* OR guillemot OR murre OR uria aalge OR razorbill OR alca torda OR puffin OR fratercula arctica OR larus OR gull*)) AND TS=(boats OR kayaks OR canoes OR jetskis OR “sailing boats” OR surfing OR “recreational fishing” OR angling OR sailboat OR yacht OR motorboat OR tourist boat OR wildlife watching boat)) AND TS=(mitigat* OR reduc* OR management) = 147 results.

10. GS – sea-based management measures near colonies

Option 1: Reducing or mitigating disturbance by boats or kayaks at seabird colonies = 806 results. Top results seem highly relevant.

Information on the time and date that search strings were used, as well as the number of records retained for screening can be found in Annex 2.

7.2 Study selection

On 17 June 2023 we performed two literature searches in WoS and two in GS (Figure 22; Figure 21 within main document); one search string was focused on land-based management measures, while the other focused on sea-based management measures.

In total, 2,313 references were identified. For each search, we selected the first 30 to 50 records after identifying a string of five consecutive less-relevant studies or to set a minimum number of served searches. In WoS, 330 records were obtained from the first search, of which the first 30, most relevant, records were exported and 147 from the second search, of which the first 30 records were exported. In GS, 1,030 records were obtained from the first search, of which the first 32, most relevant, records were exported, and 806 from the second search, of which the first 50 records were exported. The searches yielded a total of 142 records, of which 6 were duplicates (i.e. identified in more than one search) and were automatically removed prior to screening. All 136 unique records were screened at a title and abstract level to identify and exclude studies outside the review's scope, such as those records where the effect of the regulation was not tested on seabirds, studies that exclusively provide evidence of disturbance on seabirds but do not measure the effect, those that provided a general review on disturbance, and those from which the abstract could not be accessed (see Table A 2 within the main document). Studies where this criterion was unclear were kept for full-text screening. At this stage, we excluded 81% (110) of the records.

The remaining 26 records were screened in their entirety (i.e. full text) and relevant information was recorded. We additionally recorded information on the type of regulation that was tested and whether they were land-based, sea-based., or air-based (use of flying objects such as drones). We excluded studies that did not measure the effect of a disturbance, studies focused on waterbirds or non-relevant seabirds (e.g. Pelicans, Cormorants), studies which only highlight the impact of a disturbance without providing recommendations for management measures, studies focused on at-sea disturbance away from the colony, and studies where measures may not be transferable to Scotland (e.g. management of ecotourism at polar regions), and broad reviews on the subject. We retained 6 records for final assessment.

Additionally, we identified four key references that were presumed highly relevant to this topic: Batey (2013), Méndez-Roldán (2013), Dias et al. (2019) and Sutherland et al. (2021), and searched references within to identify relevant literature that may have been overlooked during the systematic literature search. We additionally searched for studies that were identified during the ‘reduction of disturbance (at sea)’ literature search. We identified, read the full-text, and extracted relevant information from six references. From this process, we retained four records for final assessment. Overall, ten references were included for the final review.

Information on the complete reference list obtained during the literature search, and the level at which each reference was eliminated can be found in Annex 3.

8. Methods of the systematic literature review on ‘Reduction of disturbance (at sea)’

8.1 Research questions, keywords, and search strings

The conservation action, the reduction of disturbance at sea, is similar to the previous conservation action, ‘reduction of disturbance (at colony)’. This review, however, will focus on the period when individuals are at sea, away from the colony during both the breeding and non-breeding period. It mainly focusses on marine vessels and on what management actions can be undertaken to decrease their impact on seabirds at sea. Therefore, the review was associated with two research questions. The first research question, ‘What are the potential population level benefits from at-sea vessel management?’, investigates the impact of disturbance management actions on seabirds whilst at sea. The second question, ‘Which management action on what type of vessel provides the strongest benefit?’ aims to identify the management action, as well as the type of vessel, that has the strongest beneficial effect on seabirds.

We identified the following keywords: ‘Disturbance’ and related terms (‘disruption’, ’marine traffic’, ‘speed’), ‘management’, ‘management action’ and related terms and examples (‘spatial management, ‘closure’, ‘reduction’, ‘mitigation’, ‘speed limit, ‘shipping lane’, ‘closure’, ‘seasonal closure’), the different type of vessels that could be found in Scotland and synonyms (‘fishing vessel’, ‘boat’, ‘cargo ship’, ‘ship’, ‘vessel’, ‘container’, ‘tanker’, ‘tugboat’, ‘sailboat’, ‘passenger ship’, ‘yacht’, ‘commercial vessel’, ‘motorboat’, ‘recreational boat’), and the English, scientific, and species group names of the focal species (‘Guillemot’, ‘Common Murre’, ‘Uria aalge’, ‘Razorbill’, ‘Alca torda’, ‘Atlantic Puffin’, ‘Puffin’, ‘Fratercula arctica’, ‘Auk’, ‘Alcid’, ‘seabird’).

We identified the most relevant keywords and conducted a pilot screening in both search engines, Web of Science (WoS) and Google Scholar (GS). During a preliminary search, during the refinement of the search strings, it was clear that there was going to be limited evidence on the topic, as most studies focused on the impact of at-sea disturbance on seabirds, rather than the effect of a management action. This observation is consistent with the findings of Sutherland et al. (2021), which also observed a lack of evidence regarding a list of management actions relating to at-sea disturbance on birds. Therefore, we decided to generate broad and specific search strings. To do so, we searched for examples of at-sea disturbance management actions that could be benefit seabirds in Scotland and identified two actions: reducing vessel speed limits and shipping lanes. We proceeded to generate search strings for each management action for both search engines. A selection of the search strings (including all those retained for the final review) and corresponding number of records are listed below. The bolded options denote the search strings used for the systematic literature review. All have a brief explanation as to why they were or were not used.

11. Web of Science (WoS) – broad search

Option 1: (TS=(vessel* OR ship* OR boat* OR cargo* OR yacht* OR sailing boat* OR recreation)) AND TS=(seabird*) AND TS=(disturbance) AND TS=(mitigat* OR reduc*) = 209 results. See option 3.

Option 2: (TS=(vessel* OR ship* OR boat* OR cargo* OR yacht* OR sailing boat* OR recreation)) AND TS=(seabird*) AND TS=(disturbance) AND TS=(mitigat* OR reduc*) AND TS=(offshore) = 22 results. Mainly studies on offshore windfarms, and less relevant to the review.

Option 3: (TS=(vessel* OR ship* OR boat* OR cargo* OR yacht* OR sailing boat* OR recreation*)) AND TS=(seabird*) AND TS=(disturbance) AND TS=(mitigat* OR reduc* OR management) = 428 results. Like Option 1 but seems to list more relevant studies. After study #50, many are focused on fishery-relating activities such as bycatch and fishing activity.

12. Google Scholar (GS) – broad search

Option 1: Management at-sea vessel disturbance on seabirds = 19,200 results. Too broad.

Option 2: Reducing the impact of at-sea vessels on auks = 7,130 results. Still too broad. Many studies relating to behaviour and threats at-sea.

Option 3: Effect of management actions of vessels at-sea to conserve auks = 5,320 results.

Most searches provide the same top 20 results.

13. WoS – reducing speed limit

Option 1: (TS=(vessel* OR ship* OR boat* OR cargo* OR yacht* OR sailing boat* OR recreation)) AND TS=(seabird*) AND TS=(disturbance) AND TS=(mitigat* OR reduc* OR management) AND TS=(speed limit*) = 6 results. Decided to keep this as it is highly likely that results will be useful for the final assessment.

14. GS – reducing speed limit

Option 1: Effect of speed limit regulation of vessels on seabirds = 19,400 results

Option 2: Effect of speed limit regulation of vessels or boats on seabirds = 18,600 results. Seem to provide the most relevant results.

Option 3: Effect of speed limit regulation of vessels on auks = 7,820 results. Mostly results on the effect of shipping activity on auks.

Similar results from all searches.

15. WoS – shipping lanes

Option 1: (TS=(vessel* OR ship* OR boat* OR cargo* OR yacht* OR sailing boat* OR recreation)) AND TS=(seabird*) AND TS=(disturbance) AND TS=(mitigat* OR reduc* OR management) AND TS=(shipping lane*) = 7 results. Too narrow.

Option 2: (TS=(vessel* OR ship* OR boat* OR cargo* OR yacht* OR sailing boat* OR recreation)) AND TS=(seabird*) AND TS=(disturbance) AND TS=(mitigat* OR reduc* OR management) AND TS=(shipping lane* OR spatial manag* OR closure) = 111 results. Added ‘spatial management’ and ‘closure’. Could provide more relevant results.

16. GS – shipping lanes

Option 1: Shipping lanes of vessels to protect seabirds = 19,700 results. Too broad.

Option 2: Effect of shipping lanes on seabirds = 5,390 results. More relevant results.

Information on the time and date that search strings were used, as well as the number of records retained for screening can be found in Annex 2.

8.2 Study selection

On 14 June 2023 we conducted three literature searches in WoS and three literature searches in GS (Figure 25; Figure 24 within main document); one broad search string and two specific search strings (one for each identified management action: reducing speed limits and shipping lanes) in each search engine.

In total, 29,855 references were identified. For each search, we selected the first 30 – 50 records after identifying a string of five consecutive less-relevant studies or to set a minimum number of served searches, and due to the time constraints of the project. In WoS, 428 records were obtained from the first search, of which the first 50, most relevant, records were exported, 6 from the second search, of which all were exported, and 111 from the third search, of which the first 30 records were exported. In GS, 5,320 records were obtained from the first search, of which the first 40, most relevant, records were exported, 18,600 from the second search, of which the first 30, most relevant, records were exported, and 5,390 from the third search, of which the first 30 records were exported. The searches yielded a total of 186 records, of which 35 were duplicates (i.e. identified in more than one search) and were automatically removed prior to screening. All 151 unique records were screened at a title and abstract level to identify and exclude studies outside the review's scope, such as those records where the effect of the conservation was not tested on seabirds or waterbirds, studies that exclusively provide evidence of at-sea disturbance birds but do not measure the effect, those that record and measure disturbance at the colony or close to the colony, those that researched marine mammals, those that focused on the effect of fishery-related activities on seabirds (e.g. bycatch, overfishing, discards), those that only researched seabird ecology at sea, those that focused on the impact of oil spills and collisions with windfarms or oil platforms on seabirds, those that focused on monitoring, tracking and/or surveying techniques of seabirds at sea, and those from which the abstract could not be accessed (see Table A 2 within the main document). Studies where this criterion was unclear were kept for full-text screening. We decided to retain studies where the management action was also tested on waterbirds, as results from these could be relevant and applicable to seabirds (but note that we did not expand the search strings or undertook further, more directed searches to include them). At this stage, we excluded 90% (136) of the records.

The remaining 15 records were screened in their entirety (i.e. full text) and relevant information was recorded. We additionally recorded information on the type of management action that was tested and the vessel type. Due to the limited evidence on the topic, our aim was to identify studies that measured the effect of at-sea disturbance on seabirds or waterbirds. We excluded studies that did not measure the effect of disturbance, studies that exclusively detected at-sea threat hotspots for seabirds and those that did not provide new evidence on the matter, broad reviews on the subject. We retained 8 records for final assessment.

Additionally, we identified three key references that were presumed highly relevant to this topic: Abdulla and Linden (2008), Furness et al. (2013b), and MMO (2018), and searched references within to identify relevant literature that may have been overlooked during the systematic literature search. We additionally searched for studies that were identified during the ‘reduction of disturbance (at colony)’ literature search. We identified, read the full-text, and extracted relevant information from six references. From this process, we retained three records for final assessment. Overall, 11 references were included for the final review.

Information on the complete reference list obtained during the literature search, and the level at which each reference was eliminated can be found in Annex 3.

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