Publication - Consultation paper
Scottish seabird conservation action plan: vulnerability report
Details the process undertaken to determine the key pressures acting on seabirds whilst at Scottish seas and at breeding colonies and used to inform the development of the Scottish seabird conservation action plan.
Annex 1: Assessing Sensitivity
Sensitivity criteria used by Rogerson et al. (2021) to score Tolerance, Recovery and Confidence.
Scoring Tolerance
Rogerson et al. (2021) assigned tolerance scores using the criteria in Table A1.1:
| Tolerance score | Definition |
|---|---|
| None | A severe decline (>50%) in the estimated size of the local population as a result of increased mortality, reduced reproductive success, displacement or any other mechanism |
| Low | A significant decline (>10 and ≤50%) in the estimated size of the local population as a result of increased mortality, reduced reproductive success, displacement or any other mechanism. |
| Medium | A moderate decline (loss of up to 10%) in the estimated size of the local population as a result of increased mortality, reduced reproductive success, displacement or any other mechanism. |
| High | No population decline is expected. Effects affecting key functional and physiological attributes of the species (e.g. food intake rate, energy expenditure rate) may occur but are buffered from feeding through to changed rates of reproduction or mortality and hence population size by virtue of species’ flexibility to respond to the pressure e.g. by redistribution, dietary shifts, increased foraging effort, etc. |
Scoring Recovery
Scoring of recovery is determined by life history parameters indicative of the recovery potential of species (Table A1.2) and are detailed in Rogerson et al (2021).
| Life history parameters | Low recovery potential | Medium recovery potential | High recovery potential |
|---|---|---|---|
| Definition | Full recovery expected within 10-25 years. | Full recovery expected within 2-10 years. | Full recovery expected within 2 years. |
| Lifespan | Long- lived (10 years +) | Moderate lifespans (5-10 years) | Short-lived (up to 5 years) |
| Age at first maturity | Deferred maturity (first breeds when more than 3 years old) | First breeds when 2-3 years old | First breeds at one year of age |
| Adult mortality rate | Low natural mortality (<15%) | Moderate natural mortality rate (15-25%) | High natural annual mortality (>25%) |
| Fecundity / reproductive success | Low reproductive output (<2 chicks per pair per annum) | Moderate reproductive output (2-5 chicks per pair per annum) | High reproductive output (>5 chicks per pair per annum) |
The framework for this was originally developed for a wider spectrum of bird species and consequently, all of the 22 seabird species covered by the Scottish Seabird Vulnerability Report fall into the low recovery category, hence, by default, the recovery score is low.
Confidence In Tolerance, Recovery & Sensitivity Scores
For each of the tolerance and recovery scores, confidence in the assessment was also scored, following a scoring system considering three confidence components (Table A1.3). For each of the components (quality of evidence, applicability of evidence and degree of concordance) a score was given and they were added up. The resulting confidence score falls between 3 and 15 points, and the degree of confidence is defined as:
- High confidence: total score >12;
- Medium confidence: total score 6 – 12; and
- Low confidence: total scores <6.
| Confidence | Quality of information sources | Applicability of evidence | Degree of concordance |
|---|---|---|---|
| High (Score = 5) | Based on Peer Reviewed papers (observational or experimental) or grey literature reports by established agencies on the feature | Assessment based on the same pressures arising from similar activities, acting on the same type of feature in comparable areas (i.e. Ireland, UK) | Evidence agrees on the direction and magnitude of impact |
| Medium (Score = 3) | Based on some peer reviewed papers but relies heavily on grey literature or expert judgement on feature or similar features | Assessment based on similar pressures on the feature in other areas | Evidence agrees on direction but not magnitude of impact |
| Low (Score = 1) | Based on expert judgement, which is not clearly documented | Assessment based on proxies for pressures e.g. natural disturbance events | Evidence does not agree on concordance or magnitude |
Table A1. 4: Seabird sensitivity to pressures not taken forward to the vulnerability analysis.
M=Medium, L=Low, S=Sensitive, NA= Not Assessed Br=Breeding, NBr=Non-Breeding
1. Water clarity changes
2. Nitrogen & phosphorus enrichment
3. Under-water noise
4. Temperature changes - local
5. Water flow (tidal current) changes – local
6. Physical removal (extraction of sub-stratum)
7. Habitat loss from coastal infra-structure
8. Mortality or sub-lethal impacts of synthetic compounds (e.g. pesticides, antifoulants)
9. Mortality or sub-lethal impacts of non-synthetic compounds (e.g. heavy metals)
| Species | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
|---|---|---|---|---|---|---|---|---|---|
| Northern fulmar | L | S | L | NA | S | NA | S | S | S |
| Manx shearwater (Br) | L | S | L | NA | S | NA | S | S | S |
| European Storm-petrel (Br) | L | S | L | NA | S | NA | S | S | S |
| Leach's storm petrel (Br) | L | S | L | NA | S | NA | S | S | S |
| Arctic skua (Br) | L | S | L | NA | S | NA | S | S | S |
| Great skua | L | S | L | NA | S | NA | S | S | S |
| Great black-backed gull | L | S | L | NA | S | NA | S | S | S |
| Herring gull | L | S | L | NA | S | NA | S | S | S |
| Lesser black-backed gull | L | S | NA | NA | M | NA | S | S | S |
| Little gull (NBr) | L | S | L | NA | M | NA | S | S | S |
| Black-legged kittiwake | L | S | L | NA | S | NA | S | M | S |
| Little tern (Br) | S | M | L | NA | NA | NA | S | S | S |
| Common tern (Br) | M | M | L | NA | NA | NA | S | M | S |
| Arctic tern (Br) | L | M | L | NA | NA | NA | S | M | S |
| Sandwich tern (Br) | S | M | L | NA | NA | NA | S | S | S |
| Northern gannet | S | S | L | NA | S | NA | S | S | S |
| Great cormorant | S | S | S | NA | L | NA | S | S | M |
| European shag | S | S | S | NA | S | NA | S | S | S |
| Razorbill | S | M | S | NA | L | NA | S | S | S |
| Common guillemot | L | M | M | NA | L | NA | S | S | S |
| Black guillemot | S | S | S | NA | S | NA | S | S | M |
| Atlantic puffin | S | S | S | NA | L | NA | S | S | S |
| Pressure | Sensitivity | Reason for not considering pressure further |
|---|---|---|
| Water clarity changes | Common tern have a medium sensitivity to water clarity changes. Common tern have a high reliance on visually locating food from the air. Increased turbidity can reduce the ability of common tern to successfully catch prey. | In Scotland, common tern may experience this pressure to a small extent in highly localised situations and over a short time period. |
| Nitrogen & phosphorus enrichment | Terns, razorbill and common guillemot have a medium sensitivity to the effects of nitrogen and phosphorous enrichment. Indirect impacts of nitrogen and phosphorous enrichment resulting in algal blooms have been recorded as causing mass mortality of seabirds. Cormorants are negatively affected by fertilizer use most likely associated with run-off from inland and estuarine locations. | In Scotland, terns, razorbill and common guillemot may experience this pressure to some extent when enrichment results in algal blooms. Nitrogen and phosphorous enrichment is mostly associated with run-off from inland and estuarine locations. |
| Underwater noise | Common guillemot have a medium sensitivity to underwater noise. Underwater noise may directly affect guillemot, being submerged for comparably long periods when diving in search for prey on the seabed. Guillemots have been found to show consistent reactions to underwater sound during controlled trials. | In Scotland, common guillemot may experience this pressure to a small extent. Limited evidence suggests a potential negative effect from underwater noise but the impact is expected to be temporary. |
| Water flow (tidal current) changes – local | Lesser black-backed gull and little gull have a medium sensitivity. Increases in water flow could increase energy expenditure of resting birds or birds diving for prey. It could also influence the availability of prey close to the water surface and species composition could be altered. These impacts could give rise to reduced body condition and therefore direct impacts. Lesser black-backed gulls are known to drift passively with the tidal current for several hours to rest. Water flow is reported to have a strong influence on little gull foraging. | In Scotland, lesser black-backed gull and little gull may experience this pressure to a small extent in localised situations. |
| Mortality or sub-lethal impacts of synthetic compounds (e.g. pesticides, antifoulants) | Kittiwake, common tern and Arctic tern have a medium sensitivity to impacts of synthetic compounds. Synthetic compounds can have impacts on seabird physiology such as hormone levels, breeding probability, hatching dates and even on genetics and behaviour. Evidence of impacts from synthetic contaminants on reproduction has been found in terns and impacts to time spent on eggs has been found in Kittiwake. | Legacy contaminants are expected to be in decline and recent studies have found declines in pollutant concentrations in colonies in the German Baltic Sea. |
| Mortality or sub-lethal impacts of non-synthetic compounds (e.g. heavy metals) | Cormorant and black guillemot have a medium sensitivity to impacts of non-synthetic compounds. Sub-lethal levels of heavy metal concentrations can lead to chronic diseases in seabirds and can have adverse effects on growth, development, reproduction, metabolism and behaviour. Bioaccumulation of mercury is known to occur in cormorants and black guillemot from their prey. | For cormorants, levels of non-synthetic compounds are very low and appear to not have any significant influence on the birds. Trends in mercury contamination have been seen to fall since 1993 and therefore this pressure is expected to be limited. |
Contact
Email: marine_species@gov.scot
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