Production of Seabird and Marine Mammal Distribution Models for the East of Scotland

This report describes temporal and spatial patterns of density for seabird and marine mammal species in the eastern waters of Scotland from digital aerial surveys. This is important in order for the Government to make evidence-based decisions regarding the status of these species and management.


3. Glossary

Term

π‘Žπ‘–

Description

Area of the ith photo

Term

Autocorrelation

Description

Successive items in a sequence are more similar to each other than more distant items in the sequence

Term

Covariate

Description

Explanatory variable which is continuous (e.g. distance to event)

Term

D surface

Description

Provides a summary of the relevant input data for the prediction both in terms of adjusted observed densities but also shows where there was actually survey effort (albeit not necessarily from the year in question) in that season. Predictions in regions of low survey effort should be treated with caution.

Term

Factor

Description

Explanatory variable which has a small number of discrete levels (e.g. period before or after event)

Term

GAM

Description

Generalized Additive Model - a generalized linear model in which explanatory variables take the form of smooth functions

Term

GAMM

Description

Generalized Additive Mixed Model - an extension to the generalized additive model (GAM) in which the linear predictor contains random effects in addition to the usual fixed effects.

Term

𝑁̂𝑐𝑖

Description

Estimated number of individuals in each ith covered segment (corrected where necessary for availability bias) of area ai.

Term

Point estimate surfaces

Description

The predicted densities for the conditions given.

Term

Overdispersion

Description

Presence of more variability than would be expected under the assumed mean-variance relationship.

Term

2.5% and 97.5% percentile surfaces

Description

The densities of the 2.5% and 97.5% quantiles for each cell of the surface, a measure of uncertainty encompassing the range of values that the model predicts there is a 95% probability of the true mean response lying within’

Term

CV

Description

Coefficient of variation – measure of a dispersion of a frequency distribution calculated as the ratio of the standard deviation to the mean, expressed in percentage.

Contact

Email: REEAadmin@gov.scot

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