Scottish Marine and Freshwater Science Vol 11 No 8
The aim of this research project was to utilise existing information to produce a new tool to apportion birds observed in transect surveys (i.e. ship-based and aerial surveys) to individual colonies. To do so, we used GPS tracking data available for a sample of colonies and colony size data for three species (black-legged kittiwake, common guillemot and razorbill). We used predicted spatial distributions from a recently published paper (Wakefield et al. 2017) estimated from GPS tracking data from breeding birds of these species as a basis for apportioning birds to colonies.

We developed a simple tool, implemented within the free R statistical programming environment, to calculate apportioning percentages for a user-defined location using each of these four methods.