Annual surveys of capercaillie in Scotland from 2010 to 2020

The population size of Capercaille Tetrao urogallus in Scotland was estimated from annual counts of males at 151 known (79-100) spring lek sites and 45 counts of males, females, and their broods in August during the period 2010-2020, combined with published survival estimates. Population size declined from an estimated 580 birds (95% CL: 462-698) in 2011 to 304 (239-369) in 2020 and the extinction probability was 23% after 25 years, 95% after 50 years and 100% after 100 years. Removing mortality associated with collisions against fences lowered extinction probabilities to 0%, 3% and 40%, respectively, emphasizing fence removal as a management priority. Greatest declines occurred in Deeside & Donside, Morayshire & Ross-shire and Perthshire & Trossachs. In the Badenoch & Strathspey stronghold, where an estimated 83% of males remain, numbers of occupied leks and lekking males have decreased in the last five years and are associated with reduced breeding success over the las..., , Data can be accessed using Excel.