Epsilon Archive for Student Projects

Abstract

Successful conservation and management of Golden Eagle (Aquila chrysaetos) requires an
in-depth understanding of its’ demographic parameters. The species in Sweden is listed as
Near Threatened and threats include increasing demands for renewable energy, collisions
with railways, illegal persecution, and lead poisoning. Breeding performance and survival
estimates can be used to increase the knowledge of the population dynamics of this apex
predator. I estimated breeding performance of Golden eagles by using citizen science data
from 44 territories in Northern Sweden from 1995 to 2015.Ring recovery data from the
National ringing database of the Stockholm museum of Natural history, were used to
estimate population and age-specific survival. Weather, voles’ density and topographic
variables incorporated to Generalized Linear Mixed Models (GLMMs) to explain the
patterns of breeding success. In continue, fecundity and survival estimates used to structure
a stage-structured Lefkovitch population projection matrix to estimate population growth,
stable stage distribution and elasticities and sensitivities of the growth rate. Long term
population fecundity was estimated to be 0.51 (young per pair) and breeding success it is
likely to be affected by vole index, snow depth and precipitation preceding the breeding
period and average temperature during the breeding. The best approximating model
explained the 29% of the total breeding variance, which questions the size of the effect of
habitat features and human-induced disturbance to Golden Eagles reproductive
performance. Survival rates were similar with those reported in the U.S. with older
individuals exhibiting higher survivorship (0.89) from the first age class (0.79). The
population exhibits a positive growth rate (1.1) while elasticities and sensitivities of the
growth rate indicate that the most influential transition for the population growth is the one
from 3 years old to 4 years old, while individuals older than 4 years old contribute more to
population growth.