Predation and reduced grazing interact to reduce recruitment and population growth in Black Brant

[摘要] ABSTRACT Dynamics of avian populations may be governed by a complex interaction between immediate effects of predation and longer-term trophic feedbacks between individuals and their foods. We used a long-term study of uniquely marked Black Brant geese (Branta bernicla nigricans) to estimate recruitment into the breeding population. We related recruitment to nest success, which directly affects recruitment 2 to 3 years later. We also assessed similarly time-lagged relationships between recruitment and number of nests in the colony, a measure of local density, and pre-fledging and first-year survival, the latter of which is strongly influenced by growth conditions and food availability for young of the year. We assessed relationships between number of recruits and explanatory variables in 2 sets of models, which either included or excluded a linear trend across years in numbers of recruits. The best-performing models in each model set explained a substantial proportion of the variation in numbers of recrui...

[学科分类] 动物科学

[关键词] Arctic fox;Alopex lagopus;Black Brant;Branta bernicla nigricans;grazing;nest success;population dynamics;predation;recruitment;survival;trophic cascade