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

• DOI: 10.1650/condor-15-109.1
• Publication Date: 2016-04-20T17:35:57Z
• Authors: James S. Sedinger; Christopher A. Ni...; Amanda W. VanDellen; Alan G. Leach; Heather M. Wilson; R. Michael Anthony
• Keywords: Branta; Fledge; Density dependence

Dynamics of avian populations may be governed by a complex interaction between immediate effects predation and longer-term trophic feedbacks individuals their foods. We used long-term study uniquely marked Black Brant geese (Branta bernicla nigricans) to estimate recruitment into the breeding population. related nest success, which directly affects 2 3 years later. also assessed similarly time-lagged relationships number nests in colony, measure local density, pre-fledging first-year survival, latter is strongly influenced growth conditions food availability for young year. recruits explanatory variables sets models, either included or excluded linear trend across numbers recruits. The best-performing models each model set explained substantial proportion variation later (85 78% sets, respectively). First-year survival was an important predictor both whereas success only lacking years. Number colony had relatively weak negative association with reflects lagged response earlier nest-predation events. Reduced grazing during events can result loss lawns thus reduced rates future cohorts goslings, are regulated abundance density broods. Our finding that insufficient maintain population results from direct effect on nests, primarily Arctic foxes (Alopex lagopus), indirect such Brant.