Predation and reduced grazing interact to reduce recruitment and population growth in black brant / James S. Sedinger, Christopher A. Nicolai, Amanda W. VanDellen, Alan G. Leach, Health M. Wilson, and R. Michael Anthony.

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Sedinger, James S

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TextSeries: Condor. 118(2) 433-444 Publication details: 2016Description: 28 cmLOC classification:

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Summary: 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 recruits 2 to 3 years later (85 and 78% in the 2 model sets, respectively). First-year survival was an important predictor of number of recruits in both sets of models, whereas nest success was important only in models lacking a trend across years. Number of nests in the colony had a relatively weak negative association with number of recruits. First-year survival reflects a lagged response to earlier nestpredation events. Reduced grazing during predation events can result in loss of grazing lawns and thus reduced growth rates of future cohorts of goslings, which are regulated by food abundance and density of broods. Our finding that recruitment is insufficient to maintain the breeding population results from both direct effect of predation on nests, primarily by Arctic foxes (Alopex lagopus), and longer-term indirect effects of such predation on first-year survival of Black Brant.

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Item type	Current library	Collection	Call number	Status	Date due	Barcode
Electronic Journal	IWWR Supported Research	Non-fiction	SED (Browse shelf(Opens below))	Available		16684

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Previous	ROT Nesting effort by wild mallards with 3 types of radio transmitters /	RUN The need for coherence between waterfowl harvest and habitat management /	SCH Hydrology of the Delta Marsh watershed : Water balance characterization and analysis of land use changes /	SED Predation and reduced grazing interact to reduce recruitment and population growth in black brant /	SEN The effects of global climate change on long-distance migratory birds /	SHE Habitat selection trade-offs, male quality and reproductive performance of female mallards /	SHE Reproductive effort and success of wild female mallards : does male quality matter? /	Next

Includes bibliographical references (pages 442-444).

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 recruits 2 to 3 years later (85 and 78% in the 2 model
sets, respectively). First-year survival was an important predictor of number of recruits in both sets of models, whereas
nest success was important only in models lacking a trend across years. Number of nests in the colony had a relatively
weak negative association with number of recruits. First-year survival reflects a lagged response to earlier nestpredation
events. Reduced grazing during predation events can result in loss of grazing lawns and thus reduced
growth rates of future cohorts of goslings, which are regulated by food abundance and density of broods. Our finding
that recruitment is insufficient to maintain the breeding population results from both direct effect of predation on
nests, primarily by Arctic foxes (Alopex lagopus), and longer-term indirect effects of such predation on first-year survival
of Black Brant.

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