Life-history attributes of Arctic-breeding birds drive uneven responses
to environmental variability across different phases of the reproductive
cycle
Abstract
1. Animals exhibit varied life-history traits that reflect adaptive
responses to their environments. For Arctic-breeding birds, traits like
foraging guild, egg nutrient allocation, clutch size, and chick growth
are predicted to be under increasing selection pressure due to rapid
climate change and increasing environmental variability across
high-latitude regions. 2. We compared four migratory birds (black brant
[Branta bernicla nigricans], lesser snow geese [Chen caerulescens
caerulescens], semipalmated sandpipers [Calidris pusilla], and
Lapland longspurs [Calcarius lapponicus]) with varied life histories
at an Arctic site in Alaska, USA, to understand how life-history traits
help moderate environmental variability across different phases of the
reproductive cycle. 3. We monitored aspects of reproductive performance
related to the timing of breeding, reproductive investment, and chick
growth from 2011–2018. 4. In response to early snow melt and warm
temperatures, semipalmated sandpipers advanced their site arrival and
bred in higher numbers, while brant and snow geese increased clutch
sizes; all four species advanced their nest initiation dates. During
chick rearing, longspur chicks were relatively resilient to
environmental variation whereas warmer temperatures increased the growth
rates of sandpiper chicks but reduced growth rates of snow goose
goslings. These responses generally aligned with traits along the
capital-income spectrum of nutrient acquisition and altricial-precocial
modes of chick growth. Under a warming climate, the ability to mobilize
endogenous reserves likely provides geese with relative flexibility to
adjust the timing of breeding and the size of clutches. Warmer
temperatures, however, may negatively affect the quality of herbaceous
foods and slow gosling growth. 5. Species may possess traits that are
beneficial during one phase of the reproductive cycle and others that
may be detrimental at another phase, uneven responses that may be
amplified with future climate warming. These results underscore the need
to consider multiple phases of the reproductive cycle when assessing the
effects of environmental variability on Arctic-breeding birds.