Abstract
- 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.
- 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.
- We monitored aspects of reproductive performance related to the timing
of breeding, reproductive investment, and chick growth from
2011–2018.
- 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.
- 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.