The intra-specific variation in life-history traits represents
functional attributes (e.g., resource use and allocation, reproductive
investment, modes of chick growth) that reflect selective forces acting
under a rapidly changing climate (Berteaux et al., 2004; Gienapp et al.,
2008). To this end, we monitored the annual arrival, pre-lay duration,
nest initiation, clutch size, and nesting effort of brant, snow geese,
semipalmated sandpipers, and longspurs, and measured relevant
environmental variables across the breeding season. We predicted that
geese would exhibit more flexibility to interannual variability in
spring temperature and snowmelt compared to semipalmated sandpipers and
longspurs by adjusting the timing of breeding and reproductive
investment due to their comparatively greater endogenous reserves and
relative flexibility along the capital-income spectrum.
Because species possess traits that may promote resilience during one
phase of the reproductive cycle but other traits which may be
detrimental at other phases, assessing the response of species to shared
environmental conditions across different phases of the reproductive
cycle (e.g., Nolet et al., 2020) provides more meaningful insights into
reproductive outcomes than assessments focused on just one phase. As
such, in addition to monitoring responses during the pre-breeding and
nesting periods, we also monitored the growth of chicks of these four
species in conjunction with climatic variables and measures of the
seasonal availability of herbivorous and insectivorous food resources.
Because numerous studies have demonstrated that rapid growth of avian
young yields larger chicks (Larsson & Forslund, 1991; Ruthrauff &
McCaffery, 2005) that survive at higher rates (Lindholm et al., 1994;
Naef-Daenzer et al., 2001) and have a higher probability of recruitment
(Cooch et al., 1993; Magrath, 1991; Sedinger et al., 1995) than smaller
same-age chicks, variation in chick growth reflects a meaningful
demographic response to environmental variability. We predicted that the
young of brant, snow geese, and semipalmated sandpipers would be more
sensitive to variation in food abundance due to their precocial nature.
We predicted that this would be reflected by relatively strong variation
in body mass as a function of food abundance compared to chicks of
longspurs, which are provisioned entirely by adults. Taken together,
assessments of climatological (temperature, wind, and snow cover) and
environmental (seasonal availability and absolute abundance of food
resources) factors in relation to life-history traits across multiple
phases of the reproductive cycle elucidate characteristics of
Arctic-breeding birds that may mitigate negative effects of future
climate change.