Spring temperature, migration chronology, and nutrient allocation to eggs in three species of arctic‐nesting geese: Implications for resilience to climate warming

Abstract

The macronutrients that Arctic herbivores invest in their offspring are derived from endogenous reserves of fat and protein (capital) that females build prior to the period of investment or from foods they consume concurrently with investment (income). The relative contribution from each source can be influenced by temporal and environmental constraints on a female's ability to forage on Arctic breeding areas. Warming temperatures and advancing Arctic phenology may alter those constraints. From 2011 to 2014, we examined relationships among spring temperature, timing of migration and reproduction, and the sources of nutrients females deposited in eggs for three sympatric species of geese that nested in northern Alaska. Compared to lesser snow geese (Anser caerulescens caerulescens) and greater white-fronted geese (Anser albifrons frontalis), black brant (Branta bernicla nigricans) were more likely to initiate follicle development during migration, resulting in fewer days between their arrival in the Arctic and the onset of incubation and requiring a relatively greater capital investment in eggs. Delaying follicle development until after their arrival in the Arctic provided snow geese and white-fronted geese an opportunity to forage near their nesting area and to deposit exogenous nutrients in eggs. With warmer spring temperatures, brant invested more capital in eggs, but snow geese invested less capital. Brant likely used capital to meet costs associated with earlier onset of follicle development when phenology was advanced, whereas snow geese used capital to compensate for poor foraging conditions during colder Arctic springs. Global warming is likely to reduce the quality of lower latitude marine habitats where brant acquire endogenous reserves and advancing Arctic phenology may increase their reliance on those reserves during reproduction. Near-term warming in northern Alaska may improve foraging conditions and favor the reproductive strategies of some herbivores such as snow geese and white-fronted geese that mainly invest Arctic nutrients in their offspring.

Spring migration duration exceeds that of autumn migration in Far East Asian Greater White-fronted Geese (Anser albifrons)

“…This strategy leads to greater investment in store acquisition in the later stages (after having migrated non-stop over the taiga forest), with longer staging at near-breeding areas. Greater White-fronted Geese breeding in Alaska seem to invest little of their endogenous stores in eggs after also staging close to or on their breeding areas (Hupp et al 2018). Despite the need for such stores, the ability of females to acquire them is likely to be a trade-off with the extent of the spring thaw at any one point in time and space (e.g.…”

Contrasting effects of the onset of spring on reproductive success of Arctic-nesting geese

“…Whether more or less capital is being used depends on the species' body size and migration distance (Hobson et al 2011), their foraging ecology (i.e. being grubbers or grazers) (Sharp et al 2013), but also on the spring food conditions (Klaassen et al 2017, Hupp et al 2018, Lameris et al 2018.…”

“…They are long-distance migrants with a virtual non-stop migration that does not allow for adjustments in timing along the way (Clausen and Clausen 2013), while breeding in an area where climate is rapidly warming (Førland et al 2011). Importantly, perhaps to prevent high thermoregulatory costs due to their small body size (Hupp et al 2018), they are the last goose species to arrive on the breeding grounds (Clausen and Clausen 2013). While in general small bird species have less scope for capital-breeding than larger ones (Meijer and Drent 1999), the interval between arrival and laying can be of overriding importance, and, based on the short interval, they are expected, like Dark-bellied Brent Geese (Branta bernicla bernicla), to be largely capital breeders investing stores into their eggs (Klaassen et al 2006).…”

“…While in general small bird species have less scope for capital-breeding than larger ones (Meijer and Drent 1999), the interval between arrival and laying can be of overriding importance, and, based on the short interval, they are expected, like Dark-bellied Brent Geese (Branta bernicla bernicla), to be largely capital breeders investing stores into their eggs (Klaassen et al 2006). While they may have some leeway to adjust to earlier springs by using even more capital stores for egg production when spring starts early, like the closely related Black Brant (Branta bernicla nigricans) (Hupp et al 2018), the options to prevent a mismatch seem to be limited; other (larger) goose species may have more options to start laying earlier in earlier years, because they simply arrive earlier (Hupp et al 2018).…”

Variable sea‐ice conditions influence trophic dynamics in an Arctic community of marine top predators

“…The isotopic values for both nitrogen (δ 15 N) and carbon (δ 13 C) in those eggs were measured since the late 1990s. These metrics are suitable proxies of trophic position and some aspects of foraging location (e.g., pelagic vs. inshore) for birds during egg formation (Hobson & Welch, 1992a, Hobson, 1993 see also Hupp, Ward, Soto, & Hobson, 2018). For 3 years during the monitoring period, black-legged kittiwake and glaucous gull isotopic values in eggs were also obtained.…”