Climate change, phenology, and habitat degradation: drivers of gosling body condition and juvenile survival in lesser snow geese

Abstract

Nesting migratory geese are among the dominant herbivores in (sub) arctic environments, which have undergone unprecedented increases in temperatures and plant growing days over the last three decades. Within these regions, the Hudson Bay Lowlands are home to an overabundant breeding population of lesser snow geese that has dramatically damaged the ecosystem, with cascading effects at multiple trophic levels. In some areas the overabundance of geese has led to a drastic reduction in available forage. In addition, warming of this region has widened the gap between goose migration timing and plant green-up, and this 'mismatch' between goose and plant phenologies could in turn affect gosling development. The dual effects of climate change and habitat quality on gosling body condition and juvenile survival are not known, but are critical for predicting population growth and related degradation of (sub) arctic ecosystems. To address these issues, we used information on female goslings marked and measured between 1978 and 2005 (4125 individuals). Goslings that developed within and near the traditional center of the breeding colony experienced the effects of long-term habitat degradation: body condition and juvenile survival declined over time. In newly colonized areas, however, we observed the opposite pattern (increase in body condition and juvenile survival). In addition, warmer than average winters and summers resulted in lower gosling body condition and first-year survival. Too few plant 'growing days' in the spring relative to hatch led to similar results. Our assessment indicates that geese are recovering from habitat degradation by moving to newly colonized locales. However, a warmer climate could negatively affect snow goose populations in the long-run, but it will depend on which seasons warm the fastest. These antagonistic mechanisms will require further study to help predict snow goose population dynamics and manage the trophic cascade they induce.

Disrupted learning: habitat degradation impairs crucial antipredator responses in naive prey

“…These services include food, shelter and crucial biological interactions such as symbioses [4]. Changes to habitats may directly or indirectly affect an organism's fitness or survival and in doing so influence the viability of a local population [5,6]. In the ocean, many of the mortal effects of habitat degradation involve modifications to the vulnerability of prey to predators [7][8][9].…”

Warmer winters reduce frog fecundity and shift breeding phenology, which consequently alters larval development and metamorphic timing

“…Within species, earlier breeding can prolong the length of the growing season, which in turn allows greater individual growth or survival, and can increase abundance (Ozgul et al, 2010;Eastman et al, 2012). A variety of examples of disrupted timing of species' interactions exist, such as between plant budburst, herbivorous insects, and predatory birds (Both et al, 2009) or geese and plants they feed upon (Aubry et al, 2013). One cause of harmful effects is the disruption of interspecific interactions.…”

Polar bears observed climbing steep slopes to graze on scurvy grass in Svalbard

“…Moreover, the climate-induced increase in the populations of geese and reindeer in Svalbard observed in recent decades has led to overgrazing of the lowland tundra vegetation (Olofsson 2006;Aubry et al 2013). As a result most plants easily grazed by herbivores barely protrude above the ground, which makes them inaccessible to polar bears.…”