Key winter habitat of the ivory gull Pagophila eburnea in the Canadian Arctic

Abstract

The ivory gull Pagophila eburnea is a rare Arctic seabird that breeds in remote locations; little is known of its winter distribution and behaviour. It is listed under Canadian legislation as 'endangered', and as 'near threatened' by the International Union for the Conservation of Nature. A > 70% population decline in the past 3 decades in Canada prompted research on ivory gulls to better understand their year-round movements and habitat requirements. Additionally, the identification of critical habitat is a research priority in the Recovery Strategy for the ivory gull in Canada. We used data from gulls tracked by satellite telemetry from the Canadian Arctic and Svalbard, Norway, as well as data from ship observations collected between 1969 and 2010. We determined that the area of highest use by these gulls in the winter was in Davis Strait, where 90% of their time was spent over sea ice. Agreement of findings among datasets through time and from different breeding regions suggests that the edge of the pack ice in Davis Strait is an annual, key habitat for ivory gulls in winter. Given the proximity of the core wintering area to known hooded seal Crystophora cristata whelping patches, we speculate that remains from seal breeding, as well as polar bear Ursus maritimus kills and pagophilic (ice-loving) fish accessed in the vicinity of pack ice have provided spatially and temporally predictable, and valuable, food resources for ivory gulls in the winter.

Confirmation of a wintering ground of Ross's Gull Rhodostethia rosea in the northern Labrador Sea

“…Finally, these findings add to the growing body of evidence suggesting that the Labrador Sea and Davis Strait form a critical wintering area for many species of marine birds (e.g. Spencer et al 2014), and collectively merit consideration for protected area status, particularly as both Threatened (Ross's Gull) and Endangered (Ivory Gull) species rely on this habitat for a significant portion of their annual cycle (Spencer 2014.…”

“…, Northern Fulmar Fulmarus glacialis – Mallory et al . , Ivory Gull Pagophila eburnea – Spencer , Spencer et al . ), and collectively merit consideration for protected area status, particularly as both Threatened (Ross's Gull) and Endangered (Ivory Gull) species rely on this habitat for a significant portion of their annual cycle (Spencer , Spencer et al .…”

An interspecific foraging association with polar bears increases foraging opportunities for avian predators in a declining Arctic seabird colony

“…Avian predators act as scavengers of polar bears on sea ice by making use of seal carcasses and other carrion left by bears (Derocher, 2012; Secretariat, 2015; Spencer et al., 2016), and have been observed following bears in nesting bird colonies (Gaston & Elliott, 2013; Madsen et al., 2019). However, beyond increasing the availability of nests for avian predators, the actual characteristics of the IFA and factors impacting foraging efficiency for avian predators are relatively understudied.…”