Predators play a key role in the functioning of ecosystems and could potentially control the abundance of their prey. As predators are at the top of the food chain, they can be good indicators of the state of the tundra ecosystem. Avian predators, mostly raptors and seabirds, are the most diverse groups of predators in the Arctic tundra and range from specialists to generalists in terms of their diet. Most species of avian predators are migrants and are only present in the Arctic during the summer to reproduce. During the short Arctic summer, they can encounter harsh conditions that could affect their breeding effort, reproductive success or even their survival. Furthermore, these species are exposed to climate change, which is predicted to be most severe at northern latitudes. For instance, raptors have already started to experience loss of breeding habitats in some regions due to the collapse of their nesting structures cause by permafrost thawing. Changes in prey distribution and abundance can also impact avian predators, especially those that are diet specialists. Hence, implementing a monitoring program of avian predators can provide useful information on the status of these species, some of which are considered vulnerable, as well as on the health of the whole tundra ecosystem.
This archive contains annual reproduction monitoring data for the four most abundant avian predators in our study area on Bylot Island: long-tailed jaegers, glaucous gulls, snowy owls and rough-legged hawks. The data set includes the GPS location of nests that are found through either systematic search along transects in suitable habitats for these species or opportunistically. We also report, whenever possible, clutch size, laying and hatching dates and hatching and fledging successes, based on observations during return visits to the nests during the breeding season.
In addition, given that these predators share a common resource (lemmings) whose abundance varies considerably from year to year, it is possible to better understand the distribution of this prey among the main avian predators of the Bylot Island using data extracted from regurgitation pellets collected at nests. This publication also contains measurements of lemming mandibles taken from these pellets which allow the size of lemmings consumed among species to be determined during the breeding season (for more details, see Schmidt et al. 2020).
