Introduction

The arrival and song of the male Snow Bunting herald the end of a long, cold, dark winter in high arctic regions worldwide. Males return to their high arctic breeding grounds in early April, when the temperature can dip as low as -30°C and food resources are largely snow covered. Such early arrival can thus be energetically costly, and unseasonable storms can occasionally be devastating for early migrants. Females arrive four to six weeks later, when days are warming and snow is beginning to melt.

Why do male Snow Buntings return to the tundra so early in spring, Unlike most other arctic songbirds, this species nests in rock cavities, so competition for territories containing high-quality nest sites is intense. The importance of nest sites to the reproductive biology of Snow Buntings is underscored by the fact that nest-site advertisement and visitation are a key part of courtship. By tucking their nests deep in narrow cracks and fissures, Snow Buntings suffer lower rates of nest predation than open-nesting arctic songbirds. This safety, however, has a cost—cold rock cavities provide a harsh microclimate for developing eggs, one that can increase incubation periods or kill developing embryos. To ameliorate this cost, male Snow Buntings feed their mates on the nest throughout incubation, an indirect form of parental care that allows females to spend more time on their nests and, as a result, achieve a shorter incubation period and a higher hatching success.

McKay’s Bunting is a rare sister species of the Snow Bunting that breeds only on two small islands in the Bering Sea. What little is known about McKay’s Bunting is summarized in an appended species account beginning on page 21.