Great Grey Shrike - Distribution and Habitat

Distribution and Habitat

The Great Grey Shrike occurs throughout most temperate and subarctic regions of the Northern Hemisphere. Generally, its breeding range is limited to areas north of 50° northern latitude in Eurasia, and north of 55° northern latitude in North America. In the high mountains of the Altai-Tian Shan region, it ranges south perhaps as far as 42° northern latitude. Its northern limit is generally 70° northern latitude, except in eastern Canada (Quebec) where it only reaches up to about 60° northern latitude. It is only found as a vagrant in Iceland, the British Isles, the Mediterranean region (excluding the Iberian Peninsula and perhaps Romania but including Cyprus), and Korea. There do not appear to be breeding records from the entire Kamchatka Peninsula; in Switzerland, Czechia and southern Germany small populations were found in the mid-20th century but have declined or even disappeared since then.

Except for the subspecies bianchii which is largely all-year resident, and subspecies excubitor in the temperate European parts of its range with their mild maritime climate, the species is a short-distance migrant. The migrations are triggered by scarcity of food and therefore, according to prey population levels, the winter range might little extend south beyond the breeding range, or be entirely parapatric to it. The populations of the Central Asian mountains mostly migrate downslope rather than southwards. Females are more prone to migration than males; they do not appear to migrate, on average, longer or shorter distances than males, and consequently are the dominant sex in many parts of the winter range. Birds leave for winter quarters a more or less short time after breeding – July to October, with most birds staying to September – and return to nest mainly in March/April, but some only arrive in May. In recent decades, the number of birds remaining on the breeding grounds all year has been noted to increase e.g. in Fennoscandia, whereas for example borealis seems to be as rare a winter visitor in northern Ohio as it was a century ago.

The preferred habitat is generally open grassland, perhaps with shrubs interspersed, and adjacent lookout points. These are normally trees – at forest edges in much of the habitat, but single trees or small stands at the taiga-tundra border. In steppe, it will utilize any isolated perch, be it fence posts, power lines or rocks. In general, some 5–15 perching sites per hectar habitat seem to be required. It avoids low grassland with no lookouts and nesting opportunities (trees or large shrubs), as well as dense forest with no hunting ground. Apart from grassland, the birds will utilize a variety of hunting habitats, including bogs, clearings or non-industrially farmed fields. Breeding birds appear to have different microhabitat desires, but little detail is known yet.