Northern Shrike

The Northern Shrike or ‘butcher bird’ is a determined pursuer of small birds and mammals, which it impales on thorns and barbed wire or wedges in forks of branchlets. It breeds in the taiga and tundra generally north of 55 degrees northern latitude in North America and 50 degrees northern latitude in northern Europe where it is known as the Great Grey Shrike. In North America it winters in southern Canada and the northern United States.

Adult Male (spring/summer)

Black mask with thin white upper eye-arch above black eye. Forehead, crown, nape and back gray. Uppertail coverts lighter gray and tail black with white outer retrices. White throat. Breast and belly white with faint gray barring. White flanks and undertail coverts. Wings are black except for white at base of primaries. Bill is large, hooked and black. Feet and legs are black.

Adult Female (spring/summer)

Sexes are similar.

Juvenile

Similar to adult but brownish with more distinct barring on chest and less distinct mask and pale bill.

General:

Medium-sized songbird with thick hooked bill. Length: 23-24cm. Wing: 30-35cm. Weight: 56-79grams.

Behaviour:

Adopts a ‘wait and attack’ approach from an exposed perch and then seizes prey in an aerial dive near the ground with its feet or bill. Often impales prey on thorns, spines, or barbed wire similar in the way butchers hang meat in their shops, hence the name ‘butcher bird’. Mice, small birds, and large insects form the bulk of the shrike’s diet.

Habitat:

Breeds in taiga and at the border of taiga and tundra, in open country with medium or tall trees or shrubs. Winters in open country with tall perches, including shrubby fields, wetlands, and forest edges.
The Northern Shrike kills more prey than it can immediately eat or feed to nestlings. Such behavior was characterized by early observers as “wanton killing,” but the Northern Shrike stores excess prey to eat later, an adaptation for surviving periods of food scarcity. Both male and female Northern Shrikes sing throughout the year and males sing especially in late winter and early spring. The Northern Shrike sometimes tries to attract small songbirds by mimicking their calls in an attempt to catch them for food. The nest is a large, bulky cup placed in trees or shrubs. Clutch size is 4-9 grayish or greenish white heavily marked with brown spots and blotches eggs.

Information:

The Northern Shrike kills more prey than it can immediately eat or feed to nestlings. Such behavior was characterized by early observers as “wanton killing,” but the Northern Shrike stores excess prey to eat later, an adaptation for surviving periods of food scarcity. Both male and female Northern Shrikes sing throughout the year and males sing especially in late winter and early spring. The Northern Shrike sometimes tries to attract small songbirds by mimicking their calls in an attempt to catch them for food. The nest is a large, bulky cup placed in trees or shrubs. Clutch size is 4-9 grayish or greenish white heavily marked with brown spots and blotches eggs.

Similar species:

Loggerhead Shrike, Northern Mockingbird.

Conservation Status:

Listed as Least Concern. Populations are thought to be stable but trends are difficult to assess because of the Northern Shrike’s rarity and remoteness of its breeding habitat in the boreal forest and tundra. Large areas of suitable breeding habitat are protected in Alaska and northern Canada which may help with the conservation status.

Capture Rates:

The Northern Shrike is a winter resident of Colony Farm. Capture rates peak in October and November as birds arrive and occurrences during April reflect migration movement northward to the boreal nesting grounds.

Molt Summary:

PF: HY partial (Oct-Dec); PB: AHY complete (Jul-Sep); PA absent-partial (Mar-Apr).
Preformative molt includes some to all med covs, 0 – 10 inner gr covs, and occasionally 1 – 3 terts, but no rects or other flight feathers. Occurs on the winter grounds.
Adult PB: some flight feathers (especially s3-s6 and pp covs) retained. Occurs on the summer grounds.
PA: partial may only occur in SYs, more study needed on PAs in ASYs.
Look for occurrence of presupplemental molt of body feathers prior to preformative molt.

The upper mandible is paler as in the photo immediately below of a HY in October compared to adults which have black mandibles (second photo below). Notice also the less prominent “toothed” beak which is more developed in the adult bird.

This HY in October is showing very obvious molt limits between retained and replaced feathers. The retained greater coverts are brown with buffy tips contrasting markedly with the glossy, black replaced greater coverts. Notice this bird has retained the 4 outer greater coverts (GCs 1-4), replaced GC 5, retained GCs 6 & 7 and replaced the innermost GCs 8-10. Notice also the contrast between the glossy, black replaced tertials (S7-S9) and retained middle secondaries (S4-S6) of this bird (red arrow).

This SY in April is also showing an obvious molt limit within the greater coverts, the 3 retained outer GCs worn and brown with buffy tips contrasting with the glossy, black replaced inner GCs. Notice also the narrow, tapered and abraded primary coverts.

This SY also in April is again showing an obvious molt limit between the replaced greater coverts and retained primary coverts. Notice again the narrow, tapered and abraded primary coverts and obvious greater alula covert (A1) molt limit, the worn, lightly pigmented and washed out lower main alula feathers (A2 & A3) contrasting with the glossy black replaced greater alula covert (red arrow).