Field Identification of Shrikes

18 Field Identification of Shrikes by R.D. James Although there are about 65 species easy. The Northern Shrike is a sum of shrikes in the world, only two are mer inhabitant of muskeg or open found in Canada, the Northern Shrike woodlands near treeline across Can (Lanius excubitor) and the ada. Formerly it was not considered Loggerhead Shrike (L. ludovicianus). to breed in Ontario, but a few summer Both are grayish-colored birds with records during the previous decade black and white wings and tails. The indicate that it also breeds sparingly, only Ontario birds of similar size probably all along the northern edge and color likely to be confused with of the province, and along James them is the Northern Mockingbird Bay as far south as the Moose River. (Mimus polyg[ottos), which also has The Loggerhead Shrike, on the white outer-tail feathers and a white other hand, is a summer resident in patch on the wings that flashes the southern fringes of the country prominently in flight. But the shrikes from the western prairies to the have proportionately shorter tails, Maritimes, where open country with shorter, stouter and strongly hooked scattered trees and shrubs or brushy bills and prominent black masks that fencerows and hedgerows provide instantly distinguish them from other nesting cover. In Ontario, they are birds. They may also be identified usually found only as far north as by their behaviour. They fly with an the Rainy River area and Thunder undulating flight, swoop upward to a Bay in the west, or Sault Ste. Marie perch when landing, tend to perch at and Sudbury in the east. A shrike the tops of trees in exposed situa found in the southern portions of tions, and hold their bodies in a Ontario in summer then, can reason rather horizontal position when ably be assumed to be a Loggerhead perched. Shrike. Any shrike seen north of While the shrikes are easy to distin Moosonee in summer probably could guish from other birds, they are be considered a Northern Shrike. sufficiently similar to each other that [Eds. Note. Loggerhead Shrikes have specific identification is not always bred once at Churchill, Manitoba.] R.D. James, Department of Ornithology, Royal Ontario Museum, 100 Queen's Park, Toronto. M5S 2C6. 19 ':··i.·~·:···· . Fig. 1. Drawings ofNorthern (above) and Loggerhead (below) Shrikes showing identification features and size differences. The Northern Shrike is 23 to 36 cm long (wing 108-120 mm) and the Loggerhead Shrike is 20 to 23 cm long (wing 91-102 mm). Both species of shrikes show would not arrive in the breeding range seasonal movements. Loggerhead of Loggerhead Shrikes before late Shrikes usually have left the province October but some may be earlier. for the south by mid-September but a Thus, during the autumn, both could few may linger even as late as De: , be seen in southern Ontario. Likewise cember. Northern Shrikes ordinarily in March and April particularly, 20 Loggerhead Shrikes may return to white feathers above the narrow black the province before the other species forehead which make the forehead has departed to the north. An ability appear unusually light. Very careful to distinguish these two similar observation is necessary if this fea species will add greatly to anyone's ture is used. confidence of field identification. Some field guides indicate that the Several features can be used to iden head of the Loggerhead Shrike is tify them but most of these must be noticeably darker than the back, but used with caution. in Ontario this is not the case. The The Northern Shrike is almost the back is seldom lighter than the head. size of a Robin while the Loggerhead Adult Northern Shrikes, unlike the Shrike is somewhat smaller. But they Loggerhead Shrike, may show some are sufficiently similar in size that light edgings to the wing coverts. unless the two are together, it is However, edgings may be worn and difficult to identify them on the be so small that they are scarcely basis of size alone (Fig. 1). The gray visible even at close range. color of the back of the Loggerhead Two of the best features to distin Shrike is darker than that of the guish these species are the bill (man Northern Shrike. This again would dible) color and barring on the breast. perhaps be useful only if the two Northern Shrikes have a pale-colored were together. There is very little lower mandible near the base, where white above the black mask on the as Loggerhead Shrikes have com Loggerhead Shrike and it is largely pletely black bills. The ROM has confined to the area in frorit of the several specimens of the Loggerhead eye. Thus, the rear part of the mask Shrike with a similar pale base to the shows little contrast to the crown lower manible, but all of these were color. In the Northern Shrike, how taken in the south or western U. S. A. ever, most of the white over the or in western Canada. These may be mask is behind the eye, creating a young of the year that have main strong contrast between the mask tained the typical bill color of a and the light gray head. juvenile while acquiring an adult In front of the eye, the black mask plumage. In Ontario, I have not seen of the Loggerhead Shrike covers any Loggerhead Shrikes in adult more area, but again this is only a plumage with a pale base to the relative difference. The black also lower mandible. I think you can be extends across the forehead over the very certain that if the base of the bill; the forehead of the Northern bill is pale, the bird is a Northern Shrike should appear white as there Shrike. is no black feathering over the bill. The breast of the Loggerhead However, the Loggerhead Shrike's Shrike is basically an unbarred and black bill·and the minimum amount very pale gray color. At very close of black feathering on the forehead range it might be possible to see may be very small, making it diffi some very faint, nearly straight, cult to distinguish between the feath transverse gray bars on the sides of ers 'behind the bill· and the bill- itself. the upper breast of some individuals, A further complication occurs be but these bars are scarcely darker cause there are often a number of than the overall breast color. The 21 breast of the Northern Shrike is summer and thus during the migra almost white, with numerous bars. tion period look like adults. The These bars are dark (not gray), are young Northern Shrikes retain a wavy, and usually cover most of the juvenal plumage for most of the breast and belly. You may have to be winter. In this plumage, they are relatively close to the bird to see this patterned as an adult but appear to barring as it is not very distinct. be more of a light brown rather than Also, I have seen adult Northern gray color. The barring on the breast Shrikes with virtually no barring, is heavier and extends up over the but any shrike with dark bars will be throat to the bill. Any brownish a Northern Shrike. looking shrike seen outside the The preceding characteristics summer season is sure to be a require a relatively close look at the Northern Shrike. If in doubt, check birds. There is one aspect of behav the throat, which is an unbarred white iour, however, that is visible at a in the juvenile Loggerhead Shrike. long distance and seems to be a very useful identification feature. When perched, the Northern Shrike repeat In summary, the key points used to edly flicks its tail up. The Logger distinguish Northern and Loggerhead head Shrike apparently never does Shrikes in the field include: the this, but holds its tail stiff. Is this a presence or absence of tail flicking, rule with no exceptions? the presence or absence of barring One additional problem is distin on the breast, the color of the base guishing juvenile birds but this pre of the lower mandible, the amount sents little difficulty. The young of black or white on the forehead Loggerhead Shrikes molt from over the bill, and the extent of white juvenal plumage by the end of the behind the eye over the mask. Plan now to take part in all OFO activities this spring/summer/autumn: 14/15 May • Pelee Week-end 22-28 September • Moosonee Field Trip 1 October • Lake Ontario Pelagic Trip 22/23 October • Annual General Meeting -London See pp. 39-40 for details.

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