The loggerhead shrike (Lanius ludovicianus) is a passerine bird in the family Laniidae. It is the only member of the shrike family endemic to North America; the related northern shrike (L. borealis) occurs north of its range, however it is also found in Siberia. It is nicknamed the butcherbird after its carnivorous tendencies, as it consumes prey such as insects, amphibians, lizards, small mammals and small birds, and some prey end up displayed and stored at a site, for example in a tree. Due to its small size and weak talons, this predatory bird relies on impaling its prey upon thorns or barbed wire for facilitated consumption. The numbers of loggerhead shrike have significantly decreased in recent years, especially in Midwestern, New England and Mid-Atlantic areas.
Taxonomy
In 1760 the French zoologist Mathurin Jacques Brisson included a description of the loggerhead shrike in his Ornithologie based on a specimen collected in Louisiana in the United States. He used the French name La pie-griesche de la Louisiane and the Latin Lanius ludovicianus. Although Brisson coined Latin names, these do not usually conform to the binomial system and are not recognised by the International Commission on Zoological Nomenclature. When in 1766 the Swedish naturalist Carl Linnaeus updated his Systema Naturae for the twelfth edition, he added 240 species that had been previously described by Brisson. One of these was the loggerhead shrike. Linnaeus included a brief description, adopted the binomial name Lanius ludovicianus (identical to Brisson's Latin name) and cited Brisson's work. The specific name ludovic is Late Latin for "Louis" and the epithet "-ianus" is to describe something being of another or possessed by it. When translated, its scientific name means something alongside the lines of "Louis’ butcher". "Loggerhead," a similar word to "blockhead," refers to the unusually large head to body ratio of this bird.
There are seven recognized subspecies:
L. l. excubitorides Swainson, 1832 – central Canada, central and west USA
L. l. migrans Palmer, W, 1898 – east North America
L. l. ludovicianus Linnaeus, 1766 – coastal southeast USA
L. l. anthonyi Mearns, 1898 – Channel Islands (off south California, southwest USA) L. l. mearnsi Ridgway, 1903 – San Clemente Island (off south California, southwest USA) L. l. grinnelli Oberholser, 1919 – extreme south California and north Baja California (northwest Mexico) L. l. mexicanus Brehm, CL, 1854 – west and central Mexico, south Baja California (northwest Mexico)
Miller, in 1931, suggested that the wing-chord-to-tail-length ratio was an important indicator for distinguishing between subspecies. Lanius ludovicianus migrans, found in eastern North America, can be distinguished from the western subspecies, L. l. excubitorides by wing length, tail length, and colour. L. l. migrans have a paler forehead than the top of the head. According to Mundy et al.’s 1997 study, there is a substantial genetic difference between the island subspecies L. l. mearnsi and the mainland subspecies L. l. gambeli due to a gene flow barrier between the two species.
Description
The loggerhead shrike is a medium-sized passerine. "Loggerhead" refers to the relatively large size of the head as compared to the rest of the body. The wing and tail length are about and long, respectively. It weighs on average , with a range of for a healthy adult shrike.
Measurement ranges
Length: Weight: Wingspan:
The adult plumage of the loggerhead shrike is grey above with a white to pale grey breast and black tarsi and feet. The bird possesses a black mask that extends across the eyes to its bill. The wings are black with a distinct white patch on the primaries. The tail is black edged with white and the irises are brown. The beak is short, black, and hooked, and contains a tomial tooth to help tear into prey. It is difficult to sex an adult loggerhead shrike in the field as they are sexually monochromatic. However, several studies have reported sexual dimorphism in plumage and size traits. Juveniles possess a paler gray plumage that is subtly vermiculated.
The loggerhead shrike can be distinguished from the northern shrike by its smaller size, darker grey plumage, and larger black face mask that covers the eye completely. It also has a shorter bill with less prominent hook. Their calls are similar.