Great grey shrikes are medium-sized, about the same size as thrushes and mockingbirds. Their upper parts are pearl grey. Their cheeks, chin and the stripe above their eyes are white. They have a dark mask from their beak to their cheeks. The space above their beak is grey. Their shoulder feathers are white and their wings are black with white tufts. Their tail is black and pointed at the tip. Their underbelly is white or grayish. Their legs and feet are black. Males and females are about the same size and color, females tend to be browner, but have the same overall color patterns. Fledglings resemble females, as they are greyish-brown all over. Fledgling also have yellow markings on their upper parts. Young shrikes get their adult plumage during their first spring. (Brady, et al., 2009; Brzezinski, et al., 2010; Harris and Franklin, 2000)
Great grey shrikes (Lanius excubitor) are found in North America, Europe, Asia and Africa. During their breeding season, they can be found in the northern United States, Canada, Norway, Spain, France, Poland, Sweden, Russia, China and other Eurasian countries. These birds spend the winter in the southern parts of the same countries and the northern continental United States. (Atkinson and Cade, 1993; Brady, et al., 2009; Cramp and Perrins, 1993; Hernandez, 1995; Peer, et al., 2011)
Great grey shrikes live in farmlands, field hedges, meadows and pastures as well as coniferous and mixed forests. Shrikes prefer lowlands and tend to avoid higher elevations. (Antczak, Marcin, 2010; Degen, et al., 1992; Kuczynski, et al., 2010; Olborska and Kosicki, 2004; Tryjanowski, et al., 2007)
Great grey shrikes are territorial, socially monogamous birds; however, because mating outside of their pairs happens sometimes, they are considered semi-polygynandrous. They begin courting each other in March and continue until April or May. Males attempt to attract females by performing several behaviors. Males face females and shiver and flutter their wings while calling or quietly singing, they may also offer a gift of food. Males also cache their food and impale their prey to entice females. Females usually reject males at first, but eventually females participate in the displays and their songs become duets. Before mating, males bob their body left and right, then give a food item to the female. Males closely guard their mate and perch high up to watch for threats. Clutches are usually produced within 10 to 15 days. Other adults may also assist by feeding the offspring; these "helpers" may be offspring from the previous year. (Antczak, et al., 2005; Antczak, et al., 2012; Lorek, 1995; Tryjanowski, et al., 2007)
Great grey shrikes breed during the summer, generally once per year, but if a replacement clutch is need they may breed twice in a year. During the breeding season, the monogamous pair bond is very strong, however, during the wintering season a new mate may be chosen. These birds nest in April and May. Mating pairs make the nests together in about one to two weeks, although nests from previous years are often reused with minor alterations. Generally nests are built 2 to 16 m above ground. Their nests are made of twigs, moss, pieces of fabric and sometimes pieces of trash; the nest is lined with twigs, roots, lichens, hairs and feathers. Eggs are usually layed in May, with an average of 7 eggs per clutch. Second clutches, if produced, are smaller than the first. Eggs are grey or blue and have yellow, red-brown and purple-grey blotches. Eggs are incubated by females for 16 to 21 days, during that time, males feed their mate. Hatchlings are naked, blind and pink-skinned. Offspring fledge after 2 to 3 weeks, usually in June or July, and become independent 3 to 6 weeks later, they become sexually mature during their first spring. (Harris and Franklin, 2000; Hernandez, 1995; Olborska and Kosicki, 2004; Tryjanowski, et al., 2007)
While females incubate the eggs, males provide food, this way females never have to leave the eggs. After the eggs hatch, females brood the offspring, as they age, females assist males in food provisioning. Weak fledglings receive extra care and feeding from either, or both parents. (Harris and Franklin, 2000)
Great grey shrikes usually live about four years, the oldest known individual lived twelve years. They are often hunted by birds and mammals; their greatest threat is from raptorial birds during their fledgling period. (Harris and Franklin, 2000)
Great grey shrikes are diurnal birds. They fly across large ranges and migrate seasonally to breeding and wintering grounds. They are territorial, but live in groups of about six or more pairs and become more solitary during the breeding season. After the breeding season, groups of breeding birds gather together and interact through flight displays, chattering and calling to one another. Great grey shrikes fly in a heavy, undulating pattern, but when attacking, they fly in a straight, determined direction. When encountering another member of their species, they show aggression by shifting to a horizontal position and fluffing their feathers, forming crests along their head. To show submission, they turn their head away or display a crouching, fluttering position while imitating a fledgling call. To prevent an attack, they point their beak vertically upward. (Antczak, et al., 2005; Harris and Franklin, 2000)
Groups of great grey shrikes tend to be about 5 km away from one another. They can have territories as small as 20 hectares, but 40 hectares are more common, territories as large as 350 hectares have also been reported. (Antczak, Marcin, 2010; Atkinson, 1997; Harris and Franklin, 2000; Olborska and Kosicki, 2004)
Great grey shrikes use vocalizations, body positions and food caches to communicate. Both male and female shrikes sing year round and use a variety of calls including alarm calls, courtship calls, submission calls, prey-attracting calls and nestling calls. Warning songs may consist of warbling strophes, whistles, long shrills and sharp whistles. Softer whistles are often used by males communicating with females and in duets between mates. To attract songbird prey, they also mimic calls, which may quite successful. When great grey shrikes encounter predators, or when they are preparing to attack prey, they perform aggressive body movements including bobbing, twisting and rapidly flipping their tail up and down. Quivering, fluttering and flashing movements are often responses to hunting preparation as well as reactions toward predators. Wing communication is also used during courtship-feeding. Males often quiver and flutter their wings before presenting females with food, when accepting food; females may quiver and flutter their wings in return. (Antczak, et al., 2012; Atkinson, 1997; Cade, 1962; Harris and Franklin, 2000; Probst, et al., 2002)
Great grey shrikes are carnivorous generalists. They search for prey by scanning the area and perching in an upright, alert posture and changing perches frequently. Once a prey item has been seen, they leave their perch and chase the animal. Once the prey is captured, great grey shrikes impale large prey items on stumps, thorns or barbed-wire, after which, the prey become easier to consume. Great grey shrikes cache prey items in thorny bushes to indicate claimed territory, attract females and hide it from competitors. They usually consume all of their prey within nine days. What they eat depends on where they live and the food sources available. In southern Europe, they eat mostly insects, whereas in northern and central Europe, mammals and birds are a larger portion of their diet. Their most frequent food items are beetles including ground beetles, dung beetles, rove beetles and darkling beetles. Other insects in their diet include bumblebees. They also eat many small mammals such as common voles, field voles, deer mice, harvest mice and wild house mice. Their avian prey includes dark-eyed juncos, white-crowned sparrows, black-capped chickadees, pine siskins, European starlings and house sparrows. Lizards and frogs are caught on occasion, but are frequently left in caches and not eaten. (Atkinson and Cade, 1993; Atkinson, 1997; Brzezinski, et al., 2010; Hernandez, 1995)
Predators of great grey shrikes include mammals and other birds. Members of family Corvidae have been known to prey upon their eggs and nestlings. Fledgling shrikes may be at risk from raptorial birds. Likewise, little owls are known predators of great grey shrikes. When predators approach, great grey shrikes vocalize and ruffle their feathers. These birds make various warning calls depending on the size and proximity of the predator. (Cade, 1962; Harris and Franklin, 2000)
In the past, nests of great grey shrikes were invaded by eggs from common cuckoos; however, these brood parasites are likely now extinct. There has also been one recorded case of interspecific helping, where yellowhammers were found feeding a great grey shrike fledgling, although great grey shrikes are larger. Some of the birds preyed upon by great grey shrikes avoid particular breeding grounds due to their presence. Since great grey shrikes are one of the first birds to occupy their territory in the spring, they may affect the other bird populations near their nests. (Drozdz, et al., 2004; Harris and Franklin, 2000; Hromada, et al., 2003; Hromada, et al., 2002; Peer, et al., 2011)
Great grey shrikes have no known negative impacts.
Great grey shrikes have no known positive impacts.
Great grey shrikes have an extensive range and are a species of Least Concern according to the IUCN Red List of Threatened Species. They have gone extinct in Switzerland and the Czech Republic, but their range is large enough to keep their overall population stable. They are impacted by changes in landscape and loss of habitat. There are often hundreds to thousands of great grey shrikes within each country they inhabit, with particularly large populations in Sweden. Only a few hundred birds or less are found in the following countries: Estonia, Belgium, Latvia, Lithuania, Netherlands and Denmark. (Harris and Franklin, 2000)
Theresa McHugh (author), Indiana University-Purdue University Fort Wayne, Mark Jordan (editor), Indiana University-Purdue University Fort Wayne, Leila Siciliano Martina (editor), Animal Diversity Web Staff.
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