Loggerhead Shrike (Lanius ludovicianus)

Description
Loggerhead Shrike

Size

  • A medium-sized songbird, slightly smaller than a robin.
  • Males and females are similar in size, measuring about 23 centimetres (9 inches) long.

Appearance

  • Plumage is grey above and white below.
  • A black mask runs from behind the shrike's eyes to the beak and across the forehead, and acts to reduce glare that might impair the bird's ability to see prey in bright sunlight.
  • The only truly predatory songbirds, shrikes possess beaks similar to those of birds of prey, with a hook at the end and tooth-like structures on the upper mandible to kill prey.
  • Males and females have similar markings and cannot be distinguished easily in the field.

Voice/Call

  • During the summer, call is a quick hugh-ee hugh-ee, or an infrequent, harsh shack shack.
Distribution
  • Over the past 40 years, the loggerhead shrike's range has become smaller and shifted southward because of habitat changes.
  • The species has disappeared from most of eastern Canada and its distribution is now patchier in the north-central and southeastern United States.
  • On the Canadian prairies, loggerhead shrike populations are comparatively more abundant locally despite a similar southward shrinking of the breeding range.
  • The loggerhead shrike currently breeds from southern Alberta, Saskatchewan and Manitoba, south to Mexico, and winters from Kansas to Mexico.
  • The Alberta breeding range has also become smaller and shifted southward and loggerhead shrike numbers have declined. However, the rate of this decline has slowed, and the population appears to have stabilized in the last decade.
  • Today, at least 3000 pairs of loggerhead shrikes are found in Alberta, mainly in the Grassland Natural Region.
Natural History

Habitat

  • The loggerhead shrike requires a combination of open, grazed areas adjacent to nesting and perching sites, and dense ungrazed vegetation that provides habitat for potential prey.
  • Abandoned farmsteads, roadsides, shelterbelts and railway rights-of-way provide suitable habitat.

Food

  • In Alberta, loggerhead shrikes prey includes:
    • Beetles and other invertebrates
    • Crickets
    • Grasshoppers
    • Horned larks
    • Juvenile ground squirrels
    • Lark buntings
    • Mice and voles
    • Vesper sparrows
  • During the breeding season, most of the items in the diet are insects, whereas in winter, half the prey items may be small rodents.
  • Vertebrate prey such as small rodents and songbirds are relatively large and those eaten during the breeding season may be critical for successful reproduction.
  • Shrikes sometimes impale various types of prey on thorny trees, shrubs and barbed wire. This behavior is the basis for the term butcher bird, another common name given to the loggerhead shrike.
  • Impaling dead prey has several functions:
    • The shrike is a songbird without strong talons, so using thorns or barbs helps the shrike to hold on to larger prey while it is torn into bite-size pieces with the strong hooked bill.
    • Impaled prey are also an emergency food source used by shrikes when fresh prey are unavailable (such as during bad weather or on a cold morning).
    • Impaling prey also appears to be part of a courtship display that lets a female know that this male's territory does indeed contain prey and, perhaps more importantly, that he can provide it.
    • Caching prey by impaling it nearby allows the female to remain close to the nest and protect her young.

When Active

  • Most loggerhead shrikes arrive in southern Alberta during the first week of May and begin their return journey south by the end of August.
Reproduction and Growth

Breeding Behaviour

  • Dense shrubs are used for nesting; usually thorny buffaloberry, common caragana or willows, and occasionally Manitoba maple and poplar.
  • Usually 6 to 7 yellowish white speckled eggs are laid in the last few weeks of May.
  • Incubation takes approximately 16 days and most hatching occurs during the first two weeks of June.
  • Only the female incubates the eggs. The male finds food and feeds her until the eggs hatch, after which both parents provide prey to the young.

Growth Process

  • After 16 days, the chicks leave the nest, and by 21 days, they are making short flights.
  • At approximately 35 days, the young are independent and forage for themselves.
Conservation and Management

Status

Loggerhead shrike are classified as Sensitive in the current General Status of Alberta Wild Species report. See:

Also see the Status of the Loggerhead shrike in Alberta report at:

In a subsequent detailed status assessment, Alberta's Endangered Species Conservation Committee identified the Loggerhead shrike as a Species of Special Concern—a species that without human intervention may soon become threatened with extinction. See information on the Endangered Species Conservation Committee and Species of Special Concern at:

Issues

  • Habitat loss and fragmentation on the breeding grounds pose the greatest threats to the loggerhead shrike.
  • Intensive agricultural practices have converted native grassland with shrubs and shelterbelts to cultivated fields, resulting in the loss of suitable breeding and wintering habitats.
  • Other threats to this species include:
    • Pesticide contamination
    • Mortality on the wintering grounds
    • Climate change
    • Increased predation upon shrikes near roadsides and fencerows
    • Increased competition with similar species
    • Human-caused disturbance while nesting

Current management

  • Under Alberta's Wildlife Act, the Loggerhead shrike is designated as a non-game animal. It is illegal to kill or harass individuals or disturb their nests at any time of the year.
  • A detailed inventory is carried out for this species every five years in Alberta.

 

Page Information

Updated: Jan 8, 2014