Louisiana strangler
| Louisiana strangler | ||||||||||||
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Louisiana strangler ( Lanius ludovicianus ) |
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| Scientific name | ||||||||||||
| Lanius ludovicianus | ||||||||||||
| Linnaeus , 1766 |
The Louisiana strangler ( Lanius ludovicianus ) is a bird of the strangler family . It is one of the endangered bird species. Its population has declined mainly due to habitat loss and the use of pesticides . Due to the overall large population and the very large distribution area, the Louisiana strangler is generally classified as not endangered. However, protective measures have been taken for individual subspecies.
The Louisiana strangler is the only representative among a total of about 30 species of strangler that occurs exclusively in North America.
Appearance
Louisiana stranglers reach an average body length of 23 centimeters. They are characterized by a large, hook-shaped beak. The head and back are gray feathered. The wings and tail are black with white feathers on the wings and on the outer tail feather. The black face mask also expands above the beak. This is how it differs from the gray shrike , which it is otherwise very similar.
Young birds are lighter than the adult birds and generally slightly brownish with fine horizontal stripes all over their bodies.
Habitat and Reproduction
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The Louisiana strangler is a bird native to the North American continent. Its breeding ground covers the semi-open regions in southern Ontario , Québec and Alberta and extends as far as Mexico. The species nests in leafy trees or bushes. The female lays four to eight eggs in a large, bowl-shaped nest made of twigs and grass.
In the southern distribution area the Louisiana strangler is a resident bird. The populations living in the northern range migrate further south during the winter half-year. Where Louisiana stranglers are resident birds, they usually occupy fixed territory as a pair, which they defend year-round.
Hunting Behavior and Food
The typical form of hunting for the Louisiana stranglers is high seat hunting. From a vantage point, they observe their surroundings and from there come down on their prey. They mainly eat larger insects as well as rodents and smaller bird species. They spear their prey on thorns because they lack the claws that are common to falcons, for example .
Island gray fox and Louisiana shrike: conflicting goals of conservation
One of the subspecies of the Louisiana shrike , the so-called " San Clemente shrike " , breeds on San Clemente Island , which belongs to the Channel Islands of California . This island, which serves as the United States Navy military base , is also home to one of the subspecies of the island gray fox . This endemic fox species, which developed from the gray fox and has typical island dwarfing , is also very endangered. The island gray foxes, whose peculiarities are to climb trees, eat birds, among other things, and the breeding Louisiana stranglers also belong to their range of prey. By the year 2000, the Navy caught and killed the foxes living on San Clemente in order to protect the Louisiana strangler. Since 2000, conservationists have been pointing out that the island gray fox is also massively threatened as a result of human habitat encroachment. The Navy then changed its protective measures in favor of this subspecies of the Louisiana strangler. The foxes are still captured but are now kept captive during the breeding season. The shrike's breeding grounds are also protected by building electric fences around them to keep the foxes away.
Subspecies
A total of 10 subspecies are distinguished, which differ slightly in their beak shape and plumage color.
- Lanius ludovicianus anthonyi
- Lanius ludovicianus excubitorides ,
- Lanius ludovicianus gambeli
- Lanius ludovicianus grinnelli
- Lanius ludovicianus ludovicianus
- Lanius ludovicianus mearnsi , San Clemente shrike, classified as Endangered.
- Lanius ludovicianus migrans , rare to very rare in the Midwest and the Northeast of the United States, classified as Endangered in Canada.
- Lanius ludovicianus nelsoni
- Lanius ludovicianus sonoriensis
In order to stabilize the subspecies Linius ludovicianus migrans in eastern Canada, a captive population was established at both the Toronto Zoo and McGill University in 1997. In 2001, Louisiana stranglers raised in captivity were released under a Wildlife Preservation Canada program . For this purpose, breeding pairs from the holdings of the Toronto Zoo and McGill University in Ontario were kept in large fenced off habitats. Young birds that grew up there were released into the wild at a time when they would have emigrated from the breeding area of the parent birds even under normal living conditions. Around 90 young birds have been released annually since 2004. Between 2 and 6.5 percent of these young birds migrated to wintering areas and returned to hatch the next year.
literature
- Jonathan Alderfer (Ed.): Complete Birds of North America , National Geographic, Washington DC 2006, ISBN 0-7922-4175-4 .
Web links
- Videos, photos and sound recordings of Lanius ludovicianus in the Internet Bird Collection
- Lanius ludovicianus inthe IUCN 2013 Red List of Threatened Species . Listed by: BirdLife International, 2012. Retrieved November 23, 2013.
Single receipts
- ^ IUCN entry for Louisiana stranglers , accessed May 17, 2015
- ↑ a b Cornell Lab for Ornithology , accessed May 15, 2015
- ↑ a b c d e Jonathan Alderfer (Ed.): Complete Birds of North America , National Geographic, Washington DC 2006, ISBN 0-7922-4175-4 . P. 407
- ↑ Wildlife Preservation Canada on the Louisiana Sanguine Resurrection Program , accessed May 15, 2015