Michigan warbler
| Michigan warbler | ||||||||||||
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Michigan warbler ( Setophaga kirtlandii ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Setophaga kirtlandii | ||||||||||||
| ( Baird , 1852) |
The Michigan wood warbler ( Setophaga kirtlandii , Syn . : Dendroica kirtlandii ) is a small bird from the genus of the wood warbler ( Setophaga ) in the family of the wood warbler (Parulidae). It is one of the rarest North American breeding birds. The IUCN classifies the Michigan warbler as near threatened .
The first known bird was shot on the farm of doctor and naturalist Jared Potter in Kirtland , Ohio , in May 1851 . This bird was completely unknown to Kirtland and he sent a sample to Spencer Fullerton Baird at the Smithsonian Institution . When the bird was described by Baird as a new species, he named it after Kirtland.
Distribution area
The Michigan warbler has one of the smallest continental breeding areas in the world. It covers a maximum of 516 square kilometers and was temporarily reduced to only 18 square kilometers. The breeding area is almost exclusively in the US state of Michigan ; the Michigan warbler only occasionally breeds in the adjacent part of Canada. The breeding areas were only discovered around 1900 when anglers happened to hear unknown bird calls.
The bird flies to the Bahamas to hibernate . Michigan warbler leave their breeding grounds in August and return in mid-May. The habitat changes in the wintering area prove to be problematic. However, it was not known for a long time where exactly the Michigan warbler hibernates in the Bahamas. In the meantime, however, it has been found that a larger number of this species can be found on the island of Eleuthera . Further studies are currently taking place with the aim of protecting the main wintering areas of this species more effectively.
habitat
The highly specialized songbird makes great demands on its habitats. It only breeds in the bottom of young specimens of Banks Pine ( Pinus banksiana ), a species of pine that occurs exclusively in northern North America. Ideally, these are pure stocks that usually only occur on sandy soils. The Banks pines must not be older than 15 years and be between two and four meters high. When the pine trees reach this size, the Michigan warbler will leave the area in search of younger trees. In the distribution of the Michigan wood warbler, there must be other, previously unknown location factors, because the bank pine is widespread in North America, but the Michigan wood warbler occurs only in a very small part of this distribution area.
It is now known that regular wildfires in the breeding areas of the Michigan warbler are necessary in order to preserve the species. The Banks pine needs fire to rejuvenate its stocks. While the older trees are destroyed in a forest fire, the pine cones only open and release their seeds at temperatures above fifty degrees Celsius. These can then germinate on the areas that have become free and form the young stocks on which the Michigan warbler depends. Today, in the regions that the Michigan warbler inhabits, the forests are specifically managed and the forest fire effect is simulated so that sufficient habitats are available for this bird.
features
Michigan warbler reach a body length of about 15 centimeters. The male has a blue-gray upper side plumage interspersed with black stripes. The underside plumage is light yellow and interspersed with gray to black stripes on the flanks. There are two pale white wing rods on the wing covers. The female has an overall duller plumage. The Michigan warbler wears a broken white eye ring around the eye. When the bird sits, it bobs up and down with its tail.
Reproduction
The male arrives in the breeding areas first. Normally, the male colonizes the same breeding area as in the previous year and immediately begins to sing in order to demarcate his territory from other conspecifics and to attract a female. The breeding season begins in late May and lasts until mid-June. The bowl-shaped nest on the sandy ground, made of grass, leaves, moss and hair, is built together. A clutch consists of three to six eggs. Two clutches are rarely hatched in the breeding season. In the second incubation, however, a clutch contains fewer eggs than in the first. The female incubates the eggs alone over a period of about 14 to 15 days. The young hatch after about twelve to thirteen days. Both adult birds take part in the rearing. The young birds put on weight quickly for the first five days and then double their weight every two days.
Threat and protection
The Michigan warbler was threatened by the brood parasitism of the brown-headed cowbird ( Molothrus ater ). When the Europeans settled North America, forests were burned to gain pasture and other usable land. Previously, the brown-headed cowbird was mainly to be found in the prairies, where it followed the large herds of bison and devoured the seeds that were thrown up and insects that were scared off. Due to the optimal conditions of colonization, it increased its range in North America north and south and settled in the newly created habitats. In the 1960s, more than 70% of the Michigan warbler 's nests were parasitized by the brown-headed cowbird. In the early 1970s, brown-headed cowbirds were specifically killed along the route through a protection program and the habitats placed under protection. As a result, brood parasitism has decreased to below 3%.
Every year a count is made by volunteers between June 6th and June 15th. The singing males are counted and multiplied by two. The counts were initially only made in 1951, 1961 and 1971 and were made annually from 1971 onwards. The researchers believe that the birds have other problems during migration and in the winter areas of the Bahamas. The Michigan wood warbler population declined to about 60% between 1961 and 1971. In 1987 only 167 males were counted. From 1996 onwards, a slow increase in stocks could be demonstrated. While there were 692 males in 1996, the number rose to 733 in 1997 and to 805 in 1998.
swell
literature
- Dominic Couzens : Rare Birds - Survivors, Evolution Losers and the Lost. Haupt Verlag, Bern 2011, ISBN 978-3-258-07629-4 .
- Jon Curson, David Quinn, David Beadle: New World Warblers. Helm, London 1994, ISBN 0-7136-3932-6 .
Web links
- Elaine Carlson: Michigan's Kirtland's Warbler Population Continues to Grow. State of Michigan - Department of Natural Resources, September 5, 2007, archived from the original on December 23, 2007 ; Retrieved May 10, 2013 .
- Kirtland's Warbler (Dendroica kirtlandii). State of Michigan - Department of Natural Resources, accessed May 10, 2013 .
- Setophaga kirtlandii in the Red List of Threatened Species of the IUCN 2008. Posted by: BirdLife International, 2008. Accessed January 31 of 2009.
- Videos, photos and sound recordings for Setophaga kirtlandii in the Internet Bird Collection