Black-backed woodpecker
| Black-backed woodpecker | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Black- backed woodpecker ( Picoides arcticus ) |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Picoides arcticus | ||||||||||||
| ( Swainson , 1832) |
The black -backed woodpecker ( Picoides arcticus ) is a medium-sized woodpecker from the genus Picoides within the subfamily of the real woodpeckers (Picinae). As with its close relatives, the spruce woodpecker ( Picoides dorsalis ) and the three- toed woodpecker ( Picoides tridactylus ), the backward-facing first toe, which is present in most other climbing woodpeckers, but largely functionless, is not developed.
The black-backed woodpecker occurs in northern North America in a wide belt from the Pacific to the Atlantic coast . While the species is nowhere common, it does not appear to be endangered at this time. No subspecies are described.
Appearance
Black- backed woodpeckers are about the size of a great spotted woodpecker . Males can grow to a length of 25 centimeters and a body weight of over 70 grams. The wingspan is just over 40 centimeters. Females are insignificantly smaller and lighter.
The upper side of this species of woodpecker is uniformly deep black. White drawings are missing. The underside is pure white, the flanks are banded in black. The wrist wings are lined with white, the outer control springs are white, the inner ones are unbanded and black. The head is also almost uniformly black. From the upper beak base, a narrow, but mostly distinctive white stripe runs slightly downwards, almost to the neck. Behind the eye, a narrow white stripe can only be seen up close and not in all individuals. The iris is dark gray, beak, legs and toes are slate gray.
In flight, black-backed woodpeckers appear largely black from above, while the bright, light underside and the very narrow, white banded wing surfaces are noticeable from below. The flight itself is a typical arched woodpecker flight.
The sexes differ only indistinctly in size and weight; the only definite distinguishing feature is the bright yellow crown of the male. This head area is uniformly black in the female. Up to the first full moult, the plumage of the young birds is less shiny in the black areas and matt grayish white on the underside. It is hardly possible to determine the sex of young birds outdoors, as both sexes usually have yellow apex plates.
Vocalizations
The presence of black-backed woodpeckers can usually only be determined by their hoes and their vocalizations. In the pre-breeding season, this type of woodpecker is acoustically noticeable both through its calls and drums, but afterwards it behaves very quietly. The calls are not far-reaching, however, and mainly consist of squashed chirping and scraping elements, which first rise in pitch and then fall. During the performance of this sequence, which both sexes express in antagonistic as well as in sexually determined situations, the head is stretched forward and waved. In addition, a series of croaking and metallic scratching calls can be heard.
Both sexes drum intensely in the pre-breeding season. The drum rolls contain up to thirty beats with a duration of about 2 seconds. Their frequency is significantly higher than that of the spruce woodpecker, which also drums very intensely.
Possible confusion
The black-backed woodpecker is very similar to the closely related spruce woodpecker, with which it shares large areas of its range. Black-backed woodpeckers are slightly larger, but these differences in size are not sufficient for a reliable distinction. The best distinguishing feature is the individually different amount of white in the back coloring of the spruce woodpecker; this is lowest in the eastern subspecies P. bacatus , but is not completely absent in any subspecies. Up close, the drawing of the outer rudder feathers and that of the yellow faceplate can serve as a good indication of differentiation: in the black-backed woodpecker, the outer rudder feathers are unbanded white, in the spruce woodpecker are banded black; the front plate of the spruce woodpecker is striped black at its edges, the black-backed woodpecker is distinctly separated from the rest of the black head plumage. The white stripe behind the spruce woodpecker is usually clearer and longer than that of the black-backed woodpecker, which can also be absent.
Black- backed woodpeckers, which occasionally occur in other species of woodpecker such as the downy woodpecker , can resemble the black- backed woodpecker , but should be able to be differentiated from it simply because of its smaller size.
distribution
The black-backed woodpecker is widespread in northern North America. Its occurrences range from Alaska in the west in a wide belt east to Newfoundland . The southernmost distribution areas are from west to east in northern and central California , in northern Wyoming and Wisconsin , in the Black Hills of South Dakota , and in the northern areas of the states of New York and Maine . The black-backed woodpecker does not occur in the central and southern areas of the Rocky Mountains .
The main distribution area of the black-backed woodpecker is in the submontane and montane zones. In the Rocky Mountains it also penetrates the subalpine zone, where breeding occurrences near the tree line around 3000 meters are known. Especially in the east of its range, it is also found in lowland areas and at sea level.
habitat
The species is largely, but not exclusively, bound to boreal and montane coniferous forests that have been damaged by fire or wind breaks. It follows the mass reproductions of wood-boring beetle species that often follow such events. Black-backed woodpeckers can then immigrate to areas where they have been absent for decades.
The tree composition of its habitat is very variable; a particular preference for a particular tree species cannot be established. The species mostly inhabits forests made up of various species of spruce, pines, larches and, in the area of the Great Lakes, also trees of life .
Black-backed woodpeckers are among the first birds to repopulate fire-damaged forest areas, often just a few months after the forest fire. In addition to the downy woodpecker and the spruce woodpecker, they are among those species of woodpecker that particularly benefit from such events. They usually stay in these regions for a few years before moving on. Areas with old, natural coniferous forests as well as fire or windthrow areas or clearings resulting from logging are preferred. Standing and lying dead wood is an essential requirement of a suitable habitat. The species also breeds in undamaged, natural coniferous forests, but does not reach the settlement densities there as in the optimal habitats affected by fires or storms.
There is only a few meaningful information on the size of the area. Black-backed woodpeckers are likely to have a relatively large space requirement. In Idaho 72 hectares were determined in Oregon 124 hectares and in Vermont 61 hectares. The space required by this species of woodpecker increases significantly as the time lag behind the fire event increases and can ultimately be over 500 hectares.
hikes
Black-backed woodpeckers do not seem to undertake regularly recurring migrations, but are nonetheless highly mobile and able to migrate irruptively over long distances. They mostly follow mass reproductions of various wood-boring beetle species. This species of woodpecker also migrates very quickly into forest fire areas, usually even if there were no breeding occurrences in the wider area before. Irruptive migratory movements can lead the species relatively far south, so in 1974/75 more than 400 black-backed woodpeckers whose breeding areas were in southern Québec and Ontario were found almost 600 kilometers south in Pennsylvania .
In unfavorable weather and food conditions , black-backed woodpeckers seem to move relatively quickly and variably in direction to more favorable areas. They can then also appear in urban areas and parks.
Food and subsistence
Black-backed woodpeckers are specialized woodpeckers whose diet mainly consists of larvae of longhorn beetles and jewel beetles . In addition, regionally other wood pests, such as the mountain pine beetle and its larvae, can play a major role. Other invertebrates such as weevils , cicadas , aphids , ants , butterflies and spiders are quantitatively insignificant . Vegetable food in the form of berries, fruits and tree seeds is consumed, but makes up less than 10 percent of the total amount of food.
Most of the food is obtained by chopping and drilling. Black-backed woodpeckers loosen the bark of the food trees over a large area and then hammer open the feeding tunnels of the wood-dwelling beetle larvae. The detached pieces of bark are often an important indicator of the presence of this species of woodpecker. Fire-damaged trees that are very quickly colonized by wood pests are preferred. Searching trunk and branch surfaces as well as hunting on the ground play only a subordinate role in the food acquisition strategies of this species.
behavior
Like all real woodpeckers, black-backed woodpeckers are diurnal. However, there are no observations on activity peaks and rest breaks, and detailed information on comfort behavior is also lacking. A small study from Oregon suggests that black-backed woodpeckers are more likely to spend the night in sheltered places outdoors than in a sleeping den. During the pre-breeding season and the breeding season, black-backed woodpeckers maintain at least the core zones of their mostly very large territories both against their conspecifics and against competitors for food and caves. No information is available about the territoriality outside the breeding season. Behavioral elements in antagonistic situations are the typical woodpecker threatening gestures such as protruding the head, swinging the head and flapping wings, often accompanied by various short and shrill calls and drums. Occasionally, direct physical attacks occur, especially in the immediate vicinity of the cave tree.
In addition to their conspecifics, black-backed woodpeckers are also very aggressive towards other woodpecker species such as the hairpecker , the white-headed woodpecker and the spruce woodpecker . In direct disputes with the hairpecker, the black-backed woodpecker is usually inferior, while it can usually prevail against the other two species of woodpecker. The black-backed woodpecker also reacts very sensitively to the presence of species from the species of the cottage warbler , as well as to that of swallow swallows . The European star does not yet play a major role as a nesting site competitor.
Breeding biology
Black-backed woodpeckers reach sexual maturity at one year and usually start brooding at this age. They lead a largely monogamous seasonal marriage, there may also be loose cohesion outside the breeding season. No information is available on courtship behavior of this species.
The construction of the nest caves begins at the end of March at the earliest, but usually not until April and can last until May. Probably a new nest box is built every year, in the construction of which the male is a little more involved than the female. The types of cave trees are very different, if possible softwood, rotten - or dead, already decaying trees are selected. The circular entrance hole is an average of 10 meters high, almost always in the trunk area.
The main laying time is in May. The earliest clutches were found in the second half of April, the latest, which are most likely new clutches, in mid-July. A full clutch that is incubated by both parents usually consists of 3–4 (2–6) round, pure white eggs, with an average size of 21.3 × 19 millimeters. The length of the breeding season is not known; for woodpeckers of similar size in similar habitats it is between 12 and 14 days. The nestling period is around 24 days, during which the young are provided with food, mainly insect larvae, by both parents. After leaving, the boys follow their parents for a while, often in two groups. No information is available on the average duration of the lead time and the subsequent dismigration .
Systematics
The black -backed woodpecker , together with the spruce woodpecker ( Picoides dorsalis ) and the Eurasian three- toed woodpecker ( Picoides trydactylus ), form the group of medium-sized three- toed woodpeckers that are widespread in the Holarctic boreal zone. Within the group of Holarctic great spotted woodpeckers ( Picoides / Dendrocopos ), apart from the three-toed species mentioned above, it is more closely related to the East Asian four-toed species such as the Kizuki woodpecker ( Dendrocopos kizuki ) or the Scopolis woodpecker ( Dendrocopos maculatus ). The genetic distance to other nearctic picoides is somewhat greater.
The black-backed woodpecker is monotypical . The sometimes described slender-beaked subspecies P. tenuirostris from the Cascade Mountains is not generally recognized.
Stock situation
Due to the inconsistent distribution characteristics of this species, the stock situation is difficult to assess, but is generally considered stable. Regionally significant decreases in stocks contrast with increases in stocks in other areas. The species does not currently appear in any national endangerment list. The total population is estimated at over 1.3 million individuals.
Better fighting of forest fires, but above all rigorous clear-cutting after forest fires, are the main causes of danger, in addition to general habitat destruction and large-scale use of insecticides to combat tree-damaging insects.
Individual evidence
- ^ Dixon & Saab (2000) BNA / Measurements
- ↑ Stark (Diss. 2002) p. 289
- ^ Dixon & Saab (2000) BNA / Distinguishing Characteristics
- ↑ Michigan Natural Features Inventory Text Engl. ( Memento of the original from March 4, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ Dixon & Saab (2000) BNA / Home Range
- ^ Dudley (2005)
- ^ Dixon & Saab (2000) BNA / Irruptive Movements
- ^ Dixon & Saab (2000) BNA / Behavior
- ^ Dixon & Saab (2000) BNA / Nonpredatory Interspecific Interactions
- ↑ a b c Dixon & Saab (2000) BNA / Breeding
- ↑ Weibl & Moore (2202) p. 71
- ↑ Birdlife international - Factsheet engl.
literature
- Rita D.Dixon, Victoria A. Saab (2000): Black-backed Woodpecker (Picoides arcticus) . In: The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology species / 509.
- Jonathan G. Dudley: Home Range Size and Foraging Habitat of Black-Backed Woodpeckers Diploma Thesis 2005 - Boise State University Text engl. (PDF; 970 kB)
- Robert D. Stark: An Analysis of Eastern Nearctic Woodpecker Drums . Diss. 2002 Ohio State University Text Engl
- Amy C. Weibel, William S. Moore: Molecular Phylogeny of a Cosmopolitan Group of Woodpeckers (Genus Picoides) Based on COI and cyt b Mitochondrial Gene Sequences. In: Molecular Phylogenetics and Evolution , Vol. 22, No. 1, January, pp. 65–75, 2002. Article pdf engl.
- Hans Winkler , David Christie, David Nurney: Woodpeckers. A Guide to Woodpeckers, Piculets, and Wrynecks of the World. Pica Press, Robertsbridge 1995, ISBN 0-395-72043-5 .
Web links
- Picoides arcticus inthe IUCN 2013 Red List of Threatened Species . Listed by: BirdLife International, 2012. Retrieved October 6, 2013.
- Good summary and sound file
- Michigan Natural Features Inventory (PDF file; 518 kB)