Spruce woodpecker

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Spruce woodpecker
Spruce woodpecker, male

Spruce woodpecker, male

Systematics
Class : Birds (aves)
Order : Woodpecker birds (Piciformes)
Family : Woodpeckers (Picidae)
Subfamily : Real woodpeckers (Picinae)
Genre : Picoides
Type : Spruce woodpecker
Scientific name
Picoides dorsalis
Baird , 1858

The American three-toed woodpecker ( Picoides dorsalis ) is a species of bird from the family of woodpeckers (Picidae). The distribution area of ​​this rather small woodpecker species covers large parts of northern North America. The species inhabits the boreal coniferous forest and especially old spruce forests with a lot of dead wood . However, it also shows a very strong preference for fresh burn areas. The food that is mainly sought on dead trees consists mainly of wood-dwelling beetles and their larvae; the animals also use tree sap on sap rivers. Overall, the species is not common, but the IUCN classifies it as “least concern”.

features

Spruce woodpeckers are quite small woodpeckers with a long, chisel-shaped, pointed beak that is very broad at the base. The ridge of the beak is straight. The species has only three toes per foot. The body length is about 22 cm. Birds of the subspecies P. d. fasciatus weigh 47-65 g; they are therefore somewhat smaller and lighter than a great spotted woodpecker . Like most woodpecker species, the species shows a clear sexual dimorphism in terms of coloration; males are also somewhat larger and, depending on the subspecies, 8 to 11% heavier than females.

In birds of the nominate form , the middle upper back (coat), the middle and lower back and the innermost shoulder feathers are white with indistinct black banding or dotted lines. The sides of the upper back, the remaining shoulder feathers, the upper wing coverts and the upper tail coverts are dark brown-black. The wings show white spots of different sizes on a brownish black background, which are largest on the inside flags and form clear white bands on the wings. The top of the tail is black, the outer three pairs of control feathers are increasingly white from the inside out. The sides of the neck are black, this black coloration becomes irregular on the sides of the chest and abdomen and ends there in dark lines. The throat and the entire rest of the body are white, in the fresh plumage with a light reddish cream color. The flanks and the under tail-coverts are clearly black and slightly banded like arrowheads. The wings are banded gray and white underneath, the underside of the tail is colored like the upper side.

The beak is ash gray, darker at the tip and lightened at the base of the lower mandible. The legs and toes are ash gray. The iris is deep dark red or brownish red.

Female spruce woodpecker

The male's forehead is black with white spots. The middle skull is brass yellow or pale lemon yellow, usually interspersed with individual black or white feather bases. The rest of the head and the neck are predominantly one color, glossy black. A narrow white stripe above the eye begins behind the eye , which widens towards the rear and runs over the rear sides of the neck to the upper back. A second white band runs from the base of the beak to the front sides of the neck, so that the beard stripe is sharply blackened again. The female has no yellow markings on the top of the head; in this area, like the forehead, the head is monochrome black with white spots and dashes.

Vocalizations

A number of calls are known for the species, including a single high "kip" , which is ranked when threatened: short, rattling calls such as "kri-kri-kri" and series of "twuit" sounds uttered at intraspecific encounters . The begging cry of the young birds is a constant chirping. Both sexes drum, the drum roll gets faster at the end.

distribution

Distribution area of ​​the spruce woodpecker

The distribution area of ​​the spruce woodpecker covers large parts of northern North America. It stretches across the North American continent from Newfoundland to Western Canada and Alaska and also extends over the Rocky Mountains south to Arizona and New Mexico . The size of the distribution area is estimated at around 7.9 million km².

Systematics

In addition to the nominate form, two other subspecies are recognized:

  • Picoides dorsalis bacatus Bangs , 1900 ; largest part of the distribution area, from Alberta to the east to Labrador and Newfoundland , to the south to Minnesota and New York . Smallest and darkest subspecies. The entire back is almost black with only a few white bands or spots, the underside of the trunk is more darkly banded than in the nominate form , the white head markings are significantly narrower and the stripe above the eyes is interrupted or even missing entirely.
  • Picoides dorsalis fasciatus Baird , 1870 ; Northwest North America from Alaska and Yukon south to Oregon . Smaller than the nominate form, the color is intermediate between the two aforementioned subspecies. The back is strongly cross-banded in dark, the white head markings are narrower than in the nominate form.

The three subspecies were previously considered to be subspecies of the very similar Eurasian three-toed woodpecker. In a molecular genetic investigation of the mitochondrial DNA , however, it was found that the Eurasian and North American subspecies each form clearly demarcated monophyletic groups and that the genetic distance is sufficiently large to give both groups species status. The North American subspecies were therefore separated from the three- toed woodpecker as a separate species, Picoides dorsalis .

Fresh burn areas, like here in Glacier National Park in Montana , are a preferred habitat of the spruce woodpecker

habitat

The species inhabits the boreal coniferous forest and especially old spruce forests with a lot of dead wood . However, the spruce woodpecker shows the highest densities on fresh forest fire areas with numerous trees that have recently died from the fire. There it comes to mass reproductions of wood-dwelling beetles, which form the main food of the spruce woodpecker; they also offer numerous trees for cave construction. At least in the northern Rocky Mountains, the species is apparently largely restricted to such fire areas; a few years after the fire incident, the population density on these areas is again decreasing significantly.

nutrition

The food is mainly obtained by chopping and hammering on the trunks and larger branches of dead trees, only rarely by poking or reading. The animals chop holes in the wood and remove bark, especially with side blows, often a tree is visited over several days and then completely debarked. The food mainly consists of wood-dwelling beetles and their larvae, which is also primarily the nestling food. Spruce woodpeckers eat ant larvae and imagines or spiders less frequently . The species is a main enemy of beetles, which can cause damage in forests during mass reproduction, e.g. B. of the bark beetle Dendroctonus obesus . Spruce woodpeckers also use tree sap on sap rivers; other plant foods such as berries and spruce seeds are only consumed occasionally.

Reproduction

Spruce woodpeckers breed in single pairs. The courtship begins hesitantly in mid-March, the peak of the courtship is reached from mid-April to mid-May. The caves are created mostly still intact trunks of dead conifers, rare in broken stems or stem rot living conifers and only occasionally in deciduous tree trunks. In two investigations, the caves were on average 5.2 and 7.7 m high. Both sexes participate in cave construction. Clutches were found between May 18 and June 16; they contain three to seven, usually four eggs, which are incubated by both partners for 12 to 14 days. The nestlings are fed by both parents. Information on the duration of the nestling period is not available, nor is there any data on the period of dependence on the parents or on the flight out.

Existence and endangerment

The species is not considered common, with an estimated world population of around 800,000 individuals. There are no reliable data on population trends, but the strong intensification of forest use and the associated suppression of fires and the removal of dead wood have probably led to a decline in the population. Overall, the IUCN classifies the species as “least concern” due to its large distribution area and large population .

Individual evidence

  1. ↑ Leonard, Jr., David L. 2001: American Three-toed Woodpecker (Picoides dorsalis): Measurements. The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from Birds of North America Online : http://bna.birds.cornell.edu/bna/species/588 , doi : 10.2173 / bna.588 .
  2. ↑ The Spruce Woodpecker at BirdLife International
  3. ^ Robert M. Zink, Sievert Rohwer, Sergei Drovetski, Rachelle C. Blackwell-Rago and Shannon L. Farrell: Holarctic Phylogeography and Species Limits of Three-Toed Woodpeckers. Condor 104, 2002: pp. 167-170
  4. ↑ The spruce woodpecker at Avibase
  5. ↑ RL Hutto and SM Gallo: The effects of postfire salvage logging on cavity-nesting birds. The Condor 108, 2006: pp. 817-831
  6. ↑ Leonard, Jr., David L. 2001: American Three-toed Woodpecker (Picoides dorsalis): Breeding. The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from Birds of North America Online : http://bna.birds.cornell.edu/bna/species/588 , doi : 10.2173 / bna.588 .
  7. ↑ The Spruce Woodpecker at BirdLife International

literature

  • Hans Winkler , David A. Christie and David Nurney: Woodpeckers. A Guide to the Woodpeckers, Piculets, and Wrynecks of the World. Pica Press, Robertsbridge 1995, ISBN 0-395-72043-5 , pp. 108-109 and 293-295.

Web links

Commons : Spruce Woodpecker ( Picoides dorsalis )  - Collection of images, videos and audio files