Pygmy Owl

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Pygmy Owl
Pygmy Owl (Glaucidium passerinum)

Pygmy Owl ( Glaucidium passerinum )

Systematics
Class : Birds (aves)
Order : Owls (Strigiformes)
Family : Real owls (Strigidae)
Genre : Pygmy Owl ( Glaucidium )
Type : Pygmy Owl
Scientific name
Glaucidium passerinum
( Linnaeus , 1758)
Subspecies
  • Glaucidium passerinum passerinum
  • Glaucidium passerinum orientale
Pygmy owls are well camouflaged due to their dark brown color

The pygmy owl ( Glaucidium passerinum ) is the smallest owl native to Central Europe . The species is also one of the dwarf owl birds worldwide . The pygmy owl is a resident of the Palearctic belt of coniferous forests, in Central Europe its occurrence was for a long time restricted to montane forests and forests in low mountain ranges. Lately the species has been able to expand its breeding area considerably and is also found in increasing numbers in lower-lying areas. Pygmy owls feed on small mammals and small birds. There are two subspecies.

Appearance

With a size of 16 to 17 centimeters for the males and 18 to 19 centimeters for the females, the bird, which is just about the size of a starling, is quite easily identifiable due to its small size , its activity profile and its behavior. Most likely it could be confused with a rough owl ( Aegolius funereus ) or in flight with a dark little owl ( Athene noctua ). The wingspan is about 35 centimeters for the male and 38 centimeters for the female. The male weighs an average of 59 grams, the female between 99 grams before the start of breeding and 69 grams at the end of the breeding season. It uses up the body's own reserves in order to maintain the incubation temperature.

The pygmy owl looks fairly uniformly dark gray-brown, breast and belly are of different lightness, but rarely pure white. On the back of the head it has the typical spots that look like eyes in unfavorable conditions. When visibility is good, a dark line can be seen. The head is small and flat-fronted with distinct white "eyebrows". The field of vision is dark, the iris of the relatively small eyes yellow. The long tail, which is banded in white several times, is very noticeable: it is often moved back and forth or, according to the wren style, erect ( stilted ).

In flight , the wings appear short and rounded, as does the tail. As a small bird hunter, his relatively noisy flight is agile and fast, in cross-country flights the wings are put on after a few quick, powerful flaps of the wings. This so-called wave flight is often interrupted by straight gliding phases.

voice

The male's call for territory is very distinctive and can be heard for more than a kilometer. It consists of bright, fluting individual elements on  üü , which are usually followed by a small aftertaste, also on ü : so ü..ü. In case of particular excitement - probably when a female or a rival appears - several ü can follow the main tone. ( Ü  … üüüüüh). These ü-series can rise in pitch and overturn at the end. The tone color is like a whistle, very bright nearby. This Reviergesang, the individual elements of which are performed every two seconds, can often be heard in late October, but not until February and March if ownership is clear. In addition, shrill whistles and vowelless 'shhh' sounds are part of the quite extensive vocal repertoire of the species.

Some small birds, above all the coal tit , react acoustically very violently to pygmy owl calls, so that based on this reaction alone, the presence of the pygmy owl can be inferred, a fact that is used when mapping the species by taking recordings of pygmy owl calls -  Sound dummies  - plays.

distribution

The distribution area extends from France to Eastern Siberia

The closed breeding area of ​​the species extends from southern Scandinavia and eastern Poland in a wide belt east-east to eastern Siberia and Sakhalin . In the north, the species is an inhabitant of the boreal coniferous forests. In addition, there are larger islands in the middle and high mountains of Central Europe, starting from eastern France via Switzerland, Austria, southern and southeastern Germany, for example in the Black Forest , Bavarian Forest , Thuringian Forest ( Vessertal Biosphere Reserve ) and Odenwald to the Carpathians and Beskids . There is also regular evidence of breeding in the Harz , Solling and the Lüneburg Heath landscape , in the latter case also in the North German lowlands . The species is also widespread in some forest islands in the Dinaric Mountains .

The pygmy owl breeds in Central Europe preferably in mountain conifer forests from 600 m to the tree line, but broods in the submontane altitude range have recently become known, for example in the Graz area at around 400 meters above  sea ​​level .

habitat

The pygmy owl is a resident of boreal coniferous forests as well as coniferous forest- dominated mixed forests . Near-natural, hardly thinned forests with correspondingly high levels of old and dead wood are preferred habitats . In forests used for forestry purposes, those with plenter management are preferred. In addition to a rich supply of food, it also needs breeding caves or half caves. Waters and bogs also seem to play a major role in the ideal pygmy owl habitat. In addition, as with many other owls, dense forests with good cover and open spaces are necessary components of an optimal pygmy owl territory. The presence of other owls seems to bother him less than the rough-owl, but a strong presence of pine marten , hawk and sparrowhawk does .

Food and subsistence

Food depot of a pygmy owl; the prey animals are headless

Pygmy is a successful small bird hunters, but its diet is very large and includes a total of 50 species of birds spotted woodpecker size. Chaffinches and coal tits are often captured. Sometimes the pygmy owl also hunts branches of its own species. Furthermore, its prey includes mammals such as shrews , rats , earth mice , bank voles and dormice , amphibians and reptiles . The proportion of bird prey varies, but rarely exceeds 50 percent.

Ground animals are spotted from a hide in the lower crown area of ​​a tree or the top of a young spruce and beaten on the ground; Birds are usually captured by surprise attacks, but chases also occur. The pygmy owl usually localizes its prey visually. During the breeding season and in cloudy weather, the pygmy owl also hunts during the day, otherwise mainly at dusk. This species does not hunt in the night itself. Birds are always plucked, mammals only roughly depilated, and the prey is eaten in bits and pieces. During the feeding season and the winter months, the pygmy owl often creates very extensive food stores.

behavior

The activity phases of the species are in the twilight hours or during the day. This applies to food acquisition, feeding and singing. Sometimes it can also be heard on bright nights. The pygmy owl can be quite conspicuous in its territory. It is often very exposed on the top of a spruce tree . After each change of location, the characteristic tail turning and tail stilts take place, also when excited, for example when spotting a prey. It is not particularly shy and allows people to get very close, especially during sunbathing, which it often indulges in with outstretched wings and fluffed plumage. In the resting phases he usually sits upright, close to a trunk, but can also be observed in an almost lying position. Males and females usually sit separately at some distance from each other.

The comfort behavior of the animal includes extensive body care consisting of scratching, cleaning and shaking. Extensive rain, snow and water baths also belong in his behavior pattern, to this extent perhaps also because he thaws his depot booty, which was frozen in winter, in his body plumage, which often makes it heavily soiled.

It is aggressive towards conspecifics throughout the year , and mated specimens are also quite shy of contact. Contact sitting can only be observed during the spring season, combined with a clearly recognizable tension, which is expressed in short pursuit flights and the sounding of alarms. Males and females use different sleeping and seating areas all year round, only the young birds seek contact with nest siblings. Male pygmy owls secure territories of around 2.5 square kilometers by chanting their territory, which are intensively defended against conspecifics - including females alien to the territory. The barn owl is tolerated in the area, even nesting caves of the two species within a radius of less than 20 meters have been detected.

Enemy behavior

Pygmy Owl in the light rain

The pygmy owl has a number of enemies due to its small size, most notably other species of owls and martens . He does not have a distinctive camouflage dress, instead he is very willing to flee to avoid enemies and by his activity in the twilight he evades the nocturnal larger owls. As soon as it sees an enemy, the owl adopts a camouflage position, whereby it stands up straight. If the enemy comes closer anyway, a quick escape ensues. In rare cases he also uses a threatening position in which he opens his eyes and puffs up the plumage, giving alarm calls and rattling his beak.

When the brood cavity is disturbed, females and young birds often keep quiet, but occasionally the squeaky beak can be heard, especially from the female; when attempting to penetrate, the mother turns over the young and attacks the attacker with beak and claw lashes. The male attacks troublemakers from the outside in spite of its small size.

Reproduction

The pygmy owl becomes sexually mature at four to five months and leads a monogamous seasonal marriage , but the same partners can breed together for several years, whereby the bond usually lapses in the autumn and winter months. Individual observations occasionally found polygyny , although it is currently not clear how often this behavior occurs.

Courtship

The animals mate twice a year, with the autumn mating in September to October to establish the territory. During this time, the male birds, sometimes accompanied by their partner, also fly during the day and try to expand their territory by singing. The courtship preceding the pairing takes place in spring, depending on the weather between February and the beginning of April. The spring balz also begins with district chants, which turn into mating calls. The latter take place in the area of ​​the cave, whereby the male sitting in the entrance hole attracts the female to the cave with various calls. Alternatively, the male, sitting on a branch, lures a female to a prey delivery with similar sounds. The male presents the prey to the female, who first responds with "squeaking" sounds and finally receives the prey. The copulation takes place on branches near the cave after corresponding calls from the male. The female then sits down on the branch and, with her head down and tail raised, asks her partner to mate. The male flies to it with a rapid trill and rises on the back of the female. The mating takes place under the strong wing beat of the male, which often bites into the plumage of the female.

Young animals in a nest box

Brood and brood care

The caves of the great spotted woodpecker , three- toed woodpecker and white-backed woodpecker are preferred as breeding caves, the pygmy owl seldom breeds in black woodpecker caves or nesting boxes . Above all, the cave must have a narrow entrance hole and be relatively deep so that the birds are protected from predators. The cave is cleaned, but no nesting material is entered. Instead, the female lays the ground with a layer of plucked down about an inch thick .

The four to seven pure white, broadly elliptical eggs are laid from mid-April and, depending on the weather, incubated by the female for up to 30 days. This loses up to 34 percent of its body weight during the breeding period. The male only appears to hand over food and lures the female out of the cave, only very rarely does it also go into the cave. There is only one annual brood, apparently even if the first brood was unsuccessful. The young hatch at the same time. A few days after hatching, the female begins regular nest cleaning, moving eggshells and balls of feces outside. The feeding is also done exclusively by the female, who receives the food from the male. After about 30 to 35 days, the nestlings leave the den and are cared for by their parents for about four weeks. Then they leave the parent's territory and scatter into the surrounding area ( dispersion migration or dismigration ).

Migratory behavior

In Central Europe, the pygmy owl is a resident bird that only leaves its breeding area in small areas when there is a severe lack of food. Young birds show less loyalty to their location, but they too do not move very far from the nursery area. Northern birds are significantly more mobile and even tend to leave their old location after population collapses ( retrogradations ) of their prey , although not to the same extent as is observed in the hawk owl or the snowy owl . In these cases, inlets or bays are only flown over in exceptional cases.

Inventory and inventory trends

The pygmy owl is one of those species that are very difficult to determine, so quantitative information is subject to considerable uncertainty. The total European population is estimated at around 35,000 breeding pairs, the Central European population is likely to be around 5,000 breeding pairs. Currently, the extent of the area is not yet fully recognized and the population is increasing, which is proven by the large number of broods in suboptimal pygmy owl habitats. The reasons for this are being discussed; the milder winters of recent years and the increase in the population of most woodpecker species, which means that the pygmy owl has an increase in nesting opportunities, may play a role.

Systematics

There are two subspecies of the pygmy owl. The nominate form Glaucidium passerinum passerinum inhabits the northern Palearctic starting in Scandinavia and the Baltic countries to the east of the Urals. This is followed by the distribution area of ​​the subspecies Glaucidium passerinum orientale , which extends over central and eastern Siberia to the Pacific. The birds of this subspecies are somewhat larger and more gray-brown, but such colorations are also quite common in Alpine- European individuals.

In the close relationship of the Sperlingskauzes in is Africa -based Perlkauz ( Glaucidium perlatum ) provided. The likewise very similar American Gnome Owl ( Glaucidium gnoma ), on the other hand, probably represents a convergence form with habitat and behavior-related similarities.

literature

Documentary film

  • Claus and Ingrid König: The little Spauz . 50-minute documentary about the pygmy owl in the Black Forest, 2007.

Web links

Commons : Pygmy Owl  - Album with pictures, videos and audio files
Wiktionary: Pygmy Owl  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ Voice example: Reviergesang with clear "lingering" on vogelwarte.ch
This version was added to the list of excellent articles on January 5, 2005 .