Gold woodpecker
| Gold woodpecker | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
_B._Walker.jpg)
Golden woodpecker ( Colaptes auratus ) |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Colaptes auratus | ||||||||||||
| ( Linnaeus , 1758) |
The gold woodpecker ( Colaptes auratus ), sometimes also referred to as copper woodpecker , is a species from the genus of gold woodpeckers ( Colaptes ) within the subfamily of the real woodpeckers . The well- sized green woodpecker species occurs in four clearly differentiated subspecies groups in large areas of northern America and parts of Central America as well as in Cuba . Like most species of this genus, the golden woodpecker lives mainly on the ground, where it feeds on insects, mainly ants, often gathered in smaller groups. It is an important source of caves for many other cave-dwelling birds, mammals and insects . The desert gold woodpecker, long regarded as a subspecies of the golden woodpecker, was separated as a separate species in 1995. Although the population of the species is declining regionally, the golden woodpecker is a common and well-known species of woodpecker in large parts of its range, which is classified as harmless by the IUCN .
The taxonomic situation has not been fully clarified. Usually 11 subspecies were described, which were divided into four subspecies groups. In 2014 the HBW proposed a change that puts the birds of the Colaptes cafer group and Colaptes mexicanoides in species rank.
Appearance
With a size of up to 35 centimeters and a maximum weight of around 180 grams, the golden woodpecker is the size of a green woodpecker, but on average a little lighter than this. The wingspan is up to 54 centimeters. Females are significantly lighter than males at an annual average of up to 20 percent. The largest and heaviest subspecies is C. a. cafer from northwest Canada , the smallest C. a. gundlachi from Grand Cayman .
Colaptes auratus auratus
The upper side is irregularly banded in dark on a brownish background. The rear sides of the fuselage are unbanded white, occasionally irregular black spots and spots are interspersed. The upper wing-coverts and the upper tail-coverts are darkly banded and brownish, the latter have a black subterminal band. The wings are dark brown, banded rather indistinctly light brownish, the feather shafts are yellow. The upper side of the tail is blackish-brown, the outer flags of the outer control feathers are hinted at with white spots. The central feathers are shafted yellow, the tip of the tail is indistinctly colored leather yellow. The underside of the fuselage is white behind the distinctive crescent-shaped black chest badge, especially slightly cream-colored on the flanks. The belly is irregularly spotted with black, drawn black on the flanks rather like arrowheads and banded blackish towards the under tail coverts. The underside of the wings is yellowish, at the tips and edges more yellow-brown. The under wing coverts have black spots. The underside of the tail is also yellowish, the tip of the tail is black.
The head is bluish gray from the forehead to the lower neck area and on the temples. In the lower neck area of the male there is a distinctive, V-shaped red neck mark. The cheeks and ear covers, throat and upper chest are cinnamon colored. The beard streak is black.
The long, pointed, downwardly curved bill is slate-colored or black, the legs and the four zygodactyl arranged toes are gray to greenish gray. The iris of the eyes is a deep brown.
Females are slightly smaller and not insignificantly lighter, but these differences are not sufficient for a reliable sex determination in the field. The most certain difference in color is the lack of a black streak of beard; this region is cinnamon-colored in the female like the rest of the head. The crescent-shaped bib is a little less intensely black than the male and a little smaller.
Young birds are already very similar to adult ones ; the sides of the head are rather gray, the parting often spotted a little black. A black rein mark can often be seen. The upper wing covers show stronger black markings, the dark banding of the upper side is wider. Immature males often show a reddish tinge of color on the crown, their beard streak is not yet clearly developed. Even in immature females, there may be an indicated streak of beard.
The flight of the gold woodpecker is quick and typically arched like a woodpecker. The upswing occurs through a series of rapid flaps of the wings; the wings are laid out during the downswing.
Coloring of the spring shafts
The color of the shafts of the wings and the central control feathers, as well as of large parts of the wing and tail underside, are the most important distinguishing features between the various subspecies, in addition to the different characteristics of the head color. The main belt of the Rocky Mountains forms the dividing line between the golden yellow colored woodpeckers of the C. a. auratus - group in the east and the woodpeckers with reddish or salmon-colored feather shafts of the C. a. cafer (Syn. Colaptes cafer ) - group in the west. C. a. mexicanoides (Syn. Colaptes mexicanoides ) is close to C. cafer and has a similar color.
The differences in color are explained by a different metabolism of β-carotinides ; Different food components previously assumed do not play a role.
About a third of the individuals in the Colaptes auratus group have individual reddish or salmon-colored feather shafts. The proportion of differently colored feathers in the same individual can vary from year to year. Reactions from previous hybridizations were used to explain this phenomenon. In a study published in 2017, Jocelyn Hudon et al. according to the fact that the berries containing rhodoxanthin from honeysuckles , which originally came from East Asia and were imported to eastern North America in the early 18th century , are responsible for the different coloration of individual feather shafts, and the effects of mixed broods play no role. Similar color deviations were also observed in the cedar waxwing and the Baltimore trupial, which also consume berries from these honeysuckles.
voice
The golden woodpecker is a very call-happy species. The most frequent call that can be heard from the establishment of the territory to the pair formation is a loud series of differently transcribed sounds. Mostly they are played with wick… wick… wick or kick… kick… kick . The average duration of this call is over 5 seconds; but it can also last almost 20 seconds. In addition, the Wicka calls play the most important acoustic role. They are relatively quiet and are arranged, emphasized and modulated differently. The series of calls, which can be heard especially during sexually intimate interactions, last up to 4 seconds. The drumming of the species is described in terms of the sound that a miniature air pressure drill makes. It is rather quiet, the single strikes remain at the same pitch and follow one another very quickly.
Mauser
Like all real woodpeckers, gold woodpeckers hatch without feathering. The first plumage of the nestling begins to grow on the sixth day. The moulting of this plumage begins with the fly out and is completed with the change of the central control feathers. The wings of the arm are not or only partially molted by the large plumage. Golden woodpeckers molt into adult plumage in the following summer. The large springs fall in descending order, starting with the proximal hand wings, the control springs are changed in pairs, the shorter outer ones failing first.
Systematics
.jpg)
_female.JPG)
The golden woodpecker is one of 9 species of the genus Colaptes within the Malarpicini tribe , which includes medium-sized to approximately large species that mostly seek their food on the ground. With the exception of Colaptes auratus and Colaptes chrysoides , which was separated from it only a few years ago , all other members of the genus are native to South America. Colaptes is most closely related to the genus Piculus , whose small to almost medium-sized species occur in Central and South America. Recent phylogenetic work shows that some species of the genus Piculus belong more to the genus Colaptes .
10–11 subspecies are currently recognized, which can be divided into four subspecies groups. The most common is C. a. auratus . This subspecies is described above.
-
- Colaptes auratus auratus ( Linnaeus , 1758) - Group: It includes the nominate form
- the subspecies C. a, which breeds in the northern United States, Canada, and Alaska . luteus Bangs , 1898 . On average it is slightly larger than C. a. auratus , is otherwise the same in most of the coloring details. Most populations of this subspecies are medium-range migrants, some are long-range migrants.
- C. a. chrysocaulosus Gundlach , 1848 : This subspecies occurs in Cuba and is common there in places. Upper side a little lighter than the nominate shape.
- C. a. gundlachi Cory , 1886 : This smallest subspecies is only native to Grand Cayman. Upper side a bit lighter, base color of the underside almost pure white.
-
- Colaptes auratus cafer - group
- It comprises 5 subspecies. What they have in common is the lack of a red neck mark; the crown and neck region is brownish. The malar region is red in males and intensely cinnamon in some females. The spring shafts of the wings and the central control springs are wild salmon colored. The cheeks, ear-covers, chin and throat are gray. A distinction is made between the subspecies
- C. c. cafer ( Gmelin , 1788) , which occurs in the Pacific belt from southernmost Alaska to northernmost California,
- C. a. collaris Vigors , 1829 , a slightly lighter and smaller subspecies lives in the Californian coastal strip southwards to northern Baja California . In addition, this subspecies colonizes some of the islands off the California coast, such as the Santa Cruz Islands . The northernmost populations undertake small-scale migrations to the south outside of the breeding season.
- C. a. mexicanus Swainson , 1827 : small and brownish subspecies from central Mexico.
- C. a. nanus Griscom , 1934 : the smallest subspecies of the cafer group roughly corresponds in size to the nominate form. It breeds in southeast Texas and northeast Mexico.
- C. a. rufipileus Ridgway , 1876 †: This subspecies wasnativeto the island of Guadalupe off the coast of Lower California.
- C. a. mexicanoides Lafresnaye , 1844 : It occurs from southern Mexico to Nicaragua. The woodpeckers are large, resemble those of the cafer group, but have a maroon-brown forehead, crown and neck color. The male's red beard is often framed in black. The spring shafts are orange, the black bib is less clearly crescent-shaped.
- C. a. chrysocaulosus : The birds in this group live much more tree-bound than the other subspecies. They are among the smallest subspecies. In the head and shaft color they correspond to the woodpeckers of the auratus group. The upper side has a clear tinge of green, the underside has very strong black spots.
In a revision of the taxonomy, the HBW proposes a separation of the Colaptes cafer group as an independent species with 5 recent subspecies, one of which, the Guadalupe golden woodpecker ( C. cafer rufipileus ) died out shortly after 1906. Likewise Colaptes mexicanoides put into species rank. According to this assessment, in addition to the nominate form, C. a. luteus , C. a. chrysocaulosus and C. a. gundlachi should be regarded as a subspecies of the golden woodpecker.
Hybridizations
All subspecies hybridize in their contact zones . The offspring show characteristics of both parents in continuous variation. The longest hybridization zone, which has remained essentially stable in length and width over the past few decades, extends from southern Alaska to Texas. It is unclear whether partners from their own subspecies group are preferred. Mixed broods with the desert gold woodpecker have not been confirmed either. A very extensive study of Colaptes auratus x Colaptes cafer ssp. Mixed broods could not find any genetic handicaps in the offspring.
distribution and habitat
The golden woodpecker is widespread from the northern transition of the tree tundra into the taiga almost across the whole of North America south to northern Mexico. Further south in central and southern Mexico or in Central America, the distribution area becomes more fragmented and disintegrates into individual distribution islands. In addition, the species inhabits Cuba and Grand Cayman. The desert areas ( Mojave and Sonora ) in the southwest of the USA and northwest of Mexico and the Baja California peninsula are not populated . These areas are the distribution area of the desert golden woodpecker. Even completely treeless areas such as the Great Plains can only colonize the species along tree-lined rivers.
The species has occurred several times in Europe, particularly Ireland and Scotland . The birds probably crossed the Atlantic, at least in part, on ships. Evidence comes from Denmark.
According to its very large area of distribution, the golden woodpecker lives in a variety of different landscapes. In addition to an adequate supply of food in open areas that are only covered with low vegetation, an adequate supply of suitable cave trees is essential. The species finds such prerequisites in sparse forests, especially on the edge of large-scale clearcuts, in young afforestation or in forest areas affected by fire incidents, windthrow or pest infestation. It colonizes tree-covered farmland, especially pasture areas, and penetrates into larger gardens, parks and similar green islands in densely populated regions. As far as the tree composition of its habitat is concerned, the species is flexible. In the north, the American aspen plays a prominent role as a breeding tree. In Mexico the species of light oak and pine inhabits mixed trees, in Central America mainly secondary forests in the rainforest belt.
As far as the animals are migratory birds, the winter habitats largely correspond to those of the breeding season. Occasionally, especially on Grand Cayman and Cuba, it is observed that the species visits more densely vegetated areas in winter.
The vertical distribution of the species ranges from sea level to heights of around 4000 meters in Mexico.
Since the species shows only slight interspecific aggression and also looks for food in groups, no territory is defended against conspecifics apart from the breeding and possibly also some sleeping caves. The breeding site itself, however, is vigorously asserted against conspecifics as well as against alien cave competitors. The distances between active nesting holes can be less than 10 meters in extreme cases, but are mostly between 100 and 200 meters.
hikes
Depending on the breeding area, golden woodpeckers are long- distance migrants , short- or medium-distance migrants or resident birds . The train distances decrease from north to south. In particular, the majority of the northern populations of the auratus group leave their breeding grounds from mid-September and mostly move in south-eastern directions. The return to the breeding areas takes place from mid-March. The borderline between mainly migratory birds and mainly resident birds is assumed to be approximately 38 degrees north of the north. Recently, a seemingly paradoxical northern migration has been observed leading golden woodpeckers into areas where they have permanent access to feeding grounds. Since 1984, gold woodpeckers have been regularly observed at the Christmas bird count in Saskatoon (52 ° N!) With outside temperatures of down to minus 40 °. The distances traveled can be considerable: a young bird that was ringed in central British Columbia in June was found in Newfoundland at the end of September after a distance of almost 5,000 kilometers.
The migration traditions of the woodpeckers of the cafer group have been less well studied . However, the Rocky Mountains appear to form a migrating sheath, causing these birds to withdraw in south or south-westerly directions. In addition to these horizontal migrations, vertical migrations of montane populations are observed. This also applies to the gold woodpeckers of Mexico and Central America.
Golden woodpeckers sometimes migrate in very large groups; they mainly fly at night.
Food and subsistence
Gold woodpeckers feed themselves and their offspring mainly on insects. Various seeds, fruits and berries are ingested to a significantly lesser extent. Ants and their developmental stages play the greatest role in insect food. Golden woodpeckers choose the ant species that occurs most frequently in their range and that is the most energy-efficient to reach. Ant food can make up 80 percent of the total amount of food. In addition, other insects are captured, especially ground beetles , Hemiptera , Diptera , butterflies , Spring terror and grilling . Aphids , worms or snails are rarely ingested. Gold woodpeckers regularly eat the seeds of various plants such as oak-leaved poison oak and other sumac plants , sunflower and thistle seeds , and various berries . Acorns also belong in the food spectrum. Gold woodpeckers often visit feeding places. Golden woodpeckers can often be seen on corn plants infested with Diatraea grandiosella , where they prey on the caterpillars of this moth species .
The continental subspecies of the golden woodpecker hunt for most of their food on the ground, while the two island races are more tree-bound. On the ground, woodpeckers hop from food source to food source, poke and drill in the ground, and occasionally they pound the ground to get to ant nests. They turn leaves, stones and twigs to get at the insects living underneath and poke in the dung of grazing animals. Tree-dwelling insects are mainly looked for on dying or already dead trees. Here, too, poking and reading are the main strategies; deeper-lying drill holes are rarely exposed by hammering. Goldpeckers pick fruits and berries from the branches or peck those that have fallen from the ground. Occasionally they hunt insects on the fly.
behavior
activity
Like all real woodpeckers, the gold woodpecker is diurnal. He leaves his sleeping place shortly before sunrise and looks for it again shortly after sunset. A variety of sheltered places serve as sleeping places, such as tree caves, old woodpecker caves or other woodpecker caves, roof gables in wooden buildings, occasionally only a trunk section under a mighty main branch. Outside of the breeding season, it spends around two thirds of its daily activity in trees and only uses a fraction of this time for foraging. The rest of the time he dozes, observes the surroundings or cleans his plumage. The remaining third he spends on the ground, here almost exclusively foraging for food. During the migration period, the migrating populations spend the nights flying, and the days roughly in equal parts dozing, resting, caring for their feathers and foraging. In the winter months, relatively more time is devoted to foraging.
Agonistic behavior
The intraspecific aggression is greatly reduced in the gold woodpecker. He only defends the breeding site and the partner, food rivalry hardly seems to exist. The arguments are heavily ritualized and very rarely lead to contact fights. The most important element is the flicker dance . The competitors sit opposite each other on a branch with their head and beak slightly raised. The head is rhythmically lowered and turned so that the tip of the beak describes an 8. The wings and tail are spread apart in order to bring out the feather signals to their best advantage, and when extremely excited the bird hops and rocks on the spot. These duels, which can last up to half an hour, are always fought by same-sex rivals; they are accompanied by loud Wicka calls. When a rival gives up, the other shouts after him.
In the pre-breeding season and the actual breeding season, the golden woodpecker encounters a number of cave competitors extremely aggressively, attacks them directly and tries to drive them away from the nesting tree. The most important of these is the established and rapidly expanding European star . The defense intensity depends on previous experience with this species, so that first-breeders in particular are often defeated. Cave competitors that the golden woodpecker aggressively encounters are also the great spotted falcon and the buffalo head duck . Quite a number of cave competitors are also predators .
Breeding biology
Courtship and pairing
Pair formation begins in February in the southernmost breeding areas and ends in mid-May in the northernmost. Overall, however, very little data are available on their phenology. The main element of courtship is a modified, slow flicker dance , in which soothing elements outweigh the aggressive ones. If a conspecific approaches, the aggressive, same-sex argument begins immediately. Other courtship elements are cave-pointing, ritualized knocking on suitable nesting trees and long rows of calls. The copulations take place on a branch near the nest cavity.
Golden woodpeckers become sexually mature as yearlings. They usually lead a monogamous seasonal partnership. Family groups can still take the train together or stay in loose contact in the winter quarters. Reparations from last year's partners should not be uncommon. Polyandry occurs in a small percentage of females. These lay clutches in the nesting cavities of two males at slightly staggered intervals. While the female is even more involved in the first clutch, the brood and rearing of the young are almost exclusively the responsibility of the male in the second.
Nesting cavity
Cave construction begins around mid-May in the northern breeding areas and, accordingly, earlier in the southern breeding areas. On Cuba and Grand Caymann as early as the end of March. The choice of the cave tree is incumbent on the female, the main work in the construction of the cave is done by the male. The type of cave tree is very variable, in northern and northeastern areas the American quaking aspen is selected disproportionately often. The majority of nesting trees are already damaged or already dead; in living trees, broken branches or other damage are often exploited. The height is extremely variable. On Nantucket , where the predominant low-growing trees only have sufficient diameter in deep trunk regions, the average height is one meter, in old Douglas fir stands in western North America it is over 11 meters. Breeding caves are also dug into various wooden structures such as telegraph poles or wooden groynes on the coast. Nest boxes are also accepted or adapted.
Since the construction of the nest cavity is part of the pairing process, the construction of a new nest cavity is started every year, but this does not necessarily have to serve as an actual nest cavity later. Often old nesting sites are reused, or those that remained unfinished last year are completed. The time it takes to set up a new hatchery depends on many factors, under favorable conditions it is a little less than two weeks. The distribution of work is also quite variable, with the male always doing the main work.
The diameter of the entrance hole, which is often slightly oval, averages 7–8.5 centimeters. The brood chamber is on average 40 centimeters below the entrance; the dimensions of the slightly concave floor area are around 165 square centimeters.
Clutch and brood
Golden woodpeckers breed once a year. A second brood only occurs if the clutch is lost early. Earliest clutches were found in mid-April, the latest, probably second clutches, at the beginning of July. In Guatemala , egg laying begins in early March. No information is available for the two island races. The clutches consist on average of over 6 (4–9) eggs, which are laid every day. Clutches with up to 12 eggs have been observed, and even larger ones are likely to have brood parasitism , which generally seems to occur relatively frequently in this species. The eggs are white, slightly shiny, and measure 2.79 × 2.16 centimeters on average. As with other birds, earlier clutches are larger than later ones. The clutches of hybrid pairs are usually smaller. Golden woodpeckers begin to brood firmly before the penultimate or last egg, so that the oldest chick hatches about ten days after the last egg is laid, the youngest a maximum of two days later. Both parents breed, the male more often and always during the night. Both parents provide the nestlings with choked insect food. You gain weight very quickly for the first 10 days, after which growth and weight gain slow down. After 24–27 days they leave the brood cavity and often the immediate breeding area together with their parents. Comprehensive data on leadership time are not available, but, as individual observations show, it should hardly last longer than three weeks. The youth dispersion has also not been adequately researched. The available investigations indicate widespread dispersal migrations.
Little data are available on breeding success. A larger study of over 1000 broods in British Columbia produced the following results: At least one nestling flew out of 71% of the broods that had started. 16% were killed by various nest robbers, almost 6% were given up due to ongoing cave competition, especially by starlings. Some broods were lost due to the wind breaking of the cave tree. The reasons why the remaining 6% failed remained unclear.
Life expectancy and exposure
As with most animal species, the death rate in the golden woodpecker is highest in the first year, especially in the first few months after leaving the country. About 43 percent of the gold woodpeckers live to be more than a year old. After that, the mortality curve flattens out somewhat. The maximum age was determined to be 9 years and two months for a woodpecker from the auratus group.
Young woodpeckers have relatively frequent accidents by flying against obstacles, they are more likely to fall victim to predators than older ones and survive food shortages or persistent bad weather conditions more poorly than experienced, older conspecifics. Among the predators, some such as squirrels , flying squirrels , raccoons and tree-climbing snakes are only dangerous to eggs and nestlings, others, such as various birds of prey, especially the hawk, prey on adult golden woodpeckers , or surprise, like species of marten , dormant woodpeckers.
Stock situation and stock development
The IUCN regards the species as safe. With a distribution area of 15 million square kilometers, the total population is estimated at 16 million individuals.
Investigations by the BBS (Breeding Bird Survey) showed, however, a not inconsiderable population decline in large parts of the distribution area. The reasons given for this are habitat loss caused in particular by modern forest management, the increasing cave competition with the European starfish, which is rapidly increasing in its population, and pesticide contamination in intensively agricultural areas. About the population of the two island races and the subspecies C. a. mexicanoides no data available.
Trivia
The golden woodpecker is the state bird of Alabama , which is also named Yellowhammer State after him.
literature
- Karen L. Wiebe, William S. Moore: Northern Flicker (Colaptes auratus). In: A. Poole (Ed.): The Birds of North America Online. Cornell Lab of Ornithology, Ithaca 2008.
- 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. 146-147, 319-321.
Web links
- Colaptes auratus in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed January 2 of 2009.
- Videos, photos and sound recordings of Colaptes auratus in the Internet Bird Collection
- Feathers of the eastern gold woodpecker
Individual evidence
- ^ Karen L. Wiebe, William S. Moore (2008) Introduction
- ^ Karen L. Wiebe, William S. Moore (2008) Systematics ; Measurements
- ↑ Jocelyn Hudon, Karen L. Wiebe, Elena Pini and Riccardo Stradi: Plumage pigment differences underlying the yellow-red differentiation in the Northern Flicker (Colaptes auratus) . In: Comparative Biochemistry and Physiology, Part B 183 (2015) 1-10.
- ↑ Jocelyn Hudon, Robert J. Driver, Nathan H. Rice, Trevor L. Lloyd-Evans, Julie A. Craves and Daniel P. Shustack: Diet explains red flight feathers in Yellow-shafted Flickers in eastern North America . In: The Auk, Volume 134, 2017, SS 22–33; doi : 10.1642 / AUK-16-63.1
- ^ Karen L. Wiebe, William S. Moore (2008) Sounds
- ^ Karen L. Wiebe, William S. Moore (2008) Appearance
- ↑ Winkler et al. (1995) pp. 307-326
- ↑ Brett W. Benz, Mark B. Robbins, A. Townsend Peterson: Evolutionary history of woodpeckers and allies (Aves: Picidae): Placing key taxa on the phylogenetic tree. In: Molecular Phylogenetics and Evolution 40 (2006): pp. 389-399; P. 395 ff.
- ↑ Juian P. Hume and Richard Walters: Extinct Birds . Poyser-London 2012. p. 224. ISBN 978-1-4081-5725-1
- ↑ del Hoyo, J., Collar, N. & Christie, DA (2016). Red-shafted flicker (Colaptes cafer). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, DA & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/467472 on October 13, 2016).
- ↑ Winkler, H., Christie, DA & Kirwan, GM (2016). Yellow-shafted Flicker (Colaptes auratus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, DA & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/56268 on October 13, 2016).
- ↑ DT Tyler Flockhart and Karen L. Wiebe: Absence of Reproductive Consequences of Hybridization in the Northern Flicker (Colaptes auratus) Hybrid Zone In: The Auk April 2009: Vol. 126, Issue 2 (Apr 2009), pp. 351-358.
- ^ Karen L. Wiebe, William S. Moore (2008) Distribution
- ^ Karen L. Wiebe, William S. Moore (2008) Behavior
- ^ Karen L. Wiebe, William S. Moore (2008) Migration
- ^ Karen L. Wiebe, William S. Moore (2008) Food Habits
- ^ Karen L. Wiebe, William S. Moore (2008) Behavior / Daily Time Budget
- ^ Karen L. Wiebe, William S. Moore (2008) Courtship and Agonistic Displays
- ^ Karen L. Wiebe, William S. Moore (2008) Mating System And Sex Ratio
- ^ Karen L. Wiebe, William S. Moore (2008) Breeding
- ^ A b Karen L. Wiebe, William S. Moore (2008) Breeding ~ Nest
- ^ Karen L. Wiebe, William S. Moore (2008) Eggs ~ Clutch Size
- ↑ Winkler et al. (1995) p. 321
- ^ Karen L. Wiebe, William S. Moore (2008) Demography and Population
- ^ Karen L. Wiebe, William S. Moore (2008) Range
- ^ Karen L. Wiebe, William S. Moore (2008) Annual And Lifetime Reproductive Success
- ^ Karen L. Wiebe, William S. Moore (2008) Life Span And Survivorship
- ↑ Data sheet BirdLife international (PDF) engl.