Yellow-beaked catfish
| Yellow-beaked catfish | ||||||||||||
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Yellow-billed lobster ( Pica nuttalli ) |
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| Scientific name | ||||||||||||
| Pica nuttalli | ||||||||||||
| ( Audubon , 1837) |
The yellow-billed magpie ( Pica nuttalli ) is a North American songbird art from the family of corvids (Corvidae). With a body length of 43 to 54 centimeters, it is the smallest living representative of the real magpies ( pica ). It stands out within the genus with its yellow beak and facial spot, but otherwise shows the usual high-contrast black and white coloration of the real magpies. The yellow-billed catfish is endemic to California, the range is limited to the California long valley and the valleys of the coastal mountains south of San Francisco . It is a key species of the Californian oak savannah, in which it is mainly found along rivers, and it breeds in the shady valleys along the long valley. Like all real magpies, it feeds on an omnivorous diet . The yellow-billed elster starts building nests between January and mid-February, which is followed by egg-laying after two to eight weeks. The clutches include one to five eggs, the young hatch after 16 to 18 days of incubation.
The species was first described by John James Audubon, who named it scientifically in 1837 and honored the naturalist Thomas Nuttall with the addition of nuttalli . The closest related species is the Hudson's elster ( Pica hudsonia ). The two species originated from a common ancestor during the Ice Ages in North America.
Today, the West Nile virus is considered to be the greatest threat to the yellow-billed elster, around 30–49% of the population has fallen victim to it since 2003. In addition, there was also a local population decline due to the disappearance of oak savannas. The IUCN currently classifies the species as harmless; however, a classification in a higher hazard category is already being discussed.
features
Build and color
Among the recent real magpies ( Pica ) the yellow-billed magpies is the smallest, probably also in comparison with the extinct Pica mourerae . In its proportions and its general morphology, however, it corresponds to the genus. With a total length of 43–54 cm, it is only slightly smaller than other species of the genus. It has the typical long tail, a strong, slightly curved beak and short wings that are clearly fingered at the tips, the ends of which reach just above the base of the tail. Its close-fitting plumage gives it a slender appearance. Males of the species grow on average 6-10% larger and 17% heavier than females, but there is a wide overlap in the dimensional ranges. Female yellow-billed stars weigh between 124 and 158 g. Their wings reach a length of 173 to 196, their tail 195 to 245 mm. The beak becomes 21-25 mm long in females, the barrel bone 42-51 mm long. In contrast, males weigh 147–181 g. Their wing length is 167-197 mm, their tail measures 220-267 mm. The beak reaches 20–32 mm in the male, while the running bone measures 41–46 mm. The tail is strongly stepped, the middle pair of control springs is significantly longer than the other control springs.
The coloration of the yellow-billed magpies corresponds - apart from a few details - to that of the other real magpies. There is no difference here between males and females. Nasal feathers , head, neck, chest, thighs, back and upper and lower tail coverts are black. Behind the eye is a small field of bare yellow skin. The rump is lighter than the adjoining back and the upper tail-covers, it tends to be more dirty-gray. The abdomen, shoulder walls and flanks are white. The wing-coverts and the wings of the hand are colored black, the wings of the hand are only white on the outside flags, their tips and inside flags are black. When the wings are put on, the white outer flags appear as a narrow white wing stripe, on the spread wing they form a large white area. The entire black plumage shows a metallic, iridescent sheen: bluish on the wings and tail, greenish on the headstock. The back, neck and chest are only faintly shiny. The beak of the yellow-billed elster is different from the rest of the genus yellow, only at the tip it is black in some individuals. Legs and claws are black, the iris is dark brown.
Young animals resemble adult conspecifics in the color of their plumage and their body structure. The black parts of the plumage appear more matt and browner and the plumage is looser overall. When determining the age, the outermost hand-wing is of particular diagnostic importance: it is wider and less sickle-shaped in juvenile yellow-billed stars than in adults. Their white and black areas are also less sharply delimited.
Flight image and locomotion
Compared to its fellow species, the yellow-billed elster has quite long wings. In flight, they act significantly longer than those of the parapatric Hudson's elster ( Pica hudsonia ). The yellow-billed elster flies in cross-country flight with fast wing beats, which are interrupted by short gliding phases. It performs dives with partially flared wings, its long tail makes it extremely agile in the air. It is also used for balancing in the branches and allows her to jump purposefully from branch to branch. The yellow-billed magpie usually moves on the ground in a striding manner. For faster progress, for example to catch prey, it switches to synchronous or asynchronous hopping. Sometimes she also flaps her wings at the same time.
Vocalizations
In their vocalizations, the yellow-billed elster shows great similarities with the Hudson's elster. Both species show a similar form of the taste typical of real magpies, which is in a higher frequency range than that of the magpie ( P. pica ). Yellow-beaked stars let it be heard at different speeds. In the slower version it attracts conspecifics and serves primarily as a hate signal , while in the faster "staccato" version it is a call to flee immediately, as tape experiments suggest. During courtship time, males sing with a soft subsong made up of soft, babbling syllables, which are interrupted by higher whistling notes. Imitated calls and chants of other bird species are sometimes woven into this song. During the breeding season the females call loudly and often with a questioning kwäi? for food, the begging cry of young birds sounds similar. When excited, yellow- beaked stars emit a metallic clicking kliep , accompanied by twitching of their tails.
distribution
The distribution area of the yellow-billed catfish is relatively small: The species is one of the few endemic species in California and only occurs there along the Central Valley and in the offshore Southern Coast Ranges .
The northernmost point of the distribution area is roughly near Redding , at the northwest end of the Sacramento Valley . From there it stretches south along the foothills of the Sierra Nevada and the Sacramento River to about Sacramento . The middle longitudinal valley between Sacramento and Fresno is largely avoided; however, a narrow corridor runs around Fresno, which connects the deposits in the western foothills of the Sierra Nevada with those in the Southern Coast Ranges. To the east of Fresno, the Artareal extends along the Sierra Nevada to Bakersfield . In the western coastal mountains it begins in the south of San Francisco Bay and extends over almost the entire South Coast Ranges to just before Santa Barbara .
The occurrence of the species is limited to California's areas with a Mediterranean climate , i.e. regions with hot, dry summers and cool, wet winters. It is tied to the type of vegetation in the oak savannah . Where oak parkland disappeared as a result of human settlement, such as in Monterey County , the yellow-billed magpie also disappeared. Something similar happened around Santa Barbara and Ventura , where the species no longer occurs due to heavy settlement activity. As a result of the industrialization of California's agriculture, the yellow-billed elster probably also withdrew from other areas where it was once frequent. However, the lack of detailed reports prior to the early 20th century makes it difficult to trace the distribution history of the species. Fossil is found in the species in the deposits of Rancho La Brea , Carpinteria and McKittrick . All three sites originate from the Pleistocene and are located at the southern end of today's distribution area. The yellow-billed magpie was presumably isolated in southern California during the Ice Ages and reached its present-day distribution after the glaciers retreated. The species is a resident bird and stays in its breeding habitat even in winter. Only in summer can flocks of young birds occasionally migrate up to 3.5 km to avoid local food shortages.
habitat
The yellow-billed elster mainly inhabits the warm, shady mountain valleys and the vegetation along rivers in the dry Central Valley. Denser stands of California white oak ( Quercus lobata ), California stone oak ( Q. agrifolia ) and other oak species are preferred to open landscapes with only a few trees. The reason for this is probably the protection against temperature extremes. The year-round availability of water and insects are crucial for the suitability of a habitat. In addition to oak savannahs, it also uses agricultural land or orchards to search for food. In places it can also be found in densely populated areas, even if it may avoid it in other places.
Way of life
nutrition
Yellow-billed stars use a wide range of food sources. They eat insects and other arthropods , grains , acorns , carrion , fry, and occasionally other small vertebrates . Compared to the Hudson's elster, there are fewer vertebrates and carcasses in the diet. Instead, it feeds on arthropods more often. Carrion becomes more important in winter and early spring, when insects are at their lowest. During the breeding season, the focus shifts to caterpillars (especially the glutton of the genus Malocosoma ) and jumping terrors , the proportion of beetles fluctuates from year to year. Jumping horrors are particularly important in the dry summer months. In September and October, they can make up around half of the diet, according to an analysis of stomach contents from the 1920s. The yellow-billed magpie also readily eats other insects that swarm in summer. Fruits and seeds take up a larger part of the food spectrum in autumn. In addition to acorns from North American red oak and Californian stone oak , the species also uses figs ( Ficus spp.), Buckthorn ( Rhamnus spp.) Or Toxicodendron diversilobum . The yellow-billed elster also visits plantations and vineyards locally to take advantage of the oversupply of fruit. Grain, on the other hand, is usually only picked up in the stubble fields after harvest.
Yellow-billed stars take most of their food from the surface of the earth or from the top layer of the soil. They rarely pick fruit from trees or bushes, and flying insects are caught jumping or flying. Yellow-billed stars search for food in dung patties or piles of leaves, floodplains are searched for earthworms. During the breeding season the foraging for food takes place in small groups, outside of the breeding season the birds move in large groups of several dozen animals. The feeding habitat consists of areas with low vegetation; The yellow-billed catfish avoid bare ground and tall grass when foraging for food. The swarms repeatedly look for rich food grounds over several days. During the breeding season, the breeding partners obtain most of the food from outside the vicinity of the nest. As with all corvids, excess food is hidden. The yellow-billed magpie usually hides at a short distance (<50 m) from the place where it was found. Pieces of food are usually hidden just below the surface of the earth and often recovered after a few days.
Social and territorial behavior
Yellow-billed stars are more sociable than their closest relatives. Throughout the year, the birds move in larger groups in search of food. Outside the breeding season, large groups often gather to sleep and forage together. The individual distance of individual birds in the flock is usually one body length; But breeding partners can also get closer. The yellow-billed magpie only defends a small area (0.6–1.9 ha ) around its nest. Outside of the breeding season, it largely gives up physical defense, but often continues to signal its claim to the territory by posing on treetops. In its breeding colonies, the species is often associated with the Bullocktrupial ( Icterus bullocki ), which is probably looking for protection from nest predators that the larger corvids ensure. Nests are usually set up close to each other in loose colonies that contain 3 to 30 breeding pairs. During the foraging fields Cory magpies often with Purpurstärlingen ( Euphagus cyanocephalus ) Gold woodpeckers ( Colaptes auratus ), Western Lerchenstärlingen ( Sturnella neglecta ), robins ( Turdus migratorius ) and starlings ( Sturnus vulgaris ).
Reproduction and breeding
The yellow-billed star probably begins to mature in the second year of life, but most birds do not breed until the third year of life. Brood partners usually meet in the second year of life. The couple partners are mostly monogamous and the breeding pairs usually exist until the death of one partner, but attempts to copulate with strange birds do occur. Males try to prevent their partner from copulating by others by guarding her during courtship and egg-laying. The male mates by approaching the female in a circling manner and fluffing up the flank plumage. In addition, there are various courtship calls and a subsong of itself, stands up and spreads its tail in the direction of the female. The female indicates her willingness to mate by a bent posture and a deep, growling call. The copulation takes 2-4 seconds.
Yellow-billed stars build their nests 10–20 m, on average 14 m high in the crown of large trees, preferably oaks. The mistletoe Phoradendron leucarpum is often used as a nest base. Both sexes take part in the nest building that takes place between December and March. The male mainly brings building material, while the female is more likely to do the actual nest building. The nest has the typical construction plan for real magpies, in which larger branches are woven into a spherical construction and then lined with mud, grass, hair and other fine material on the inside. It can reach a diameter of 90 cm and take up to two months to build. After about ten days (at the earliest in mid-March, usually from the beginning of April), the female lays 5–7 eggs in the finished nest, from which the young hatch after a further 16–18 days. Incubation is done by the female alone, while the male brings in food. The young birds are usually fledged no later than 30 days after hatching, but they often fly out beforehand. For the next 10–14 days, they are fed exclusively by their parents, and they remain dependent on them for around 45 more days. The chicks hatch from around 65% of all eggs, usually one to three young fly out.
Diseases, predators and causes of mortality
As a relatively large songbird and colony breeder, the yellow-billed magpie apparently has only a few serious predators; the capture of adult birds by other animals is rarely observed. Occasionally, it falls prey to larger birds of prey such as red-tailed hawks ( Buteo jamaicensis ) and golden eagles ( Aquila chrysaetos ); also goshawk ( Accipiter gentilis ), peregrine falcon ( Falco peregrinus ) or great horned owl ( Bubo virginianus ) are among the predators of adult birds. Clutches and nestlings may be eaten by pine snakes ( Pituophis melanoleucus ), which often clear the nests of sympatric species. The great nesting height of the yellow-billed elster may serve to avoid the pine snake; the parapatric Hudson's elster broods much lower, but earlier. Chain snakes ( Lampropeltis getula ) occasionally plunder clutches from nests at low heights. In addition to various featherlings (Mallophaga spp.) And louse flies (Hippoboscidae spp.), Yellow-billed stars are also attacked by protozoa of the genus Leucocytozoon . The West Nile virus has caused high mortality rates in the populations since 2003, to which around 30-49% of the population fell victim between 2004 and 2006. 78% of all yellow beaked stars found dead carried the virus between 2004 and 2006, antibodies have so far only been found in one individual. Poison baits, which are actually aimed at rodents, also contribute to mortality.
One of the main causes of mortality in both adult and nestling birds is apparently starvation, as has been suggested by breeding biology studies and an annual population decline during the food shortages in summer and autumn. After the first brood, males have a slightly higher average life expectancy at 3.6 years than females at 3.3 years. Around 70% of the breeding population survive each year. The oldest yellow-billed stars found in the wild were over ten years old. Two ringed females were still breeding when they were nine years old.
Systematics
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| Internal systematics of the real magpies according to Lee et al. 2003 |
The first description of the yellow-billed magpie comes from the year 1837. John James Audubon presented the species in his works Ornithological Biography and the accompanying volume The Birds of America as "Corvus nuttalli". In the specific epithet nuttalli he honored the naturalist Thomas Nuttall , who had sent Audubon bellows and reports on the species. For a long time the species was regarded as the sister taxon of the magpie ( Pica pica ). It was believed that it once inhabited all of North America, but was pushed back to California by the Ice Ages and eventually replaced by the Magpie in the rest of the continent. It was only through comparative behavioral studies and molecular genetic studies that the North American Hudson's elster ( P. hudsonia ) was recognized as a separate species and the yellow-billed elster was compared as a sister taxon. Their common ancestor probably immigrated from Siberia to North America in the Pleistocene . 625,000–750,000 years ago the ancestors of the Yellow-billed and Hudson's Elster were separated by the glaciation of the continent. Both species are still very similar in behavior, but inhabit different climatic zones and do not meet in their areas of distribution. The yellow-billed elster is monotypical , which means that no subspecies are recognized for the species .
Inventory and status
The population density of the yellow-billed magpie varies, depending on their nesting behavior, regionally often significantly. Breeding colonies can ensure a high density locally, while potentially suitable habitats are not used elsewhere. Only about 10% of the 650,000 hectares of California oak savannah are used by the species. Reliable population estimates for the species are not available.
The IUCN classified the species as safe in 2012 ("least concern"). According to studies from 2007 and 2008, the population of the West Nile virus, which has been detected in California since 2003 , decreased drastically by around 30 to 49% between 2004 and 2006. It is unclear whether the species continued to decline after 2006. An upgrade to a hazard category on the IUCN Red List is already being discussed. The conversion of the oak savannah poses a further threat to the stocks locally. Occasional persecution as an agricultural pest and unintentional poisoning can also have a critical effect. Above all, more precise stock examinations are considered to be urgently needed in order to find out how strongly individual factors affect the stock.
literature
- John James Audubon: Ornithological Biography. Adam & Charles black, Edinburgh 1838. doi: 10.5962 / bhl.title.48976 . ( Full text )
- Tim Birkhead: The Magpies. The Ecology and Behavior of Black-Billed and Yellow-Billed Magpies. T & AD Poyser, London 1991. ISBN 978-1-4081-4024-6 .
- Peter Enggist-Düblin, Tim Robert Birkhead: Differences in the Calls of European and North American Black-billed Magpies and Yellow-billed Magpies. In: Bioacoustics 4, 1992. pp. 185-194.
- Edwin Richard Kalmbach: The Magpie in Relation to Agriculture. In: USDA Technical Bulletin 24, 1927. pp. 1-34. ( Full text )
- Sang-im Lee, Cynthia S. Parr, Youna Hwang, David P. Mindell, Jae C. Choea: Phylogeny of Magpies (Genus Pica) Inferred from mtDNA Data . In: Molecular Phylogenetics and Evolution 29, 2003. doi: 10.1016 / s1055-7903 (03) 00096-4 , pp. 250-257.
- Steve Madge , John Marzluff : Family Corvidae (Crows and Allies). In: Joseph del Hoyo, Andrew Elliot, David Christie (Eds.): Handbook of the Birds of the World. Volume 14: Bush-shrikes To Old World Sparrows. Lynx Edicions, Barcelona 2009. ISBN 978-84-96553-50-7 , pp. 494-640.
- Nicolaas AM Verbeek: Comparison of Displays of the Yellow-billed Magpie (Pica nuttalli) and Other Corvids. In: Journal of Ornithology 113 (3), 1972. pp. 297-314. doi: 10.1007 / bf01647510
Web links
- S. Butchar, M. Derhé, CJ Sharpe: Yellow-billed Magpie Pica nuttalli . BirdLife International, www.birdlife.org, 2012.
- Walt Koenig, Mark Reynolds: Yellow-billed Magpie (Pica nuttalli) . In: A. Poole: The Birds of North America Online . Cornell Lab of Ornithology, Ithaca 2009. doi: 10.2173 / bna.180 .
- Pica nuttalli in the endangered Red List species the IUCN 2012. Posted by: BirdLife International, 2012. Accessed July 21, 2012 found.
Individual evidence
- ↑ a b Audubon 1838, p. 450.
- ↑ Birkhead 1991, p. 26.
- ↑ a b c d e f g h i j k l m n o p Koenig & Reynolds 2009. Retrieved May 23, 2012.
- ↑ Enggist 1992, p. 189.
- ↑ Verbeek 1972, p. 303.
- ↑ Linsdale 1937, p. 15.
- ↑ Madge & Burn 1994, p. 122.
- ↑ a b c Kalmbach 1927, p. 28.
- ↑ Birkhead 1991, p. 100.
- ↑ a b c Joe Taylor: Yellow-billed Magpie (Pica nuttalli): eligible for uplisting? BirdLife International: Globally Threatened Birds Forum. Listed on December 22, 2011. Online, accessed July 21, 2012
- ↑ Madge & Marzluff 2009, p. 606.
- ↑ Lee et al. 2003, p. 255.
- ↑ Lee et al. 2003, p. 256.
- ↑ Butchart et al. 2012. Retrieved July 23, 2012.
