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Yellow-billed Magpies in central coastal California had significant variation in laying date of first egg and clutch size within and among years. The length of the breeding season was shorter than for other magpies, but timing of breeding varied widely among years. Early breeders laid larger clutches and, for successful nests, fledged more young than later breeders. Breeding coincided with peak food abundance and breeding early, relative to a particular year's food peak, resulted in higher reproductive success. However, variation in annual reproductive success was not correlated with precipitation or temperature. First-year and mixed-age pairs laid later and smaller clutches than older pairs. First-year females fledged fewer young than older females. Heavier females laid eggs earlier than lighter females. Number of breeding attempts was the most important determinant of reproductive success among years.
Po wzroście liczebności w połowie XX wieku potem w południowo-zachodniej Polsce polne ptaki krukowate Corvidae (w przeciwieństwie do miejskich) silnie zmniejszyły swoje populacje. W niniejszej pracy porównano nieliczne konkretne dawne dane ze stanem obecnym. Liczebność wrony siwej Corvus cornix na trzech dolnośląskich powierzchniach próbnych badanych w latach 1960. lub 1970. oraz ostatnio (2008–2009) zmniejszyła się ponad 30-krotnie, z 7–53 p do 0–2 par. Obserwacje z pociągu (wzdłuż ok. 1250 km tras) potwierdziły obecną niską jej liczebność na rozległym obszarze południowo- zachodniej Polski, jak również sugerują obecną niską liczebność gawronów C. frugilegus, kawek C. monedula i śródpolnych srok Pica pica. Przyczynami jest prawdopodobnie splot dwóch czynników: a) zastąpienie niskotrawiastych pastwisk oraz upraw buraka cukrowego i ziemniaków przez wysokotrawiaste łąki oraz wielkopowierzchniowe uprawy zbóż ozimych, rzepaku i kukurydzy; b) pojawienie się i wzrost liczebności kruka Corvus corax. Dwa rodzaje obserwacji oraz test wokalny sugerują, że zniknięcie z krajobrazu rolniczego bardzo widocznych gniazd wron i srok, może być spowodowane drapieżnictwem gniazdowym kruków
Black-billed Magpies possess distinctive patterns of black and white on their flight feathers which have been suggested to be family-specific. Such a phenomenon could potentially provide a simple field-method for recognising related or unrelated offspring. Using a combination of wing plumage patterns and multilocus DNA fingerprinting the relationship between plumage variation and genetic relatedness in the European Black-billed Magpie was investigated. The plumage of nestmates was more similar to each other than to young in other nests. However, extra-pair offspring could not be identified from nestmates through plumage differences. Within brood similarity may be explained by full-siblings sharing plumage characteristics through random inheritance, or through a shared rearing environment. Extra-pair offspring may resemble their half-sibs due to shared maternal plumage characteristics and a common rearing environment.
Acta Ornithologica
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1997
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tom 32
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nr 1
121-126
Magpie Pica pica is widely distributed over the built-up areas of Berlin. A population increase is observed at least from the 60s up to now. Over about 20 years population changes are documented in different parts of Berlin. Some main lines of increase are shown for two different habitat types: residential district and closed built-up zone of the city. The method of territory mapping was applied including search for nest stands. The population changes are different for both parts (less steep in the residential district). Recent abundances in the central block building districts exceed those from the residential districts, however, the new top number ist 32 p/km² for a high-rise building area. Since 1991, winter birds were censused in different habitats of Berlin since 1991, during the winter periods 1991 and 1992 with varying plot size, and from 1993 to 1995 on 5ha plots. Magpie uses the residential district with high frequency and abundance. There is some concern about comparability of abundances from winter and breeding seasons. The daily range of a roosting winter community of up to 420 birds is estimated at about 12 km², which means an abundance of up to 3,5 ind./10ha rather near to numbers found on 5ha plots, however, exceeding numbers expected from the breeding season. Henceforth, during winter time Magpies may prefer other habitat types than in the breeding season.
The Black-billed Magpie, Pica pica sericea, was introduced in Japan from Korea about 400 years ago. It inhabits a restricted area in northern Kyushu, but has relatively high nesting density in some areas (> 20 pairs per km²). Most nests are built in the vicinity of human habitation, even in the midst of cities. Most clutches are laid in March and April. Mean clutch size (6.2) and mean number of hatchlings (4.2) are within the ranges of values for European and North American races. Nesting success is low, with only 18% of clutches surviving to fledge. Predation, mainly by crows, is a major cause of failure, accounting for 81% of clutch loss and 84% of brood loss. Low nesting success may have taken place in recent years. Nests on utility poles are more successful than those in trees. Nesting on utility poles has been increasing, occupying more than 50% of total number of nests. The range of the Black-billed Magpie has been gradually expanding in Japan.
The adaptive significance of female extra-pair copulation behavior was investigated in Yellow-billed Magpies, Pica nuttalli, a socially monogamous species. Research was carried out in central coastal California, U.S.A. Observations of female behavior towards extra-pair males during the breeding season suggest that females display a preference for certain extra-pair males. In addition, observations confirm that females can successfully resist male copulation attempts. However, based on a small sample, no significant difference in fledging success was found for nests at which extra-pair visits occurred and those at which they did not. Multilocus DNA fingerprinting analysis is in progress to determine the rate of extra-pair fertilizations. These data will be analyzed for correlations between female behavior towards extra-pair males and those males successfully gaining extra-pair fertilizations, and for differences in fledging success between nests with extra-pair fertilizations and those without extra-pair fertilizations.
Research on the Magpie Pica pica was conducted in the limits of urbanized part of Lvov (66.5km2) in the summer of 1994-1995, and the winters of 1993/94 and 1994/95. The work was based on an ecological (landscape mosaic) division of the city. The number of breeding Magpies was estimated to be 520 pairs (0.8 pair/10ha). The highest density of birds was recorded in parks and areas of one family houses (1.2 pair/10ha), less in the modem housing estates (0.7 pair/10ha), and the lowest in the central and industrial districts (0.4 pair/10ha). The number of wintering Magpies in Lvov is about 2000 (3 ind./10ha). The highest density was recorded in rural zones of the town (8.4 ind./10ha), the least in the industrial zones (1.8 ind./10ha). In winter outside of the town Magpies were counted at a communal roost, which gathered up to 1700 individuals.
Variability in morphological features is one mechanism by which recognition of individuals or kin, crucial to many social interactions, can occur. Patches in the remiges of magpie wings (white patches with black tips) contain information regarding the bearer's age and sex. Juvenile wing patches of both Black-billed Pica pica hudsonia and Yellow-billed Magpies Pica nuttalli contain between 10 to 12 feathers with variable lengths of white. Our investigations examine the relationship between wing patch morphology and relatedness. We measured the black tips on the primaries of one wing on 29 fledglings from seven nests. We derived a discriminant function based on the length of black on three inner primaries that successfully assigned 75 % of the birds to their natal nests (random assignment = 14% correct). We also compared the total length of black tips in the wing patches of young from 33 nests. We found less variation in the patch size within than between nests (log transformed ANOVA F = 8.339, p < 0.001; Kruskal-Wallis H = 113.6, p < 0.001). These results suggest that familial resemblance is encoded in juvenal magpie wing patches. Family recognition may be important both to the parents, who provide protection and food for their young, as well as between siblings, who apparently know each other.
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