Demographic mechanism of a historical bird population collapse reconstructed using museum specimens

Long-term studies of demographic rates provide clues about the external causes of animal population declines, but systematic monitoring is rarely in place until after the decline has occurred. This study evaluates alternative hypotheses about the demographic mechanisms underlying the historical collapse of corncrake (Crex crex) populations in Britain and Ireland in the late nineteenth and early twentieth centuries using characteristics of museum specimens. The proportion of adult corncrakes that are 1-year old was estimated from feather characteristics of birds collected before, during and after the population decline and showed a marked transitory reduction during the decline. This pattern would be expected if the decline was caused by a large reduction in the recruitment of young birds to the breeding population and is the opposite of what would be expected if a change in adult survival had caused the decline. These results are consistent with previous suggestions that the corncrake population decline was caused by adverse effects on breeding productivity caused by the mechanization of the harvesting of hay crops

Zur Schädlingsvertilgung einiger Singvogelarten in einem Schwarzkiefern/Eichen-Mischbestand im Beynamer Wald bei Ankara*

erdogan, ali/0000-0001-5970-6030WOS: 000177359300003Analysis of nestling food in four species of Parus and one species of Ficedula using the 'Halsringmethode' showed a high quota of adults and caterpillars of the important forest pests: Tortrix viridana, Euproctis chrysorrhoea, Diprion pini, and Lymantria dispar . These four major pest species amounted in the nestling food of Parus major to 50 %, P. coeruleus to 52.6 %, P. ater to 40.9 %, and Ficedula hypoleuca to 30.2 %

A metapopulation approach to the population biology of the song sparrow Melospiza melodia

In this paper, we describe spatial variation in the demography of the Song Sparrow Melospiza melodia. Long-term population studies of birds have generally considered only single sites in optimal habitat, but recent theory has shown the value of taking spatial variation in population dynamics into account. In this theory, collections of local populations in habitat patches connected by dispersal are defined as metapopulations. We review metapopulation models briefly and then use these ideas in a study of the Song Sparrow. Sparrows were studied on islands of varying size and degree of isolation from the North American continent. For analysis, these islands are grouped into three areas. Sparrows on the isolated Mandarte Island usually reproduced and survived well over 17 years but suffered from catastrophic mortality in some winters. After such events, the population recovered quickly without much immigration. Sparrows on smaller islets near Mandarte also survived and reproduced well during 4 years, and they did not experience severe mortality in a winter in which those on Mandarte declined by over 90%. These small islets frequently exchanged first year birds, but only one yearling bird moved between the small islets and the more isolated Mandarte. Sparrows at one of two sites on the larger Westham Island, near the continental mainland, survived less well than on the small offshore islands. Reproduction on Westham Island was poor because of frequent nest failure and high levels of brood parasitism by Brown-headed Cowbirds Molothrus ater. Despite this poor reproduction and survival, the Westham population remained stable as a result of immigration. We interpret the dynamics of these sparrow populations in terms of H.R. Pulliam's source-sink metapopulation model