Time filter

Source Type

Sempach, Switzerland

A fundamental goal of conservation biology is the establishment of knowledge to increase the probability that population declines can be halted. Population biology plays a central role in this endeavour. Population analyses allow to recognise the demographic mechanisms underlying population change and to assess the effects of different management actions on future population developments. These insights may result either in targeted conservation actions or in the formulation of new focal hypotheses about population change. A central element of every population analysis is a population model which describes the link between population size and the demographic rates (survival, recruitment, emigration, immigration). In this essay I illustrate how population analyses provide insights for the conservation of four species (Eurasian Hoopoe Upupa epops, Eurasian Eagle-Owl Bubo bubo, Bearded Vulture Gypaetus barbatus, Red Kite Milvus milvus). The first two case studies are retrospective, they identify demographic reasons for observed population change in the past. The second two case studies are prospective, they compare the effects of different management actions on the future development of the populations. Population analyses are not only central in conservation biology, they are equally important for setting sustainable harvest bags in exploited populations. The need to assess human impacts on wildlife will increase. Since an impact assessment of all actions needs to be performed at the level of populations, the demand for population biology is likely to increase as well. Source

A mild winter with little snow in the north but massive amounts of snow in southern Switzerland was followed by a mild und sunny spring. Summer was cool with high rainfall, autumn again mild. For the first time a pair of Arctic Terns Sterna paradisaea nested in Switzerland. For the fifth time breeding was confirmed for Ferruginous Duck Aythya nyroca. A family of Garganey Anas querquedula was observed, for the first time since 2006. Northern Shoveler A. clypeata (one family) and Common Shelduck Tadorna tadorna (one family) were confirmed breeding as well. Three to four families of Eurasian Dotterel Charadrius morinellus were observed in the border region of Switzerland and Austria. The Subalpine Warbler Sylvia cantillans was breeding for the fourth time. The Bearded Reedling Panurus biarmicus was found at three new sites, and the Eurasian Penduline Tit Remiz pendulinus was probably breeding, for the first time since 2006. A pair of Little Egrets Egretta garzetta probably made a nesting attempt. Red-crested Pochard Netta rufina (244 broods), Common Eider Somateria mollissima (5 broods), Great Cormorant Phalacrocorax carbo (1504 broods), White Stork Ciconia ciconia (376 broods), Bearded Vulture Gypaetus barbatus (9 broods) and European Bee-eater Merops apiaster (66 broods) reached their highest breeding numbers. With 10 breeding pairs Purple Heron Ardea purpurea reached the highest number since 1972. Similarly, the 68 singing males were the highest number for Corn Crake Crex crex since 2000, and the 49 territories the highest number for Common Rosefinch Carpodacus erythrinus since 1996. On the contrary, only 563 pairs of Black-headed Gull Larus ridibundus were counted, the lowest number since the start of systematic surveys in 1984, and only three Ortolan Bunting Emberiza hortulana territories were left. © 2015, ALA. All rights Reserved. Source

The Red-crested Pochard Netta rufina colonised Switzerland in the 20th century. In 1927 the first nest was found in the Swiss part of Lake Constance (Bodensee), ten years after the first breeding records on the German side. Until 1964, when the first brood was confirmed on Lake Zurich, breeding was restricted to Lake Constance. Until 1980 breeding records in Switzerland remained scarce but since then breeding has been confirmed every year. In the 1990s a rapid increase started, reaching 222 confirmed broods in 2011. The number of breeding pairs for this year was estimated at around 450. The increase happened in parallel to the massive increase in wintering numbers from a few hundred in the mid-1980s to a maximum of over 30 000 in 2009. Redcrested Pochards breed mainly on the large lakes of the Swiss plateau, with the highest numbers on sites where wintering birds concentrate. Apart from isolated records on Lac de Joux at 1000 m a.s.l., breeding is restricted to lowland areas (below 600 m). Lake Neuchâtel, leading the list of the most important wintering sites together with Lake Constance, holds around half of the Swiss breeding population. In the last decade, the species has increasingly spread to small waterbodies. Data collected by volunteers give an insight into the breeding biology, although no systematic sampling has taken place. The Red-crested Pochard has a long breeding season. Hatching dates were recorded between the end of April and beginning of September, with an overall peak in July. Records of clutches on Lake Neuchâtel, where Red-crested Pochards nest mainly on artificial islands, indicate a high degree of interspecific nest parasitism, in particular with Mallard Anas platyrhynchos, the most abundant breeding duck species in Switzerland. Mixed families were commonly recorded as well. In most cases these were led by females of other species, mostly Mallard (80% of 219 families from across Switzerland), followed by Tufted Duck Aythya fuligula (16%), Common Pochard A. ferina (3%) and Common Eider Somateria mollissima (1%). Only in seven cases were ducklings from other species led by a Redcrested Pochard female. In six of these cases the family contained ducklings of Tufted Duck, in one of Mallard. Source

Jacot A.,Schweizerische Vogelwarte | Reers H.,Max Planck Institute for Ornithology (Seewiesen) | Forstmeier W.,Max Planck Institute for Ornithology (Seewiesen)
Behavioral Ecology and Sociobiology | Year: 2010

The recognition of food-provisioning parents is crucial for fledglings of many bird species. Vocalizations are the most commonly used cues in avian parent-offspring communication, and it has been shown in several species that fledglings respond specifically to their parents' contact calls. However, fledglings occasionally also react to unrelated adults. Such responses may reflect recognition errors or alternatively a strategy of fledglings to obtain food or other direct benefits from unrelated adult birds. In a playback experiment, we tested whether zebra finch Taeniopygia guttata fledglings perceive variation in adult call signatures to recognize their parents and whether the propensity to respond to unrelated individuals is related to the gender of adults and to signal properties of male and female calls. Male calls are learnt and show high intra-sexual variation, which may improve the accurate recognition of the father's individual signature. In contrast, calls of adult females are innate, show lower intra-sexual variation such that the mother's call is more likely to be confused with another female call. We demonstrate that fledglings are able to recognize their parents. In addition, fledglings reacted more strongly to unrelated females compared with unrelated males. Our findings suggest that responses to unrelated adults may reflect recognition errors and indicate the importance of variation in identity signals for individual recognition processes in parent-offspring communication. © 2010 Springer-Verlag. Source

Korner-Nievergelt F.,Schweizerische Vogelwarte | Huppop O.,Institute For Vogelforschung Vogelwarte Helgoland
Vogelwarte | Year: 2010

Publishing ornithological data requires the application of adequate statistical methods. With the improvement of methods, software requirements are arising, but available proprietary programs are often far beyond the financial limits of the users. The statistic package R is a free but nevertheless very sophisticated alternative. Regrettably, it is not easy to get started with R since it is not clickable and needs the typing of code. This article is a step by step introduction for R-beginners. The reader can experience the input of data, their handling and visualisation at his computer. We guide the user through a t-test and develop a simple linear model including analysis of residuals. Finally, we suggest books for further reading. © DO-G, IfV, MPG 2010. Source

Discover hidden collaborations