20 research outputs found
Strong population decline of Citril Finches Carduelis citrinella at postbreeding sites in the northern Black Forest
Ein Vergleich der BestĂ€nde von Zitronenzeisigen an traditionellen, nachbrutzeitlichen SammelplĂ€tzen im Nordschwarzwald ergab signifikante RĂŒckgĂ€nge in vier von fĂŒnf Gebieten. Bei anhaltendem RĂŒckgang ist mit dem völligen Verschwinden der Art im Nordschwarzwald zu rechnen. Mögliche Ursachen bestehen in der Ănderung der Landnutzung durch die Aufgabe der traditionellen Almwirtschaft und durch Wiederbewaldung der Hochlagen. AuĂerdem ist ein negativer Einfluss durch eine deutliche KlimaverĂ€nderung und damit verbundene VerĂ€nderung in der Schneeauflage, Vegetation und den Wachstumsperioden wahrscheinlich. Deutliche PopulationsrĂŒckgĂ€nge in benachbarten Gebieten wie den Alpen (RĂŒckgang der Dispersion) könnten ebenfalls ein wichtige Rolle fĂŒr die Populationsentwicklung des Zitronenzeisiges an der Arealgrenze im Nordschwarzwald spielen.A comparison of Citril Finch populations at traditional postbreeding assembling sites in the northern Black Forest comfirmed a significant decline of the species. Possible reasons may be found in changes in land use due to the end of traditional pasturing and reforestation in the mountainous areas. Additionally a negative influence due to global warming and the linked change in vegetation composition and periods of growing is highly likely. Probable macroecological reasons such as the decline of populations in neighbouring areas (e.g . Alps) and the reduction of population exchange by dispersion may play an important role for the decline of Citril Finches at their northern areal boundaries as well
Successful broods of a hybrid between redstart Phoenicurus phoenicurus and black redstart Phoenicurus ochruros
Zwischen 2000 und 2002 wurde ein phĂ€notypisch intermediĂ€rer Hybride aus Gartenrotschwanz Phoenicurus phoenicurus und Hausrotschwanz P. ochruros wĂ€hrend der Brutzeit im Nordschwarzwald beobachtet (Ruhestein, 950 m NN; Kreis Freudenstadt; Baden-WĂŒrttemberg). Solche Rotschwanz-Hybriden wurden schon mehrfach im Freiland nachgewiesen. Angaben zu Habitat, Bruterfolg, Nachwuchs und Fitness von Hybrid-RotschwĂ€nzen im Freiland sind allerdings sehr selten. Es ist wahrscheinlich, dass die enge Nachbarschaft von Bruthabitaten beider Arten das Auftreten von Hybriden begĂŒnstigen. Der hier beschriebene Vogel brĂŒtete drei Jahre hintereinander erfolgreich mit einem Hausrotschwanz-Weibchen und zog mindestens zwei bis drei Jungvögel pro Brut groĂ.Between 2000 and 2002 a male phenotypical intermediate hybrid between redstart Phoenicurus phoenicurus and black redstart P. ochruros. was observed regularly during the breeding season in the Northern Black Forest (Ruhestein, 950 m NN; district Freudenstadt; Germany). Similar redstart hybrids have been documented several times. However, descriptions on habitat selection, breeding success, offspring and fitness of such hybrids in the field are very rare. It is highly likely that close neighbourhood of breeding habitats of the two redstart species is responsible for the occurence of mixed broods. The hybrid documented in this study was breeding successfully each year with a black redstart female and raised at least two to three fledglings per brood
Predation strategy of the Eurasian Jay (Garrulus glandarius) and antipredator response by the Citril Finch (Serinus citrinella)
Ăs prou conegut que el gaig Ă©s un predador important de nius d'ocells. AquĂ es descriu la conducta de cerca d'un gaig el 7 de juny de 2002 a l'estaciĂł d'esquĂ de la Vansa, al Prepirineu catalĂ . Durant un perĂode de quatre minuts, l'ocell va inspeccionar quatre pins negres a la cerca de possibles nius d'altres ocells. El gaig va examinar les zones mĂ©s espesses de l'arbre, començant per les parts inferiors de les branques laterals i va acabar a la capçada. El comportament de la cerca va despertar el rebuig de mitja dotzena de llucaretes, probablement parelles que niaven als voltants, que seguien el gaig mentre es movia pels arbres, alhora que emetien crits antipredadors. La Vansa Ă©s una Ă rea amb una alta densitat reproductora de llucareta (12-15 parelles/10 ha), la qual cosa converteix els nius d'aquesta espĂšcie probablement en un dels objectius preferits per a la depredaciĂł del gaig
VariaciĂł entre localitats en la mida de lâou de la Llucareta (Carduelis citrinella) al Prepirineu catalĂ
Es va estudiar la variaciĂł de la mida de lâou en la Llucareta en dues Ă rees dâalta i baixa qualitat dâhĂ bitat al Port del Comte, al Prepirineu catalĂ . Tot i que la mida de la mostra va ser força baixa, es van obtenir evidĂšncies dâous mĂ©s grans amb volums mĂ©s grans al lloc dâalta qualitat. Aquestes dades es corresponen amb els resultats dâestudis previs en els quals es va trobar considerable variaciĂł entre aquestes dues localitats pel que fa a supervivĂšncia, condiciĂł fĂsica, velocitat de la muda, selecciĂł de dieta i Ăšxit reproductor. Aquestes dades suggereixen que la qualitat dâhĂ bitat i la qualitat de les femelles tambĂ© afecten la mida de lâou en aquestes subpoblacions properes
Resident and migrant birds use livestock dung pats for foraging
Low intensity grazing is an increasingly used tool in conservation. It creates beneficial conditions for biodiversity by shaping structural diverse habitats. An important resource provided by grazing are dung pats because many species are associated with those, especially arthropods. Because most birds depend on arthropods as a food source, dung pats may improve food availability. To investigate the role of dung pats as food-providing resources for birds, we conceived a camera trap study in the Black Forest National Park (Germany). Up to eight camera traps were simultaneously placed at dung pats of Heck cattle ( Bos taurus ) and Konik horses ( Equus caballus ) on low intensity grazing pastures. They recorded 229 foraging events of 26 different bird species between June 2021 and January 2022. Common Blackbirds ( Turdus merula ) were the most common foraging birds, typically breaking up dung pats in search of food and foraging up to 21 minutes at a single dung pat. Most other birds mainly picked up food items from the surface of dung pats. Birds used dung pats for foraging during the whole study period, even if they were covered with snow. Our study shows that dung pats can provide food for many bird species and highlights the importance of permanent low intensity grazing in conservation
Morphological Shifts of the External Flight Apparatus across the Range of a Passerine (Northern Wheatear) with Diverging Migratory Behaviour
We studied morphological differentiation in the flight apparatus of the four currently recognised sub-species of Northern Wheatears, Oenanthe oenanthe. Considering all measured birds without assigning them a priori to any sub-species we found a clinal morphological shift. Relative wing length, wing pointedness, and the degree of tail forking were positively correlated with migratory distance, whereas tail length (relative to wing length) was negatively correlated. The large-sized, longdistance migrant ââGreenlandâ â Wheatear, O. o. leucorhoa, is characterized by relatively longer, broader and more pointed wings and more forked tails, similar to the smaller-sized nominate Northern Wheatear, O. o. oenanthe, from North Europe, Siberia and Russia. In contrast, the short distance migrant ââSeebohmâsâ â Wheatear, O. o. seebohmi, from northwest Africa, possesses much rounder wings, and the tail is relatively longer and less forked. Sub-species with intermediate migratory habits (different populations of nominate Northern Wheatear, O. o. oenanthe, and ââMediterraneanâ â Northern Wheatear, O. o. libanotica) show, as expected, intermediate features according to their intermediate migratory behaviour. Our results are congruent with other inter- and intraspecific studies finding similar adaptations for energy-effective flight in relation to migration distance (morphological migratory syndrome)
Was everything better in the good old days? Declining body mass in the Garden Dormouse (Eliomys quercinus)
Garden Dormouse (Eliomys quercinus) populations have shown a drastic decline over the last 20-30 years, the reasons for this decline are still unknown. In wild animals, body mass is a good indicator of fitness and survival probability, especially in hibernating species like dormice. Fat accumulation before the onset of hibernation and juvenile growth are crucial to survive the following winter. We conducted a capture-mark-recapture study in the Black Forest (south-western Germany) between 2018 and 2021 and compared the body mass of captured Garden Dormice with data collected between 2003 and 2005. Furthermore, we investigated the dietary spectrum of this species by faecal analyses. The results show that adult Garden Dormice nowadays have a significantly lower body mass (difference 11 ± 2.8 g) before the onset of hibernation than two decades ago. Furthermore, juveniles showed a significantly lower body mass gain in the years 2018-2021 compared to juveniles in 2003-2005. Dietary analyses have revealed that insects represent the main food resource for juvenile Garden Dormice and also in adults during pre-hibernation fattening. This study shows, that the body mass of the Garden Dormice in the Black Forest has decreased over the last two decades, which could reduce their reproductive success and their survival rate, especially during hibernation. A reason for this body mass reduction could be the severe decline of insects leading to an insufficient availability of the key food resource of this species. In particular, reproductive females might not be able to cover their investment during gestation and lactation
Was everything better in the good old days? Declining body mass in the Garden Dormouse (Eliomys quercinus)
Garden Dormouse (Eliomys quercinus) populations have shown a drastic decline over the last 20-30 years, the reasons for this decline are still unknown. In wild animals, body mass is a good indicator of fitness and survival probability, especially in hibernating species like dormice. Fat accumulation before the onset of hibernation and juvenile growth are crucial to survive the following winter. We conducted a capture-mark-recapture study in the Black Forest (south-western Germany) between 2018 and 2021 and compared the body mass of captured Garden Dormice with data collected between 2003 and 2005. Furthermore, we investigated the dietary spectrum of this species by faecal analyses. The results show that adult Garden Dormice nowadays have a significantly lower body mass (difference 11 ± 2.8 g) before the onset of hibernation than two decades ago. Furthermore, juveniles showed a significantly lower body mass gain in the years 2018-2021 compared to juveniles in 2003-2005. Dietary analyses have revealed that insects represent the main food resource for juvenile Garden Dormice and also in adults during pre-hibernation fattening. This study shows, that the body mass of the Garden Dormice in the Black Forest has decreased over the last two decades, which could reduce their reproductive success and their survival rate, especially during hibernation. A reason for this body mass reduction could be the severe decline of insects leading to an insufficient availability of the key food resource of this species. In particular, reproductive females might not be able to cover their investment during gestation and lactation
Was everything better in the good old days? Declining body mass in the Garden Dormouse (Eliomys quercinus)
Garden Dormouse (Eliomys quercinus) populations have shown a drastic decline over the last 20-30 years, the reasons for this decline are still unknown. In wild animals, body mass is a good indicator of fitness and survival probability, especially in hibernating species like dormice. Fat accumulation before the onset of hibernation and juvenile growth are crucial to survive the following winter. We conducted a capture-mark-recapture study in the Black Forest (south-western Germany) between 2018 and 2021 and compared the body mass of captured Garden Dormice with data collected between 2003 and 2005. Furthermore, we investigated the dietary spectrum of this species by faecal analyses. The results show that adult Garden Dormice nowadays have a significantly lower body mass (difference 11 ± 2.8 g) before the onset of hibernation than two decades ago. Furthermore, juveniles showed a significantly lower body mass gain in the years 2018-2021 compared to juveniles in 2003-2005. Dietary analyses have revealed that insects represent the main food resource for juvenile Garden Dormice and also in adults during pre-hibernation fattening. This study shows, that the body mass of the Garden Dormice in the Black Forest has decreased over the last two decades, which could reduce their reproductive success and their survival rate, especially during hibernation. A reason for this body mass reduction could be the severe decline of insects leading to an insufficient availability of the key food resource of this species. In particular, reproductive females might not be able to cover their investment during gestation and lactation