Strong population decline of Citril Finches Carduelis citrinella at postbreeding sites in the northern Black Forest

Ein Vergleich der Bestände von Zitronenzeisigen an traditionellen, nachbrutzeitlichen Sammelplätzen im Nordschwarzwald ergab signifikante Rückgänge in vier von fünf Gebieten. Bei anhaltendem Rückgang ist mit dem völligen Verschwinden der Art im Nordschwarzwald zu rechnen. Mögliche Ursachen bestehen in der Änderung der Landnutzung durch die Aufgabe der traditionellen Almwirtschaft und durch Wiederbewaldung der Hochlagen. Außerdem ist ein negativer Einfluss durch eine deutliche Klimaveränderung und damit verbundene Veränderung in der Schneeauflage, Vegetation und den Wachstumsperioden wahrscheinlich. Deutliche Populationsrückgänge in benachbarten Gebieten wie den Alpen (Rückgang der Dispersion) könnten ebenfalls ein wichtige Rolle für 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 phänotypisch intermediärer Hybride aus Gartenrotschwanz Phoenicurus phoenicurus und Hausrotschwanz P. ochruros während der Brutzeit im Nordschwarzwald beobachtet (Ruhestein, 950 m NN; Kreis Freudenstadt; Baden-Württemberg). Solche Rotschwanz-Hybriden wurden schon mehrfach im Freiland nachgewiesen. Angaben zu Habitat, Bruterfolg, Nachwuchs und Fitness von Hybrid-Rotschwänzen im Freiland sind allerdings sehr selten. Es ist wahrscheinlich, dass die enge Nachbarschaft von Bruthabitaten beider Arten das Auftreten von Hybriden begünstigen. Der hier beschriebene Vogel brütete drei Jahre hintereinander erfolgreich mit einem Hausrotschwanz-Weibchen und zog mindestens zwei bis drei Jungvögel pro Brut groß.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)

És prou conegut que el gaig és un predador important de nius d'ocells. Aquí es descriu la conducta de cerca d'un gaig el 7 de juny de 2002 a l'estació d'esquí de la Vansa, al Prepirineu català. Durant un període 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 més 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 és una àrea amb una alta densitat reproductora de llucareta (12-15 parelles/10 ha), la qual cosa converteix els nius d'aquesta espècie probablement en un dels objectius preferits per a la depredació del gaig

Variació entre localitats en la mida de l’ou de la Llucareta (Carduelis citrinella) al Prepirineu català

Es va estudiar la variació de la mida de l’ou en la Llucareta en dues àrees d’alta i baixa qualitat d’hàbitat al Port del Comte, al Prepirineu català. Tot i que la mida de la mostra va ser força baixa, es van obtenir evidències d’ous més grans amb volums més grans al lloc d’alta qualitat. Aquestes dades es corresponen amb els resultats d’estudis previs en els quals es va trobar considerable variació entre aquestes dues localitats pel que fa a supervivència, condició física, velocitat de la muda, selecció de dieta i èxit reproductor. Aquestes dades suggereixen que la qualitat d’hàbitat i la qualitat de les femelles també afecten la mida de l’ou 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 ‘‘Greenland’ ’ 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 ‘‘Seebohm’s’ ’ 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 ‘‘Mediterranean’ ’ 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

Geographic variation in coal tit song across continents and reduced species recognition between Central European and Mediterranean populations

Intraspecific variation of passerine song may influence mate choice and consequently provides a potential mechanism for premating reproductive isolation in birds. Notable geographic variation of songs is particularly common in widespread bird species, such as the coal tit Periparus ater (Aves, Passeriformes, Paridae) having a large trans-Palearctic distribution range including allopatric populations. In this study, measurement and analysis of 16 song parameters from different Western Palearctic populations showed a relatively uniform song in all continental European and the island populations of Corsica and Sardinia. Song variation among and within these populations seems so variable that there is a broad geographical overlap of acoustic parameters between populations. However, songs from northwest African and Cypriot populations had lowest minimum frequencies and were thus significantly different from continental European, Corsican and Sardinian populations. To test for intraspecific species recognition and potential acoustic isolation of different Palearctic populations, we carried out field playback experiments on Central European coal tit males with songs from populations of the Eurasian (Germany, Latvia, Russian Far East, Japan) and the Mediterranean region (northwest Africa, Cyprus, Corsica, Sardinia). Eurasian song types elicited similar strong territorial reactions in Central European coal tits as local control songs. In contrast, none of the Mediterranean songs evoked any notable reaction. Thus, there is geographic variation in coal tit song across continents that coincides with reduced species recognition between Central European and Mediterranean populations