Marc I. Förschler

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, long-distance 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 “Seebohms” 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).

Extraordinary high natal philopatry in a migratory passerine

Natal dispersal is a key component of population dynamics in birds. It guarantees the genetic exchange of populations, favours range expansions and reduces intraspecific competition. In general, natal philopatry of migratory passerines is quite low (0–13.5%). In this study, we give evidence that, under specific conditions, migratory populations of passerine birds may show a considerably elevated natal philopatry. In a Linnet Carduelis cannabina population on the remote island of Helgoland in the North Sea, we found an extraordinary high return rate of yearlings (38%), which corresponds exactly to the annual survival rate of the species. Despite being completely migratory, the Linnets of Helgoland apparently return to a large extent to their native area and consequently might support the population maintenance on the island. Further studies are needed to reveal if this high natal philopatry is only an unusual 1-year event or a general characteristic of this partially isolated island population.

The species status of the Corsican finch Carduelis corsicana assessed by three genetic markers with different rates of evolution

Citril finches Carduelis c. citrinella and Corsican finches Carduelis c. corsicana represent two closely related forms, endemic to European mountains and some Mediterranean Islands. Their taxonomic status has recently been disputed based on the results from mitochondrial genes. We show that the use of different genetic markers may lead to different results in these two putative species. Using the mitochondrial ATP8+6 we found a clear difference between C. c. citrinella and C. c. corsicana (3.2%) suggesting a divergence time of 1.2MYR. In contrast, no clear difference was found using two nuclear genes. The mismatch between the different markers suggests that the separation of C. c. citrinella and C. c. corsicana is likely to be a rather recent event, involving bottlenecks, which have enhanced the divergence in the mtDNA. Our results call for caution when using mtDNA alone for assessing times of divergence and rates of evolution. We did not find any support for the view that C. c. corsicana is more related to Carduelis carduelis than C. c. citrinella as proposed by previous studies.

Phylogeography, pre-zygotic isolation and taxonomic status in the endemic Cyprus Wheatear Oenanthe cypriaca

AbstractThe insular endemic Cyprus Wheatear Oenanthe cypriaca has been considered as a subspecies of Pied Wheatear O. pleschanka. However, due to several differences in behaviour, habitat selection and morphology, it is currently treated by most authors as an independent species. Here, we used mitochondrial nucleotide sequences of the cytochrome oxidase subunit 1 gene (679 base pairs), playback experiments and dummy presentations to assess the status of O. cypriaca. For the playback experiments we used the conspecific song, and heterospecific songs of the two subspecies of Black-eared Wheatear O. hispanica hispanica and O. hispanicamelanoleuca, O. pleschanka, and Finsch’s Wheatear O. finschii. Experimental dummy presentations included O. cypriaca, O. pleschanka and a dark and light morph of O. h. melanoleuca. O. cypriaca responded significantly stronger towards the conspecific model and towards conspecific playbacks than towards heterospecific stimuli. ML and BI analyses support the close relationship between O. cypriaca, O. pleschanka and O. h. melanoleuca. With a relative high posterior probability value (0.98), O. cypriaca clusters closer to O. h. melanoleuca from Iran and Israel (on migration) and O. pleschanka from Iran than to O. pleschanka obtained from Kazakhstan, Russia, Mongolia and wintering areas in East Africa (Kenya). The scenario suggests that O. cypriaca might be either a relatively young taxon, which is yet behavioural distinct, but genetically still similar to its sister populations on the mainland. Alternatively, we may assume a close relationship as an indication for potential ongoing hybridisation processes involving all three forms.ZusammenfassungPhylogeographie, Taxonomie und präzygote Isolation beim ZypernsteinschmätzerOenanthe cypriaca Endemismus auf Inseln ist ein bekanntes Phänomen. Der Zypernsteinschmätzer Oenanthe cypriaca brütet nur auf Zypern und wurde lange Zeit als Unterart des Nonnensteinschmätzers O. pleschanka bezeichnet, obwohl einige Autoren besonders aufgrund des Gesangs ihn als eigene Art betrachteten. In dieser Studie untersuchten wir die mitochondrielle Nukleotidensequenz der Cytochrome oxidase subunit 1 um das phylogeographische Muster und die genetische Struktur von O. cypriaca zu bestimmen. Zusätzlich wurden noch Playbackexperimente und Modellpräsentationen durchgeführt (dummies). Dies sollte einen Hinweis auf die präzygote Isolation geben. Die Studie fand im März/April 2008 und Mai 2009 statt. Verschiedene Playbacks wurden benutzt: konspezifischer Gesang und heterospezifischer von Mittelmeersteinschmätzer O. h. hispanica/melanoleuca, O. pleschanka und Felsensteinschmätzer O. finschii. Experimentelle Dummy Präsentationen beinhalteten Modelle von O. cypriaca, O. pleschanka und sowohl eine dunkle als auch eine helle Morphe von O. h. melanoleuca. O. cypriaca reagierte signifikant stärker auf konspezifischen Gesang und konspezifische Modelle als auf O. pleschanka und die anderen Oenanthe-Arten. 679 Basen Paare (bp) der mitochondriellen Cytochrome c oxidase subunit 1 (CO1) wurden untersucht. Die Maximum-Likelihood und Bayesian Inference Analysen unterstützten die nahe Verwandtschaft zwischen Oenanthe cypriaca, O. pleschanka und O. h. melanoleuca. Dieselbe Analyse allerdings zeigte interessanterweise, dass—mit hoher bootstrap Wahrscheinlichkeit—O. cypriaca ein Cluster bildet, indem die Art näher mit O. h. melanoleuca aus Iran und Israel (vom Durchzug) und O. pleschanka aus Iran als mit O. pleschanka aus Überwinterungsgebieten in West Afrika (Kenia) verwandt ist. Die Daten dieser Studie unterstützen teilweise den Status des Zypernsteinschmätzers als eigenständige Art, aber die molekulare Analyse zeigt, dass die Artbildung wahrscheinlich noch sehr jung ist oder Hybridisationsprozesse stattfinden.

Convergent evolution of morphological and ecological traits in the open-habitat chat complex (Aves, Muscicapidae: Saxicolinae)

Open-habitat chats (genera Myrmecocichla, Cercomela, Oenanthe and relative) are a morphologically and ecologically cohesive group of genera with unclear phylogenetic relationships. They are distributed mostly in open, arid and/or rocky habitats of Africa and Eurasia. Here, we present the most comprehensive molecular phylogenetic analysis of this group to date, with a complete taxon sampling at the species level. The analysis, based on a multilocus dataset including three mitochondrial and three nuclear loci, allows us to elucidate the phylogenetic relationships and test the traditional generic limits. All genera are non-monophyletic, suggesting extensive convergence on similar plumage patterns in unrelated species. While the colour pattern appear to be a poor predictor of the phylogenetic relationships, some of the ecological and behavioural traits agree relatively well with the major clades. Following our results, we also propose a revised generic classification for the whole group.

Vocal types in crossbill populations (Loxia spp.) of Southwest Europe

The evolution of crossbills is one of the most fascinating topics in evolutionary ecology. Recent studies have shown an astonishing divergence in terms of vocalisation between morphologically quite similar crossbill populations in the Red/Common Crossbill complex (Loxia curvirostra) of North America and Europe. Some evidence even indicates the existence of “cryptic” species with different vocal types and bill sizes, which are adapted to different conifer species. However, there is so far no strong genetic evidence for the existence of separate species, although assortative mating occurs with respect to bill size. To understand the role of vocalisation in the speciation process of crossbill taxa, basic studies that assess the distribution of vocal types of crossbills and the use of different habitats and resources are needed. In our study, we investigated the occurrence of crossbill vocal types in Southwest Europe. In addition to the well-known vocal types described first by Robb (Dutch Birding 22:61–107, 2000) for the Benelux and Great Britain, we discovered at least six more vocal types in the Mediterranean area. Some vocal types were found exclusively in rather small areas, e.g. in the Pyrenees, the Sierra de Cazorla, Sierra de Javalambre and on Corsica, and appeared to be tightly linked to certain habitat types and pine species. Overall, vocal types in the Mediterranean had a more local occurrence than vocal types from northern populations, which were more widely distributed. This might reflect the nomadic behaviour of northern European crossbills, which feed, in contrast to Mediterranean crossbills, mostly on rather unstable food sources, especially spruce seeds. Furthermore, the vocal types of Mediterranean crossbills show at least some similarities to the vocal types of the rather sedentary crossbills of North Europe (L.pytyopsittacus, L. scotica), which are as well adapted to pine seeds. This might reflect a common ancestry of crossbills adapted for pines. We therefore suggest the existence of two main groups of crossbills in Europe: one group that is rather sedentary and feeds mainly on pine seeds (L. pytyopsittacus, L. scotica and the Mediterranean forms), and another group in Central, Northern and Eastern Europe that is highly nomadic and mostly feeds on spruce seeds (L. curvirostra). Further studies are needed to unravel the consistency of vocal types and the genetic relationship between the different forms, and to provide more evidence for the degree of assortative mating of crossbills with distinct vocalisation breeding in sympatry.

A song analysis of the insular Cyprus Short-toed Treecreeper, Certhia brachydactyla dorotheae, supports its subspecies status (Aves: Passeriformes)

Abstract We studied the song of the insular Cyprus Short-toed Treecreeper, Certhia brachydactyla dorotheae Hartert, 1904, and compared it with the songs of mainland populations. The song of dorotheae differs from the Central European and south-west European subspecies brachydactyla Brehm, 1820 and megarhynchos Brehm, 1831 most obviously in the number of elements and elements per second, with the effect that the song of dorotheae appears to have a slower rhythm. Furthermore, the starting frequency and ending frequency of their songs are lower. Our findings provide additional support for the subspecific status of the island population of the Short-toed Treecreeper, Certhia brachydactyla dorotheae, on Cyprus.

Morphometric diagnosability of Cyprus Wheatears Oenanthe cypriaca and an unexpected occurrence on Helgoland Island

Capsule We found closely related Cyprus Wheatears Oenanthe cypriaca and Pied Wheatears Oenanthe pleschanka to differ significantly from each other in 14 external morphometric characters, supporting the independent taxonomic status of both forms. An additionally measured old specimen from Helgoland unexpectedly turned out to be a Cyprus Wheatear, the first record for Germany.

Absence of insular density inflation in Corsican Finches Carduelis citrinella corsicanus

Abstract. The insular syndrome predicts a number of differences between insular and mainland populations. One such prediction is that island populations tend to exhibit density inflation. This prediction was examined by comparing the population densities of mainland Citril Finches (central and south-west Europe) and insular Corsican (Citril) Finches (Mediterranean islands). Contrary to the hypothesis of density inflation in island populations, no indication of higher densities in Corsican Finches (0.6–2.1 pairs/10 ha) was found in comparison with Citril Finches (1.3 pairs/10 ha). In fact, population densities in the mainland population of the Catalan Pre-Pyrenees (7–10 pairs/10 ha) were extraordinarily high in comparison with all other study areas.