Phoenicurus

Abstract: The effects of forest thinning and fragmentation on bird species were studied in northern Finland in 1982-1985. Based on line transect censuses bird communities of vir gin and thinned pine forests, and contiguous and fragmented spruce forests were com pared. There were no statistically significant differences in total bird densities in virgin and thinned pine forests, nor in uniform and fragmented spruce forests. The structure of bird communities was, however, different both in pine and spruce forests. The densities of the generalist species Phylloscopus trochilus, Carduelis flammea and Twdus iliacus and the marsh-nesting Motacilla flava were higher, and those of Parus cinctus, Perisoreus infaustus and Phoenicurus phoenicurus were lower in thinned forests than in virgin pine forests. Forest fragmentation had a positive effect on the densities of Ph. trochilus, T. iliacus and C. flammea, and a negative effect on the group of northern taiga species (Tetrao urogallus, Picoides tridactylus, Parus cinctus, Perisoreus infaustus, Pinicola enucleator and Emberiza rustica). Line transect censuses had been carried out in the vicinity of the study area already in the 1940s and 1950s. Densities of the most common species in virgin forests were com pared using the 1940-50 censuses and the present results. Fringilla montifringilla had in creased fivefold from the 1940-50 period to the 1980s, but this was probably due to a collapse, caused by several cold winters, in the 1940s. Densities of species preferring old forests, such as P. cinctus, Ph. phoenicurus and P. infaustus, had remained nearly the same in the study area from the 1940-50s to the 1980s, although these species have drastically declined in the whole of northern Finland due to silvicultural practices. In my study area the densities probably remained almost unchanged as, even today, there are large, virgin forests left. The importance of these forests in the conservation of declining northern bird species is emphasized.

Abstract: Mitochondrial DNA usually shows low sequence variation within and high sequence divergence among species, which makes it a useful marker for phylogenetic inference and DNA barcoding. A previous study on the common redstart (Phoenicurus phoenicurus) revealed two very different mtDNA haplogroups (5% K2P distance). This divergence is comparable to that among many sister species; however, both haplogroups coexist and interbreed in Europe today. Herein, we describe the phylogeographic pattern of these lineages and test hypotheses for how such high diversity in mtDNA has evolved. We found no evidence for mitochondrial pseudogenes confirming that both haplotypes are of mitochondrial origin. When testing for possible reproductive barriers, we found no evidence for lineage-specific assortative mating and no difference in sperm morphology, indicating that they are not examples of cryptic species, nor likely to reflect the early stages of speciation. A gene tree based on a short fragment of cytochrome c oxidase subunit 1 from the common redstart and 10 other Phoenicurus species, showed no introgression from any of the extant congenerics. However, introgression from an extinct congeneric cannot be excluded. Sequences from two nuclear introns did not show a similar differentiation into two distinct groups. Mismatch distributions indicated that the lineages have undergone similar demographic changes. Taken together, these results confirm that deeply divergent mitochondrial lineages can coexist in biological species. Sympatric mtDNA divergences are relatively rare in birds, but the fact that they occur argues against the use of threshold mtDNA divergences in species delineation.

Abstract: Summary Data are presented for the fat and water contents of 410 specimens of 11 species of trans-Saharan migrants collected on the northwest coast of Egypt in autumn. Mean fat contents vary from 37% of lean dry weight in Hirundo rustica to 110% in Sylvia communis. There is also much variation in the range of fat contents within individual species, Muscicapa striata and Lanius collurio being exceptionally closely grouped and P. phoenicurus widely dispersed. The results for each species are discussed in relation to their migratory circumstances. On the basis that the birds concerned would have started to cross the eastern Mediterranean with at least 11/2 times as much fat as they contained on landing in Egypt, comparisons are made with data for spring migrants in western Africa and with American trans-Gulf migrants. Water contents, discussed as % of lean dry weight, show considerable variation within each species:the coefficient correlating this percentage with % fat is around 0.50 except in Lanius (0.98) and Oriolus (0.92). On investigating the relationship between wing-length and lean dry weight, we did not find a strong correlation in any of the species and caution in accepting conclusions to the contrary is indicated.

Abstract: Population densities of Palearctic migrant and African birds were estimated from 444 point counts, that estimated minimum density, at 10 sites in the Sahel zone of northern Nigeria during December–January 1993/94. In total, 15 Palearctic species were recorded during point counts averaging 5 species per site, and 76 African species averaging 24 species per site. The densities of Palearctic migrants varied from 1 bird ha-1 in semi-desert and highly degraded woodland, up to 8 birds ha-1 in dense Sahelian woodland. Common Whitethroats Sylvia communis were most abundant (up to 0.7 birds ha-1) in sites rich in Piliostigma reticulata trees; Subalpine Warblers S. cantillans were most abundant (up to 5.9 birds ha-1) in sites rich in Acacia spp. and Cassia sieberiana; Lesser Whitethroats S. curruca and Redstarts Phoenicurus phoenicurus were associated with high overall tree densities (both up to 0.6 birds ha-1); Northern Wheatears Oenanthe oenanthe occurred at densities of about 1 bird ha-1 at very low tree density...