Integrative taxonomy of the Changeable Hawk-Eagle Nisaetus cirrhatus complex (Accipitriformes: Accipitridae) in India.

The Changeable Hawk-Eagle Nisaetus cirrhatus complex is represented by two taxa in mainland India: N. c. cirrhatus in the northern plains and peninsula and N. c. limnaeetus in the Himalayan foothills. Traditionally these taxa have been regarded as subspecies of one species, but recently they have been proposed to be different species. Here, we use an integrative taxonomic approach based on considerations of plumage, biometrics, genetics and vocalizations. Several plumage characters are significantly different between the two taxa, but crest length was the only one of 56 characters that was diagnostically different, with no overlap. About 30% of the birds had intermediate crest lengths, suggesting that they are hybrids or backcrosses, as also supported by the microsatellite results. PCAs of adult plumage show many intermediate individuals, irrespective of whether these birds were collected near a putative contact zone. There is restricted gene flow between the two taxa, presumably as a result of their largely allopatric distributions. On current knowledge, reproductive isolation appears to be weak at best, and we therefore recommend continuing to regard limnaeetus and cirrhatus as conspecific.

The effects of low levels of pollutants on the reproduction of golden eagles in western Norway.

The reproductive success of golden eagles was studied in an area in western Norway between 62 degrees and 63 degrees N between 1973 and 1999. Addled eggs were collected for analysis of chemical pollutants from nine territories; five from coastal areas and four from inland. The coastal sites had lower annual reproductive output than inland sites, and the eggs had a higher content of organochlorine compounds. There were relatively strong negative correlations between reproductive output and (1) shell thickness and (2) DDE concentration in eggs. The data indicate that the golden eagle may be a particularly sensitive species to DDE. It is proposed that the higher organochlorine content found in the eggs of coastal birds was caused by a contribution of marine birds to the diet, as opposed to inland eagles which have a prey basis consisting almost entirely of terrestrial herbivores such as grouse, mountain hare and cervids. Our data-set on reproductive output is, however, too small to establish a general relationship between DDE contamination and reproductive output in golden eagles.