The interplay of colour and bioacoustic traits in the differentiation of a Southeast Asian songbird complex.

Morphological traits have served generations of biologists as a taxonomic indicator, and have been the main basis for defining and classifying species diversity for centuries. A quantitative integration of behavioural characters, such as vocalizations, in studies on biotic differentiation has arisen more recently, and the relative importance of these different traits in the diversification process remains poorly understood. To provide a framework within which to interpret the evolutionary interplay between morphological and behavioural traits, we generated a draft genome of a cryptic Southeast Asian songbird, the limestone wren-babbler Napothera crispifrons. We resequenced whole genomes of multiple individuals of all three traditional subspecies and of a distinct leucistic population. We demonstrate strong genomic and mitochondrial divergence among all three taxa, pointing to the existence of three species-level lineages. Despite its great phenotypic distinctness, the leucistic population was characterized by shallow genomic differentiation from its neighbour, with only a few localized regions emerging as highly diverged. Quantitative bioacoustic analysis across multiple traits revealed deep differences especially between the two taxa characterized by limited plumage differentiation. Our study demonstrates that differentiation in these furtive songbirds has resulted in a complex mosaic of colour-based and bioacoustic differences among populations. Extreme colour differences can be anchored in few genomic loci and may therefore arise and subside rapidly.

Genetic Structure in Japanese and Thai Populations of the Japanese Sparrowhawk Accipiter gularis.

The Japanese sparrowhawk Accipiter gularis is a small raptor that breeds in Northeast Asia. The species consists of the widespread and mostly migratory subspecies A. g. gularis that is common in East Asia, including Japan, and the resident and endangered subspecies A. g. iwasakii which inhabits the Ryukyu and Yaeyama Islands in Okinawa, southern Japan. Given the minimal knowledge about the migration of the species, in this study we sought to compare the genetic variation of the populations breeding in Japan with those migrating through Southeast Asia. We sequenced 761 bp of mitochondrial DNA Control Region from each of 21 A. gularis collected during the breeding season in Japan and from 20 individuals intercepted on migration in Thailand. We detected 26 haplotypes among the 41 individuals which differed significantly between Japan and Thailand. Migrants in Thailand were presumed to have originated from a wide area in Eastern Eurasia. The phylogenetic and network analyses demonstrated that the haplotypes of all A. g. gularis detected in Japan were genetically close. Moreover, the Okinawa haplotypes of A. g. iwasakii were clustered with moderate genetic variation. The information presented here can be used towards implementing future conservation actions.

Autumn migration tracks of Helopsaltes grasshopper-warblers from Northeast Asia support recent taxonomic assignments.

Migration strategies are genetically inherited in most songbirds, and closely related species can exhibit markedly contrasting migration programs. Here, we investigate the autumn migration of one Helopsaltes grasshopper-warbler from a population near Magadan, North East Russia, based on light-level geolocation. Although often considered to belong to Middendorff's Grasshopper-warbler H. ochotensis, recent genetic studies suggest that birds from this population are more closely related to Pallas's Grasshopper-warbler H. certhiola. We compare the migratory behavior of the Magadan bird with two Pallas's Grasshopper-warblers tracked from populations in the Kolyma River valley and the Amur region, Russia. We found similar migration patterns in all three tracked individuals, with stopover sites in eastern China and wintering sites in mainland Southeast Asia, within the known range for Pallas's Grasshopper-warbler. Furthermore, based on morphological data compiled during bird ringing, we were able to confirm the presence of potential "Magadan grasshopper-warblers" during spring and autumn migration in Thailand. Our scant data provide further evidence that Magadan Helopsaltes, notwithstanding their morphological resemblance to Middendorff's Grasshopper-warbler, constitute a population of Pallas's Grasshopper-warbler.

Complex postbreeding molt strategies in a songbird migrating along the East Asian Flyway, the Pallas's Grasshopper Warbler Locustella certhiola.

Molt strategies have received relatively little attention in current ornithology, and knowledge concerning the evolution, variability and extent of molt is sparse in many bird species. This is especially true for East Asian Locustella species where assumptions on molt patterns are based on incomplete information. We provide evidence indicating a complex postbreeding molt strategy and variable molt extent among the Pallas's Grasshopper Warbler Locustella certhiola, based on data from six ringing sites situated along its flyway from the breeding grounds to the wintering areas. Detailed study revealed for the first time that in most individuals wing feather molt proceeds from the center both toward the body and the wing-tip, a molt pattern known as divergent molt (which is rare among Palearctic passerines). In the Russian Far East, where both breeding birds and passage migrants occur, a third of the adult birds were molting in late summer. In Central Siberia, at the northwestern limit of its distribution, adult individuals commenced their primary molt partly divergently and partly with unknown sequence. During migration in Mongolia, only descendantly (i.e., from the body toward the wing-tip) molting birds were observed, while further south in Korea, Hong Kong, and Thailand the proportion of potential eccentric and divergent feather renewal was not identifiable since the renewed feathers were already fully grown as expected. We found an increase in the mean number of molted primaries during the progress of the autumn migration. Moderate body mass levels and low-fat and muscle scores were observed in molting adult birds, without any remarkable increase in the later season. According to optimality models, we suggest that an extremely short season of high food abundance in tall grass habitats and a largely overland route allow autumn migration with low fuel loads combined with molt migration in at least a part of the population. This study highlights the importance of further studying molt strategy as well as stopover behavior decisions and the trade-offs among migratory birds that are now facing a panoply of anthropogenic threats along their flyways.

A new species of Muscicapa flycatcher from Sulawesi, Indonesia.

The Indonesian island of Sulawesi, a globally important hotspot of avian endemism, has been relatively poorly studied ornithologically, to the extent that several new bird species from the region have been described to science only recently, and others have been observed and photographed, but never before collected or named to science. One of these is a new species of Muscicapa flycatcher that has been observed on several occasions since 1997. We collected two specimens in Central Sulawesi in 2012, and based on a combination of morphological, vocal and genetic characters, we describe the new species herein, more than 15 years after the first observations. The new species is superficially similar to the highly migratory, boreal-breeding Gray-streaked Flycatcher Muscicapa griseisticta, which winters in Sulawesi; however, the new species differs strongly from M. griseisticta in several morphological characters, song, and mtDNA. Based on mtDNA, the new species is only distantly related to M. griseisticta, instead being a member of the M. dauurica clade. The new species is evidently widely distributed in lowland and submontane forest throughout Sulawesi. This wide distribution coupled with the species' apparent tolerance of disturbed habitats suggests it is not currently threatened with extinction.