A molecular phylogeny of the harriers (Circus, Accipitridae) indicate the role of long distance dispersal and migration in diversification.

The monophyly of the raptorial Circus genus (harriers) has never been in question, but the specific status of many, often vulnerable island endemic, taxa remains uncertain. Here we utilise one mitochondrial and three nuclear loci from all currently recognised Circus taxa (species and subspecies) to infer a robust phylogeny, to estimate the divergence date and to reconstruct the biogeographic origins of the Circus group. Our phylogeny supports both the monophyly of Circus and polyphyly of the genus Accipiter. Depending on the rate of molecular clock used, the emergence of the harrier clade took place between 4.9 and 12.2mya which coincides with the worldwide formation of open habitats which extant harriers now exploit. The sister relationship of the Northern Harrier C. cyaneus hudsonius and the Cinereous Harrier C. cinereus contradicts previous classifications that treated the former as conspecific with the Hen Harrier C. cyaneus cyaneus. Thus both should be elevated to species status: C. hudsonius and C. cyaneus. Further, the African Marsh C. ranivorus and the European Marsh C. aeruginosus Harriers emerge as sister species. The remaining marsh harriers exhibit very little genetic diversity, and are all recently diverged taxa that exhibit allopatric distributions. Considering their sister relationship and geographic proximity, we recommend treating C. approximans and C. spilonotus spilothorax as subspecies of C. approximans. For C. spilonotus spilonotus C. maillardi maillardi and C. maillardi macrosceles, their plumage and morphometric differences, phylogenetic relationship and geographic distributions make lumping of these taxa as a single species complicated. We thus propose to recognise as separate, recently evolved species: C. spilonotus, C. maillardi and C. macrosceles. Biogeographic inferences on the ancestral origin of harriers are uncertain, indicating that the harriers emerged in either the Neotropics, Palearctic or Australasia. We are, however, able to show that speciation within the harriers was driven by long range dispersal and migration events.

Foraging activity of the snail kite, Rostrhamus sociabilis (Aves: Accipitridae) in wetlands of southern Brazil / Atividade de forrageio de gavião-caramujeiro, Rostrhamus sociabilis (Aves: Accipitridae) em áreas úmidas do sul do Brasil

The snail kite (Rostrhamus sociabilis) is widely distributed in the American continent. Its specialised diet consists mostly of the gastropod mollusk Pomacea sp and its foraging strategy probably varies depending on the season, prey availability, and climate factors, which can be reflected in its semi-nomad behaviour. This study was aimed at examining the hunting strategy of the snail kite, and its association with climate factors and habitat heterogeneity. Direct observations of birds between January 2010 and March 2011 in southernmost Brazil revealed that hunting was still the predominant foraging strategy (79% of records) to capture mollusks. Despite morphological specialisations to extract mollusks from the shells, the handling time (average = 92.4 s) was twice as much the time between prey search and capture (average = 55 s). The increase in the number of mollusks ingested apparently occurs when the resting time on perches or any other substrates near the hunting sites decreases between successive unsuccessful attempts. The correlation between the number of consumed preys and the climatic variables examined was low. Regarding habitat heterogeneity, our findings suggest that birds forage preferentially in marshes with low vegetation, which may increase the access to mollusks. The hunting efficiency of the snail kite was high (76 % successful attempts) compared to those of other birds of prey.

O gavião-caramujeiro (Rostrhamus sociabilis) possui ampla distribuição no continente americano e apresenta dieta especializada no molusco gastrópode Pomacea sp. Possivelmente, a estratégia de forrageio da espécie responde às variações sazonais na disponibilidade de presas, bem como aos fatores climáticos, o que pode refletir em seu comportamento seminômade. O objetivo desse estudo foi avaliar a estratégia de caça do gavião-caramujeiro, buscando suas associações quanto aos aspectos climáticos e à heterogeneidade do habitat. Observações diretas das aves, feitas entre janeiro de 2010 e março de 2011 no extremo sul brasileiro, revelaram que, para a captura dos moluscos, as aves usaram predominantemente a estratégia de caça do tipo still hunting (79% dos registros). Apesar de apresentar especializações morfológicas para a extração dos moluscos da concha, a avaliação do tempo empregado na manipulação (média = 92,4 s) foi quase o dobro do desprendido entre a procura e a captura (média = 55 s) das presas. Aparentemente, o aumento no número de moluscos ingeridos ocorre por meio de redução no tempo de repouso entre sucessivas investidas de captura mal sucedidas, tal como pelo uso de poleiros ou quaisquer outros substratos próximos aos locais de captura. O número de presas consumidas apresenta baixa relação com as variáveis climáticas testadas. Quanto à heterogeneidade do habitat, os dados sugerem que as aves forrageiam preferencialmente em banhados com cobertura vegetal rasteira, o que poderia aumentar a acessibilidade aos moluscos. O gavião-caramujeiro apresentou alta taxa de eficiência de caça (76% das investidas tiveram êxito), revelando a eficiência da estratégia de caça desta ave quando comparada a outras aves de rapina.

Temporal influence on foraging strategies, territoriality and nomadic tendencies of Snail Kite, Rosthramus sociabilis (Viellot, 1817) in an urban Neotropical wetland / Temporalidade e estratégias de forrageamento, territorialidade e deslocamento do gavião-caramujeiro Rosthramus sociabilis (Viellot, 1817) em uma área urbana úmida Neotropical

The foraging, territoriality and displacement of the Snail Kite were studied over 232 hours of observations in an urban lake during the dry and wet seasons. The temperature and rainfall variations were used to correlate with predation rates and the correlation coefficients were 0,39 and 0,34, respectively. Snail Kites spent more time foraging during the wet than the dry season when perching is more frequently recorded. The higher predation in the wet season can be explained by the higher abundance of apple snails and the energy demand for reproduction. In the wet season, the territories were smaller and the conspecific conflicts decreased as prey were more available. However, due to the lack of food in the dry season, intra-specific conflicts and expansion of male territories were observed and the female and immatures were expelled from their foraging area to another location. In this way, site tenacity of Snail Kites should be interpreted in relation to the variations on food and dominance gradients according to the temporal changes (time) and foraging sites (space).

Foram estudados os comportamentos territoriais e de forrageio do gavião-caramujeiro em uma lagoa urbana durante as estações seca e chuvosa. Observaram-se esses comportamentos durante 232 horas, sendo a amostragem divida em períodos matutino e vespertino. A maior atividade de forrageio foi observada durante o período matutino. Os principais itens predados foram espécimes do gênero Pomacea spp. No entanto, durante o período de seca, os gaviões-caramujeiros também predaram caranguejos. Essas aves exibiram diferentes estratégias de forrageamento e territorialidade durante as diferentes estações. Os gaviões-caramujeiros dispenderam maior tempo de forrageamento durante a estação chuvosa e maior tempo pousados, durante a estação seca. A expansão/contração dos territórios realizados pelos machos é dependente da disponibilidade de alimento, que varia durante as estações: a) estação seca (pouco alimento): conflitos agonísticos intraespecíficos, seguidos de expansão dos territórios; b) estação chuvosa: conflitos agonísticos decresceram à medida que a oferta de alimento aumentou e, consequentemente, houve redução do tamanho dos territórios. Desse modo, conclui-se que os padrões de movimentação para forragear e estabelecer territórios são altamente dependentes da distribuição de recursos no espaço e no tempo, e estão também associados ao comportamento social, por meio de dominância dos machos.

Radiographic evaluation of cardiac size in four Falconiform species.

To establish reference values for the cardiac size during radiographic examination in 4 species of Falconiformes used for falconry, lateral and ventrodorsal radiographs were examined from healthy birds of 4 species: Harris' hawks (Parabuteo unicinctus) (n = 48), peregrine falcons (Falco peregrinus) (n = 35), saker falcons (Falco cherrug) (n = 19), and lanner falcons (Falco biarmicus) (n = 13). On the lateral view, ratios between the length of the heart from base to apex and total length of the carina were calculated. On the ventrodorsal view, ratios between the width of the heart at its widest point and the distance between the ribs at the same level and between the width of the coracoid immediately caudal to the humeral articular surface in the shoulder joint and width of the heart and the distance between the ribs were calculated. No differences were found between species in the ratio of length of the heart/length of the carina. The ratios of width of the heart/distance between ribs and width of the heart/coracoid width differed between hawks and falcons but did not differ between the 3 falcon species.