Population size of threatened and endemic birds of the Cerrado in Estacao Ecologica de Itirapina, a fragmented area in the State of Sao Paulo, Brazil

The pressures for land use change have led to an increasing isolation of habitat remnants throughout the world. The goal of this study was to estimate the population size and density of some endemic and threatened species in a nature reserve in the Cerrado biome. One hundred and thirty four point transects were undertaken at the Estacao Ecologica de Itirapina (EEI), one of the last natural grassland savannah remnants in Sao Paulo state, in the south-east of Brazil between September and December 2006 and densities estimated for seven species (four endemic to the Cerrado, one near-endemic and two grassland specialists). Neither species reached the minimum viable population size of 500-5000 individuals. Four species, White-banded Tanager, White-rumped Tanager, Black-throated Saltator and Sharp-tailed Tyrant have populations ranging from 112 to 248 individuals, while the other species have a low population (< 60 individuals). The mean densities of Sharp-tailed Tyrant and Cock-tailed Tyrant in the EEI grassland showed similar values to those observed in larger areas of the Cerrado, which may indicate that the EEL grassland area is well conserved. In spite of the restricted size of the EEI, small areas can maintain some endemic and threatened bird populations, thus contributing to local biodiversity and the ecological processes in the region. The capacity of fragments of Cerrado (similar to 2,000 ha) to maintain populations of endemic and threatened bird species is unlikely to be effective in the long term.

CLEANING ASSOCIATIONS BETWEEN BIRDS AND HERBIVOROUS MAMMALS IN BRAZIL: STRUCTURE AND COMPLEXITY

Birds that remove ectoparasites and other food material from their hosts are iconic illustrations of mutualistic-commensalistic cleaning associations. To assess the complex pattern of food resource use embedded in cleaning interactions of an assemblage of birds and their herbivorous mammal hosts in open habitats in Brazil, we used a network approach that characterized their patterns of association. Cleaning interactions showed a distinctly nested pattern, related to the number of interactions of cleaners and hosts and to the range of food types that each host species provided. Hosts that provided a wide range of food types (flies, ticks, tissue and blood, and organic debris) were attended by more species of cleaners and formed the core of the web. On the other hand, core cleaner species did not exploit the full range of available food resources, but used a variety of host species to exploit these resources instead. The structure that we found indicates that cleaners rely on cleaning interactions to obtain food types that would not be available otherwise (e.g., blood-engorged ticks or horseflies, wounded tissue). Additionally, a nested organization for the cleaner bird mammalian herbivore association means that both generalist and selective species take part in the interactions and that partners of selective species form an ordered subset of the partners of generalist species. The availability of predictable protein-rich food sources for birds provided by cleaning interactions may lead to an evolutionary pathway favoring their increased use by birds that forage opportunistically. Received 30 June 2011, accepted 10 November 2011.

GAUDY JUVENILE PLUMAGES OF CINEREOUS MOURNER (LANIOCERA HYPOPYRRA) AND BRAZILIAN LANIISOMA (LANIISOMA ELEGANS)

We describe the juvenile plumages of the Cinereous Mourner (Laniocera hypopyrra) and the Brazilian Laniisoma (Laniisoma elegans). Both L. hypopyrra and L. elegans possess a dramatically conspicuous plumage as juveniles in contrast to the generally cryptic plumage pattern exhibited by most juvenile birds. They are predominantly covered by cinnamon-orange feathers with black terminal spots, contrasting with the nest and the predominant colors of their environment. This colorful plumage presumably makes them more at risk from predation by visually oriented animals (e.g., raptors and primates), during one of the most vulnerable phases of their life, and strongly suggests these plumages function as a true, or false (mimicry), signal of 'unprofitability'. Previous knowledge concerning the phylogenetic relationships between these two genera, and the juvenile plumage patterns of other species placed in the Tityridae indicate this shared character in L. hypopyrra and L. elegans represents a synapomorphy within this clade, thereby providing additional evidence of their relationship. Received 13 December 2011. Accepted 1 May 2012.

Within-winter movements: a common phenomenon in the Common Pochard Aythya ferina

Waterbirds are often observed to move between different wintering sites within the same winter—for example, in response to food availability or weather conditions. Within-winter movements may contribute to the spreading of diseases, such as avian influenza, outside the actual migration period. The Common Pochard Aythya ferina seems to be particularly sensitive to infection with the highly pathogenic avian influenza virus H5N1 and, consequently, could play an important role as vectors for the disease. We describe here the within-winter movements of Pochards in Europe in relation to topography, climate, sex and age. We analysed data provided by the Euring data bank on 201 individuals for which records from different locations from the same winter (December–February) were available. The distances and directions moved within the winter varied markedly between regions, which could be ascribed to the differing topography (coast lines, Alps). We found no significant differences in terms of distances and directions moved between the sexes and only weak indications of differences between the age classes. In Switzerland, juveniles moved in more westerly directions than adults. During relatively mild winters, winter harshness had no effect on the distances travelled, but in cold winters, a positive relationship was observed, a pattern possibly triggered by the freezing of lakes. Winter harshness did not influence the directions of the movement. About 41% (83/201) of the Pochards that were recovered at least 1 km from the ringing site had moved more than 200 km. A substantial number of birds moved between central/southern Europe and the north-western coast of mainland Europe, and between the north-western coast of mainland Europe and Great Britain, whereas no direct exchange between Great Britain and central/southern Europe was observed. Within-winter movements of Pochards seem to be a common phenomenon in all years and possibly occur as a response to the depletion of food resources. This high tendency to move could potentially contribute to the spread of bird-transmitted diseases outside the actual migration period.

Detection histories for eight species of Amazona parrots in Venezuela during the NeoMaps bird surveys in 2010

Documenting changes in distribution is necessary for understanding species' response to environmental changes, but data on species distributions are heterogeneous in accuracy and resolution. Combining different data sources and methodological approaches can fill gaps in knowledge about the dynamic processes driving changes in species-rich, but data-poor regions. We combined recent bird survey data from the Neotropical Biodiversity Mapping Initiative (NeoMaps) with historical distribution records to estimate potential changes in the distribution of eight species of Amazon parrots in Venezuela. Using environmental covariates and presence-only data from museum collections and the literature, we first used maximum likelihood to fit a species distribution model (SDM) estimating a historical maximum probability of occurrence for each species. We then used recent, NeoMaps survey data to build single-season occupancy models (OM) with the same environmental covariates, as well as with time- and effort-dependent detectability, resulting in estimates of the current probability of occurrence. We finally calculated the disagreement between predictions as a matrix of probability of change in the state of occurrence. Our results suggested negative changes for the only restricted, threatened species, Amazona barbadensis, which has been independently confirmed with field studies. Two of the three remaining widespread species that were detected, Amazona amazonica, Amazona ochrocephala, also had a high probability of negative changes in northern Venezuela, but results were not conclusive for Amazona farinosa. The four remaining species were undetected in recent field surveys; three of these were most probably absent from the survey locations (Amazona autumnalis, Amazona mercenaria and Amazona festiva), while a fourth (Amazona dufresniana) requires more intensive targeted sampling to estimate its current status. Our approach is unique in taking full advantage of available, but limited data, and in detecting a high probability of change even for rare and patchily-distributed species. However, it is presently limited to species meeting the strong assumptions required for maximum-likelihood estimation with presence-only data, including very high detectability and representative sampling of its historical distribution.

Sex-specific foraging during parental care in a size-monomorphic seabird

Sex differences in foraging behaviour are typically studied in size-dimorphic taxa. Data on sex-specific behavior in monomorphic taxa are needed to test theories of reproductive investment. It has been suggested that in seabirds foraging niche separation may be related to decreased intersexual competition for food between cooperating pair-bonded individuals. Alternatively, sex differences in foraging niches may be driven by different nutritional requirements of females associated with the reproductive costs of egg production and oviposition. To assess these possibilities, we studied a size-monomorphic colonial seabird, the Australasian Gannet (Morus serrator) at the Cape Kidnappers gannetry, New Zealand. We recorded maximum dive depths, and distinct diet composition of incubating females as indicated by stable isotopic signatures. Results suggested greater female foraging effort during early times of incubation, indicated by significantly deeper maximum dives. Sex-specific foraging patterns across other breeding stages were more variable. Nitrogen stable isotopic values showed that incubating females occupied a different trophic position compared to males at the same breeding stage, and also from those of gannets of both sexes at later stages of parental care. Overall, the data are consistent with cost-of-oviposition compensation in females necessitating male-bias in parental care in biparental breeders. Further research is needed to unravel the implications for the evolution of sex differences in behavior in this and other monomorphic taxa.