Seasonal variation in grey crowned crane (Balearica regulorum) abundance in the Ngorongoro Crater,Tanzania

There are few quantitative estimates of numbers of Africa's endangered grey crowned cranes (Balearica regulorum), yet conservation of this species will depend on such estimates. We used line-transect distance sampling on multiple 2-km segments of an existing road network to estimate the abundance of grey crowned cranes in a portion of the Ngorongoro Crater, Tanzania, during the wet (April) and dry (August) seasons of 2016. We analysed data from 106 transects on which we observed 174 groups of 1–61 cranes (median and mode = 2). Abundance and density estimates on the areas surveyed were best modelled without group size as a covariate and indicated that mean crane densities were significantly lower in the wet season (2.4/km²) than in the dry season (20.2 cranes/km²). Even based on survey areas of different size, minimum estimated numbers of cranes in the Crater (wet season: 108–133; dry season: 362–401) likely reflect the concentration of cranes in the nonbreeding (dry) season in the perennial wetlands of the Crater and reinforce the notion of the Crater being a key seasonal habitat for crane populations in northern Tanzania, as previously suggested in the literature.     

Influence of sea turtle nesting on hunting behavior and movements of jaguars in the dry forest of northwest Costa Rica

Jaguars (Panthera onca) are opportunistic predators that prey on large profitable prey items, such as sea turtles at nesting beaches. Here, we use jaguar and sea turtle track-count surveys, combined with satellite telemetry of one jaguar, to evaluate whether jaguar hunting behavior and movements are influenced by seasonal sea turtle nesting in the Sector Santa Rosa of Área de Conservación Guanacaste in northwest Costa Rica. We used generalized linear models to evaluate the effect of moon phase and sea surface temperature on olive ridley (Lepidochelis olivacea) and green turtle (Chelonia mydas) nesting abundance, as well as the combination of these predictors on the frequency of jaguar predation activity (proximity to nesting beaches) and movements. For home-range size and location analyses, we calculated kernel density estimates for each season at three different temporal scales. Sea turtle nesting season influenced jaguar activity patterns, as well as sea turtle abundance was related to jaguar locations and predation events, but jaguar home-range size (88.8 km² overall) did not differ between nesting seasons or among temporal scales. Environmental conditions influenced sea turtle nesting and, as a consequence, also influenced jaguar movements and foraging activity. Our study defined the home range of a female jaguar in the tropical dry forest and its relationship to seasonally abundant turtles. Additional information related to the effect of tourism on jaguar–sea turtle interactions would improve conservation of these species at unique nesting beaches in the area.     

Post-construction avian mortality monitoring at Project West Wind

Abstract

Post-construction avifauna investigations were undertaken at Project West Wind, Meridian Energy Limited's 62-turbine wind farm on the Wellington south coast. These investigations were required in accordance with the resource consent conditions to quantify the level of avian mortalities occurring at the wind farm, particularly in regard to New Zealand falcon (Falco novaeseelandiae), kākā (Nestor meridionalis) and kererū (Hemiphaga novaeseelandiae). This is the first comprehensive study at a New Zealand operating wind farm. The methods included three field components necessary to calculate annual estimates of mortalities across the wind farm site: routine turbine searches; carcass detection trials; and carcass removal trials. Results from years 1 and 2 of a three-year programme are presented. To date, mortalities have been recorded for 17 taxa at 18 of the 24 study turbines. There have been no recorded mortalities of falcon, kākā or kererū. Australasian harrier (Circus approximans) has been the species for which the most mortalities have been recorded. Overall estimated annual mortality rates for years 1 and 2 were calculated to be approximately six and five birds per turbine respectively.     

Changes in the breeding wader populations of the machair of the Western Isles,Scotland, between 2000 and 2007

Capsule The machair of the Uists continues to support one of the most important assemblages of breeding waders in Europe, but there have been major variations in population change across the archipelago, the causes of which are poorly understood.     

Combining archive territory mapping data and aerial photography to investigate bird–habitat relationships: a case study from the Lincolnshire coast

Capsule Habitat associations of breeding birds in a complex coastal environment are clear, interpretable and mostly consistent between years.

Aims To match archive territory mapping data with historical aerial photographs and develop data handling and analytical techniques for the study of bird–habitat relationships.

Methods Bird registrations were digitized from archive British Trust for Ornithology Common Birds Census maps and habitat characteristics from contemporaneous aerial photographs. The resulting maps were overlaid and ranks of habitat preference for 15 species calculated using compositional analysis. Similarity analysis identified species with consistent habitat profiles across years. Cluster analysis identified groups of species with similar patterns of habitat use.

Results A total of 5400 registrations of 15 species in 14 habitats were analysed. Of these, 13 species showed stable patterns of habitat association across survey years. Clear differences and similarities in habitat preferences among the species were identified. The results may be used to inform conservation and management programmes in this and similar environments.

Conclusions Extensive archives of bird survey data can be used to study bird–habitat relationships and to measure the effects of natural and anthropogenic environmental change if contemporaneous aerial photographs can be sourced.     

Winter bird communities in forest plantations in western England and their response to vegetation,growth stage and grazing

This paper presents the results of a study of wintering bird communities across a wide range of coniferous, broadleaved and mixed forest stands in the Forest of Dean, western England. Bird communities of broadleaved and coniferous woodland differed with respect to their species composition. The mean number of individual birds recorded increased linearly with woodland age and was not influenced by woodland type, stand size or the presence of grazing. Woodland age and type and the presence or absence of grazing all significantly influenced bird species richness and the proportions of the bird community made up by granivores, insectivores and omnivores. Broadleaved stands held more species than coniferous stands. Ungrazed stands held significantly more species, particularly seed-eating species, than grazed stands and this effect was independent of woodland type. Ordination was used to relate variation in tree species composition and stand structure to bird community composition. A larger number of species was associated with broadleaved stands and stands with abundant undergrowth than was associated with coniferous stands or stands with little undergrowth. Woodland age had less effect on bird community composition than the extent of undergrowth and the conifer to broadleaf ratio. The results of this work have relevance to the enhancement of winter bird communities in commercial forests.     

Habitat selection by Skylarks Alauda arvensis wintering in Britain in 1997/98

The results of a national survey of wintering Skylarks Alauda arvensis undertaken by the British Trust for Ornithology (BTO) between November 1997 and February 1998 are reported here. Over three visits, volunteers counted Skylarks and mapped habitats in 541 1-km squares selected from the Skylark's winter range based on BTO Winter Atlas data and a stratified random sampling approach. Four landscape strata were defined from the Institute of Terrestrial Ecology landscape classification: arable, pastoral, marginal upland and saltmarsh. The survey counts underestimated Skylark abundance, but were good measures of relative abundance across habitat types. The two best predictors of Skylark presence–absence at the landscape scale were the availability of coastal and farmland habitats. Squares with saltmarsh had the highest densities and occupancy (80% of squares). At the patch scale crop stubbles, especially weedy cereal stubbles, were used significantly more than expected by chance. Oilseed rape was positively selected whereas cereal crops were used in proportion to availability and grazed grass was avoided. Skylarks avoided fields smaller than 2.5 ha and selected fields larger than 7.5 ha. We estimate that in midwinter there may be less than 1–2 ha of weedy cereal stubble per 1-km square. We recommend the retention of over-winter stubbles for the conservation of Skylarks and other farmland birds, and research on stubble management and effects on grain availability and arable weed regeneration on Skylark use.     

The archaeobotanical significance of immature millet grains: an experimental case study of Chinese millet crop processing

We present evidence from ethnography and experimental processing of foxtail millet (Setaria italica (L.) P. Beauv.) in China that spikelets containing incompletely filled (or immature) grains constitute a significant portion of typical millet harvests and are removed along with other by-products after threshing and winnowing. This study provides a baseline for the identification of immature foxtail grains in archaeobotanical assemblages. Immature millet grains are a frequent component of archaeobotanical assemblages in Neolithic and Bronze Age China, and criteria for their recognition are presented based on our modern experimental result and illustrated with archaeobotanical examples from Shandong and Henan. It is seed morphology rather than size that plays a determinative role in the identification of foxtail millet. It is suggested that those grains with a narrow egg-shaped embryo, which is about 5/6 of the whole grain, and having a round shape can be classed as foxtail millet even though they are small, flat and squashed. While different grades of immaturity in millet grains might be defined, the interpretative potential of these appears to be negligible as all immature grains are concentrated in winnowing waste. This study confirms the suggestion that the ratio of immature to mature millet grains can be employed in archaeobotany in considering whether or not early stage crop processing (threshing and winnowing) contributed to the formation of particular archaeological millet assemblages.     

Metapopulation Dynamics Enable Persistence of Influenza A,Including A/H5N1, in Poultry

Highly pathogenic influenza A/H5N1 has persistently but sporadically caused human illness and death since 1997. Yet it is still unclear how this pathogen is able to persist globally. While wild birds seem to be a genetic reservoir for influenza A, they do not seem to be the main source of human illness. Here, we highlight the role that domestic poultry may play in maintaining A/H5N1 globally, using theoretical models of spatial population structure in poultry populations. We find that a metapopulation of moderately sized poultry flocks can sustain the pathogen in a finite poultry population for over two years. Our results suggest that it is possible that moderately intensive backyard farms could sustain the pathogen indefinitely in real systems. This fits a pattern that has been observed from many empirical systems. Rather than just employing standard culling procedures to control the disease, our model suggests ways that poultry production systems may be modified.