What attracts birds to newly mown pasture? Decoupling the action of mowing from the provision of short swards

Many bird species flock to forage on newly mown grass swards. Several potential benefits are offered by such swards, including increases in prey availability (flush of foliar prey, reduced physical obstruction to surface and soil prey) and a foraging environment with fewer visual obstructions, so allowing predators to be detected more easily. We performed a field experiment using captive Common Starlings Sturnus vulgaris foraging in bottomless enclosures on newly mown swards (within 1 h) and old mown swards (48 h). We performed the experiment during winter months and standardized sward height to exclude other confounding effects in order to determine the temporal benefits of mowing for species foraging on soil invertebrates. We found no differences in the vigilance or time budgets of Starlings foraging on newly or old mown swards. Intake efficiency (prey captured per 100 roots) was greater on newly mown swards, suggesting that Starlings used less energy to obtain their prey on that substrate. It is possible that mowing alters the microclimate of the soil and sward, causing invertebrate availability to decline over time, which causes the lower foraging efficiency. Mowing is a technique often used to manipulate grassland habitats in ecological research; it has recently been advocated as a conservation management tool for wintering bird populations. We suggest that care should be taken when designing such studies to avoid confounding the factors under investigation with temporal changes in prey availability.     

Polymorphic microsatellite loci from the West Nile virus vector Culex tarsalis

Since its introduction in 1999, West Nile virus (WNV) has spread across North America. Culex tarsalis is a highly efficient WNV vector species. Many traits such as virus susceptibility, autogeny and host preference vary geographically and temporally in C. tarsalis. Culex tarsalis genomic libraries were developed and were highly enriched for microsatellite inserts (42–96%). We identified 12 loci that were polymorphic in wild C. tarsalis populations. These microsatellites are the first DNA‐based genetic markers developed for C. tarsalis and will be useful for investigating population structure and constructing genetic maps in this mosquito.     

Prevalence and diversity patterns of avian blood parasites in degraded African rainforest habitats

Land use changes including deforestation, road construction and agricultural encroachments have been linked to the increased prevalence of several infectious diseases. In order to better understand how deforestation affects the prevalence of vector-borne infectious diseases in wildlife, nine paired sites were sampled (disturbed vs. undisturbed habitats) in Southern Cameroon. We studied the diversity, prevalence and distribution of avian malaria parasites ( Plasmodium spp.) and other related haemosporidians (species of Haemoproteus and Leucocytozoon ) from these sites in two widespread species of African rainforest birds, the yellow-whiskered greenbul ( Andropadus latirostris , Pycnonotidae) and the olive sunbird ( Cyanomitra olivacea , Nectariniidae). Twenty-six mitochondrial cytochrome b lineages were identified: 20 Plasmodium lineages and 6 Haemoproteus lineages. These lineages showed no geographic specificity, nor significant differences in lineage diversity between habitat types. However, we found that the prevalence of Leucocytozoon and Haemoproteus infections were significantly higher in undisturbed than in deforested habitats ( Leucocytozoon spp. 50.3% vs. 35.8%, Haemoproteus spp. 16.3% vs. 10.8%). We also found higher prevalence for all haemosporidian parasites in C. olivacea than in A. latirostris species (70.2% vs. 58.2%). Interestingly, we found one morphospecies of Plasmodium in C. olivacea , as represented by a clade of related lineages, showed increased prevalence at disturbed sites, while another showed a decrease, testifying to different patterns of transmission, even among closely related lineages of avian malaria, in relation to deforestation. Our work demonstrates that anthropogenic habitat change can affect host–parasite systems and result in opposing trends in prevalence of haemosporidian parasites in wild bird populations.     

High-Speed Cell Sorting of Infectious Trophic and Cystic Forms of Pneumocystis carinii

ABSTRACT. The separation of Pneumocystis carinii life-cycle stages while preserving infectivity is a hitherto unresolved challenge. We describe an original, reproducible, and efficient method for separating trophic from cystic forms of P. carinii using a high-speed cell sorter. The large amounts of highly purified (99.6±0.3%) infectious trophic and cystic forms can now be used to elucidate the poorly understood P. carinii life cycle.     

Factors affecting retreat‐site selection by coppertail skinks (Ctenotus taeniolatus) from sandstone outcrops in eastern Australia

Abstract Coppertail skinks (Ctenotus taeniolatus) are medium‐sized diurnal lizards that are widespread in eastern Australia. Field surveys on sandstone outcrops in the Sydney region showed that these animals use available rocks non‐randomly: coppertails were found under large, sun‐exposed rocks on deep soil. Choice trials in the laboratory documented selection of retreat sites that were warm, with substrate preferences shifting in a diel cycle. Lizards selected retreats with rock substrates during the day but with sandy substrates at night. Rocky retreats attain higher temperatures during daylight hours, but burrows in sand beneath rocks may provide greater protection against ingress by nocturnal predators. During fieldwork we rarely found lizards under rocks with either ants or centipedes, suggesting that coppertails may avoid these predatory invertebrates. Tongue‐flick trials showed that the lizards could discriminate among common ant species based on chemosensory cues, but apparently could not detect centipede chemical cues. In experimental trials, the lizards did not avoid retreat sites scented by either ants or centipedes. Our data thus suggest that retreat‐site selection in coppertails is driven by abiotic cues (rock size, sun exposure and substrate type) that may confer fitness benefits in terms of thermoregulation and predator avoidance, with biotic cues playing a less important role.     

Influence of Climatic Factors on Pneumocys Carriage within a Socially Organized Group of Immunocompetent Macaques (Macaca fascicularis)

ABSTRACT. As monkeys-derived Pneumocystis is closely related to P. jirovecii , simian populations should be considered as valuable models for the understanding of the epidemiology of human pneumocystosis. In the present study, the impact of environmental factors on the carriage of Pneumocystis was evaluated in socially organized group of immunocoinpetent macaques (Macuca fascicularis). The tribe, maintained in partial release al the Primatology Center of Strasbourg in France, comprised 29 animals at the end of the study. From December 2000 to November 2002, deep nasal swab samples were collected monthly from each animal under general anaesthesia. The presence of Pneurmocystis DNA was assessed by nested PCR of mtLSU rRNA gene. No case of pneumocystosis was reported during the study. Pneumocystis DNA was detected in 166 out 01 481 swab samples examined (34.5%). The number of macaques with detectable Pneumocystis DNA was highly variable from one month to another. However, Pneumocystis carriage was clearly correlated to the mean precipitation rates.     

Combining geometric morphometrics with pattern recognition for the investigation of species complexes

The parasitoid Hymenoptera contain a large number of species complexes that are as yet unresolved by traditional taxonomic studies. Evolutionary studies as well as biological control programmes often require further investigations which cannot rely on simple qualitative morphological characters; in many cases, particularly with dried specimens housed in museums, molecular approaches cannot be used. Recent developments in geometric morphometrics and statistical exploratory approaches open new perspectives for the objective evaluation of morphological characters in this taxonomic context. In this study, geometric morphometrics and pattern recognition approaches were applied to the wing shape and venation of two closely related braconid species considered to differ by subtle qualitative morphological head characters. Exploratory analyses such as kernel density estimates and Gaussian mixture analyses were used to explore the structure of the data in the multivariate morphometric space. Discrimination techniques (linear discriminant functions and neural networks combined with cross‐validations) were used to estimate the taxonomic value of qualitative characters. Gaussian mixtures highlighted the existence of two non‐overlapping groups. A good congruence was found between one of the two groups and the a priori defined Bassus tumidulus. The misclassification rate was higher for B. tegularis specimens, which also appeared morphometrically heterogeneous. Discrimination between the two a priori defined species was incomplete with misclassification rates higher than, or equal to, 6%. In most cases, the lack of congruence between species and morphometrically defined subgroups could be related to specimens that exhibited ambiguous qualitative character states. In summary, if two entities are present, they still need to be defined morphologically, while B. tegularis heterogeneity calls for further investigation of specimens of known origin and hosts. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 80, 89–98.     

Habitat affects escape behaviour and alarm calling in Common Starlings Sturnus vulgaris

Animals should adapt their escape behaviour to both physical and social surroundings in order to maximize their probability of survival. Cover can be both obstructive, reducing the visibility of the surroundings and hindering escape, and protective, providing refuge. We investigated how the provision of cover (long grass) affected (1) the escape behaviour and (2) the alarm call behaviour of Common Starlings Sturnus vulgaris responding to a model hawk during a simulated attack. Starlings always retreated away from the predator and sometimes alarm-called. Their escape trajectory was close to the ground when escaping in long grass, which could be explained by either tall swards hindering take-off or such swards being used as protective cover. On short grass their escape trajectory was much steeper (> 45°). We also investigated the use of alarm calls in Starlings according to predictions arising from the costs and benefits to callers and receivers. Callers could benefit from using alarm calls through dilution or confusion if their use initiates flock departures, thus reducing their probability of being targeted. If there is no cost to the producer of alarm calls we predicted that detectors should call at all times to gain these benefits (i.e. irrespective of grass length), but if their use is costly we predicted that they would be used only when the benefits outstrip the costs. In this case we would predict that alarm calls would be given when other (visual) signals were impaired on long grass but not when they were effective on short grass. Starlings used alarm calls on long grass when visibility was reduced more frequently than on short grass, suggesting that calling has a cost to the producer. The contrasting escape strategies of Starlings in relation to a relatively small (10 cm) change in grass height demonstrates the potential importance of habitat structure in determining predation risk.