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.     

Intrasexual competition underlies sexual selection on male breeding coloration in the orangethroat darter,Etheostoma spectabile

Elaborate, sexually dimorphic traits are widely thought to evolve under sexual selection through female preference, male–male competition, or both. The orangethroat darter (Etheostoma spectabile) is a sexually dichromatic fish in which females exhibit no preferences for male size or coloration. We tested whether these traits affect individual reproductive success in E. spectabile when multiple males are allowed to freely compete for a female. The quality and quantity of male coloration were associated with greater success in maintaining access to the female and in spawning as the primary male (first male to participate). On the other hand, sneaking behavior showed little correlation with coloration. Male breeding coloration in E. spectabile may therefore demonstrate how intrasexual competition can be a predominant factor underlying the evolution of male ornaments.     

Genetic dissection of neural circuitry regulating behavioral state using conditional transgenics

Conditional transgenic animals are useful tools that can be used to determine the detailed anatomic and molecular bases of sleep–wake regulation. This short review highlights some of the most recent molecular biological technologies for “systems-level” sleep research in freely behaving animals. These technical advances include a wide range of approaches from conditional deletion of genes based on the Cre/loxP technology to RNA interference to the in vivo reversible manipulation (silencing and activation) of neurons by tetracycline-controlled tetanus neurotoxin or the expression of genetically modified receptor-channel complexes. In combination with these advanced genetic techniques, adeno-associated viral vectors (AAVs) represent a versatile gene delivery system for stereotaxic-based brain microinjections and regionally restricted transduction of neuronal cell populations.

     

Carbon accumulation and vertical accretion in a restored versus historic salt marsh in southern Puget Sound,Washington, United States

Few comparisons exist between vertical accretion (VA) and carbon accumulation rates (CARs) in restored versus historic (i.e. reference) marshes. Here, we compare these processes in a formerly diked, sparsely vegetated, restored salt marsh (Six Gill Slough, SG), whose surface is subsided relative to the tidal frame, to an adjacent, relatively pristine, historic salt marsh (Animal Slough, AS). Six sediment cores were collected at both AS and SG approximately 6 years after restoration. Cores were analyzed for bulk density (BD), % loss of ignition, % organic carbon, and ²¹⁰Pb. We found that sharp changes in BD in surface layers of SG cores were highly reliable markers for the onset of restoration. The mean VA since restoration at SG (0.79 [SD = 0.29] cm/year) was approximately twice that of AS (0.41 [SD = 0.16] cm/year). In comparison, the VA at AS over 50 years was 0.30 (SD = 0.09) cm/year. VA consisted almost entirely of inorganic sediment at SG whereas at AS it was approximately 55%. Mean CARs at SG were somewhat greater than at AS, but the difference was not significant due to high variability (SG: 81–210 g C m^?2 year^?1; AS: 115–168 g C m^?2 year^?1). The mean CAR at AS over the past 50 years was 118 (SD = 23) g C m^?2 year^?1. This study demonstrates that a sparsely vegetated, restored salt marsh can quickly begin to accumulate carbon and that historic and restored marshes can have similar CARs despite highly divergent formation processes.