Tree Selection and Landscape Analysis of Eastern Red Bat Day Roosts

ABSTRACT Declining bat populations and increasing demands on forest resources have prompted researchers to investigate tree roost selection of forest bats. Few studies, however, have investigated different spatial scales and landscape pattern as criteria for selection of tree roosts. In 1999 and 2000, we radiotracked 23 eastern red bats (Lasiurus borealis) to 64 day roosts. Using univariate and multivariate comparisons, we tested roost tree variables with random tree data at 3 circular spatial scales: roost tree, plot, and landscape. We found 15 variables that were entered in a stepwise discriminant analysis to best differentiate between the roost and random samples; 11 (73.3%) were landscape variables measured with a geographic information system. On average (x̄ ± SE), red bats roosted in deciduous trees (42.0 ± 2.1 cm dbh) that were located in plots with more (3.1 ± 0.1 m²) basal area, higher (84.0 ± 1.3) percentage of canopy closure, and lower (27.2 ± 2.2) percentage of groundcover than random plots. At the landscape scale (by percent magnitude), red bat buffers (1,000-m-radius circle) had significantly less development (81.6%), less feeding operations (70.4%), more deciduous (52.9%) and pine forest (63.8%), and fewer local roads (5.4%) but more trails (94.1%), open water (61.4%), wetland areas (80.4%), and stream areas (63.1%) than random buffers. Red bat roost trees were significantly closer (χ² = 22.0088, df = 1, P < 0.001) to trails (106.2 ± 13.3 m) than to streams (279.4 ± 28.5 m). Our results suggest that red bats in our study area select roosts in mature riparian forests near trails, open water, and wetlands. The high percentage of landscape values in the discriminant analysis lends support to using landscape metrics as an investigative technique of resource selection. We recommend that managers consider landscape factors when protecting red bat day-roost habitat.     

Circadian rhythms in the blowfly, Phormia terraenovae: control of phase within the range of entrainment

ABSTRACT Locomotor activity of individual blowflies, Phormia (= Protophormia) terraenovae R.D. (Diptera, Calliphoridae) was recorded by means of running wheels. A few days after emergence, adult flies were placed in the wheels and exposed to at least two of four light-dark cycles (LD) differing in cycle duration T (LD 11:11, 12:12, 13:13 and 14:14 h). The intensity of illumination was 400 lux in L and 2 lux in D. From the actograms, phase-angle differences were read off between onset of activity and light-on (ψ/_onset), and between end of activity and light-off (ψend)- Within the range of entrainment, ψ changed systematically from negative values in T =22 h to positive values in T =28 h: the mean change in ψ per hour change in T , expressed in degree of the full circadian cycles, was 20^o. Standard deviations of ψ around its mean were computed for ten-cycle intervals; in ψ_onset and in ψ_end standard deviation was minimal when 4ψ was close to zero, and increased steadily with increasing negative or positive ψ -values.     

Fisheries stock assessment and decision analysis: the Bayesian approach

The Bayesian approach to stock assessment determines the probabilities of alternative hypotheses using information for the stock in question and from inferences for other stocks/species. These probabilities are essential if the consequences of alternative management actions are to be evaluated through a decision analysis. Using the Bayesian approach to stock assessment and decision analysis it becomes possible to admit the full range of uncertainty and use the collective historical experience of fisheries science when estimating the consequences of proposed management actions. Recent advances in computing algorithms and power have allowed methods based on the Bayesian approach to be used even for fairly complex stock assessment models and to be within the reach of most stock assessment scientists. However, to avoid coming to ill-founded conclusions, care must be taken when selecting prior distributions. In particular, selection of priors designed to be noninformative with respect to quantities of interest to management is problematic. The arguments of the paper are illustrated using New Zealand's western stock of hoki, Macruronus novaezelandiae (Merlucciidae) and the Bering--Chukchi--Beaufort Seas stock of bowhead whales as examples     

Oral susceptibility of Aedes albopictus to dengue type 2 virus: a study of infection kinetics, using the polymerase chain reaction for viral detection

Female Aedes albopictus mosquitoes, aged 1 week, were infected with DEN-2 dengue virus. The kinetics of infection in mosquito brain and mesenteron were monitored using DNA probes with polymerase chain reaction (PCR) amplification of target DNA sequences coding for DEN-2 virus envelope protein, compared with the standard immunofluorescence assay technique (IFA). Rates of virus detection in the mesenteron of orally infected mosquitoes rose to 38% by day 4 post-inoculation, then declined until day 8, followed by irregular peaks around days 11-14 and subsequently. In mosquito head squashes, virus was detected from day 4 onwards, reaching 38% positive by day 18. Salivary glands of all the same females were found to be positive for virus by day 8 onwards. Parenterally infected Ae.albopictus females were all positive for DEN-2 in the brain and salivary glands 8 days post-inoculation. In every case, results obtained with the PCR matched those from the IFA. Our DNA probe with PCR procedure can therefore be utilized as a sensitive and reliable method for studies of DEN-2 vectors.     

Rooting down the aphid's tree – the oldest record of the Aphidomorpha lineage from Palaeozoic (Insecta: Hemiptera)

The new genus and species Lutevanaphis permiana gen.n. et sp.n. , represents the oldest Aphidomorpha, new superfamily Lutevanaphidoidea superfam.n. and new family Lutevanaphididae. This taxon is described from the Middle Permian of the Lodève Basin, southern France. The presence of very small Aphidomorpha in the Middle Permian contradicts the hypothesis of the ‘Lilliput effect’ that is presumed to have affected the insect fauna during the Early to Middle Triassic, after the end‐Permian crisis. Very small insects were present well before the end of the Permian; their relative rarity is attributable probably to taphonomic biases.     

Circadian rhythms in the blowfly, Phormia terraenovae: the period in constant light

ABSTRACT. Locomotor activity of individual blowflies, Phormia (=Protophormia) terraenovae R.D. (Diptera, Calliphoridae), was recorded by means of running wheels made of Perspex (plexiglass). At various intervals after hatching, flies were placed in the wheel in continuous light (120 lx). The period of the free-running rhythm was often shorter than 24 h initially, but lengthened later and stabilized after 15–20 days at values around or above 25 h. The mean period was independent of age in both sexes. Within a range from 2 to 2000lx the period did not depend in a systematic way on intensity of illumination; no activity could be recorded below 1 lx.     

Spring phenology in boreal Eurasia over a nearly century time scale

It has been widely reported that tree leaves have tended to appear earlier in many regions of the northern hemisphere in the last few decades, reflecting climate warming. Satellite observations revealed an 8-day advance in leaf appearance date between 1982 and 1991 in northern latitudes. In situ observations show that leaf appearance dates in Europe have advanced by an average of 6.3 days from 1959 to 1996. Modelling of leaf appearance on the basis of temperature also shows a marked advance in temperate and boreal regions from 1955 to 2002. However, before 1955, reported studies of phenological variations are restricted to local scale. Modelling, ground observations and satellite observations are here combined to analyse phenological variations in Eurasian taiga over nearly a century. The trend observed by remote sensing consists mainly in a shift at the end of the 1980s, reflecting a shift in winter and spring temperature. In western boreal Eurasia, a trend to earlier leaf appearance is evident since the mid-1930s, although it is discontinuous. In contrast, the strong advance in leaf appearance detected over Central Siberia using satellite data in 1982–1991 is strengthened by late springs in 1983–1984; moreover, in this region the green-up timing has displayed successive trends with opposite signs since 1920. Thus, such strong trend is not unusual if considered locally. However, the recent advance is unique in simultaneously affecting most of the Eurasian taiga, the leaf appearance dates after 1990 being the earliest in nearly a century in most of the area.