Group Effects and Background Color Patterns Affect the Exploratory Behavior of Tree Sparrows

Exploratory behavior serves the function of acquiring information when facing environmental uncertainty, thus plays an important role for animals living on patchy or ephemeral resources. Our study tested the hypothesis that exploratory behavior is affected by ecological factors associated with the risk of predation. We conducted experiments to examine exploration behavior of wild‐caught Eurasian tree sparrows (Passer montanus) under the influences of background color patterns (white or camouflaged) and group sizes (single vs. five sparrows). We further conducted two‐pattern choice experiments and offered sparrows backgrounds combining those two color patterns. In comparisons with single sparrows, flocking sparrows had shorter landing latencies, started exploring sand patches earlier, spent less total time on the ground before pecking at the first patch and nearly successfully located and pecked all patches. In contrast, sparrows responded nearly indifferently to the two single‐pattern backgrounds; yet when given a choice, sparrows still favored the camouflaged portion in the two‐pattern backgrounds and first landed more frequently there. Twice as many patches were left untouched on the two‐pattern backgrounds, mostly by single sparrows, than on both types of single‐pattern backgrounds. In tests of flocks, sparrows that first landed on the ground to initiate exploration had a higher chance to also first explore a sand patch than random expectation on single‐pattern backgrounds, but not necessarily on two‐pattern backgrounds. Our results demonstrate context‐specific effects of social exploration, suggest possible influence of individual variation and offer evidence for advantages of group living in situations where explorers have to cope with environmental uncertainty.     

Concentration and risk assessments of mercury along the elevation gradient in soils of Langtang Himalayas,Nepal

The fragile Himalayan region could be regarded as the sink for various pollutants transported from urbanized and polluted areas of South Asia. Therefore, in order to understand the concentrations, spatial distribution, pollution, and risk assessments of toxic heavy metal, mercury (Hg), surface soil samples were taken from the central Himalayas in the Langtang region. The average THg concentration in the Langtang Himalayas was 35.75 ± 24.41(ngg^?1), which is comparable to the Tibetan top soil values and slightly lower than world average soil values. In addition, an inverse relationship of THg with elevation were observed (i.e. decrease in concentration with increase in elevation) in the Langtang Himalayan soils. Meanwhile, THg concentrations and TOC% were significantly positively correlated at both the depths (0–10 and 10–20 cm), inferring the sorption capacity of organic carbon for Hg. The results of the geo-accumulation index (I_geo), enrichment factor (EF), and pollution index (PI) indicated limited or no pollution by Hg in the Himalayan soils. Further, surface soils had a low potential ecological risk in the region. Therefore, the Hg value from this study could be used for the further evaluation and calculation of I_geo, EF, and PI for water, soil, and aerosol in the Himalayan region as background reference value. However, Hg pollution from long-range transport and atmospheric deposition (wet/dry) in future could not be ignored in the Himalayan region.     

Predicting the distribution of livestock grazing pressure in rangelands

Abstract Because grazing by livestock is one of the primary threats to rangeland biodiversity, but is unevenly distributed in space, rangeland monitoring programmes need to take account of the distribution of grazing pressure in order to distinguish between grazing‐induced change, seasonal fluctuations and changes that are a result of other threats. Livestock watering places are one of the major influences that give spatial expression to gradations in grazing activity. Using research results from the goldfields of Western Australia, we show how distance from water can be incorporated in spatial models to predict cumulative grazing pressure at different sites within paddocks. Two surrogates of grazing activity are illustrated: one relying on a commercially available model, and one developed from measures of track density. Factors other than distance from water can also have profound effects on the distribution of grazing pressure and its impacts at landscape and regional scales, and we review some of these briefly. Finally, we outline key spatial implications for the design of rangeland monitoring programmes.     

Nucleotide sequence of the woodchuck hepatitis virus surface antigen mRNAs and the variability of three overlapping viral genes

A cDNA library was constructed from the liver of a woodchuck chronically infected with woodchuck hepatitis virus (WHV). A clone, pWS23, encompassing the entire surface and X genes of WHV was isolated. Comparison of the complete nucleotide (nt) sequence of pWS23 with those of genomic DNAs from two different WHV isolates showed that it contained a nearly full-length copy of the major mRNA encoding the viral surface antigen (5 mRNA). It was colinear with the WHV genome over 1858 nt and terminated 22 nt downstream from the variant polyadenylation signal within the core gene. Evidence for heterogeneity of the 5′ -terminal region of the S mRNA came from direct sequencing of the 5′ extremities of 20 cDNA inserts, similar to that of pWS23, isolated from a second cDNA library of the same woodchuck liver. In agreement with previous mapping studies of hepadnaviruses, two main initiation regions of S mRNA were localized 27–30 nt upstream and 22–49 nt downstream from the pre-S2 initiation codon. Further analysis of the amino acid sequences of the surface, polymerase and X genes of WHV showed a high conservation among three WHY isolates and a similar distribution of conserved and variable regions in woodchuck and human hepatitis B viruses.     

Percentage Points of Multivariate t Distribution with Zero Correlations and their Application

The k-variate t distribution plays an important role in the application of Multiple Comparison Procedures, Ranking and Selection Procedures, and Estimation of Ranked Parameters. This distribution was considered by several authors in the past and is now widely used. In this paper, tables of some percentage points of the multivariate t distribution are tabulated for given probability level γ = 0.80, 0.90, 0.95, and 0.99; population size k = 2(1)20; and degrees of freedom v=2(1) 30(5)60 with common correlation coefficient ? = 0. The accuracy of the percentage points is specifically determined (and is up to the fourth decimal place). An application of these tables is considered for interval estimation of the largest mean of k(≧2) normal populations.