Ruffed grouse brood habitat on reclaimed surface mines in West Virginia

Human-imprinted ruffed grouse (Bonasa umbellus) chicks were used to evaluate grouse brood food and cover conditions on reclaimed surface mines in northern West Virginia. Reclaimed surface-mined areas did not provide the quality of habitat for ruffed grouse chicks that unmined land provided. On the surface-mined areas, grasslegume reclamation provided the poorest cover and next to the lowest feeding rates. Of the surface-mined areas a 25-year-old reclaimed mine planted to autumn olive had canopy provided a more favorable micro-climate for insects and herbaceous vegetation was established around the edge. Planting rows of shrubs in addition to the current practice of planting grasses and legumes on surface-mined areas is suggested to create ruffed grouse brood habitat.     

Can modeling improve estimation of desert tortoise population densities?

The federally listed desert tortoise (Gopherus agassizii) is currently monitored using distance sampling to estimate population densities. Distance sampling, as with many other techniques for estimating population density, assumes that it is possible to quantify the proportion of animals available to be counted in any census. Because desert tortoises spend much of their life in burrows, and the proportion of tortoises in burrows at any time can be extremely variable, this assumption is difficult to meet. This proportion of animals available to be counted is used as a correction factor (g0) in distance sampling and has been estimated from daily censuses of small populations of tortoises (6-12 individuals). These censuses are costly and produce imprecise estimates of go due to small sample sizes. We used data on tortoise activity from a large (N = 150) experimental population to model activity as a function of the biophysical attributes of the environment, but these models did not improve the precision of estimates from the focal populations. Thus, to evaluate how much of the variance in tortoise activity is apparently not predictable, we assessed whether activity on any particular day can predict activity on subsequent days with essentially identical environmental conditions. Tortoise activity was only weakly correlated on consecutive days, indicating that behavior was not repeatable or consistent among days with similar physical environments.     

Social foraging and dominance relationships: the effects of socially mediated interference

In socially foraging animals, it is widely acknowledged that the position of an individual within the dominance hierarchy of the group has a large effect upon its foraging behaviour and energetic intake, where the intake of subordinates can be reduced through socially mediated interference. In this paper, we explore the effects of interference upon group dynamics and individual behaviour, using a spatially explicit individual-based model. Each individual follows a simple behavioural rule based upon its energetic reserves and the actions of its neighbours (where the rule is derived from game theory models). We show that dominant individuals should have larger energetic reserves than their subordinates, and the size of this difference increases when either food is scarce, the intensity of interference suffered by the subordinates increases, or the distance over which dominant individuals affect subordinates increases. Unlike previous models, the results presented in this paper about differences in reserves are not based upon prior assumptions of the effects of social hierarchy and energetic reserves upon predation risk, and emerge through nothing more than a reduction in energetic intake by the subordinates when dominants are present. Furthermore, we show that increasing interference intensity, food availability or the distance over which dominants have an effect also causes the difference in movement between ranks to increase (where subordinates move more than dominants), and the distance over which dominants have an effect changes the size of the groups that the different ranks are found in. These results are discussed in relation to previous studies of intra- and interspecific dominance hierarchies.     

Phylogenetic relationships within the class holothuroidea,inferred from 18S rRNA gene data

This molecular phylogenetic analysis of 18S ribosomal RNA (18SrDNA) gene sequences from 16 species of holothuroid, suggests strong support for an alternative taxonomic scheme to replace the existing classification. When trees drawn from the 18S rDNA data were constrained to show expected relationships between the holothourid orders, they were significantly worse than the best tree under SH tests. These analyses indicated strongly that the subclass Aspidochirotacea is paraphyletic. Sequences from the order Dendrochirotida grouped with aspidochiroitid sequences, with high bootstrap support, to the exclusion of the elasipod sequence. In line with recent morphological studies the order Apodida were a basal sister group to the other three holothuroid orders examined and the Dendrochirotida was a derived holothuroid order. Brendan F. Keegan, Richard Powell: R.I.P     

Philopatry and mother-daughter associations in bushy-tailed woodrats: space use and reproductive success

Social groups in mammals are often based on overlapping generations of philopatric females, yet few researchers have examined fitness consequences of associations between females and their daughters. We examined survival and reproductive consequences of sharing a natal site with one's mother or daughter in wild bushy-tailed woodrats (Neotoma cinerea). Bushy-tailed woodrats reside on discrete rocky outcrops, and females tend to spend their entire reproductive life on their natal outcrop. Mothers and daughters that co-existed on the natal outcrop were closely associated in space. Juvenile females were more likely to survive their first winter to become breeding yearlings at their natal site if their mother was also present at the natal site during the winter. Juveniles survived equally well with or without their mother where densities of adult females were experimentally reduced, suggesting that females enhance their daughter's survival by facilitating their access to limited resources. Yearling females exhibited no reproductive costs from association with their mothers at the natal site during the breeding season; in fact, yearlings that bred at the natal site simultaneously with their adult mothers tended (P = 0.07) to experience fewer reproductive failures than did those that bred in the absence of their mothers. Mothers did not experience any detectable costs when sharing a natal site with a daughter. We conclude that bushy-tailed woodrats exhibit stable, fitness-enhancing associations among mothers and their philopatric daughters.     

影响瑞典最大湖泊中冰河时代残余体片脚类动物Monoporeia affinis (Lindstrom)数量波动的因素

在瑞典最大的三个湖泊中人们研究了影响冰河时代残余体片脚类动物Monoporeis affinis的长期(1982-000年)种群密度的因素.在所有的三个湖泊中,Monoporeia数量都有较大的波动,在维纳恩和拉伦湖中还出现了明显的密度峰值.在维纳恩湖中,片脚类动物的显示出在一年期间内它和春季最大硅藻的生物体积有非常重要的关系.韦特恩湖中硅藻生物体积和Monoporeia密度间没有这种关系可能是由于此湖泊较深及其营养浓度比较低.在富营养的梅拉伦湖中.夏季氧不足(＜4mgO2/L)可能是一个重要的调节因素.均温层的温度显示在1989～1994年间深湖水存在一个明显的温暖周期.维纳和韦特恩湖均温层温度和总的太阳照射有关.然而和北大西洋波动冬天指数有关的既不是均温层水温也不是硅藻的生物体积.我们推测温度和接近湖底的氧气浓度的变化通过作用于种群的补充幼体成功率(繁殖)和幼体(年轻的)存活率来对种群密度起负面影响.