Geographically peripheral populations are likely to experience suboptimal conditions, and several population characteristics may be influenced. The aim of the present study was to assess characteristics of the populations of hazel, forest and fat dormice on the northern periphery of their ranges in continental Europe in comparison to populations situated in the rest of their ranges. The dormouse populations analysed were found to be distinct from other populations in many aspects of their ecology. On this northern periphery of the ranges, the dormouse activity season is shorter and ends earlier. The population density is also lower, but inter-annual abundance dynamics are comparatively stable. Except the shorter breeding season however, there is no clear general pattern regarding other aspects of reproduction. The composition of the vegetable food used by dormice is rather specific. Contrary to expectations, the proportion of food of animal origin is not increased in the dormouse diets. The main habitat requirements of dormice are similar to those in other parts of their ranges, though the composition of woody plant species in the dormouse habitats is different. Dormice living on the northern periphery of their ranges show a high degree of adaptability to local conditions, but factors limiting their distribution are not clear yet.
There are isolated populations of the endangered butterfly, Pyrgus sidae, on the Iberian Peninsula. The mark-release-recapture method was used to study the population parameters, the use of resources and the spatial distribution of a population in the centre of Spain. The estimated number of males and females within the population were similar and did not differ significantly from a ratio of 1 : 1. Total population size was estimated to be 569 ± 83 individuals. Potentilla recta is the principal adult nectar source and larval food plant, and its abundance is correlated with the number of marked and recaptured butterflies. The average total distance moved between capture and recapture was significantly greater for males than females, but the average daily distances moved were similar for both sexes. The spatial distribution of the movements of males and females was of a uniform type and lacked a predominant flight direction, which is typical of sedentary species. Continuing the traditional land use (cattle grazing or hay mowing) of the habitat of the species keeps the habitat open, which is necessary if the butterfly is to survive at this locality. These management practices favour P. recta, which would otherwise succumb to competition from invasive shrubs. Taking into account the habitat requirements of this species, it is important to conserve the mosaic of meadows already present in the area.
The Indian river shad, Gudusia chapra, is a commercially important clupeid that contributes to subsistence and artisanal fisheries in inland waters in Bangladesh. Population parameters for this species were collected from a study of a population in a large perennial pond in Mymensingh, Bangladesh from May 2003 to April 2004. The gonado-somatic indices indicated a spawning season in spring, with a mean birth date estimated as 30 April. The growth equations, provided by three models, for males and females respectively, were: Lt = 140.42 (1- exp (-0.026 (t + 6.717))) and Lt = 145.39 (1- exp (-0.025 (t + 7.113))) for the von Bertalanffy model; Lt = 121.53 exp (-exp (-0.050 (t - 8.274))) and Lt = 124.95 exp (-exp (-0.048 (t - 8.421))) for the Gompertz model; and Lt = 114.27 / (1 + exp (-0.074 (t – 14.260))) and Lt = 117.19 / (1 +2 exp (-0.071 (t - 14.524))) for the Robertson model, where Lt is standard length (mm) at age t (weeks). Growth was best described by the von Bertalanffy growth equation for both male and female based on Chi-squared (χ2) values and Akaike’s information criterion. The absolute growth rates of males were slower than that of females. The von Bertalanffy growth model expressed in terms of body weight (BW) yielded functions for males and females of: BWt = 53.63 (1- exp {-0.028 (t + 6.320)))3 and BWt = 53.89 (1- exp (-0.023 (t + 9.215))3, respectively.