Population dynamics can be analysed at the spatial and temporal scales by using museum specimens. DNA-based sex determination systems can be applied to many biological samples, including preserved museum specimens. Systems applicable to historical DNA of non-mustelid species were adapted to obtain short but sufficiently informative fragments of mustelid sex-linked genes. Here, I used the two most popular methods — SRY amplification and polymorphism analysis of ZFX/ZFY genes — to determine sex of individuals belonging to several mustelid species. Positive results of SRY amplification (115 bp) in males and the lack of the product in females were confirmed by the analysis of sex-specific mutations in the ~90 bp fragment of ZFX/Y for five species: Neovison vison, Mustela putorius, Mustela erminea, Lutra lutra, and Meles meles. For Martes foina, the analysed ZFX/Y fragment did not differ between male and female samples. For Mustela nivalis, only a male sample was available and no reference ZF sequences were found.

In temperate forests, red wood ants (Formica aquilonia) are considered ecosystem engineers affecting ecosystem properties and functions. Possible effects of F. aquilonia ants on species communities of invertebrates and plants were studied in the pine-dominated Geitaknottane forest reserve, Norway. Species richness of carabids, lichens and epiphytes (tree-living lichens and bryophytes) was negatively affected by ant mound density. Species of all groups, except for lichens and snails, were affected either positively or negatively by ant presence. Food availability and interference competition are plausible explanations of decreased species richness and negative species associations in carabids; while collecting, foraging and changed chemical environment may explain decreased species richness in lichens and epiphytes. Thirteen out of 15 plant and invertebrate species were weakly associated with ant mound density. Associations of only two species (Carabus violaceus and Drusilla canaliculata) were negative, while Pella humeralis and Agroeca proxima were associated positively and very strongly with ant mounds. Positive associations with ants of those invertebrates may be a response to excessive abundance of food and chemical mimicry.

Changes in winter climate is a possible explanation for dampened population cycles in voles. For voles living in the subnivean space for several months of the year, we may expect that winter conditions affect survival. We examined the effect of different winter climate descriptors (snow depth, subnivean temperature, snow crust) and different intrinsic factors (sex, age, physiology, behaviour estimated as the longest distance travelled between traps) on winter survival of bank voles Myodes glareolus in southeastern Norway by live-trapping voles monthly along elevation gradients. We tested whether winter conditions alone (winter hypothesis), intrinsic factors alone (intrinsic hypothesis), or winter conditions in combination with age and sex were more important for winter survival of voles (multiple factor hypothesis). Our results do not support the winter hypothesis as there were no relations between winter survival and snow depth, snow crust and subnivean temperature. We found strongest support for the intrinsic hypothesis, where the distance travelled was positively correlated with survival. We hypothesize that this behavioural descriptor is related to food resources and their importance during winter, where an increased activity range (distance travelled between traps) increase the access to food resources.

We analyzed data collected from 19 428 necropsied brown lemmings (Lemmus trimucronatus) collected over a period of 22 years near Barrow, Alaska. Here we report on seasonal and cyclic patterns in reproductive activity of females and males, population structure, adult body size, condition (weight per unit length and body fat), and wounding. We also provide the first detailed information on these characteristics at low population densities. The seasonal pattern of reproduction included short summers (about 2.5 months) with intense reproduction, long winters (about 6.5 months) with moderate reproduction, and virtual cessation of breeding during the short springs and autumns (1.5 months each). Overall sex ratios appeared equal, but the proportion of males decreased during summer. The proportion of immature lemmings increased in late summer and autumn after intense summer breeding, then declined in winter. Adult body weight and condition (weight per unit length) peaked in summer when the food supply also peaked, but body fat, though still minimal, peaked in winter. The greatest incidence of wounding occurred in males, but wounding increased in both sexes during early summer, the period of most intense breeding. As reported previously for arvicoline rodents, a longer summer reproductive season occurred during the low and increase phases, but no change in litter size occurred during the cycle. Contrary to earlier reports, a much lower frequency of pregnancy occurred during the high phase, but later reproductive maturation during the high phase received little support. The sex ratio generally changed little during the course of a population cycle, but the proportion of females did decline during springs when the population increased to high densities. We found a greater proportion of adults during the high and decreasing phases, reflecting the reduced reproduction during those phases. Higher body weights and better condition of adults occurred during high densities. Wounding (fresh scars from bites) also peaked during years with high densities, though only for adult males and non-reproductive females. Overall, it appeared that nutrition strongly influenced seasonal changes in reproduction, population structure, and body condition; predation affected both seasonal and cyclic changes in population structure and survival; and that nutrition, and perhaps social strife, caused cyclic changes in reproduction, survival, and body size.

In this work, I assessed the effects of toe-clipping on sprint speed and run rate (number of runs per meter) of Epidalea calamita toads from agricultural land and their natural habitat. I videotaped toads in individual trials along a linear runway. Afterwards, I randomly assigned toads to two groups: control toads, which were not clipped, and experimental toads, whose third toe in each hind limb was immediately clipped. One hour later, I videotaped a second trial. Sprint speed in the first and second trials was similar in both groups. Likewise, run rate was not affected by toe-clipping. Sex and habitat had no effect on the effect of toe-clipping on locomotor performance. These findings suggest that toe-clipping should not increase toads' risk to become prey or hinder searching for prey or mates.

Live trapping is an invaluable and commonly used technique for studying small mammal populations. There are several types of commercially available live-traps, but some models have been shown to differ in terms of species-specific efficiency. Such differences could lead to biased results, and knowledge of such bias is important when comparing results of different studies. The Ugglan Special live-trap is one commonly used type, and it is available in several different models. I studied performance of the two most common models (No. 1 and No. 2) to find out whether they differ in terms of overall efficiency and body-mass-dependent efficiency, when trapping small rodents. I used 48 traps of each model in boreo-nemoral forest during three years, which amounted to 3456 trap nights, during which 268 bank voles (Myodes glareolus) (26%) and wood mice (Apodemus sylvaticus) (74%) were captured. There was no difference in body mass between the animals captured by the two trap models. Model No. 2, however, was more efficient in capturing bank voles, but not wood mice, than model No. 1. This difference may have been caused by the difference in the entrance design. This species-specific dissimilarity in trap efficiency should be taken into account when using Ugglan Special live-traps in ecological research relying on mark–recapture methods. Additional studies are needed to see if other species of small mammals are affected in similar ways and if the differences are consistent among habitat types.

We studied trophic resource use and availability in three populations of the common frog (Rana temporaria): one from the subarctic (Kilpisjärvi, Finland), and two (alpine and low-altitude valley populations) from the Retezat Mountains (Southern Carpathians, Romania). We used stomach flushing to sample consumed prey, and estimated prey availability using pitfall traps and netting. In addition, we analyzed the geographical pattern of feeding based on published records covering the entire range of the species. Feeding intensity varied, both spatially and according to frog size. Adults consumed prey of higher richness and more prey items than juveniles. There was latitudinal variation in prey consumption, with populations from extreme habitats (alpine and arctic) having the highest prey richness. This high feeding plasticity partly explains why Rana temporaria is widespread and reaches high altitudes and latitudes in Europe.

We analysed migration distances of sub-adult and adult grey herons (Ardea cinerea) ringed in Poland between 1932 and 2014 when migrating to wintering and stop-over areas. The research was based on 239 ring recoveries during non-breeding periods from 92 ringing sites in Poland. We used location of ringing sites, age of bird, and year of recapture to explain variation in the observed distances between breeding and stop-over as well as wintering areas. We found variation in the location of non-breeding areas of grey herons from northern and southern Poland. Migration distance of grey herons increased with latitude, with birds from northern Poland spending the non-breeding period further away than birds from southern Poland. Considering possible shortening of the migration distance due to climate change, we analysed frequency of recoveries from the vicinity of the breeding site, Mediterranean and sub-Saharan zones. Despite reported claims of climate change leading to migration distance becoming shorter, we found that distance to those areas was not affected significantly by year. In contrast to previous studies made in western Europe, age of bird did not affect migration distance.