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Most ecological studies with multiple independent variables use null hypothesis testing with full or stepwise models, or AICc-based model selection, but these approaches have not yet been compared using simulated data with known effect sizes. We compared these using ecologically relevant sample sizes, effect sizes, predictor numbers, collinearity and different degrees of explorative setups. Sample size and collinearity governed parameter identification success and parameter estimation accuracy, while the effect of the statistical modeling approach was comparatively smaller. Stepwise regression increased false detection rate compared with full models in settings where this error rate was overall low, but generally reduced the high detection failure rate in small samples. When reintroducing removed predictors to the final model, stepwise regression often improved the accuracy of point estimates relative to full models. The performance of AICc model selection and model averaging depended on the exact method, and did not differ overall from null hypothesis testing approaches.
We developed a set of microsatellite markers for the fan-tailed gerygone (Gerygone flavolateralis), host of a brood parasite, the shining bronze-cuckoo (Chalcites lucidus). We used 454 pyro-sequencing to establish 17 polymorphic microsatellite markers. The number of alleles per locus ranged from 6 to 18, the expected heterozygosity from 0.328 to 0.931 and the polymorphism information content from 0.306 to 0.916. The developed set of microsatellites will allow us to determine the gerygone's mating system, which is crucial to understand inheritance of dichromatism in skin colour of their chicks.
We estimated population abundances of the bear, lynx, wolf and wolverine in Finland in 1865–1915 by combining official bounty statistics with verified knowledge on annual intrinsic growth and mortality rates of these species. We used an annual backwards iteration method for all of these species, starting from a systematically-adjusted population size in 1915. According to our results, there had been approximately 1000 bears and an equal number of wolves in Finland until their decline started around 1875. As for lynx, it appears that its population increased markedly in the first quarter of our study period, but seemed not to have exceeded 3500 in the 19th century. Concurrently with the assumed strong growth of the lynx population, a marked increase took place in sheep and goats killed by large carnivores. The number of wolverines prior to 1885 appears to have been varying between 300 and 600.
The diet of wisents (Bison bonasus) inhabiting the Carpathians, studied during a snow-cover period, consisted of 46.8% of woody species consumed in the following manners: debarking (86.3% of dry mass), gnawing (12.6%) and browsing (1.1%). The top two species consumed were the common ash (39.5%) and fir (22.9%). Of the 23 consumed tree and shrub species, 19 species were debarked and 10 were browsed. Fallen trees, cut tree branches and logs of seven woody species were gnawed. The proportion of consumed woody species was positively correlated with snow depth. When ground flora were available, the percentage of twigs and tree bark in the wisent diet decreased, and brambles provided 99.1% of the consumed ground flora dry mass. Access to timber remnants at logging sites and non-valuable species like the willow or aspen may significantly reduce debarking of economically important tree species.
Ornithological research classified as topographic shared certain characteristics, including location type descriptions, full species lists of breeding birds for each location type, and usually at least a relative estimate of each species' abundance. Bird topographic research was inspired by the Finnish plant topographers, most notably J. P. Norrlin, and was presented as an explicit research programme by J. A. Palmén in 1885. We investigated the structure of and concepts used by 30 bird topographic studies published before 1930. The first clearly bird topographic study was published in 1886 (C. Brander), and since the 1920s topographic studies were gradually replaced by modern-type quantitative bird censuses. Terminology used in topographic studies varied. A commonly used concept was ståndort. In our material, the term “biotope” was first used in 1928. The term “topography” was occasionally used by Finnish ornithologists until the 1960s. The topographic approach improved the quality of faunistic reports, inspired later quantitative field censuses of birds, and even contributed to the study of habitat selection by birds.
Birds of different sex and age are known to differ in morphology and physiology. We investigated leucocyte profiles and body condition of the Savi's warbler (Locustellaluscinioides) in relation to sex, age and moulting status. We caught birds during the post-breeding period at the stopover site in northern Poland. Of the leucocyte profiles, we examined the heterophil/lymphocyte ratio (H/L), and the number of leucocytes, lymphocytes and heterophils per 10 000 red blood cells (RBC). We found a significant effect of the pentad × age interaction on the H/L ratio. In adults, body condition (BC, size-adjusted body mass) was similar in both sexes. Among adults, females had higher numbers of leucocytes and heterophils per 10 000 RBC and a lower relative number of lymphocytes compared to males. It is possible that subtle sex differences in parental care at the end of the breeding period account for these differences. They may be too subtle to affect BC, but are visible at some leucocyte variables. Moreover, BC of adults decreased with date, indicating the presence of migratory birds using our study area as a stopover site. Moulting adults had higher numbers of all leucocytes and lower H/L values than unmoulted individuals, suggesting a lack of trade-off between the immune system and moulting.
The European roe deer (Capreolus capreolus) is the most abundant and widespread cervid species in Europe. Despite being the subject of extensive research elsewhere, knowledge of the roe deer in Portugal is scarce. Here we review and summarize the available information on its distribution in Portugal, with the emphasis on: (i) historical distribution, (ii) current distribution and abundance, and (iii) main conservation/management problems. The roe deer is native to Portugal and its populations always persisted in a few patches to the north of the Douro river until the 1990s, when a series of reintroduction programmes restored this species to central and south Portugal. Currently, a natural expansion of the original and reintroduced populations is taking place. The roe deer is present and well established in mountain ranges in north Portugal and is naturally expanding its range towards the border with Spain (west-central Portugal). A number of threats to the species such as potential interspecific competition with the red deer and livestock, along with inadequate management, human disturbances (both roads and human settlements) and climate change have been identified. It is therefore imperative to identify research and monitoring gaps, and finally to draw conclusions under a holistic framework. This will ensure that informed decisions concerning the roe deer management are made at the national level, taking into account that changes in land use occur continuously, possibly affecting the deer abundance.
The aim of this study was to investigate the effect of CO2-induced seawater acidification (pH 8.1; control pH 7.0 and 6.0) on the survival, behaviour and metabolic rate of the Baltic clam Macoma balthica during short- (36 hours) and long-term (14 days) exposures. Total metabolic rate and gaping behaviour (shell opening and closing) were determined based on heat dissipation measurements using an isothermal twin calorimeter of the Calvet type. The survival and burrowing behaviour during long-term exposure were observed every day. Short-term exposure to reduced pH did not significantly affect the resting or active metabolic rate. Neither were there any significant changes in gaping behaviour. However, long-term exposure significantly affected burrowing behaviour. In the lowest-pH treatment, both resting and active metabolic rates were also significantly higher than in the control.
Antlers are costly structures produced annually by male cervids using minerals obtained from their diet and from resorption of their skeleton. Availability and nutritive quality of food resources therefore have a great impact on the investment of males in these secondary sexual traits. We studied the structure, mineral composition and mechanical quality of antlers of the Siberian wapiti (Cervus canadensis Sibiricus), Père David's deer (Elaphurus davidianus) and Vietnamese sika deer (Cervus nippon pseudaxis), three closely-related cervid species. The three herds investigated were maintained under the same feeding and management conditions (one male per herd) throughout a 3-year study period. We showed that there was no significant inter-specific difference in antler composition of the three species under the same feeding regime. However, mechanical properties varied between the Siberian wapiti and the other two species; and structural characteristics were different among all of them. Our results show that antler composition has a similar chemical profile across species when grown under the same feeding regime whereas the internal structure and mechanical properties appear to be species dependent.
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