The aim of this study was to analyze the relation between physical condition, measured as the Kidney Fat Index (KFI), and some reproductive parameters of Lepus granatensis in Navarra province, Spain. Samples were collected between October 2001 and January 2003, totaling 174 hares (87 males and 87 females). All the hares were sexed and classified in three age categories (immature, young and adult). Fertile males and females were present in all monthly samples. Kidney weight was greater in females than in males for all the age classes and kidney weight variation along the year was not significant. Ranges of perirenal fat accumulated were larger in females but mean weight of fat for all hares was similar in males and females. Body weight and kidney fat weight was directly related both for males and females. Global pattern of fat deposition along the year was similar for both sexes. The amount of perirenal fat in adult fertile hares reaches maximum values just before the main reproduction period and reproductive state conditioned kidney fat levels. Pregnancy induces fat deposition in females and factors such as the number of embryos and the stage of gestation influence kidney fat levels.

We provide an updated distribution and dispersal rate of the European hare (Lepus europaeus Pallas, 1778) introduced in South America, with georeferenced record localities. According to our results the current geographic distribution of the European hare, would cover practically all of Argentina, Chile and Uruguay, southeastern Peru, southwestern Bolivia, southeastern Paraguay, and central part of southern Brazil. During the process of invading new areas, the hare has occupied very dissimilar environments, from the bushy steppes and Andean deserts of Bolivia and Peru to the dry and humid forests and wooded savannahs of Paraguay and Brazil. This would explain the variation observed in the dispersal rates that varied between 10 and 37 km/year.

The aim of the present paper was to compare the picture of habitat selection obtained by using 1) different home ranges and core areas and 2) different methods (compositional analysis, Jacobs index and selection ratio), in radio-tracking studies of mammals. The experimental animal was the Eurasian badger Meles meles, radio-tracked in southern Finland in 2006–2007. The total home ranges used in the study, minimum convex polygon (MCP) and 95% fixed kernel home range (K95) differed in size, MCP being larger. Therefore its habitat composition resembled more that of the landscape, and comparison between K95 and the study area revealed better habitat selection within the landscape (second order selection). The proportions of two common habitat types (fields and spruce forests) differed between the core areas used in the study. Comparison between the smallest core area (K50) and MCP revealed best habitat preferences within the home range (third order habitat selection). Comparing the distribution of individual location points in different habitats to the habitat composition of home ranges did not reveal habitat preferences of badgers. The use of compositional analysis together with Jacobs index in habitat selection studies is recommended, because the simple selection ratio was not very sensitive.

The Azorean bat (Nyctalus azoreum), the only endemic mammal of the Azores archipelago (Portugal), diverged recently from its mainland relative, the Leisler's bat (N. leisleri). Although the two species are phenotypically very different, mtDNA studies detected very low genetic divergence between them, which could question the validity of the species status of N. azoreum. In order to assess the genetic variability in each species and check for present levels of gene flow between the two taxa, eight microsatellite loci were genotyped and analysed. The results indicated lower genetic diversity in the insular species. Many unshared alleles were found between the two species and no evidence of migrants, which provides strong support against any contemporary gene flow between them. The species status of the Azorean bat is discussed in the light of the cohesion species concept, and we conclude that it is an isolated species with a high conservation value.

A comparison was made between the absolute and actual fecundity of C. taenia and allotriploid Cobitis females from a diploid-polyploid population inhabiting the Bug River, of Vistula River basin in Poland. All specimens were measured, weighed and aged. The absolute fecundity was determined by a gravimetric method using 29 ovaries (three of C. taenia, 25 of triploids and one of tetraploid). The actual fecundity was estimated according to the method adopted by Halačka et al. (2000) and used five ovaries of C. taenia and 40 of Cobitis triploids. Absolute fecundity of C. taenia under analysis ranged from 1 819 to 3 302 eggs and equaled 2 487 on average. It was significantly lower than absolute fecundity of an exclusively diploid population in Klawój Lake described previously (Juchno & Boroń 2006a). Absolute fecundity of triploid females ranged from 285 to 3 710, with an average of 1 577 eggs, whereas the fecundity of tetraploid Cobitis female was low, with only 882 eggs. The highest actual fecundity of C. taenia as well as of triploids was observed after they laid their first batch of eggs.

Size-frequency data were collected for two rheophilic fish species, Cottus perifretum and Leuciscus cephalus, at the confluences of 18 lowland tributaries along the regulated River Meuse (the Netherlands) between May 2004 and April 2005. Cottus perifretum is a resident species, using these stream mouth habitats throughout its entire life: i.e. as a spawning, nursery and adult habitat. Leuciscus cephalus is a transient species that uses these stream mouth habitats only as a temporary 0 juvenile habitat during fall and early winter. This study suggests that the stream mouth habitats along the River Meuse fulfil different ecological functions for C. perifretum and L. cephalus.

The Neretva chub, Squalius svallize is an endemic species of the Adriatic basin of the southeastern Europe. Altogether, 60 specimens were caught by gill nets from the Neretva river area, the oldest being seven years old. The most dominant item in the diet of S. svallize during winter season were larvae of Trichoptera and Diptera. Diptera larvae were also dominant during spring and summer. In autumn period the largest amount in stomach content were Trichoptera larvae and Gastropoda. Plant material was present in stomach content but not dominant food item. The von Bertalanffy formula, counted from the back calculated growth in total length, appeared to be: L_t= 35.3 (1-e ^{-0.15 (t 1.40)}). The phiprime of Neretva chub (ln base) is Φ'=5.23. The length-weight relationship, including the fish from the entire growing period, demonstrated positive allometric growth with a b-value of 3.47. The average value for condition factor was CF = 0.98±0.14 (min = 0.76; max = 1.29).

Over the past 150 years, the waters of the Czech Republic were experimentally stocked or invaded by a total of 41 alien (non-native) fish species. The following species have become fully naturalized and produced self-sustained populations: Carassius gibelio, Pseudorasbora parva, Ameiurus nebulosus and Gasterosteus aculeatus, which produced stable populations in several spatially limited localities. In some cases Oncorhynchus mykiss, Salvelinus fontinalis and Coregonus maraena will produce instable temporary populations based on released material obtained from fish farms and ponds. The occurrence of the remaining acclimatized alien species (Coregonus peled, Ctenopharyngodon idella, Hypophthalmichthys molitrix, Aristichthys nobilis) in natural ecosystems and fishponds depends on stocking fish obtained from artificial spawning and cultures. The documented annual average production of alien species fit for human consumption amounts to around 2 000 tonnes, i.e. 8.2% of the annual average production of marketable fish cultures in the Czech Republic. A significant negative impact of the introduced species on native ichthyofauna has been ascertained as regards its ecological, biological properties, biodiversity and health. Considered a typical invasive alien species, Carassius gibelio heavily depressed the occurrence and numbers of indigenous Carassius carassius populations and also contributed to the decreased numbers of Tinca tinca, Leucaspius delineatus and other native cyprinid fish. P. parva and A. nebulosus show a much weaker and limited impact. The introduction of C. idella was accompanied by the introduction of the tapeworm species, Bothriocephalus gowkongensis, which subsequently caused heavy losses in cultures of Cyprinus carpio. In 2008, Neogobius melanostomus was recorded for the first time in this country at the confluence of the Morava and Dyje rivers.

For the last 800 years, 35 alien fish species have been introduced, mainly intentionally, in Polish inland waters. The paper reviews the present state of alien fish fauna in Poland, with special attention paid to those considered to be invasive. Till now 26 species have been reported as naturalized, acclimatized or casual and it means that 34% of fish fauna are non-indigenous species. The majority came from North America, Eastern Asia and Siberia or different regions of Europe. More than 65 % of all introductions took place in the last 60 years. After the World War II the rapid expansion was noted specially for brown bullhead, Ameiurus nebulosus and gibel, Carassius gibelio. In the recent decade similar explosive spread has been observed for three Neogobius species (round goby, N. melanostomus, racer goby, N. gymnotrachelus, monkey goby, N. fluviatilis), Amur sleeper, Perccottus glenii and topmouth gudgeon, Pseudorasbora parva. The occurrence of introduced fish species resulted in several negative changes in aquatic environments. Some of them are as follows: hybridisation with native species, destruction of spawning grounds and habitats for many freshwater organisms, decrease of native fish reproduction success due to predation on eggs and offspring and finally the aliens might be vectors for parasites and diseases.