The influence of American mink odour on the spatial distribution and behaviour of water voles

The perception and assessment of predation risk often cause changes in the activities of animals and induce behavioural responses that may in turn affect their movements and distribution. To simulate high predation risk in a midfield pond riparian habitat, we used fresh faeces from ranch American mink Neovison vison and recorded behavioural responses of water voles Arvicola amphibius. In areas where mink odour was deployed, the numbers of captured vole individuals and their trappability were significantly lower than in control areas. Several voles migrated from the zones with deployed mink faeces to the areas without faeces, thus proving that increased predation risk affects the distribution of individuals in a population. The response to mink odour was much more pronounced in females than in males; in areas with deployed mink faeces, not a single female was trapped. We conclude that although American mink is a non‐native, invasive predator, water voles respond to mink odour by reducing their activity and/or by avoiding places with higher predation risk.     

Physiological consequences of captive conditions in water voles (Arvicola terrestris)

Re-introductions of captive-bred animals are increasingly common in wildlife conservation and it is important that they fulfil their potential. To foster this goal we examined variations in stress levels in a captive-bred population of water voles Arvicola terrestris in response to housing conditions and radio-collaring, using weight loss and leukocyte coping capacity (LCC) as measures of relative stress, to investigate the impacts of housing conditions, handling and radio-collaring on this species. Thirty-eight water voles (22 males and 16 females) were used in the investigation, 25 housed in outdoor enclosures and 13 in laboratory cages. During the 6-week study, LCC, body weight and urine refractive index (URI, an indicator of hydration levels) were recorded once a week for each individual in weeks 1, 2, 4 and 6. After the first sample, radio-collars were attached to 20 individuals (10 males and 10 females) taken from both housing types. Throughout the experiment laboratory-cage housed voles weighed less, had lower LCC scores – indicating a reduced ability to combat infection – and had higher URIs than outdoor-enclosure voles. This suggests that the laboratory-cage voles were more stressed and dehydrated than the outdoor-enclosure voles. Weights and LCC scores of both housing groups decreased as the study progressed, suggesting that elements of the study, such as repeated handling, may have caused stress to both groups. Evidence suggested a short-term effect of radio-collaring on immuno-competence. We conclude that captive housing conditions, repeated manipulation and radio-collaring had demonstrable physiological effects on the water voles studied. We recommend that the effects of husbandry and tagging practices upon captive-bred mammals be closely studied as part of the quest to improve the success of the re-introductions to which they contribute.     

Phylogeographic structure and postglacial evolutionary history of water voles (Arvicola terrestris) in the United Kingdom

The phylogeographic pattern of mitochondrial DNA variation in water voles (Arvicola terrestris) from 57 localities across the United Kingdom and representative samples from Spain, France, Switzerland and Finland was determined from sequence variation in the central portion of the control region. Twenty-seven different haplotypes were resolved which formed two distinct phylogenetic clades. This major division separated haplotypes found in Scotland from those found in England and Wales. Nested clade analysis of haplotypes indicated that such a division was a consequence of allopatric fragmentation. The haplotypes found in Switzerland, France and Spain clustered with Scottish haplotypes, whereas the haplotype from Finland clustered with the English/Welsh haplotypes. These patterns indicate that contemporary Scottish populations are derived from an Iberian glacial refugium, whereas English and Welsh populations are derived from an eastern European refugium. As such, the postglacial recolonization of the United Kingdom must have involved two colonization events, either in different localities with no subsequent contact, or as two waves separated over time, with the second wave of colonizers displacing the first. An analysis of molecular variance (AMOVA) identified significant population genetic divergence within both the major clades, indicative of restricted gene flow and regional population isolation. The implications of both phylogeographical and population genetic structure are discussed in context with the conservation of water voles in Britain.     

Bark consumption by small rodents in the northern and southern hemispheres

The distribution and environmental conditions of bark consumption by small rodents were compiled for the northern and southern hemispheres. Main bark consumption occurred under snow at peak cyclic density and in the dry season of annually fluctuating rodent populations, respectively. The species responsible appeared more folivorous in the north. Among woody species that are damaged, a large number were in both cases exotics. Various defences against bark consumption have evolved, including secondary compounds. However, this defence appears inadequate when indigenous trees are grown under new environmental conditions. It is pointed out that the stem and bark are very sensitive components of perennial trees and bushes and that this potential but usually well protected resource will only be used in crucial situations by various mammals. In view of the many unsuccessful attempts to prevent small rodent damage by bark consumption, costs for rodent damage should be included in any cost–benefit analyses for plantations of exotic species or indigenous species under new conditions. Screening and even selection for resistant varieties may be needed at large scale plantations.     

Analysis of major histocompatibility complex class II gene in water voles using capillary electrophoresis‐single stranded conformation polymorphism

Analysis of a single strand conformation polymorphism (SSCP) using capillary electrophoresis (CE) is a novel method to study polymorphism of DNA sequences in large scale population studies. We optimized CE‐SSCP analysis to study the major histocompatibility complex (MHC) class II alpha gene (DQA) polymorphism. Short‐chain linear polyacrylamide (6%) as sieving matrix, TrisCl (pH 8.5) as buffer for sample dilution, and 27 °C, 9 kV as electrophoresis parameters were suitable for sufficient resolution of all alleles. We found that almost 25% of clones contained a PCR (polymerase chain reaction) artefact and strict criteria have to be applied when using cloning and sequencing to analyse the allelic diversity of MHC genes.     

Tawny owl reproduction and offspring sex ratios under variable food conditions

Tawny owl reproduction and offspring sex ratios have been considered to depend on the abundance of small voles. We studied reproductive performance (laying date, clutch and brood size) during 1995–2003 and offspring sex ratios from 1999 to 2003 in relation to the abundance of small voles and food delivered to the nest in a tawny owl population in southern Finland. Abundance of small voles (field and bank voles) was based on trappings in the field, and estimates of food delivery was based on diet analysis of food remains in the nest boxes. In this population, reproductive output was not related to the abundance of small voles. Analysis of food delivered to the nest showed that the prey weight per offspring varied more than twofold between years and revealed that this difference was mainly related to the proportion of water voles in the diet. Only the number of water voles correlated with laying dates. Offspring sex ratios were weakly male biased (55%) but did not differ from parity. Sex ratios were not related to the abundance of small voles, and we found no evidence that parents delivered more food to nests with proportionally more offspring of the larger (female) sex. Our results underline the notion that populations may differ in their sex allocation pattern, and suggest such differences may be due to diet.     

Behavioural responses of captive hippopotamus(hippopotamus amphibius)in lactation season:Maternal investment and plasticity of infant self-independence

In order to promote hippopotamus management in the captive and ex-situ environment, especially the control of behavioural and physiological status during breeding and lactation seasons, we conducted a preliminary study on behavioural responses of a pair of hippos including both mother and infant in Hangzhou Wildlife Park, China. The study of the captive hippos for about 1-month in the lactation season was carried out during August and September, 2009. The behavioural patterns were identified by all occurrence sampling and instantaneous scanning sampling methods with 5-10 min intervals. As a result, mother-offspring conflicts and interactions did occur throughout the whole study period. Early maternal investment showed a positive trend in activity rhythms (slope = 0.0014, Z = 0.3027, P ＜0.001) and a negative trend (slope = -0.0066, Z = 0.8807, P＜0.001) in territorial occupation of water, all of which supported our hypotheses that the mother hippo might exert less care for the infant and cut down on her own obligations in nursing. For infant self-independence, during the whole lactation season, the primary trends of activities and territorial occupation dynamics of the infant hippo were slightly different from before, judging from linear models (slope = -0.0017, Z = 0. 3309, P＜0.001). However, the frequencies of activities were not stable, especially at around 12 days of age. The trends of territorial occupation (slope = -0.0071, Z= 0. 904, P＜0.001) also showed negative dynamics in water body occupation by the time the infant hippo grew up. The general trend (slope = -0.005, Z = 0.06, P＜0.001) of suckling dynamics was demonstrably negative, with an upwards fluctuation at period 3 (10-15th day). This also illustrated that as the infant developed, the dependency on the mother was reduced at the end of the lactation season. In addition, a sharp decline between P3 and P4 also supported the mother-offspring conflict theory. In general, time budgets of hippos in active behaviour were (31.8±2.1)% for the mother and (32.1 ±2.6)% for the infant. Spatial distributions in water within temporal limitations were (80.1 ±2.7)% for the mother and (81.8±2.7)% for the infant. Behavioural dynamics showed strong synchronous relations between maternal investment and infant independence. Our current short-term investigation proves to be a key in management and conservation of hippopotami during the lactation season.     

Activity patterns at the Arctic Circle: nocturnal eagle owls and interspecific interactions during continuous midsummer daylight

Circadian rhythms result from adaptations to biotic and abiotic environmental conditions that cycle through the day, such as light, temperature, or temporal overlap between interacting species. At high latitudes, close to or beyond the polar circles, uninterrupted midsummer daylight may pose a challenge to the circadian rhythms of otherwise nocturnal species, such as eagle owls Bubo bubo. By non‐invasive field methods, we studied eagle owl activity in light of their interactions with their main prey the water vole Arvicola amphibius, and their competitor the white‐tailed eagle Haliaeetus albicilla during continuous midsummer daylight on open, treeless islands in coastal northern Norway. We evaluated circadian rhythms, temporal overlap, exposure, and spatial distribution. The owls maintained a nocturnal activity pattern, possibly because slightly dimmer light around midnight offered favourable hunting conditions. The eagles were active throughout the 24‐h period as opposed to the strictly diurnal rhythm reported elsewhere, thus increasing temporal overlap and the potential for interference competition between the two avian predators. This may indicate an asymmetry, with the owls facing the highest cost of interference competition. The presence of eagles combined with constant daylight in this open landscape may make the owls vulnerable to interspecific aggression, and contrary to the available literature, eagle owls rarely exposed themselves visually during territorial calls, possibly to avoid detection by eagles. We found indications of spatial segregation between owls and eagles reflecting differences in main prey, possibly in combination with habitat‐mediated avoidance. Eagle owl vocal activity peaked in the evening before a nocturnal peak in visual observations, when owls were active hunting, consistent with the hypothesis of a dusk chorus in nocturnal bird species. The owls may have had to trade‐off between calling and foraging during the few hours around midnight when slightly dimmer light reduced the detection risk while also providing better hunting conditions     

Entodiniomorph Ciliates from the Stomach of Hippopotamus amphibius, with Descriptions of Two New Genera and Three New Species

Entodiniomorph ciliates, belonging to the family Cycloposthiidae, are described from the stomach contents of Hippopotamus amphibius. Monoposthium acanthum gen. n., sp. n., with typical cycloposthiid structure, differs from other genera in having only 1 caudalium. Parentodinium gen. n., represented by P. africanum sp. n. and P. ostrea sp. n., although superficially resembling Entodinium, is considered to be a relatively unspecialized cycloposthiid.