Burrow architecture and digging activity in the Cape dune mole rat

While females are traditionally thought to invest more time and energy into parental care than males, males often invest more resources into searching and displaying for mates, obtaining mates and in male-male conflict. Solitary subterranean mammals perform these activities in a particularly challenging niche, necessitating energetically expensive burrowing to both search for mates and forage for food. This restriction presumably affects males more than females as the former are thought to dig longer tunnels that cover greater distances to search for females. We excavated burrow systems of male and female Cape dune mole rats Bathyergus suillus the, largest truly subterranean mammal, to investigate whether male burrows differ from those of females in ways that reflect mate searching by males. We consider burrow architecture (length, internal dimensions, fractal dimension of tunnel systems, number of nesting chambers and mole mounds on the surface) in relation to mating strategy. Males excavated significantly longer burrow systems with higher fractal dimensions and larger burrow areas than females. Male burrow systems were also significantly farther from one another than females were from other females' burrow systems. However, no sex differences were evident in tunnel cross-sectional area, mass of soil excavated per mound, number of mounds produced per unit burrow length or mass of soil excavated per burrow system. Hence, while males may use their habitat differently from females, they do not appear to differ in the dimensions of the tunnels they create. Thus, exploration and use of the habitat differs between the sexes, which may be a consequence of sex differences in mating behaviour and greater demands for food.

European hare (Lepus europaeus) invasion ecology: Implication for the conservation of the endemic Irish hare (Lepus timidus hibernicus)

European hare Lepus europaeus populations have undergone recent declines but the species has successfully naturalised in many countries outside its native range. It was introduced to Ireland during the mid-late nineteenth century for field sport and is now well established in Northern Ireland. The native Irish hare Lepus timidus hibernicus is an endemic subspecies of mountain hare L. timidus and has attracted major conservation concern following a long-term population decline during the twentieth century and is one of the highest priority species for conservation action in Ireland. Little is known about the European hare in Ireland or whether it poses a significant threat to the native mountain hare subspecies by compromising its ecological security or genetic integrity. We review the invasion ecology of the European hare and examine evidence for interspecific competition with the mountain hare for habitat space and food resources, interspecific hybridisation, disease and parasite transmission and possible impacts of climate change. We also examine the impact that introduced hares can have on native non-lagomorph species. We conclude that the European hare is an emerging and significant threat to the conservation status of the native Irish hare. Invasive mammal species have been successfully eradicated from Ireland before and immediate action is often the only opportunity for cost-effective eradication. An urgent call is issued for further research whilst the need for a European hare invasive Species Action Plan (iSAP) and Eradication strategy are discussed.

Mammals and agri-environment schemes: hare haven or pest paradise?

1. Agri-environment schemes (AESs) are designed to create landscape-scale improvements in biodiversity. While the specific aims of AESs do not always include the enhancement of species of conservation concern, associated conservation strategies, such as the UK Biodiversity Action Plan, often rest on the assumption that AESs enhance environmental conditions and thereby improve the conservation status of target species. However, there is little evidence for the general efficacy of AESs in this respect. 2. To evaluate the effects of the Environmentally Sensitive Area (ESA) scheme, a widespread AES in Northern Ireland, a spotlight survey of the relative abundance of three mammal species, Irish hare Lepus timidus hibernicus, European rabbit Oryctolagus cuniculus and red fox Vulpes vulpes, was conducted. Of these, the Irish hare is a priority species for conservation action and the focus of a species action plan, while rabbit and fox are commonly considered agricultural pests. The effects of ESA designation and habitat on each species were assessed at 150 ESA and 50 non-ESA sites, matched for landscape characteristics. 3. The ESA scheme had no demonstrable effect on the abundance of Irish hares, and this agri-environment scheme did not target the landscape and habitat variables associated with hares. 4. In contrast, the abundance of rabbits and foxes was significantly greater within ESAs than the wider countryside. Agricultural factors such as reduced livestock stocking density, reduced overgrazing and field boundary enhancements may create more favourable conditions for both species. Aside from the implications for farm economics, the proliferation of rabbit populations within conservation areas may raise issues concerning the grazing of important plant communities, while increases in fox populations may adversely affect ground-nesting birds and other animal species of conservation concern. 5. Synthesis and applications: The abundance of rabbits and foxes corroborates recent work that suggests AESs may benefit common species but can not be relied upon to encourage rarer species. The Irish hare species action plan relies on agri-environment schemes to enhance the species’ status and realize the target of increasing the hare population by 2010 by promoting suitable habitat. However, the ESA scheme is unlikely to help in achieving these objectives. Targeted and evidence-based agri-environment prescriptions are clearly required in order to ensure the realization of species-specific conservation targets.

The response of small mammals to natural and human-altered edges associated with Afromontane forests of South Africa

An increase in edge area reduces the effective size of habitat fragments and thus the area available for habitat-interior specialists. However, it is unclear how edge effects compare at different ecotones in the same system. We investigated the response of a small mammal community associated with Afromontane forests to edge effects at three different habitat transitions: natural forest to grassland (natural edge, structurally different vegetation types), natural forest to mature plantation (human-altered edge, structurally similar vegetation types) and natural forest to harvested plantation (human-altered edge, structurally different vegetation types). We predicted that edge effects should be less severe at natural ecotones and at similarly structured contiguous vegetation types than human-altered ecotones and differently structured contiguous vegetation types, respectively. We found that forest species seemed to avoid all habitat edges in our study area. Surprisingly, natural edges supported a less diverse small mammal community than human-altered forest edges. However, edge effects were observed deeper into native forests surrounded by mature alien plantations (and more so at harvested plantations) than into native forests surrounded by native grasslands. The net effect of mature plantations was therefore to reduce the functional size of the natural forest by creating a larger edge. We suggest that when plantations are established a buffer zone of natural vegetation be left between natural forests and newly established plantations to mitigate the negative effects of plantation forestry.

Insights into torpor and behavioural thermoregulation of the endangered Juliana's golden mole

The cryptic, subterranean ways of golden moles (Chrysochloridae) hamper studies of their biology in the field. Ten species appear on the IUCN red list, but the dearth of information available for most inhibits effective conservation planning. New techniques are consequently required to further our understanding and facilitate informed conservation management decisions. We studied the endangered Juliana's golden mole Neamblysomus julianae and aimed to evaluate the feasibility of using implantable temperature sensing transmitters to remotely acquire physiological and behavioural data. We also aimed to assess potential body temperature (T-b) fluctuations in relation to ambient soil temperature (T-a) in order to assess the potential use of torpor. Hourly observations revealed that T-b was remarkably changeable, ranging from 27 to 33 degrees C. In several instances T-b declined during periods of low T-a. Such 'shallow torpor' may result in a daily energy saving of c. 20%. Behavioural thermoregulation was used during periods of high T-a by selecting cooler microclimates, while passive heating was used to raise T-b early morning when T-a was increasing. In contrast to anecdotal reports of nocturnal patterns of activity, our results suggest that activity is flexible, being primarily dependent on T-a. These results exemplify how behavioural patterns and microclimatic conditions can be examined in this and other subterranean mammal species, the results of which can be used in the urgently required conservation planning of endangered Chrysochlorid species.

Hibernation and non-shivering thermogenesis in the Hottentot golden mole (Amblysomus hottentottus longiceps)

Although heterothermy (hibernation and torpor) is a common feature among mammals, there is debate over whether it is a derived or ancestral trait relative to endothermic homeothermy. Determination of the physiological characteristics of primitive mammals is central to understanding the evolution of endothermy. Moreover, evaluation of physiological mechanisms responsible for endothermic heat production [e.g. non-shivering thermogenesis (NST)] is key to understanding how early mammals responded to historical climate changes and colonised different geographical regions. Here we investigated the capacity for NST and heterothermy in the Hottentot golden mole, a basal eutherian mammal. NST was measured as the metabolic response to injections of noradrenalin and heterothermy by recording body temperature in free-ranging animals. We found that hibernation and torpor occurred and that the seasonal phenotypic adjustment of NST capacity was similar to that found in other placental mammals. Using phylogenetically independent contrasts, we compared measured values of NST with those obtained from the literature. This showed that all variation in NST was accounted for by differences in phylogeny and not zoogeography. These findings lend support to the observation that NST and heterothermy occur in the Afrotheria, the basal placental mammalian clade. Furthermore, this work suggests that heterothermy, rather than homeothermy is a plesiomorphic trait in mammals and supports the notion that NST mechanisms are phylogenetically ancient.

Climate change-linked range expansion of Nathusius' pipistrelle bat, Pipistrellus nathusii (Keyserling & Blasius, 1839)

Aim To examine the effect of climate change on the occurrence and distribution of Pipistrellus nathusii (Nathusius' pipistrelle) in the United Kingdom (UK).Location We modelled habitat and climatic associations of P. nathusii in the UK and applied this model to the species' historical range in continental Europe.Methods A binomial logistic regression model was constructed relating the occurrence of P. nathusii to climate and habitat characteristics using historical species occurrence records (1940-2006) and CORINE land cover data. This model was applied to historical and projected climate data to examine changes in suitable range (1940-2080) of this species. We tested the predictive ability of the model with known records in the UK after 2006 and applied the model to the species' known range in Europe.Results The distribution of P. nathusii was related positively to the area of water bodies, woodland and small areas of urbanization, and negatively related to the area of peat/heathland. Species records were associated with higher minimum temperatures, low seasonal variation in temperature and intermediate rainfall. We found that suitable areas have existed in the UK since the 1940s and that these have expanded. The model had high predictive power when applied to new records after 2006, with a correct classification rate of 70%, estimated by receiver operating characteristic analysis. Based on climate projections, our model suggests a potential twofold increase in the area suitable for P. nathusii in the UK by 2050. The single most influential climate variable contributing to range increase was the projected increase in minimum temperature. When applied to Europe, the model predictions had best predictive capability of known records in western areas of the species' range, where P. nathusii is present during the winter.Main conclusions We show that a mobile, migratory species has adapted its range in response to recent climate change on a continental scale. We believe this may be the first study to demonstrate a case of range change linked to contemporary climate change in a mammal species in Europe.

First record of greater white-toothed shrew Crocidura russula in Ireland

1. Skeletal remains of greater white-toothed shrew Crocidura russula were recovered from barn owl Tyto alba and kestrel Falco tinnunculus pellets collected at 15 locations in Counties Tipperary and Limerick in Ireland in September 2007 and March 2008. Seven greater white-toothed shrews were trapped at four locations in Tipperary in March 2008. This is the first Irish record of C. russula and compelling evidence that the species is established in Ireland.

Distribution and status of the Red Squirrel (Sciurus vulgaris) and Grey Squirrel (Sciurus carolinensis) in Ireland

The distributions of the Red and Grey Squirrel were surveyed in Northern Ireland and the Republic of Ireland between 1994 and 1996. Survey methods differed between the two studies. In the former, all suitable habitat, of at least 15 ha, was inspected for species presence or absence. In the Republic, data were gathered through questionnaires to governmental and independent wildlife bodies. The combined results indicate that the Red Squirrel remains widespread and locally abundant, and is present in all but two counties. The Grey Squirrel is now more widespread than ever before, and can be found in 22 of the 32 counties. Its range expansion has varied from 0 km/yr to an estimated 13.4 km/yr, as various geographical features, principally rivers, have hindered its progress in certain directions.

‘Invasional meltdown’: evidence for unexpected consequences and cumulative impacts of multispecies invasions

Empirical support for ‘invasional meltdown’, where the presence of one invading species facilitates another and compounds negative impacts on indigenous species, is equivocal with few convincing studies. In Ireland, the bank vole was introduced 80 years ago and now occupies a third of the island. The greater white-toothed shrew arrived more recently within the invasive range of the bank vole. We surveyed the abundance of both invasive species and two indigenous species, the wood mouse and pygmy shrew, throughout their respective ranges. The negative effects of invasive on indigenous species were strong and cumulative bringing about species replacement. The greater white-toothed shrew, the second invader, had a positive and synergistic effect on the abundance of the bank vole, the first invader, but a negative and compounding effect on the abundance of the wood mouse and occurrence of the pygmy shrew. The gradual replacement of the wood mouse by the bank vole decreased with distance from the point of the bank vole’s introduction whilst no pygmy shrews were captured where both invasive species were present. Such interactions may not be unique to invasions but characteristic of all multispecies communities. Small mammals are central in terrestrial food webs and compositional changes to this community in Ireland are likely to reverberate throughout the ecosystem. Vegetation composition and structure, invertebrate communities and the productivity of avian and mammalian predators are likely to be affected. Control of these invasive species may only be effected through landscape and habitat management.