Ecology and activity of mesic Afrotropic mole-rats

This Ph.D. thesis focuses on the ecology and activity of mesic Afrotropic mole-rats. In particular, ecological characteristics in habitats of two mole-rat species with different social system, the solitary Heliophobius argenteocinereus and social Fukomys whytei, were analysed in an area of sympatry and the results are discussed in relation with available ecological data on other species. Two studies bring to light novel data on the ecology and behaviour of the free-living largest social bathyergid, the giant mole-rat Fukomys mechowii, especially in relation to ecological characteristics in its natural habitat, burrow system architecture, kin structure and spatial and temporal activity patterns. In the final study, new data on the field metabolism of the silvery mole-rat H. argenteocinereus are presented. These new findings are discussed in further detail and expand upon existing explanations for low resting metabolism in subterranean rodents and the differences in field metabolism in relation to seasonality of habitat

Diet composition of Common Kestrels Falco tinnunculus and Long-eared Owls Asio otus coexisting in an urban environment

We studied dietary composition of urban populations of Common Kestrels (Falco tinnunculus) and Long-eared Owls (Asio otus) under fluctuating vole abundance. We tested hypotheses that the proportion of alternative prey in the diet increase with decreasing vole abundance throughout the years and that alternative prey differ between raptors due to different daily activities and/or hunting techniques. Finally, we tested whether the proportion of voles in the diet is influenced by the nest position within the city

Spatial and temporal activity patterns of the free-living giant mole-rat (Fukomys mechowii), the largest social bathyergid.

Despite the considerable attention devoted to the biology of social species of African mole-rats (Bathyergidae, Rodentia), knowledge is lacking about their behaviour under natural conditions. We studied activity of the largest social bathyergid, the giant mole-rat Fukomys mechowii, in its natural habitat in Zambia using radio-telemetry. We radio-tracked six individuals during three continuous 72-h sessions. Five of these individuals, including a breeding male, belonged to a single family group; the remaining female was probably a solitary disperser. The non-breeders of the family were active (i.e. outside the nest) 5.8 hours per 24h-day with the activity split into 6.5 short bouts. The activity was more concentrated in the night hours, when the animals also travelled longer distances from the nest. The breeding male spent only 3.2 hours per day outside the nest, utilizing less than 20% of the whole family home range. The dispersing female displayed a much different activity pattern than the family members. Her 8.0 hours of outside-nest activity per day were split into 4.6 bouts which were twice as long as in the family non-breeders. Her activity peak in the late afternoon coincided with the temperature maximum in the depth of 10 cm (roughly the depth of the foraging tunnels). Our results suggest that the breeding individuals (at least males) contribute very little to the work of the family group. Nevertheless, the amount of an individual's activity and its daily pattern are probably flexible in this species and can be modified in response to actual environmental and social conditions

Activity of radio-tracked mole-rats and associated environmental conditions during the 24-h day.

<p>Mean ± SD is presented for the four subordinate (non-breeding) family members. Black bars indicate the dark phase of the day.</p

Actograms of the six giant mole-rats radio-tracked during the three continuous 72-h radio-tracking sessions.

<p>Dark bars represent bouts of activity (occurrence outside the nest).</p

Home range sizes and proportions of outside-nest fixes of the radio-tracked mole-rats.

<p>The home ranges (HR) are computed as a set of 4-m grid cells (GC) covering all radio-fixes and as the minimum convex polygon (MCP). Numbers in parentheses signify percentages from the whole family's HR. Exclusive HR size is an area of GCs which contain radio fixes of the focal individual only. Numbers in parentheses are the mean values expected under given sample size if no spatial preferences of the animals occur. The values were obtained based on 1000 permutations with coordinate pairs of the outside-nest fixes of all family non-breeders randomly exchanged. The <i>p</i>-values refer to the test of the hypothesis that the size of the exclusive HR is a by-product of the sample size (see Materials and methods for details).</p>1)<p>Including individuals which were not radio-tracked.</p

Home ranges of the radio-tracked giant mole-rats.

<p>Squares with a black outline represent the GC home range; white squares represent the exclusive home range of a particular individual; the grey area represents GCs of the whole family HR except the GCs already depicted. Dots represent radio-fixes, crosses mark nests and open circles show food sites.</p

Habitat and Burrow System Characteristics of the Blind Mole Rat Spalax galili in an Area of Supposed Sympatric Speciation.

A costly search for food in subterranean rodents resulted in various adaptations improving their foraging success under given ecological conditions. In Spalax ehrenbergi superspecies, adaptations to local ecological conditions can promote speciation, which was recently supposed to occur even in sympatry at sites where two soil types of contrasting characteristics abut each other. Quantitative description of ecological conditions in such a site has been, nevertheless, missing. We measured characteristics of food supply and soil within 16 home ranges of blind mole rats Spalax galili in an area subdivided into two parts formed by basaltic soil and pale rendzina. We also mapped nine complete mole rat burrow systems to compare burrowing patterns between the soil types. Basaltic soil had a higher food supply and was harder than rendzina even under higher moisture content and lower bulk density. Population density of mole rats was five-times lower in rendzina, possibly due to the lower food supply and higher cover of Sarcopoterium shrubs which seem to be avoided by mole rats. A combination of food supply and soil parameters probably influences burrowing patterns resulting in shorter and more complex burrow systems in basaltic soil