Martyn L. Gorman

High hunting costs make African wild dogs vulnerable to kleptoparasitism by hyaenas

The African wild dog Lycaon pictus is critically endangered, with only about 5,000 animals remaining in the wild. Across a range of habitats, there is a negative relationship between the densities of wild dogs and of the spotted hyaena Crocuta crocuta. It has been suggested that this is because hyaenas act as ‘kleptoparasites’ and steal food from dogs. We have now measured the daily energy expenditure of free-ranging dogs to model the impact of kleptoparasitism on energy balance. The daily energy expenditures of six dogs, measured by the doubly labelled water technique, averaged 15.3 megajoules per day. We estimated that the instantaneous cost of hunting was twenty-five times basal metabolic rate. As hunting is energetically costly, a small loss of food to kleptoparasites has a large impact on the amount of time that dogs must hunt to achieve energy balance. They normally hunt for around 3.5 hours per day but need to increase this to 12 hours if they lose 25% of their food. This would increase their sustained metabolic scope to a physiologically unfeasible twelve times the basal metabolic rate. This may explain why there are low populations of wild dogs in regions where the risk of kleptoparasitism is high.

A mechanism for individual recognition by odour in Herpestes auropunctatus (Carnivora: Viverridae)

Abstract The anal pockets of Herpestes auropunctatus are used in marking and give a distinctive odour to the animal. The contents of the pocket include six, short-chain, odorous carboxylic acids; these are produced from sebum and apocrine secretions by bacterial action. The relative concentrations of the six acids vary from one individual to another, giving each a different odour. Mongooses can discriminate between the anal pocket contents of conspecifics and also between synthetic odours made from pure acids.

Scent-marking with the subcaudal gland by the European badger, Meles meles L.

Abstract European badgers, Meles meles, possess a large subcaudal gland which is used for scent-marking the territory and other members of the clan. It was shown experimentally that a badger can distinguish secretions from different individuals. Dominant males scent-mark most, and lactating females more than other females. Scent-marks are distributed along the border of the territory, on bedding materials and around the sett, and on all members of the clan, especially females and cubs. The data support, in many details, the hypothesis that scent-making in badgers serves to establish an asymmetry of contest during encounters with intruders.

Mitigating carnivore–livestock conflict in Europe: lessons from Slovakia

Conflicts with human interests have reappeared following recovery of large carnivores in Europe. Public acceptance is higher than historically but there is a need to identify effective, acceptable techniques to facilitate coexistence. We present a case study of predation on livestock in Slovakia. Damage, mitigation measures and public opinion were assessed using compensation records, analysis of farm conditions, questionnaire surveys, semi-structured interviews, diet analysis and on-farm trials of livestock-guarding dogs. Economic damage was inconsequential on a national scale but high locally: c. 80% of reported losses occurred at 12% of sheep flocks. Grey wolves Canis lupus were held responsible for four to six times more damage than brown bears Ursus arctos , although livestock occurred in only 2 of 78 wolf faeces during spring–autumn, when sheep and cattle were most vulnerable. Losses to Eurasian lynx Lynx lynx were negligible. Compared to other sectors of society shepherds had the most negative attitudes, particularly towards wolves, despite compensation payments. Appropriate use of livestock-guarding dogs was associated with fewer losses: median loss at trial flocks with predation was 70% lower than at control flocks. We conclude that identifying vulnerable farms and targeting them for mitigation could reduce damage, although lack of motivation and awareness are obstacles. This study shows that damage levels need not be excessive despite high predator densities in human-dominated landscapes. Conflicts were unevenly distributed, with much of the variation explained by local conditions and husbandry practices, especially preventive measures. Livestock-guarding dogs are particularly appropriate where wolves are present in proximity to unfenced pastures.

Ranging behaviour and time budgets of male wood mice Apodemus sylvaticus in different habitats and seasons

Abstract Radiotelemetry was used to measure the range areas, activity patterns and time budgets of 21 adult male wood mice (Apodemus sylvaticus) between May 1991 and August 1992. The study investigated variation in range, total distance travelled, speed of movement and time budgets between wood mice in the nonbreeding and breeding seasons in a deciduous woodland (n = 8 and 6 respectively). We also examined habitat differences by estimating these same parameters for wood mice inhabiting maritime sand-dunes in the breeding season (n = 7). Insufficient males of an appropriate mass for radiotracking were captured to study the sand-dune mice in the nonbreeding season. Significant variation was found across both season and site. In the breeding season, in woodland, range areas were 5 times larger than during the nonbreeding season. Wood mice on the sand-dunes exploited ranges 28 times greater than their woodland counterparts. The pattern of variation in range area was parallelled by significant differences in total distances and average speeds travelled per night. Diurnal activity, c. 60 min day−1, was frequently recorded, at both sites, but only, in the breeding season, which was attributed to the need to forage in order to maintain energy balance. The comparatively lower availability of food on the sand-dunes was considered the main factor explaining the greater range area, total distance moved, speed travelled and level of activity of animals at this site.

Seasonal variation in the resting metabolic rate of male wood mice Apodemus sylvaticus from two contrasting habitats 15 km apart

Abstract Diurnal and nocturnal resting metabolic rates of winter- and summer-acclimatized adult male wood mice Apodemus sylvaticus from two adjacent populations, 15 km apart, were measured. One population lived in deciduous woodland, and experienced a narrower daily range of temperatures than the second population, which inhabited maritime sand-dunes. Ambient temperature and body mass had significant effects on the resting metabolism of mice, excluding winter-acclimatized sand-dune animals where only temperature explained significant amounts of the observed variation. Only in this latter group could a thermoneutral zone be determined, with a lower critical temperature of ca. 25 °C and resting metabolism of 0.155 W. Nocturnal resting metabolic rates were significantly greater than diurnal levels. Winter acclimatization was associated with reductions in thermal conductance and resting metabolism, thus minimizing energy expenditure at rest. Site differences in thermoregulatory strategies were only found in winter, thermal conductances remained similar but mice from the sand-dunes had significantly lower metabolic rates than those from the woodland. Winter acclimatization in wood mice was influenced by factors in addition to photoperiod. Intra-specific and individual variations in resting metabolism, as shown in this study, potentially have a pronounced effect on the daily energy expenditure of a free-living animal.

Prey selection by African wild dogs (Lycaon pictus) in southern Zimbabwe

This study was an investigation of the diet and of prey selection by a population of African wild dogs Lycaon pictus in the Save Valley Conservancy (SVC) in the south-east lowveld of Zimbabwe. The diet of the dogs, based on the number of kills for each species located, consisted almost entirely of impala Aepyceras melampus (74%) and kudu Tragelaphus strepsiceros (22%), the two most abundant medium-sized antelope in the area. The level of selection for different prey classes killed by the wild dogs was investigated and it was found that the wild dogs: (1) exhibited strong selection for a number of prey classes on a seasonal basis; (2) selected kudu throughout the year but showed little selection between the other prey species; (3) selected the young of both impala and kudu and selected males at times of the rut. Bone marrow analysis showed that prey killed by the wild dogs on SVC were in poorer condition than unselectively culled individuals suggesting the selection of the weaker individuals in the prey populations.

The use of 65Zn for estimating populations of carnivores

Carnivore populations are difficult to measure by conventional methods. We have developed a new method which involves catching one or more individuals from a population and injecting them with the isotope 6 Zn. The radio-isotope appears in the faeces and assuming that the proportion of labelled to unlabelled faeces will equal the proportion of labelled to unlabelled individuals it is possible to estimate the size of the population. We have shown that the method gives an accurate estimate for a population of captive badgers of known size and we have used it in the field to estimate the sizes of wild badger populations.

Apparent Absorption Efficiency and Gut Morphometry of Wood Mice, Apodemus sylvaticus, from Two Distinct Populations with Different Diets

Interpopulation variation in the diet of the wood mouse, Apode‐mus sylvaticus, is well documented. In this study, we examined the gut morphology and apparent absorption efficiencies of two populations of wood mice whose diet in the field was known to differ. One population inhabited sand dunes, where food availability was relatively low and the diet was dominated by invertebrates. The other population lived in deciduous woodland, with greater food availability and a diet consisting primarily of seeds. Wood mice from the woodland had longer small intestines and total digestive tract lengths than mice from the sand dunes. However, these differences had no effect on the apparent absorption efficiencies of dry mass or energy when the mice were fed mealworms, wheat grain, or All‐Bran diets (apparent energy absorption efficiencies of 88%, 89%, and 65%, respectively). The population differences in gut morphometry may be linked to different resource availabilities at the two field sites.

Conservation: Oryx go back to the brink

Trade in Arabian oryx, which are being poached from the wild and sold to illegally to private collectors, is threatening the long-standing oryx conservation project in Oman. Following a recent population crash caused by poaching, the project organizers have taken 40 animals back into captivity — where, if need be, they can form a breeding herd should wild oryx once again be wiped out in Oman.