In Northern Ireland, the native Gammarus duebeni celticus and introduced Gammarus tigrinus occur in the same river and lake systems. This study examined the outcome of encounters between the two amphipod species in the same patch of lake/pooled area of river. A laboratory simulation of a lake/river habitat indicated that G. d. celticus and G. tigrinus differed in distribution within the same complex habitat. Cannibalism was low for both species in single and mixed species treatments. However, G. tigrinus suffered heavy intraguild predation (IGP) from G. d. celticus in mixed species treatments, with 22% of the laboratory population of G. tigrinus being eliminated within 4 days. There was negligible reciprocal predation of G. d. celticus by G. tigrinus. It is proposed that IGP may account for G. tigrinus occurring more frequently and in greater abundance in patches of lotic and lentic systems where predatory G. d. celticus is absent or scarce.

Leaping primates are specialized for hindlimb-propelled locomotion within arboreal habitats. As a group, they include members of Galagonidae, Lemuriformes and Tarsiidae. Postcranial characters analysed here include humeral and femoral diaphyseal rigidity, articular surface areas and lengths. Data for leaper taxa are compared with corresponding data for less specialized small primates. The more generalized comparative primates include both closely related prosimians and distantly related platyrrhines (New World monkeys). In addition, the leapers are subdivided for further analysis according to body size and taxonomic association. Questions addressed concern the identification of functionally and/or phylogenetically linked traits in leaper postcrania. Results indicate that leapers as a group have relatively higher femoral diaphyseal rigidity and longer femora than do more generalized primates. These traits are also present in Pithecia pithecia, a platyrrhine leaper included for comparison. These enhanced properties probably function in resisting large hindlimb forces incurred during leaping, and in producing longer, more efficient leaps. Most of the large-bodied lemuriform leapers are further distinguished in having relatively bigger femoral heads and reduced humeral rigidity. The small-bodied leapers, galagonids and tarsiids, do not differ in either femoral head surface area or in any of the humeral properties from more generalized primates. Pithecia has a large femoral head like lemuriforms, but it is not reduced in humeral rigidity. Aspects of hip joint structure and mobility may be related to femoral head size in lemuriforms and Pithecia. Explanations regarding reduced lemuriform humeral rigidity are also explored. Differences between lemuriform primates are also present, most notably in aspects of the distal humerus. Indrids are characterized by relatively reduced trochleae, while many lemurids have relatively small capitula. These features are interpreted with regard to frequencies of suspensory behaviour and quadrupedalism.

The impact of deliberate culling of fox populations has been much debated. Although a local (< 10 km2) impact has been accepted, previous authors have denied that culling has any impact on a larger scale because local losses are compensated through immigration. Rather, it has been claimed that at this scale fox density is determined by resources, mediated through social behaviour and breeding suppression. We determined the impact of culling on a regional scale (> 1000 km2), using data on culling (Heydon & Reynolds, 2000), fox density (Heydon, Reynolds & Short, 2000) and productivity. The three U.K. study regions (size 1238–2322 km2) were in mid-Wales (A), the east Midlands (B) and East Anglia (C). High productivity in regions A and C was associated with low density, high culling mortality and high overall mortality (all relative to region B), indicating that density was suppressed by culling. In region B (moderate) breeding suppression was associated with a higher density and lower cull than in regions A and C, implying that fox density was closer to the maximum sustainable by resources. We conclude that the impact of culling in different regions of Britain is variable, dependent on the regional prevalence, methods, and history of culling. However, it is clear that in a range of circumstances culling can substantially depress fox numbers, and that current fox densities reflect a history of culling. This conclusion is fundamental in considering the management of fox predation in farming and conservation contexts.

Maximum dive depths of common diving petrels Pelecanoides urinatrix were measured monthly over > 1 year, from January 1995 to February 1996, with miniature gauges attached to the birds at Mayes Island, Kerguelen Archipelago. Overall, maximum dive depths of 347 diving petrels averaged 31 ± 6 m (range: 8–64 m), with a mode at 30–35 m. Mean maximum dive depths differed significantly over the study period. The lowest value (22 ± 8 m) was obtained in winter and it was associated with euphausiid crustaceans, suggesting a change in foraging behaviour associated with a shift in the main prey consumed. During the breeding season, birds fed mainly upon the hyperiid amphipod Themisto gaudichaudii (66% of the total number of prey), followed by the large carnivorous copepod Paraeuchaeta antarctica (15%) and zoea larvae of the crab Halicarcinus planatus (13%). Comparison of the diving capabilities of diving petrels (genus Pelecanoides) with those of other diving seabirds suggests that, relative to body mass, diving petrels can dive deeper than penguins and also possibly than alcids, and are thus the most proficient divers among birds.

We studied home-range size, home-range overlap and use of habitat in a population of striped skunks Mephitis mephitis in eastern Tennessee. Variables determined to influence home-range size were season and body weight: skunks had larger ranges in the spring than in winter and heavier females had larger ranges. Habitat, sex and sample sizes of radio-fixes did not correlate with home-range size. All home ranges overlapped by 1.4–100% of the range area. There was no pattern of greater intersexual than intrasexual overlap; this differs from many other carnivore studies. Movements of individuals and distribution of den sites indicated that striped skunks, irrespective of sex or size, prefer edge habitat in comparison to forest or field.

Two new species of mites, Foveacheles (Proxistella) simulata n.sp. and Rhagidia longiseta n.sp., are described, and the little-known Foveacheles (Proxistella) terricola (C. L. Koch) is redescribed. All species were found inhabiting underground spaces in talus formations in the Czech Republic and Austria.

Roost selection by tree roosting noctules Nyctalus noctula and Daubenton's bats Myotis daubentonii was determined by comparing roost characteristics with the characteristics of randomly chosen tree cavities in the area. The following parameters were determined for 81 noctule roosts and 27 Daubenton's bat roosts: tree species, type of cavity (woodpecker or natural), entrance height, compass direction of entrance and distance to the edge of the wood. Roost choice of both bat species was similar except that Daubenton's bats used woodpecker cavities less than noctules. Both bat species were selective in their roost choice. Daubenton's bats preferred oaks over beeches, and noctules preferred woodpecker cavities over natural cavities, indicating dependence on woodpeckers. Both bat species preferred to roost close to the edge of the wood. Roosting close to the edge of the wood may reduce commuting flight costs for both species or may be preferable for thermoregulatory reasons.

Sibling rivalry seems to contradict Hamilton's rule of maximizing inclusive fitness (Hamilton, 1964). However, when critical resources are scarce and the competitors are close kin the individual must weigh the direct versus the indirect components of its inclusive fitness (Mock & Parker, 1997). In facultatively siblicidal species, conflicts arise mainly because of the phenomenon of ‘parental optimism’, in which the parents attempt to raise a larger brood than the average amount of expected resources allow (Lack, 1954; Temme & Charnov, 1987; Mock & Forbes, 1995). If critical resources are low, weaker or subordinate offspring may be killed by a stronger or dominant sibling. Sibling mortality may result from direct physical damage and/or socially enforced starvation (Mock, 1984).

We studied the feeding apparatus of three species of northern ruminants representative of three feeding types: muskoxen Ovibos moschatus, Norwegian reindeer Rangifer tarandus tarandus and high Arctic Svalbard reindeer Rangifer tarandus platyhrynchus and Siberian musk deer Moschus moschiferus. The shape of the muzzle, the incisor arcade, the incisiform and the molariform teeth indicate that these species are selective feeders, irrespective of their body size or their position on the gazer-concentrate selector continuum of feeding types. Narrow muzzles seem well adapted for selective feeding on the diminutive but highly nutritious plants, or parts of plants, on tundra swards and Arctic-alpine meadows and enable the animals to maximize nutrient intake during the short summer. However, their small mouths presumably also restrict reindeer and muskoxen to taking small bites, thereby achieving low rates of dry matter intake when feeding on the very short swards in winter. This is partially obviated by two general strategies; a reduction of energy requirements in winter and, in Norwegian reindeer, migration inland to where foraging conditions are generally more favourable. In Svalbard reindeer, which have little access to lichens or other easy digestible plants in winter, rumen fill increases through the accumulation of slowly fermenting fibrous foods. Despite their narrow muzzles, reindeer and muskoxen are unable to avoid ingesting a certain amount of poor quality forage in winter and cope with this by appropriate modification of digestive function.

The goal of this study was to investigate whether or not beavers Castor fiber albicus improve the quality of their food plants by dam construction, resulting in periodic flooding associated with the deposition of mud and nutrients on their feeding grounds. For this, food selection of beavers was studied in relation to plant chemicals in the Spessart mountains (central Germany). The concentrations of the preferred plant chemicals were compared between individuals of the same plant species growing in areas that were flooded periodically and areas that were edaphically dry. Plants eaten by beavers contained higher concentrations of nitrogen and lower concentrations of neutral detergent fibre and hemicellulose than neighbouring plants that were not eaten. Neither nitrogen concentrations nor neutral detergent fibre contents differed significantly between plants from the dry and wet sites. Thus, beaver activities did not improve the chemical quality of their food plants.

The uptake of volatile fatty acids (VFAs) from bacterial fermentation of forage in the rumen is enhanced by the presence of papillae which greatly increase the surface area of the mucosa of the rumen. The degree of papillation, expressed as the surface enlargement factor (SEF), seems to be closely related to the level of microbial activity and the rate of production of VFAs in the rumen. In several species of wild ruminants the SEF decreases markedly in winter, apparently in response to a decrease in the quality and availability of forage and also, presumably, in the level of ruminal microbial activity. Contrary to expectation, however, no reduction in the rate of production of VFAs in winter has been detected in semi-domesticated reindeer at natural pasture in northern Norway. We investigated the body mass, the composition and quality of the diet and the morphology of rumen papillae in adult female reindeer free-living at natural pasture. Animals were slaughtered in matched aged groups of nine on four occasions: in autumn (September) and winter (November, February and March). The composition and quality of the diet was determined by morphological and chemical analysis of plant fragments recovered from the rumen. The carcass mass of the animals did not differ significantly between collections. The animals ate vascular plants and lichens from 37 different genera. The composition of the diet varied little between months except for the inclusion of a substantial proportion (25.8% of fragments) of lichens in March. The mean density of rumen papillae increased from 55.6 papillae/cm2 in September to 75.7 papillae/cm2 in March (P < 0.001). All other parameters, including the length and perimeter of the papillae and the SEF of the rumen, were lower in March compared with September. However, the mean SEF increased from 8.8 in February to 10.6 in March (P < 0.05), indicating increased ruminal fermentation in late winter. We propose that the increase in the SEF in March might be associated with the increase in the proportion of lichens in the diet. Lichens are highly digestible in reindeer but do not score highly in conventional analyses of diet quality owing to the unusual chemical structure of the structural carbohydrates of which they are composed.

Evidence for individuality of odour profile, coding for individual identity, was sought in scent profiles derived from natural secretions of the preorbital gland of red deer Cervus elaphus (n = 26), sika deer C. nippon (15), fallow deer Dama dama (50), Chinese muntjac Muntiacus reevesi (23) and Chinese water deer Hydropotes inermis (53); from metatarsal secretions from red deer (n = 35), sika (30), fallow (193) and roe deer Capreolus capreolus (26), and from roe deer interdigital glands (n = 48). Volatiles were eluted from sample materials at body temperature, to restrict analysis to those elements that would occur within the natural odour signal; the different volatile elements were then separated by gas chromatography. For each species considered, secretions from at least one scent gland were individually distinct and sufficiently complex to code for identity. Within our samples no two individuals produced identical odour profiles; yet in analysis of metatarsal gland secretions of individual fallow deer sampled in successive years, odour signatures of individuals remained consistent over time. The wider potential for individual coding was assessed through calculation of the number of different possible combinations of all volatiles recovered in any species×gland system. Every secretion considered seems to have the potential to provide individually characteristic signals (with the exception of secretions from the fallow deer preorbital gland, which notably contained no odour information under any analytical system). Complexity of signals differed markedly between species as did the gland-type responsible for production of the most complex or distinctive signal. No simple evolutionary patterns are apparent to account for this variation and we suggest that the form of gland selected for production of a signal carrying information about individual identity is a function of habitat type and sociality.

In a recent paper, Dawson et al. (1999) investigated how the morphology of the contour and downy afterfeathers of gentoo penguins Pygoscelis papua function as thermal insulators. Their model considered how the morphology of individual feather barbs interact to create an efficient insulatory barrier. They noted that, during diving, the feathers must be compressed and return to their original configuration due to stored strain energy. In addition, the downy feathers of penguins have to withstand significant wind loading whilst the birds are on land (Taylor, 1986). Despite the obvious necessity for mechanical competence and resilience of down feathers, we still know little about their mechanical performance.

Conspecific recognition was investigated in the eusocial and subterranean Damaraland mole-rat Cryptomys damarensis. This species out-breeds and is xenophobic. Differences in the frequency of agonistic behaviours between male–male pairs were used as an indication of recognition. Focal males were tested with familiar, unfamiliar, and foreign conspecifics. Males directed significantly more aggression towards unfamiliar colony mates and foreign conspecifics than towards familiar colony mates. This happened even though both focal and test animals retained contact with their natal colonies and, therefore, any group cue. Furthermore, when male–male pairs were returned to their natal colonies they continued directing aggression towards each other but not towards the rest of the colony. These results suggest that the Damaraland mole-rat uses individually distinct cues rather than kin-specific cues based on genetic relatedness.

The cheetah Acinonyx jubatus is an atypical felid, well known for having blunt, only slightly curved, and only partly retractile claws, clearly an adaptation for high-speed locomotion in the pursuit of swift mammals. However, saying that prey ‘is usually knocked down by the force of the cheetah's charge’ (Nowak, 1999) is incorrect, because this predator actually relies on the claw of the first digit of the forepaw, the so-called dewclaw, to hook the fleeing prey off balance. Although (1) this was understood by Indian huntsmen through their use of tame cheetahs and published (Burton, 1950) in a natural history journal circulating well outside India, (2) wounds attributable to the dewclaws of cheetahs were later observed (Schaller, 1972) on prey animals in Africa, the area of most research on this felid, and (3) the information from India was finally reported (though with the wrong year in the citation) in an authoritative book on African mammals (Kingdon, 1977), no systematic study of the dewclaw itself, or of explicitly related questions, has been made. Perhaps the general connotation of the term ‘dewclaw’, as intended for a non-functional claw on a rudimentary digit as in the case of dogs, has masked the importance of what is not only a strongly curved and sharply pointed, but also a very large claw in the cheetah. In fact, this specialization of the cheetah has escaped the attention of behaviourists (Eaton, 1970), anatomists (Gonyea & Ashworth, 1975), and palaeontologists (Adams, 1979).

Tooth succession was followed in captive greater cane rats Thryonomys swinderianus of known ages with the aid of regular radiographs. The incisors and single premolar tooth (dP 4/4) in each quadrant are persistent deciduous teeth that are not replaced by permanent teeth. Tooth succession is relatively slow, with eruption of the lower cheek teeth in advance of the upper ones. During the first 5 months of post-natal development, three cheek teeth per quadrant become functional. Another 5 months elapse before the fourth cheek tooth erupts. The same slow growth can be seen in the increase in mass, which only doubles 5 months after puberty (5 months).