Data are presented on the demography and reproductive success of cheetahs (Acinonyx jubatus) living on the Serengeti Plains, Tanzania over a 25-year period. Average age at independence was 17.1 months, females gave birth to their first litter at approximately 2.4 years old, interbirth interval was 20.1 months, and average litter size at independence was 2.1 cubs. Females who survived to independence lived on average 6.2 years while minimum male average longevity was 2.8 years for those born in the study area and 5.3 years for immigrants, with a large proportion of males dispersing out of the Plains population. Females produced on average only 1.7 cubs to independence in their entire lifetime and their average reproductive rates were 0.36 cubs per year or 0.17 litters per year to independence. Variance in lifetime reproductive success in the cheetah is similar to that of other mammals.

No significant negative correlations were found between adult cheetah population size and numbers of cubs reaching independence, implying that the Plains population had not reached carrying capacity. Annual numbers of adult female cheetahs only were correlated with rainfall. Adult female cheetah numbers were not correlated with adult female lion numbers on the Plains, however, reproductive rates of cheetahs were negatively correlated with the presence of lions while cheetahs had cubs. Moreover, cheetah reproductive success was lower during the period of high lion abundance (1980-1994) than during the earlier period of relatively few lions (1969-1979). Litter size at independence dropped from 2.5 to 2.0, lifetime reproductive success declined from 2.1 to 1.6 cubs reared to independence, and the reproductive rate (cubs/year) decreased from 0.42 to 0.36 from the earlier to the later period.

Cheetah reproductive success showed little association with the presence of Thomson's gazelle at sightings except for a negative correlation between large numbers of gazelle (200±500) and reproductive success possibly because hunting success decreases with increasing prey herd size, or because cheetahs always lose in direct competition with other predators which are attracted to large congregations of prey. In addition, cheetah reproductive success was negatively correlated with the presence of Grant's gazelles (11 or more) perhaps because Grant's gazelles were more likely to occur consistently in dry areas.

The population biology of Paradistomum orientalis, a dicrocoeliid trematode occurring in the gall bladder of the garden lizard Calotes versicolor, was investigated during 1991-1993. The prevalence and abundance of the fluke were high throughout the year and demonstrated no seasonal fluctuations. The maturation cycle of the fluke followed an annual pattern. The recruitment of the fluke was restricted to the period September to February, with a peak during September. Mature flukes occurred throughout the year, facilitating continuous release of eggs into the macroenvironment. Rainfall plays a major role in governing the maturation cycle, by regulating the population density of the snail host and the feeding activity of the definitive host. The frequency distribution of the fluke followed the overdispersion pattern, fitting the negative binomial model. There is no evidence for the existence of parasite-induced host mortality. On the other hand, competition for space and nutritive resources under crowded conditions serves as a major regulatory force and is the key factor responsible for maintaining the equilibrium of parasite densities during different months. The infrapopulation of the fluke remained stable over several years.

Timing of birth was determined for 292 roe deer (Capreolus capreolus) fawns belonging to 146 litters on an island in central Norway between 1991 and 1994, and for 33 fawns belonging to 19 litters from an inland site from 1995 to 1997. On the island site there was no significant variation between years in the mean date of birth, 22 May, nor was there any significant effect of dam age, fawn sex, or litter size. Individual does tended to give birth close to the same date in consecutive years. Mean birth date at the inland site was 5 June. The births showed a relatively high degree of synchrony with 80% occurring within 26 days and 24 days at the island and inland sites, respectively. Copulation dates were much more synchronized than birth dates on the island site. Gestation length averaged 301 days, although individuals varied by up to 26 days. When comparing published data from European populations, there appears to be extensive variation in timing of birth, while birth synchrony is very conservative. There appears to be little possible anti-predator benefit for roe deer in any pattern of birth synchrony. Because of their high post-natal investment and large litter size, we hypothesize that roe deer are constrained to give birth close to the peak of forage productivity.

Male Teleogryllus oceanicus prefer to call from refuges and from these protected sites produce signals that contain more trill elements than produced by males calling without the protection of refuges. We tested the vulnerability of male crickets to predation from two species of gleaning bats, Nyctophilus major and N. geoffroyi. Crickets called from the floor of darkened fly-ways where bats preyed on calling rather than silent males. Both species of bat used passive listening to locate their prey rather than echolocation. Those crickets calling from refuges avoided predation. By counting the number of passes each bat made over paired speakers emitting different digitized songs, we tested the bat's preference for different call elements or the total number of sound elements in the song per unit time. When the total number of sound elements of each signal was balanced, bats preferred trills to chirps, and when call length differed, bats preferred those signals with more total sound elements. We discuss the possibility that predation by bats is a form of counter-selection on calling in T. oceanicus.

The distribution of the bush-dwelling snail Theba pisana (Helicidae) in Israel is restricted to the coastal plain. It is known as an annual semelparous species, but recent studies revealed that part of the population has a biennial life cycle.

The present study examined the water economy and resistance to desiccation throughout the life cycle under natural conditions in the field, and by exposing samples of various size (age) groups to three weeks of laboratory desiccation during various seasons.

We found that resistance to desiccation in Theba pisana is age-dependent as young snails lost more water than adults during desiccation. In general, high rates of water loss during desiccation were noted in growing snails during winter and spring, and low rates were recorded during the summer aestivation in all age groups. A small part of the natural population ceased growing and entered an early aestivation, thereby avoiding the otherwise high rates of water loss.

We conclude that resistance to desiccation is entrained in the annual life cycle of T. pisana and that survival under natural desiccating conditions depends on the maturation, and on the ontogenetic development of the water preserving mechanisms. The age-dependent water economy of the snail dictates the timing of aestivation and the establishment of a new set-point which is reflected in the clustering behaviour, secretion of a calcareous epiphragm, and a selective compartmentalization of body fluids.

Among insects, the modified labium of Stenus species is one of the most specialized prey-capture structures. However, the question of its adaptive value has remained unanswered, since many species make use of their mandibles as an alternative capture technique (Bauer & Pfeiffer, 1991). In order to elucidate the biological significance of the specialized labium, within- and between-species comparisons of the performance abilities (i.e. velocity, mode of prey seizure, range, rate of occurrence and capture success) of both capture techniques were carried out. These investigations were performed in standardized prey-capture experiments, primarily by means of video-recordings and prey-capture cinematography. In addition, direct observations under semi-field conditions concerning habitat choice and searching behaviour were used to assess possible selection factors arising from the environment.

In standard experiments, most investigated species catch springtails much more successfully with the labium than with the mandibles, thereby stressing the selective value of the labium. The marked capture success of the latter is attributable to its large range, its high capture velocity and its capability of fixing prey at the moment of contact. The prey-capture experiments revealed interspecific differences in agility and reaction ability, which, to some extent, can be explained by differences in eye morphology. Some agile species, which usually forage on bare ground (e.g. S. comma), depend on the labium capture mechanism to a lesser degree. However, most species are not agile and forage in densely structured habitats such as plant debris or vegetation. The specialized labial apparatus of Stenus is thought to provide a biological advantage in that it permits these predators, in spite of their limited reaction ability and agility, to catch prey that are capable of rapid escape responses.

As part of a study on the ecological strategies related to adaptation to the subterranean habitat of genus Ctenomys (tuco-tucos), a natural population of C. talarum was live-trapped at Necochea (Buenos Aires Province, Argentina) with the aim of providing information on its population ecology. Population size was consistently low throughout the study and was related to the low habitat productivity. Mortality rates were low, although for juveniles the estimations were higher than for adults. Individuals have an average life expectancy of 22-25 months, but some individuals lived at least three years. Reproductive activity started by July and ended by March, when last known pregnancies were recorded. This long reproductive season allowed a gradual incorporation of young over an extended period of time, with a restricted period of recruitment lacking. Sex ratio did not depart from 1:1 and appears to be density dependent. The spatial distribution of individuals was clumped and corresponded to the patchy distribution of suitable habitats. The results are compared and contrasted with those from previous demographic studies performed in other conspecifics as well as in other subterranean rodents.

We studied the behaviour of free-ranging female mouflon sheep (age 3-5 years) in the period periparturition. The study area is situated in the north-east of Germany (52°59′N, 13°50′E). For continuous data collection, we used the storage-telemetry-system ETHOSYS. Activity and foraging behaviour of five females were recorded every second by electronic sensors integrated in a collar round the sheep¨s neck (weight 300 g). Whenever the animals visit a special ‘link-station’, installed at a combined saltlick/feeder station, the recorded data are transmitted from the collar to the station and then to a laptop. In addition, we recorded continuously the presence of sheep at the saltlick using a camera-system, including a daylight and an infra-red camera.

Activity of female mouflon ranged from 8 to 10 hours daily during late winter. The animals spent the major part of that time feeding (70-80%). The sheep visited the saltlick every two to three days regularly. However, from late March to early April, every animal stayed away from the ‘link-station’ for about two weeks. This meant spatial isolation from social companions. When returning, these sheep were accompanied by a lamb. Parturition was assumed to take place during 2-3 consecutive days of markedly decreased activity. In the night from the first to the second day of this period, we found a unique activity pattern observed in all sheep. A short activity bout during the second half of the night was interpreted as the exact time of lambing. Spatial and temporal changes in behaviour during parturition are discussed with regard to other wild ungulates as well as domestic animals.

The helminth parasites from more than 300 cetaceans stranded on the coast of England and Wales during the period 1990-1994 were identified, this being the largest organized survey of cetacean parasites yet undertaken. Thirteen species of cetaceans were examined, although the majority were common (harbour) porpoises Phocoena phocoena (n=173) and common dolphins Delphinus delphis (n=101). The parasites found included 11 species of nematode (Anisakis simplex, Pseudalius inflexus, Torynurus convolutus, Stenurus globicephalae, S. minor, Halocercus delphini, H. invaginatus, H. lagenorhynchi, H. taurica, Crassicauda boopis, Crassicauda sp.), five cestodes (Diphyllobothrium polyrugosum, D. stemmacephalum, Phyllobothrium delphini, Monorygma grimaldii, Tetrabothrius sp.), five digeneans (Campula oblonga, Oschmarinella albamarina, O. rochebruni, Lecithodesmus palliatus, Pholeter gastrophilus) and two acanthocephalans (Bolbosoma capitatum, B. physeteris). The results of this survey are tabulated and each helminth species is discussed in terms of its biology and pathogenicity.

We studied the foraging behaviour and energetics of the nectar-feeding bat, Leptonycteris curasoae (=L. sanborni), in the Sonoran Desert near Bahia Kino, Sonora, Mexico, using radio-telemetry, light-tagging, and focal plant observations to answer three questions: (1) How far do these bats fly in a night and at what energetic cost? (2) How do they harvest nectar and pollen from columnar cacti that offer large but temporally variable nectar rewards? (3) What are the implications of their foraging behaviour for gene flow within populations of their food plants? L. curasoae visited flowers of three species of columnar cacti in April through June. Many bats roosted on Isla Tiburon 20 km from the Mexican mainland and commuted about 30 km to the mainland to feed. Bats flew for about 5 h each night for a total distance of about 100 km. Individuals foraged alone or in small groups in overlapping areas of 1-3 km2; and visited the same feeding areas on successive nights. Within feeding areas, bats visited the flowers of many cactus plants, visited most flowers <5 times, and removed about 0.1 mL of nectar per visit. Although bats flew nearly continuously early in the evening, they did most of their feeding between 24:00 and 02:00. When visiting flowers of Pachycereus pringlei (cardon), bats apparently waited until flowers had accumulated 0.8 mL of nectar before feeding, which suggests that rates of nectar secretion influence the timing of feeding in these bats. We estimate that the daily energy budget of L. curasoae is at least 40 kJ and that bats make about 80-100 visits to cactus flowers to acquire this energy. Foraging areas typically contain thousands of cactus flowers, and thus food does not appear to be a limited resource for these bats during the spring. The cost-efficient flight of this bat makes it an excellent pollen vector for self-incompatible, widely spaced desert cacti.

Genital mechanics are studied in five species from three genera of neotropical pholcid spiders. The study focuses on the function of a pointed and upward projecting (‘pup’) apophysis on the male pedipalpal femur: it engages an indentation in the genital bulb during copulation. This character is geographically restricted to spiders in Central and North America and the West Indies and is considered a key character of the monophyletic ‘Modisimus group’. This includes the genera Modisimus Simon, 1893, Psilochorus Simon, 1893, Bryantina Brignoli, 1985, Anopsicus Chamberlin & Ivie, 1938, and some species now misplaced in Coryssocnemis Simon, 1893 and Blechroscelis Simon, 1893. Evidence for the polyphyly of the following genera is presented: Psilochorus, Coryssocnemis, and Blechroscelis. Some notes on the reproductive biology of the species studied are briefly presented.