Until the mid 1970s only a few grey seal Halichoerus grypus pups were born each year on the Isle of May, Scotland, but 1408 pups were born there in 1994. We examined changes in overall site use, individual pupping site fidelity and success in relation to local population density and topography. The area of the island used by seals for breeding has increased as the population increased. Between 1988 and 1994 an index of the proportion of the island's northern area occupied by seals increased from 0.48 to 0.65, while the average population density in these occupied areas decreased over the same period. Although seals have begun to breed in southern parts of the island that were unused previously, other apparently suitable breeding areas on the island remain vacant. Fine scale digital elevation models were constructed using a GIS to evaluate the topographic characteristics of occupied areas and assign topographic ‘costs’ to areas used by seals for breeding on the Isle of May. Seals were associated generally with areas close to the numerous access points from the sea. New areas occupied in the later years of the study had a higher topographical ‘cost’ than the traditional sites. Thus, in an expanding colony such as the Isle of May, areas colonized early in the colony's history were those close to access points and/or standing water and at low elevations. Subsequent expansion resulted in an increase in the areas occupied by seals, but these newly colonized areas were less suitable, and their occupiers were subject to increased topographic ‘costs’. Pup mortality rates were similar in areas of high and low breeding density. Aggressive behaviour between breeding females is the likely mechanism which acts to limit local animal density. Mothers marked at the Isle of May since 1987 returned there to breed with few exceptions, and most females that returned were faithful to their previous pupping sites (median distance between sites used in consecutive breeding seasons = 25 m). Site fidelity persisted even when a previous pupping was unsuccessful and most individuals' pupping locations did not change gradually with time. Comparison with other colonies suggests that the spatial scale of site fidelity is related to the scale of topographic variation within the breeding site.

Any interpretation of archaeological animal bone assemblages benefits greatly from a knowledge of animal behaviour patterns and population dynamics, but there are difficulties in directly imposing modern data onto past, often non-analogue environments, and in assuming species-specific behaviour. This paper suggests that behavioural ecology – which stresses adaptation – provides a fruitful approach for predicting ethological details of past wild animal populations. The study focuses on the genus Gazella, whose remains are commonly found on archaeological sites in south-west Asia in the period 20,000–7500 before present (BP), and whose role in human societies has been much debated. Following a behavioural ecological method, selected data from 18 modern observed gazelle populations are summarized, compared, and the factors that influence and constrain the animals' behaviour are discussed. The potential for using the principles of behavioural ecology to predict factors such as gazelle social structure, reproductive strategies and mobility patterns in past environments is considered, and the value of such an approach for zooarchaeological interpretation is demonstrated.

Morphology of statoliths and anatomy of statocysts were studied in five species of Gonatidae, Moroteuthis robusta (Onychoteuthidae) and Galiteuthis phyllura (Cranchiidae) from the northern Bering Sea, and Todarodes pacificus (Ommastrephidae) from the Pacific waters near Japan. A special experiment was carried out in order to observe statolith mobility on the macula statica and possible endolymph flows within the statocyst in freshly caught gonatid squid Berryteuthis magister. It was found that the statolith may deviate at small acute angles around three axes running through its centre of rotation (located near the spur) without any visual damage of its attachment area to the macula. This finding enabled us to re-consider previous theories and to create a new model of the squid statocyst functioning with the statolith as detector of multidimensional movement. Two types of statolith morphology are distinguished: demersal type statoliths characteristic of near-bottom decapods, and pelagic type statoliths characteristic of all pelagic squids and not dependent on their systematic position. Phylogenetic and ecological features of the statocyst and statolith structure are established. Possible evolutionary trends in development of different types of statocysts in decapods are discussed.

Populations of the Central American spiny rat Proechimys semispinosus isolated on eight small islands in Panama were sampled monthly for 1 year to examine the relationships of demography to tree species composition and forest structure. Demography was characterized by calculating seven variables from the monthly census data. Tree species composition was determined by marking, measuring and identifying all trees ð 10 cm in diameter at breast height (dbh) on each island. Forest structure (tree stature, density and species richness) was quantified by measuring seven variables at each of the 470 sampling stations. Bivariate correlations were computed between spiny rat demography and tree species composition and forest structure. To examine whether islands with more similar tree species composition or forest structure supported P. semispinosus populations with more similar demography, dendrograms based on complete-linkage cluster analysis were constructed. Spiny rat densities were correlated positively with the density of large-fruited fig trees and non-linearly to an index of forest age based on tree species composition. Spiny rat densities were not related to any structural variable. Dendrograms based on cluster analysis showed that spiny rat demography did not map onto forest structure, overall tree species composition or any group of selected tree species except figs Ficus spp. Thus, islands with more similar fig tree composition contained spiny rat populations with more similar demography. Tree species composition, which partly determines resource abundance, is apparently more important than forest structure in influencing spiny rat demography. Proechimys semispinosus has a temporally and spatially variable demography, and this flexible demography, in concert with an ability to use diverse resources, presumably promotes abundance and persistence in heterogeneous tropical forests and may contribute to the ubiquity of this rodent.

All 20 of the Bulwer's petrels Bulweria bulwerii of Selvagem Grande (30°09′N, 15°52′W) equipped with maximum depth gauges had dived during the feeding trips performed during the incubation period, the mean maximum depth being 2.4 ± 1.0 m (range: 1.0–5.3 m). The depth reached showed no correlation with the breeding experience of the birds, with the length of their trip or with their body size and there were no differences between males and females. Thus, the Bulwer's petrel are among the numerous Procellariiformes which perform regular but comparatively shallow dives, unlike shearwaters (Puffinus) and diving petrels (Pelecanoides) which can reach depths of several tens of metres.

The ovaries and oocytes of a iulid millipede Catamicrophyllum caifanum Verhoeff 1920, were studied in an oak woodland and a planted pine forest in the Mediterranean region in northern Israel. The changes in the stages and number of oocytes are described throughout the activity period of this millipede: October–February. Four stages of female germ cell development could be distinguished: (1) the early stages of oogenesis when the female germ cells (= oogonia) are still embedded in the germ layers of the ovarian epithelium; (2) two sizes of previtellogenic oocytes entering the ovarian lumen are distinguishable. Small ones (< 0.1 mm) observable only in microscopic sections, and larger ones (0.2–0.45 mm) that could be seen under the dissecting microscope. The small previtellogenic oocytes were present in the ovary throughout the study period. The oocytes apparently undergo vitellogenesis during autumn; (3) with the accumulation of yolk, a third stage consisting of small, medium and large vitellogenic oocytes can be discerned; (4) the mature, post-vitellogenic oocytes, elliptic in shape and yellowish in colour, appear towards the end of autumn. In winter only post-vitellogenic oocytes are found, disappearing from the ovary towards the end of winter. The number of mature, post-vitellogenic oocytes is positively correlated with the female's body size. Catamicrophyllum caifanum has therefore an annual oogenetic cycle breeding once yearly during winter. This, together with the fact that its ovary contains oocytes belonging to different stages (= generations), indicates that it can breed at least four and possibly up to seven times during its lifetime.

The interdental and interspecific variation in the prevalence and severity of macroscopic fluorotic alterations of the permanent mandibular cheek teeth (P2–4, M1–3) was studied in 331 roe deer and 62 red deer exhibiting severe dental fluorosis. The material originated from the fluoride-polluted region of the Ore mountains and their southern foreland (Czech–German border region). Scoring of dental fluorosis was based on an ordinal measurement scale with six scores (score 0: unfluorosed, scores 1–5: increasing severity of fluorotic alterations). The observed variation in dental fluorosis both within the cheek tooth row of a species and between certain homologous teeth of roe and red deer could be related to the development of the dentition in the two species, especially the timing of tooth crown formation in relation to weaning and the subsequent period, where the animals feed upon (fluoride-contaminated) plant material. The lower prevalence (roe deer: 3%, red deer: 42%) and severity (fluorosis scores ð 2) of dental fluorosis in the M1 compared to the other permanent cheek teeth were attributed to the fact that the crown formation of this tooth takes place largely (roe deer) or to a considerable extent (red deer) prenatally and during the period of milk feeding. It is assumed that during these ontogenetic stages several mechanisms (partial placental diffusion barrier to fluoride, low fluoride content of milk, rapid clearance of fluoride from the blood resulting from a high skeletal growth rate) to some extent protect the developing teeth from increased fluoride exposure. Therefore, in both species apparently only the (late) maturation stage of M1 amelogenesis can be affected by fluoride in a way to induce visible enamel changes. The higher prevalence and severity of fluorotic lesions in the M2 of red than roe deer was related to the fact that in the former species crown formation of this tooth, like in the P2–4 and M3 of both species, takes place completely post-weaning.

Founder effects, together with access to unoccupied ecological niches, may allow rodent populations on isolated islands to evolve constellations of life-history traits that distinguish them from their mainland relatives, for example in body size, litter size, and longevity. In particular, low intrinsic mortality risks on islands with reduced predator numbers and not subject to harsh winter climates may in principle support the development of stocks with extended longevity. Conversely, the conditions under which laboratory rodents are typically bred are thought to select for genotypes that produce large, rapidly maturing races with high early reproductive rates but diminished longevity. To test these ideas, and to generate new mouse stocks suitable for genetic and molecular analysis of the processes that time life-history events, we have developed specific pathogen-free stocks from mice trapped from three distinct populations: the U.S. mainland (Idaho) and the tropical Pacific islands Majuro and Pohnpei. Mice from all three locations were found to be shorter and lighter, to have smaller litters, and to have higher faecal corticosterone levels than mice of a genetically heterogeneous stock derived from four common laboratory inbred strains. Among the wild-derived stocks, mice from Pohnpei and Majuro were significantly lighter and shorter than Idaho-derived animals, even in populations kept from birth under identical housing conditions. Litter size and reproductive success rates did not differ significantly among the three wild-derived stocks. Although further work will be needed to see if, as predicted, the wild-derived stocks differ from one another and from laboratory mice in longevity, these stocks provide useful tools for genetic dissection of factors that regulate body size and reproductive success.

New Zealand fur seals in the New Zealand area are increasing in number following earlier depletion by Polynesians and Europeans. Otago Peninsula, South Island is a region where recent re-colonization has occurred. We identified 27 breeding and 41 non-breeding colonies in 1998. At higher densities the shortage of space in breeding colonies may initiate emigration by first-time breeders to suitable sites nearby. This hypothesis assumes philopatry (repeated return to a natal site) and site fidelity (repeated return to a non-natal site). We quantified the rate of increase in pup production at Otago Peninsula since the early 1980s using annual counts of fur seals ashore from 1994 to 1998 and data on pup numbers before 1994 from the literature. The exponential rate of increase (b) ranged from 0.22 to 0.30 (95% confidence interval) and the average (arithmetic) rate of annual increase (r) was 0.30. To search for evidence of philopatry, site fidelity and immigration, relationships between counts of pups established colonies in 1996–1998 were measured and found to be highly correlated. We then tested whether new breeding colonies were established nearer to existing breeding colonies than would be expected by chance. There was significant spatial clustering of new breeding colonies around the 6 focal (established) colonies. We found no evidence for an association between the appearance of new colonies and r at nearby established colonies. Increasing numbers of fur seals on Otago Peninsula have resulted in the rapid proliferation of colonies, and their clustering is indicative of a ‘spill-over’ effect where young individuals choose to breed near to established breeders.

Many studies of co-operatively breeding vertebrates have shown that social groups which contain more helpers experience higher reproductive success. Few of these studies, however, have demonstrated that this is a causal relationship. Using data on a co-operatively breeding population of European badgers Meles meles, this study shows that the relationship between helper number and group reproductive success is a spurious one generated through the effect of territory quality. Within this population, most variation in cub production, growth rate and survival is explained by variation in food availability between years and between territories. Unusually for mammals, juvenile mortality is markedly higher in females than in males. After controlling for such effects, helpers appear to have only negative effects upon group reproductive success, and mothers with helpers are in poorer condition at the end of the breeding period than those without helpers. A high proportion of helpers are sexually mature females which have failed to breed as a result of intense competition for resources. Under such circumstances, alloparental care represents a low-cost, low-benefit behaviour which may mitigate the negative impact that non-breeding group members have upon the reproductive success of their close relatives.

The triple jaws of the leeches Limnatis nilotica and Hirudo medicinalis (both Hirudinidae, Hirudininae) are compared, using the stereomicroscope and scanning electron microscopy (SEM). The jaws of Limnatis are relatively small, rounded and soft, bearing about 30 flat-topped, rough-surfaced teeth, and papillae which presumably secrete saliva. Limnatis sucks blood in stages from internal soft vascular tissue, often in the pharynx, and may stay inside the host for several weeks. Evidence is strong that it is unable to pierce external skin. Hirudo jaws are rigid, have no papillae and bear about 60 sharp teeth, each tooth possessing a secretory aperture on its side, close to the tip. In contrast to Limnatis, Hirudo is an external feeder. It pierces the skin and usually gorges itself with blood in one meal, after which it detaches itself from the host. It gains from six to nine times its weight in a meal, and remains satiated for 3–18 months. The ingested blood of Limnatis, unlike that ingested by Hirudo, is particulate and resembles a liver homogenate. This is probably a result of some scraping by its teeth as the jaws thrust towards a blood vessel. The relationship between jaw anatomy and feeding habits of L. nilotica and H. medicinalis is shown. Clearly, each species has adapted to the particular environment supplying its food (soft internal tissues, external skin).

The developmental pattern of Polystoma indicum Diengdoh & Tandon, 1991 occurring in the urinary bladder of the frogs Rhacophorus nigropalmatus, R. reinwardtii and Polypedates leucomystax from Meghalaya (north-east India) was studied. Non-ciliated larval stages were recovered in the gyrodactyloid-I and post-gyrodactyloid-I stage mostly from the branchial chambers of the tadpoles; only rarely were they found in the intestines. These stages possessed features of bladder-destined forms and showed a gradual acquisition of 2, 4 and then 6 opisthaptoral suckers, coupled with an increase in the size of the body and various structures. While a conspicuous increase was noticeable in the dimensions of the hamuli, the size of the microhooks remained almost the same from the 2-suckered larval stage to the adult. The larval migration to the final destination seems to follow an external route leading to the cloaca of the metamorphosing host. The prevalence data of both the larvae and the adult flukes indicate a preference towards R. nigropalmatus amongst the three rhacophorid host species. The gyrodactyloid-II, i.e. neotenic larvae were not encountered at all either on the external gills of the very young tadpoles or even in the branchial chambers of the older ones.