Although sex biases in natal dispersal are well known among birds and mammals, female-biased dispersal in polygynous mammals is rare. North American porcupines are polygynous and recent evidence suggests that natal dispersal in this species may be female-biased. We used data on disappearances, immigration, and reproductive behaviours to characterize natal dispersal and examine the extent to which inbreeding avoidance may motivate natal dispersal in porcupines. We predicted that, if female porcupines were the predominant dispersers, rates of disappearance and immigration would be higher for females than for males. Also, if females disperse to avoid mating with fathers, then the mean age of females at first conception should be less than the mean residence time of adult males. Population data suggested that natal dispersal was female-biased because a higher proportion of females (31%) disappeared than males (11%), and 78% of 18 immigrants observed in the population were females. Data on pregnancies indicated that female age at first conception ([ape ]25 months) was less than the mean residence time of adult males ([ape ]26 months), suggesting that female porcupines may disperse to avoid incestuous matings with fathers. Little is known regarding potential resource competition between mothers and offspring, or on how philopatric males avoid mating with their mothers. Additional data are needed in these areas to interpret dispersal tendencies in porcupines.

This study addresses the question of how three species of flightless feather lice (Phthiraptera) specific to a brood parasitic bird, the common cuckoo (Cuculus canorus), are transmitted from one cuckoo generation to the next in the absence of any direct contact between parent and young. None of 21 cuckoo nestlings examined shortly before fledging carried cuckoo lice; nor were any lice found in 19 nests in which cuckoos had laid. Cuckoos returning to Japan for their first breeding season were as likely to be lousy as, and carried similar louse loads to, older birds. These field observations are consistent with data arising from examination of museum skins from European breeding areas and from African wintering areas, and it is concluded that cuckoos acquire their lice between leaving the nest in summer and returning to the breeding grounds the following spring. This acquisition probably occurs via direct body-to-body contact between cuckoos, a supposition bolstered by some observations.

The kidneys of Anna's hummingbird (Calypte anna) differ in several significant ways from those of other birds that have been examined. The kidneys of this nectarivore contain very little medullary tissue; 90% of the total volume of the kidneys is cortical tissue, with medulla accounting for only an additional 2%. More than 99% of the nephrons are the so-called ‘reptilian type’), which lack the loop of Henle. The few looped (‘mammalian type’) nephrons are incorporated into only a few medullary cones per kidney. The loopless nephrons are similar to those of other birds. However, the looped nephrons differ in that they lack the thin descending limb of the loop of Henle, which is found in other birds and is thought to play an important role in the countercurrent multiplier system in the avian kidney. Instead, the cells of the nephron segment following the pars recta of the proximal tubule resemble those of the thick ascending limb, with the large populations of mitochondria that are typical of transporting epithelia and no reduction in cell height. The absence of a descending thin limb in Anna's hummingbird is not necessarily a correlate of the hummingbird's liquid diet, because thin limbs have been documented in the kidneys of two other hummingbird species, the rufous hummingbird (Selasphorus rufus) and the broad-tailed hummingbird (Selasphorus platycercus). The functional correlates of the unique renal morphology in Anna's hummingbird warrant further study.

Two large (dorsal mantle length 42.5 and 47.5 cm), mated spent females of circum-Antarctic bathypelagic cranchiid squid Galiteuthis glacialis were caught early in March 1992 at the surface of the ice hole in the western Weddell Sea over depths 1915-1920 m by the team of the U.S.A.-Russian Ice Station Weddell-I. The structure of the reproductive system of adult females is described for the first time in detail.

Both were gelatinous, devoid of tentacles, with empty or almost empty stomachs. The empty spermatangia (sperm reservoirs of spermatophores) 30-35 mm in length were distributed in the mantle tissues parallel to the mantle surface and to each other in the dorso-anterior part of the mantle: 13 in one female, parallel to the body axis, and 20 in the other, parallel (13) or perpendicular (7) to the body axis. In the latter case, they represented probably two mating events. The spermatangia lay nearer to the inner than the outer mantle side and opened by a round window on the inner side; the skin with chromatophores above them remained intact. The spermatozoa had one flagellum and rod-like heads, length 5.0-5.3 μm, width 1.2-1.5 μm. The most characteristic features are: a very simple type of blood vessel branching making each micro-gonad currant-like, not grape-like; a very compact disposition of oviducal, nidamental glands and gill, forming a united complex located on both sides of the mantle cavity; and an ovary connected by mesentery along all its length with the continuation of the stomach from the caecum to the end of the gastrogenital ligament. Only immature degenerating trophoplasmatic oocytes, length 0.9-1.4, av. 1.0-1.2 mm, were contained in ovaries; only one mature egg (length 3.3 mm, width 2.4-2.5 mm) was found in each female. The absence of oocytes <0.9 mm and 1.5-3.2 mm indicates that the maturation of oocytes proceeds rather synchronously, one large portion of eggs (some tens of thousands) matures in a short time while others degenerate. The residual fecundity is assessed to be approximately 20,000 eggs.

It is hypothesized that mating occurs shortly before spawning and that mature males do not undergo gelatinous degeneration and do not lose tentacles. Spermatophores are placed on the inner side of the female's mantle with the aid of the male's tentacles and/or arms (less probably by the penis), but the exact mode of implantation is unclear. Spawning probably occurs at depths of adult habitat (approx. 500±2500m), may be multiportional but short; the exhausted female loses neutral buoyancy, rises to the surface and dies. Rising to the surface after spawning is a common feature of females of many meso- and bathypelagic squids undergoing gelatinous degeneration during maturation (Onychoteuthidae, Gonatidae, Histio-teuthidae, Cranchiidae, etc.) and may explain the common occurrence of large deep-water squids in the stomachs of seabirds, including those incapable of diving, and marine mammals.

We report on a comparative scanning electron microscopical study of trophi morphology of the two species making up the Class Seisonidea of Phylum Rotifera. The trophi of the two are generally similar, with morphological differences being interpreted as the result of adaptations to different food sources: the trophi of Seison nebaliae are adapted to particle-feeding, that of Seison annulatus probably functions by piercing the integument of the host using the fulcrum tip, and subsequently sucking out haemolymph. This difference in feeding ecology is believed to contribute to the co-occurrence of both species on the same host. A new hypothesis on the evolution of rotifer trophi is proposed.

We use information on the at-sea distribution of radio-tagged seals to identify the summer foraging areas used by 31 harbour seals from two different haul-out sites in the Moray Firth, N.E. Scotland. We then determine whether seals tend to occur over particular sediment types or water depths as hypothesized by Härkönen (1987b), and assess whether local geographical variations in diet composition can be related to local differences in available foraging habitat.

The majority of seals foraged within 30 km of their haul-out site, consequently there was broad overlap between the foraging areas used by animals from the same site, but little overlap in the areas used by seals from different sites. Most seals foraged in water depths of 10-50 m with mainly sandy sea-bed sediments. Data on the distribution of dive depths of five seals which were fitted with time-depth-recorders indicated that seals were generally diving on, or close to, the sea-bed. Occasional pelagic dives between the more common benthic dives were also observed. Between-site differences in the seals' use of different water depths and sea-bed sediments suggest that local geographical variations in diet were related to local differences in foraging habitats, but that habitat use also differed between individual seals.

Population ecology and reproduction of the fat dormouse (Myoxus glis L.) were studied in central Germany in the years 1992 and 1993. Animals were captured in wooden live-traps twice a month, during trapping periods lasting three days each, and marked individually by tattooing. Demographic results show that, in three subpopulations, population structure differed extremely between 1992 and 1993. In 1992, more adult than subadult dormice occurred in the study area and the reverse was found in 1993. Subadults emerged from hibernation a little before or together with adult dormice. Adult males emerged significantly earlier than adult females. After a year with good reproductive success (1992), a total lack of reproduction was observed in 1993. Juvenile dormice were neither found in traps nor in nest-boxes. The assessment of gonadal states indicated that all males (adult and subadult) remained in a state of testicular regression throughout the year 1993. Also, no female was found lactating. Reproductive failure coincided with a lack of food resources in the autumn of 1993 (e.g. fruits of oaks and beeches). Body mass changes imply high energy expenditure prior to mating in adult males. It seems likely that males in years with low food availability do not invest energy in reproduction.

The indigenous wildcat, Felis silvestris Schreber, 1775, and the introduced domestic cat, F. catus L., have been sympatric in Britain for more than 2000 years. As a result of interbreeding, any distinction between these two forms has become obscured, although a range of morphological criteria (pelage patterns, body measurements, gut lengths, skull morphometrics) and genetic techniques (immunological distances, electrophoresis, DNA hybridization) have been used previously to distinguish between them.

A sample of 333 wild-living cats in Scotland was assessed for coloration and markings of pelage, standard body measurements and weights, and (for carcasses only) limb bone lengths, intestine lengths, and skull measurements. These cats were also classified as wildcat, hybrid, or domestic cat according to traditional pelage criteria.

Multivariate analyses on these variables, for adult cats, failed to show any clearly distinct groups. When each of the variables was analysed separately, only the distribution of limb bone and intestine length measurements suggested the possibility that two groups might exist. Group 1 cats had short intestines and long limb bones. Group 2 consisted of cats with long intestines and short limb bones. Although the characteristics defining cats in Group 1 were similar to those traditionally associated with wildcats, they exhibited a much broader range of pelage and coloration than traditionally described.

The groups exhibited a degree of geographical separation. The distribution of Group 1 cats was found to be related to certain environmental variables, namely mean annual temperature and land with poor potential for forestry and agriculture, suggesting that there may be a biological basis for the separation. The implications of these results on the identification and taxonomy of the wildcat are significant. The concept of the wildcat and the domestic cat as separate species can be challenged. The paper highlights the complexity and difficulties for conventional taxonomy when used as a means for distinguishing between a wild type and its domesticated form where there is interbreeding.

The annual cycle of adult butterflies was studied at seven rocky outcrops located along an altitudinal gradient in a northern Spanish mountain area (Picos de Europa) with a Eurosiberian climate in 1993 and 1995. Both total abundance and number of species of butterflies peaked in summer at all study sites. The cumulative species number uniformly increased over the season until late summer. These results imply that butterflies concentrated their activity when temperatures were higher in the year. Regardless of their diversity and total abundance, timing of the flight period was later for assemblages at high altitude than for assemblages at low altitude. A similar trend in increasing delay in flight period was found when data were analysed separately for each species. The duration of the flight period of assemblages was correlated with abundance in 1993, but it was correlated with altitude in 1995. Most species tended to show shorter flight periods at high altitudes in both study years. These altitudinal changes in timing of adult flight are likely to be linked with effects of temperature on developmental rates of early stages of the life cycle. Changes in duration of the flight period, however, might be partly related to variability in species abundance.

Sarcocysts morphologically not distinguishable from Sarcocystis gracilis of roe deer (Capreolus capreolus, Cervidae) were found in the skeletal musculature of dwarf zebu and humpless cattle (Bos taurus, Bovidae). We contribute to the identification of this species by means of scanning electron microscopy. Special attention is paid to the species-specific cyst wall structure. Our findings confirm previous descriptions by light and transmission electron microscopy and support the peculiarity and uniqueness of the cyst wall type ‘gracilis’.

The ranches of Laikipia District, Kenya, provide a very important refuge and conservation area for wildlife. Leopards (Panthera pardus) are the most numerous large predator and create problems by killing livestock. Both small and young wild ungulates, as well as small domestic stock, provide prey so that the leopards achieve unusually high densities. This study, using radio-tagging techniques, examines the spatial relationships between resident and transient leopards on a 200 km² ranch in the Lolldaiga Hills. About 25 leopards (including estimates of subadults and cubs) live on the ranch. Typically, females occupy exclusive home-ranges of mean extent 14.0 km² although there is some overlap with subadult females. The home-ranges of resident males, with a mean of 32.8 km², do not overlap each other but do overlap female territories. Transient males move through the area. Analysis of home-range and home-range occupancy, was carried out using three methods: minimum convex polygon, grid cell, and harmonic mean. The information provided by these three different methods is compared, and the social status of the leopards is discussed.

The foot pads of five rodents were studied by means of gross morphology and histology. The secretory portions of the glands are placed caudad to the openings of the ducts in species that mostly walk on the ground. This way the secretions are pressed out during walking by rolling on the foot pads craniad. In climbing species, the secretory portions are placed underneath the openings of the ducts and lead to secretion delivery during climbing by grasping. With their small and flat pads with few glands, digging species have a rather smooth and dry volar aspect to work in a shovel-like way. In contrast, climbing species have large and soft foot pads with a lot of glands. The thickness of the cornified layer is positively correlated with the density of glands and increases strikingly from digging to climbing species. Although scent production is possible for these glands, this points to a function of the secretions in connection with the cornified layer. In climbing species, the secretions of glands can moisten the skin and thereby heighten the friction between volar and climbing surface to prevent the animal from slipping. The density of glands per unit of surface is doubled in the ridged skin of Muscardinus avellanarius in comparison with the coned skin in Micromys minutus. While M. minutus mainly climbs by grasping stalks of reed and can tighten the grip by increasing the grasping force, M. avellanarius often climbs by pressing the volar aspect on to the bark, whereby friction is increased by the moistened skin.

This study is an investigation into the influence of activity on otter (Lutra lutra) spraint production and composition, based on feeding trials involving captive, tame otters. Trials were of two types: ‘active’ where animals were encouraged to run, swim and dive for at least 33% of the time during the first six hours after each meal, and ‘inactive’ where activity varied between zero and 18% of this period. Trial types were balanced for number of fish, meal volume and fish size. Activity was found to have a large effect on spraint production and composition. For active trials, median minimum gut transit time was 67 minutes and median number of spraints per trial was 23. Corresponding figures for inactive trials were 170 minutes and 14, respectively. Of ingested salmonid (Salmo spp.) atlas vertebrae, 60% were recovered in spraints after active trials, while only 32% were recovered after inactive ones. Analyses of these effects showed that our previous models for estimating prey size distribution from bones recovered in spraints gave a better fit for inactive than for active trials. As otters in the wild are likely to spraint mostly during periods of activity, especially foraging, further feeding trials were undertaken to refine an earlier model better to mimic the field situation. Trials, involving active otters, were undertaken to: (i) produce in vivo bone to fish length equations for salmonid atlases and eel (Anguilla anguilla) thoracic vertebrae; and (ii) model the size-related differential recovery of these bones. These refined equations are more soundly based to provide estimates of prey size distribution than the earlier ones and their use in future studies of size-selection is recommended. The present study also highlights the potential limitations of extrapolating from the captive situation to the wild.

Mortality factors and hatching success of 422 terecay turtle (Podocnemis unifilis) nests on seven beaches in the Nichare and Tawadu Rivers, Venezuela, were studied following the oviposition phase. Beaches (3.4-28.4 km2), predominantly sandy, and bordered by riparian vegetation, were searched to record nest numbers and their distribution. Elevation and surrounding plant cover were measured for each nest. Most nests were found close to the vegetation's edge (0-11 m), at a significant distance from the water's edge (21-80 m), in more open ground, and along the highest points of the beach (1-2.5 m above the water's edge). Nest density was positively correlated with beach elevation but not with beach dimensions. Most nests were concentrated in less than 10% of beach area, along the upper 20% of the beach. Average clutch size was 20.1±1.7 eggs, but larger clutches were found significantly further away from vegetation. No significant correlation between hatching success and clutch size was found.

A large proportion of nests were subject to animal and human predation but environmental factors (especially flooding) affected some. The major cause of egg loss was human predation. Most clutches collected by humans were found away from vegetation, on the upper 10-20% of beaches, in exposed unvegetated sites. Animals preyed upon those nests along the vegetation's margin (1-2 m) in the upper 0-9% of beaches, in sites of high plant cover (75-100%). Nests reaching the incubation phase were mainly located in the open areas, which are more prone to human predation. About three-quarters of nests showed high hatching rates (91-100%). However, hatchability was highest furthest away from the vegetation. Our results indicate that humans are collecting eggs mostly from sites in which nests have the larger clutches and the higher potential hatching success. Because of this relationship between nest viability and location, sustainable yield programmes must consider where harvesting can take place and must avoid the application of standard harvests per nest.