Captive-born mountain gazelles (Gazella gazella), including 28 radio-collared and 54 tagged animals, were freed in Hawtah Reserve, Saudi Arabia, during 1991–95. The size (as minimum-area convex polygons) and spatial distribution of their individual ranges were determined from daytime radiotracking and sightings. Some adult males were territorial and territorial fidelity was >94%. Territories were maintained year-round and were arranged linearly along the wadi floor. Initially, the size of territories decreased as their density increased, but after density stabilized, median territory area was 0.6 km2. The ranges of up to four released females were centred on each territory and female core areas were arranged in clusters along the wadi. Female ranges became smaller as the density of territories increased. After females had dispersed, their annual range averaged about 1 km2 during both 1993 and 1994 in wadis without domestic livestock and where, consequently, plant standing crop was high. Where camels foraged and plant standing crop was low, female ranges averaged 4.6 and 1.6 km2 during these two years. Some females shifted their core area, and their annual range was twice as large. The range area of non-territorial males averaged 6.7 km2 and extensively overlapped the ranges of other bachelors. Bachelor males occasionally passed through territories, but some wadi sections were used often by bachelors and seldom by females. The size and spatial distribution of gazelle ranges did not change seasonally, despite the temporal variation in rainfall. Runoff concentrated in wadis and the consistent food supply there allowed gazelles to occupy small ranges, even though annual rainfall was low (<150 mm).

Communications from the Mammal Society, which have been published twice yearly, in June (see pp. 209–244, this issue) and December, will cease from the end of this year. From January 1999, this Section of the Journal of Zoology will be allocated to Short Communications, and contributions will be welcomed on all taxa within the general field of zoological research, both invertebrate and vertebrate. Three copies of each paper, following the Instructions for Contributors printed at the back of the Journal of Zoology, should be sent directly to Dr M. L. Gorman, Editor of Short Communications, Journal of Zoology, Department of Zoology, Aberdeen University, Tillydrone Avenue, Aberdeen AB24 2TZ, Scotland, U.K. Tel.: +44 (0)1224 272850; fax: +44 (0)1224 272396; e-mail: m.gorman@abdn.ac.uk.

The intensive study of the Arctic skua (Stercorarius parasiticus) population on Fair Isle has provided an example of the maintenance of a stable polymorphism by sexual selection in conjunction with assortative mating (O'Donald, 1983). We tested several of O'Donald's hypotheses using data collected from the large colony of Arctic skuas on Foula. There was some evidence for assortative mating of the phenotypes but this did not confer any short-term fitness advantage. In contrast to the situation on Fair Isle, we found little indication that sexual selection took place for dark males since no differences in timing of breeding or productivity were evident between the two male phenotypes in new partnerships. Nor could we detect variation in adult body size, body condition, or any life-history characteristic between melanic and pale birds of either sex. Many of the selection pressures documented on Fair Isle appear to be absent at the neighbouring Foula, despite a fair degree of gene flow between these colonies. The frequency of pale adults on Foula and in Shetland as a whole has declined since the 1970s, indicating that currently directional selection may be favouring the melanic phenotypes at the southern end of the breeding range.

During the year, 162 papers have been published in the 12 monthly parts of volumes 241–243. The December issue (Volume 243, part 4) was the last number of the Journal to be published by Oxford University Press, and Assistant Editor Angela Stroud left at the end of the year. She had copy-edited manuscripts for the Journal for more than 10 years, and I would like to express my personal thanks to her, as I am sure would all authors, for her painstaking and faultless work. From January 1998 the Journal is being published by Cambridge University Press and I hope that all subscribers approve of the new format.

We examined data on live-captured polar bears (Ursus maritimus) from western Hudson Bay relative to differential maternal investment and facultative sex ratio theory. In spring, shortly after den emergence, we found no differences in mass or body length of cubs in litters of one or two. In triplet litters captured in spring, male cubs were larger than females in both mass and body length, possibly due to sibling competition for limited maternal resources. In cubs captured during autumn, sex-based differences in mass and body length were found only in litters of one with males larger than females. Yearling males captured in autumn were heavier and longer than females in litters of one and two. In twin litters of one male and one female cub in spring and autumn, we found no differences in mass or body length. Except singleton female cubs in spring and female and male triplets in spring, cub and yearling mass were correlated with maternal mass. Mothers with singletons in spring were more likely to have male cubs but, in general, there was little evidence to suggest that mass or age of mothers influenced offspring sex. Litter size, maternal mass, and maternal age all influenced cub and yearling size, but offspring sex was less important. Results suggest that female polar bears do not normally invest differentially between offspring of different sexes except in triplet litters in spring.

The feeding habits of the neotropical river otter Lontra longicaudis were studied in a headwater stream of the Atlantic Forest, south-eastern Brazil, for 17 months. The otters fed mainly on fish (93% of the scats), but invertebrates were also frequent items in the diet (78.9% of the scats), as observed for the same species in lentic habitats and for other species of Lontra as well. It is suggested that the high proportion of invertebrates in the diet in comparison to Lutra is related to differences in the dentition of the two genera. The observed seasonal variation in the diet of L. longicaudis was probably a result of fluctuations in the abundance of a main prey item, a megalopteran larva (Corydalus sp.). Prey selection, regarded as differences between rates of predation and relative abundance of food items, was demonstrated for the two most important groups of otter prey: fish and crustaceans. Although they are able to capture mobile prey, otters seem to prefer feeding on prey showing lower escape ability – among fish they select armoured catfish, and among crustaceans they select crabs.

The results are described of a capture–recapture study of the Australian arboreal marsupial, the mountain brushtail possum (Trichosurus caninus Ogilby). Adult, subadult and juvenile T. caninus were captured during 11 trapping periods and at 70 different trap placement sites between June 1992 and November 1995 in a 40 ha area of mountain ash (Eucalyptus regnans F. Muell.) forest in the central highlands of Victoria, south-eastern Australia. A total of 80 (37 male and 43 female) T. caninus were captured, comprising 45 adults, 14 subadults and 21 juveniles when first trapped. This gave a total of 333 captures of T. caninus from approximately 4600 trap nights.

The Jolly–Seber–Cormack approach was employed to model the frequency of recapture as simple product functions of the survival and capture probabilities for each inter-trapping interval. Using this method, we explored the relationships between survival and capture probabilities of T. caninus and a range of potential explanatory variables including sex, age class, time, and trap location.

The results of our analyses indicated that there was a high probability of recapture of T. caninus – P = 0.80 (0.03 SE – with females significantly (P < 0.05) more likely to be caught than males. There was spatial heterogeneity across our study site in the probability of recapture of T. caninus, and animals inhabiting areas of old growth were more likely to be retrapped than animals in younger forest where potential nest sites within large standing dead trees with hollows are decaying rapidly and are at high risk of collapse. There were no significant differences between the survival rates of different sexes or age classes, and the monthly value for the probability of persistence calculated for T. caninus was 97.7% (0.48%).

Our study demonstrated that T. caninus is long-lived with high levels of survival among individuals of all age classes once young animals have emerged from the pouch. Animals have relatively high site affinity and are readily recaptured, often at exactly the same place, or very close to, where they were first caught. Some juveniles have taken up permanent residence in the natal territory, which may result in opportunities to mate with close relatives.

The behaviour of this rainforest dragonfly was studied in the Kakamega Forest, West Kenya. Seven different activities were distinguished: perching, sun-flights, patrolling, inspection, interspecific, intraspecific, and sexual flights. Two-act sequences of these behaviours were analysed and quantified to determine significant transition probabilities. Sun-flights into the tree canopies were the most common flight activity and followed any other behaviour significantly more often than expected. Coming back from a sun-flight, the males preferentially perched or patrolled; after patrolling males typically perched. Most of the time the males spent perching in their territory (32% of total time in territory). Proposed functions of these territorial behavioural activities in Notiothemis robertsi are deduced from these results.

The male reproductive cycles of three species of vespertilionid bat (Nyctophilus geoffroyi, N. major and Vespadelus regulus) are described. Descriptions are based on the degree of testicular and cauda epididymal development estimated from field captures, and for N. geoffroyi, on histological examination of fixed specimens and assays of their testicular testosterone concentrations. All species were found to undergo a dissociated pattern of reproduction; the activity of the testes and accessory glands of reproduction were asynchronous. Spermatogenesis occurred in summer/early autumn (December–March) and testes generally regressed before mating began in autumn (March–May). Spermatozoa were stored in the cauda epididymides during the mating period. Leydig cells of N. geoffroyi involuted prior to mating but the prostate gland remained enlarged and secretory during winter (June–August), regressing in late spring (November). Testicular testosterone concentrations were greatest when Leydig cells were maximally enlarged, and concentrations were low during the mating period. The reproductive cycle of all species apparently involved asynchrony between primary and secondary sexual function, which is typical of vespertilionid bats inhabiting temperate latitudes. As mating occurs when sperm stores cannot be replenished, selection for prudent sperm allocation may be expected.

Intra- and interspecific variation are analysed for the post-natal skull of the lacertid lizards Gallotia galloti, Acanthodactylus erythrurus, Algyroides marchi, Lacerta monticola, Lacerta vivipara, Podarcis bocagei, Podarcis hispanica, Podarcis muralis, Psammodromus algirus and Psammodromus hispanicus. Individual variations identified include: the presence/absence, number and morphology of some structures, mainly in the lacrimal, sclerotic ossicles and maxilla; the number and location of foramina and the degree of ossification of some processes in chondrocranial bones. No differences have been found between the sexes with respect to presence and morphology of the bones but some species show sexual dimorphism in the size and robustness of the head and this may be reflected in the individual. The most substantial variations seen are ontogenetic: the appearance of new traits; development of articulations; differences between species in the timing of the stages of development of a given structure; changes in the relative position of some cranial elements; and the degree of calcification or ossification of processes. A total of 63 characters showing interspecific variations are identified. Some have not previously been described while others used in previous studies are redefined here on the basis of new morphological information obtained.

It is proposed that many of the morphological, physiological and behavioural traits that characterize domestic sheep and goats and distinguish them from their wild ancestors (e.g. diminished sexual dimorphism; diminution in brain, body and horn size and changes in shape of the horns; changes in pelage coloration) were shaped, to a large extent, by unconscious selection. It is argued that once founder herds had been assembled and controlled by humans, the very transfer of these animals from their wild environments into the widely different human-made husbandry system caused automatically drastic changes in selection pressures. Several adaptations, vital for survival in the wild, lost their fitness under the new conditions and broke down. New traits (which characterize domestic caprines) were promptly and unconsciously selected for. Protection from predators, culling of young males, protection from the elements, and changes in land use and in food and water supplies are considered the main ecological factors introduced by humans at the start of caprine domestication.

We evaluate the shifts in the selection pressures brought about by each of these changes, and sketch their expected impact on the morphology, physiology and behaviour of the human-controlled herds. We also indicate which of the domestication traits (expected to be automatically selected for under the new set of conditions) are detectable in animal remains recovered from archaeological excavations.

We describe the size and developmental state at birth, examine factors which influence intra- and inter-year variation in post-natal growth, and derive age-predictive equations and logistic growth parameters for the eastern pipistrelle bat, Pipistrellus subflavus. Ambient and roost temperature and insect abundance were lowest, and precipitation highest, before and during the post-natal growth period in 1982, as compared to 1981. We found no sex differences in the size of pups at birth or in post-natal growth rates in a given year; however, body mass and length of forearm of neonates differed significantly between years, being smaller in 1982 than in 1981. During the first two weeks of post-natal growth in both years, the body mass and length of forearm of pups increased linearly at mean rates of 0.15 g.day−1 and 1.12 mm.day−1, respectively. Post-natal growth rates for length of forearm and body mass were the same during the early linear phase of growth, but the intercept for body mass was less and growth trajectories were more variable in 1982. Length of forearm was the least variable and thus most reliable character for estimating age of P. subflavus pups during the first 14 days of post-natal growth. When length of forearm was used in combination with mean changes in the length of the fourth metacarpal-phalangeal epiphyseal gap, we derived reliable age-estimation equations ranging from 1 to 45 days. Litter size averaged 1.96 and 1.93 at birth, but this was reduced to one by the time pups became volant. At birth, litter mass represented 44, and 54% of the post-partum mass of females in 1981 and 1982, respectively. This maternal effort during pregnancy is among the highest reported for bats. At weaning, the body mass of pups approached 80% of adult post-partum body mass, and the length of forearm exceeded 90% of adult female size. Our results suggest that size at birth and post-natal growth are influenced by ambient and roost temperature, rainfall, and the quantity of insects available to pregnant and lactating females. Thus, energetic constraints on both mothers and pups can lead to inter-year and inter-individual differences in maternal effort and post-natal growth of pups.

Density-dependence in juvenile survival may be difficult to detect if survival is also affected by density-independent factors. We investigated the relationships among weather parameters, population density, and lamb survival of bighorn sheep with long-term data from a marked population where we manipulated population density. We distinguished neonatal survival and winter survival. Density interacted with weather variables to affect neonatal survival; spring and winter temperatures had a positive effect on neonatal survival only when population density was high. Neonatal survival was positively affected by spring precipitation independently of population density. Winter survival was positively correlated with temperature and precipitation during the previous spring, negatively correlated with density, and independent of winter temperature or snowfall. The effect of weather on lamb winter survival did not vary with density. Bighorn lambs are well adapted to harsh winter weather, but spring weather influenced survival of lambs at birth and during the subsequent winter, possibly through its effects on forage availability. Our study clearly demonstrates density-dependence in lamb survival. Some of the effects of weather on lamb survival are density-independent, others are mediated by an interaction with population density.

Influence of habitat type on the group size of sika deer was analysed on the basis of 2718 individuals observed in 708 groups, in the area where deer are under pressure neither from predators nor hunters. From spring to autumn, the percentage of individuals observed in the largest groups in open woodland was higher than both in clearings and closed woodland. In early winter, the percentage of individuals aggregated in the largest groups was highest in the clearings, while in late winter, the percentage of individuals observed in the largest groups was highest in the closed woodland. Besides, the percentage of large groups observed in the morning and evening (when most of deer are active) was much higher than during daytime (when level of deer activity is lower). Changes in food availability are suggested to be a factor responsible for variation in sika deer group size in different habitats.

The growth and the food requirements of the European barn owl (Tyto alba) were studied in three groups of captive chicks. One group of chicks, raised in ad libitum food conditions by their parents, was used to measure body mass and linear growth of a number of structural body components at their characteristic growth rate. A second group of chicks, hand-raised with food ad libitum until fledging, was used to measure food requirement at the characteristic growth rate. A third group, hand-raised with restricted feeding, was used to specify the plasticity of growth and food requirements still compatible with a normal development at fledging. Chicks of both sexes of the first two groups experienced an overshoot in body mass (maximum of 391 g) when approximately 40 days old, followed by a decrease (to a mass of 314 g) until fledging at 60 days old, giving a mass distribution with age in the form of a bell-shaped curve. The daily food intake also showed a bell-shaped curve with a peak value of 80 ± 10 g of fresh mice/day when the body mass was maximum. The decrease of food intake preceding fledging was spontaneous. The average daily food intake was 67 ± 17 g/day between the ages of 20 and 60 days. In the restricted feeding group, however, the same timing for linear growth and fledging was achieved with a 17% reduction of daily food intake. For the same fledging body mass as the ad libitum fed group, there was a flattening of the body mass curve. The significance of the overshoot in body mass and food intake is discussed in terms of the chick's and brood's advantages and in terms of parental investment in this species with hatching asynchrony.

The egg and hatchling of Sepia officinalis L. is relatively large, compared with those of other cephalopods. We review the information on growth, chromatophores, behaviour, prey capture, colour and body patterns of this sepiid, for correlation with changes in morphology and development of its central nervous system. We compare the early life of S. officinalis with that of the common octopod, Octopus vulgaris, Cuvier 1797. Sepia officinalis is initially benthopelagic but subsequently is mostly benthic in habit. Octopus vulgaris enters the plankton immediately after hatching and spends several weeks there before it settles to a life spent mostly on the bottom.

The cave-dwelling Congeria kusceri is described and aspects of its unique ancestry and biology elucidated in the context of its, for a bivalve, similarly unique habitat. The species lives in subterranean waters of the Dinaric karst of the former Yugoslavia. C. kusceri is acutely heteromyarian in form commensurate upon its lifestyle of byssal attachment to the walls of either permanently or periodically inundated karst caves. Shells are sometimes covered by travertine, precipitated calcium carbonate, and the tubes of the, similarly unique, serpulid Marifugia cavatica. Neither species occurs outside such caves and, as a consequence, the shell and tissues of C. kusceri are colourless and there are few sense organs, i.e. no statocysts and light receptors, although the pallial papillae possess tiny sense cells and there is a supra-branchial osphradium.

Mantle fusions are extensive and involve the inner folds posteriorly to create the siphons, but also the inner surfaces of the middle folds ventrally so that here the mantle is largely covered by a thin (4–5 μm), fibrous, periostracum and there are, on the separated middle folds around the pedal gape, external ciliary cleansing tracts. There are internal cleansing tracts too, but the former have been identified, hitherto, only in representatives of the Pectinidae. In terms of general anatomy, Congeria kusceri has large ctenidia and tiny labial palps as an adaptation to the mineral waters of its habitat containing little food and, thus, that little is rejected when collected. There are few sorting currents in the stomach either and the intestine is short.

The aragonitic shell comprises two layers, outer and inner, both with a homogeneous crossed-lamellar structure. Each shell valve, however, contains many growth checks, represented by thin prismatic layers. Assuming that a growth check is formed once each year, possibly in late summer when water levels fall in the caves, making them accessible for investigation, an individual of, for example 12.7 mm shell length, was possibly 25 years of age. If so, an individual of 25 mm would be very much older. Because, with age, the species lays down growth checks at progressively reduced increments, a lifespan of many decades may be possible. Extreme reduction in shell growth causes marginal thickening and incurving. The species is dioecious, i.e. separate sexes, with females brooding lecithotrophic (70 mm) eggs in the ctenidia, the ®lament bases of which become highly glandular. Mature and brooding individuals occur when water levels are low in the caves, suggesting that internal fertilization takes place at this time too, sperm transfer being in the Ælm of surrounding water to prevent loss. Fertilized eggs probably hatch either as larvae with a short planktotrophic life or as crawl-away juveniles. Analysis of large samples suggests that recruitment is probably low, and there is evidence that the species is threatened by pollution of its habitat.

When prey availability depends on water depth, a diver should choose an optimal depth for foraging. A model that predicts the optimal foraging depth for a diver is presented in this paper. General predictions derived from the model are: (1) optimal foraging depth is always shallower than the depth at which prey density is the highest, even if the depth of the highest prey density is within easy reach; (2) a larger diver should make deeper and longer dives and stay longer on the surface than smaller divers for optimal foraging; (3) foraging efficiency of larger divers is not always greater than smaller divers, although the larger divers forage at the depth of higher prey density. These predictions, derived from the model, are consistent with the comparative studies of diving behaviour in marine birds.

A radio-collared, female black-footed cat (Felis nigripes) was followed for a total period of 575 hours, over seven observation periods spanning 18 months, in the Kimberley region of the Northern Cape Province, South Africa. Data on reproduction and scent marking were collected by direct observation. The predominant form of scent marking was urine-spraying, the frequency of which fluctuated during the year and seemed to be related to changes in the reproductive cycle. Marking frequency increased dramatically approximately one and a half months before mating, and conception of the first litter of the breeding season occurred at a low frequency during pregnancy, and was entirely absent when the cat was rearing young. This strongly indicates a primary function in the advertisement of female reproductive condition, although an additional role in the maintenance of social spacing is suggested. Scent marks were not restricted to the borders of the animal's range, but corresponded to those areas used most intensely during the year.

White-lipped peccaries (Tayassu pecari) and collared peccaries (Tayassu tajacu) are common ungulates of Amazonia that are integral to the ecosystem and are important sources of meat for local people. Information on the reproduction and productivity of peccaries is essential for implementing management practices that conserve peccary populations over short and long time-scales. This paper examines the reproductive biology of white-lipped and collared peccaries in the northeastern Peruvian Amazon in and around the Tamshiyacu-Tahuayo Community Reserve. Skulls and reproductive tracts of white-lipped and collared peccary were examined from hunted samples collected by local people, as part of a participatory wildlife management programme. In this Amazonian site both white-lipped and collared peccaries were in follicular and luteal stages year round. Similarly, conceptions, births and pregnancies were aseasonal for both species. Of white-lipped peccary females, 32.4% were pregnant (n = 219 adult females examined) compared with 46% of collared peccary females (n = 89 adult females examined). Overall, gross productivity was 0.53 foetuses/adult female for white-lipped peccaries and 0.89 foetuses/adult female for collared peccaries. Gross fecundity (number of female young produced/number of adult females) was 0.26 for white-lipped peccaries and 0.37 for collared peccaries. The estimated parturition–conception interval was 250 days (192–331 at the 90% confidence interval) for white-lipped peccaries and 129 days (80–205 at the 90% confidence interval) for collared peccaries. This study shows that reproductive productivity of white-lipped peccary is lower than collared peccary in the northeastern Peruvian Amazon. This difference in reproductive productivity has implications for management strategies, and suggests that white-lipped peccaries are more susceptible to the effects of hunting than collared peccaries.