The role of diet on the growth, survival and movement of red grouse Lagopus lagopus scoticus chicks was examined. We compared two areas of moorland in Scotland: a dry heath with a low density of red grouse and poor chick survival; and a wetter heath/bog with relatively higher red grouse numbers and higher rates of chick survival. There were no differences in clutch size or the proportion of eggs hatching between the two moors but brood survival was significantly lower on the dry heath. Radio-tagged hens with broods were monitored during the first 12 days following hatching; the chicks were captured, weighed and faecal samples collected. Invertebrate samples were collected within brood feeding ranges. Analysis of chick faeces was used to identify dietary components. Heather comprised the major dietary component on both moors. Invertebrates formed a higher component of diet on the wet moor, and this was positively correlated with growth rates, which in turn were positively correlated with chick survival. We present data from an experiment carried out in 1982, in which chicks showed higher growth rates with increasing insect availability. We also show that broods in which all the chicks survived (4–10 days) had smaller home-range areas than broods in which some of the chicks died during this period. We suggest that the differences in chick survival between the two populations were the result of variations in the abundance of invertebrates, particularly tipulids. The protein provided by a high invertebrate component in the diet is, therefore, an important determinant of the growth and survival of young red grouse chicks in some areas.

Comparative studies show that variation in sperm morphometry across taxa is associated with the environment in which sperm function, and the species' mating pattern dictating the risk of sperm competition. Accordingly, sperm have evolved to function in a non-self environment (in contrast to somatic cells) and sperm morphometry is predicted to be optimized independently of the individual male producing them, but is the result of selective forces arising directly from the fertilization and competitive environment in which sperm will operate. Males within a population are therefore under stabilizing selection to produce an optimal distribution of sperm sizes. The nature of this distribution was explored using consistent techniques to measure detailed sperm morphometry for 10 species in a range of taxa from insects to humans. Although we expected variance in sperm morphometry to be optimized by every individual male through stabilizing selection at a population or species level, we found the exact opposite; for every species examined there was significant variation between individual males in the total lengths of the sperm they produced. A significant variation is reported between individual males for every species in the sizes of each sperm head, mid-piece and flagellum component. The between-male variation exists consistently in wild, domestic and human populations, subject to a wide range of levels of inbreeding. In gryllid crickets sperm length is shown to be male-specific and is repeatable between successive ejaculates. Between-female variation in ova size (data are presented for trout) is explainable by individual female fecundity optimization strategies; however, the adaptive significance of widespread between-individual variance in male gamete size is counter-intuitive and difficult to interpret, particularly as the limited evidence available shows that sperm morphometry is not condition-dependent or resource-constrained. The differences, however, do suggest negligible influences from haploid expression in the development of sperm morphometry – if haplotypic expression were manifested we would expect more profound variation within a male's sperm population (to reflect the inherent within-male variance in haplotypes derived from recombination) rather than the significant between-male differences we found that suggests the diploid control of spermatozoal phenotype

The mode by which individuals disperse, and the cost of dispersal, are of great importance in attempts to understand variation in reproductive skew in animal societies. In this paper we report detailed information on dispersal and pack formation in banded mongooses Mungos mungo. Six pack fission events were recorded among 11 packs over 22 months. Pack fission occurred under two distinct circumstances. First, groups of individuals were evicted from their natal group as a result of intense aggression from other group members. A small fraction of group members was responsible for most of the aggression. Both sexes helped to attack and evict individuals from the group, and both males and females were driven out of their natal groups en masse. The second mode of pack fission occurred when groups of same-sex individuals left their natal group voluntarily to join dispersing individuals of the opposite sex, thereby forming new packs. Dispersing groups were more frequently involved in fights with rival packs of mongooses compared to established groups, and in one instance these fights seemed to be responsible for severe injury and increased mortality among members of a dispersing group. The observations of eviction provide one line of evidence that the presence of subordinates is sometimes detrimental to dominants, contrary to the assumptions of concession models of reproductive skew.

Colonies of the Mashona mole-rat Cryptomys darlingi are founded from a single reproductive pair of animals that are genetically unrelated by descent. All non-reproductive animals are the progeny of the reproductive pair. Non-reproductive colony members do not seem to be suppressed from reproduction at the level of the pituitary. In colonies in which the reproductive female is removed or dies, there is strict incest avoidance and the colony remains reproductively quiescent. Reinstatement of sexual activity in a queenless colony may be brought about in the laboratory by the introduction of unfamiliar and unrelated adult males. In the queenless colony under study, there was a marked change in the dominance hierarchy with an increase in Landau's index of linearity from 0.61 to 1.0 on the introduction of two unrelated males. The two new males became the most dominant within the colony. All previously non-reproductive females exhibited heightened urinary oestradiol 17β and progesterone concentrations on the introduction of the males. However, it was only the older and most dominant non-reproductive female that became the new reproductive female and produced a litter of three pups 70 days after the initial introduction.

The highveld mole-rat Cryptomys hottentotus pretoriae exhibits an extreme reproductive division of labour. Reproduction in this seasonally breeding social mole-rat is restricted to a breeding pair. The non-reproductive females seem to be physiologically suppressed from reproducing, whereas the non-reproductive males are restricted from sexual activity through incest avoidance. Circulating basal concentrations of luteinizing hormone (LH) between reproductive and non-reproductive females were not significantly different, yet the response to an exogenous gonadotrophin-releasing hormone (GnRH) challenge was significantly lower in non-reproductive females when compared to reproductive females. The mean basal LH concentration in non-reproductive females was not significantly different in and out of the breeding season. However, the magnitude of the LH response in non-reproductive females out of the breeding season was greater than in the breeding season. The ovaries of reproductive females showed little change with respect to season. However, reproductive females had enhanced follicular activity in comparison to their non-reproductive counterparts. This suggests that non-reproductive females are under stricter control from the reproductive female when she is pregnant. The tropical African mole-rats exhibit a continuum of socially induced infertility with differing social species inhabiting regions of varying degrees of aridity. In this spectrum, a predominantly behavioural repression is found amongst non-reproductive females in social mesic-adapted species, whereas a strictly physiological suppression is operative amongst non-reproductive females in arid-adapted social species. Here we show that the mesic-adapted highveld mole-rat does not fit this trend in that the non-reproductive females seem to be physiologically suppressed. We discuss this in light of the seasonality of breeding and the ecological constraints that may operate during times of drought.

Inter-sexual segregation between habitats or between sites within a habitat is very widespread in sexually dimorphic ungulates. As an explanation, it has been suggested that males, because of their larger forage requirements, are driven from preferred, high quality forage habitats into marginal habitats of lower forage quality but higher forage biomass by female competition (‘indirect competition hypothesis’). However, this hypothesis has hardly been tested. In the present study, we tested the indirect competition hypothesis for site segregation of red deer on the Isle of Rum, Scotland, within two vegetation communities: short Agrostis/Festuca grassland and Calluna heath. We predicted that: (1) males should choose sites within each vegetation community that are of higher forage biomass but lower forage quality, than sites selected by females; (2) the degree of inter-sexual site segregation should be highest within the vegetation community in which indirect competition was most intense. We found that the sexes were significantly segregated between sites within both vegetation communities, but males did not use sites of lower forage quality or of higher forage biomass than did females. Moreover, degree of site segregation was not significantly higher in the vegetation community in which competition was more intense (i.e. short Agrostis/Festuca grassland). We conclude that the indirect competition hypothesis cannot explain site segregation in red deer on the Isle of Rum.

Domestic lamb mortality on an open forested and alpine summer range in the municipality of Målselv in northern Norway was investigated. Two hundred and fifty-three lambs in four of the area's six flocks were randomly fitted with mortality transmitters and monitored throughout the summer grazing season from June to September. Total losses in the six flocks were 183 (22.9%) lambs and 20 (4.2%) ewes. The carcasses of 69 lambs, 36 of which had radio-collars, and six ewes were recovered. Of the collared lambs, eight (22%) died as a result of disease and 27 (75%) were killed by predators. Implicated predators included red fox Vulpes vulpes, lynx Lynx lynx, golden eagle Aquila chrysaetos and wolverine Gulo gulo. Diseased animals included those diagnosed with pasteurellosis, disrupted intestinal functions and advanced coccidiosis. The remains of one lamb were too decomposed for necropsy, though there was no evidence that it had been attacked by a predator. Factors associated with losses were identified using logistic regression. Age of lamb at time of release on the summer range and age of dam were statistically associated with lamb losses (P<0.05). Mortality was higher among older lambs and those of year-old ewes. Parameters commonly associated with lamb size and growth were not statistically associated with mortality. The negative association between lamb mortality and age of dam may be related to the quality of maternal care provided by ewes of different ages, particularly vigilance in the habitat of predators. Similarly, the positive association between mortality and age of lamb may be related to changing lamb behaviour, specifically increased distance from ewe, as lambs grow older and more independent. Predators, when present, are a major cause of mortality in free-ranging lambs, as in most wild ungulates.

This note presents plantar micro-tattooing (subcutaneous injection of Chinese ink) as a good alternative to toe-clipping, which is often used to identify individual rodents. The method was tested under laboratory conditions on voles Microtus arvalis from birth to sexual maturity. This easy, harmless and inexpensive technique could be used in the field, and not only on pups but also on adults of different species.

This paper provides a comparison of the landbirds of all main zoogeographical regions, based on the most recent (Sibley–Monroe) listing and classification of the world's birds. This classification arranges 9416 landbird species (i.e. excluding seabirds) into 2002 genera, 140 families and 23 orders. On this basis, the Neotropical region holds 36% of all known landbird species and 45% of genera, the Afrotropical region holds 21% of species and 24% of genera, the Indomalayan region 18% of species and 22% of genera, the Australasian region 17% of species and 23% of genera, the Palaearctic region 10% of species and 14% of genera and the Nearctic region 8% of species and 15% of genera. These major continental regions thus show 4.6-fold variation in species numbers or 9.1-fold variation in species numbers per unit area. The region of Oceania, comprising many Pacific Islands, holds only 2% of the world's bird species and 4% of genera. About 92% of all bird species on the continental parts of the Neotropical, Afrotropical and Australasian regions are endemic to those regions, compared to 64% of the Indomalayan, 54% of the Nearctic and 46% of the Palaearctic species. The Oceania region has the smallest number of endemics, but these form 87% of all species occurring naturally in this region. About 91% of all landbird species breed in only one zoogeographic region, another 8% in two regions, with the remaining 1% in three to seven regions. Only four species breed in all seven regions. Similarities in the species composition of different regions were compared using Jaccard and Simpson indices. As expected, each region shares the greatest number of species with the closest other region and the fewest species with the most remote region. As in previous analyses, the Neotropical and Australasian regions emerged as having the most distinctive avifaunas. Regions that hold large numbers of landbird species also hold large numbers of genera and families, as well as high species-per-genus and species-per-family ratios. Comparable levels of diversity thus extend through all these taxonomic categories. This implies that, whatever factors have promoted particular levels of avian diversity in the different regions, they are of long standing. As found in previous studies, species-per-genus and species-per-family ratios are lower in island than in continental avifaunas. No relationship is apparent between the size of each zoogeographical region and the numbers of species, genera and families found there; rather those regions with tropical forest have many more bird taxa overall than those without.

The analysis of life-history traits suggests that the age and size of female mammals at parturition will affect the birth size and survival of their offspring. We collected data from 252 mother–pup pairs of northern fur seals on Bering Island, Russia, during the 1994 and 1996 breeding seasons to determine the interrelationships among the mothers' age and mass, the sex of the pup, the parturition date, and the length and mass of the pup at birth. Among reproductive females of 19 years, mass increased with age. The mean mass of the oldest class of females (20–23 years) was lighter than the 16–19 year age group but not different from the mean mass of the 7- to 15-year-old females; a quadratic model of mass on age gave similar results, and indicated a maximum mass at age 19 years. We suggest that this may be an effect of a higher rate of survival among leaner animals. Female pups were lighter than males at birth. There was no evidence that the sex ratio of pups differed from 1:1 over the range of observed mothers' mass and age or parturition dates. Older mothers tended to give birth earlier than younger mothers, and heavier mothers earlier than lighter mothers. The relationship of the size of pups at birth and their mothers' age was adequately described with a quadratic model, which predicted a maximum size for mothers at age 12–13 years. The size of pups at birth and the size of their mothers was described with a logistic model which predicted that the size of pups increased for mothers up to 41 kg, with no further increase for heavier mothers. The total amount of variability in birth size explained by the combined models is < one-third of the total, which implies that other influences, such as the contribution of the fathers and individual variation, are also important. The relative maternal investment, measured as the ratio of pup mass to mothers' mass, ranged from 20% for younger and smaller females to 10% for older and heavier females. In addition, relative maternal investment was found to be higher than for other pinnipeds.

Allozyme and morphometric variation was studied in two populations of moles, Talpa europaea and T. romana, in an area of sympatric occurrence (Palazzo, near Assisi, central Italy) located along the known parapatric contact boundary. The electrophoretic analysis revealed 36 moles characterized by a genome of T. europaea, and 29 moles with a genome of T. romana. The extension of the overlap zone was c. 2 km along the north–south direction. Fourteen specimens recognized as T. europaea had an Ada allele typical of T. romana, while two specimens identified as T. romana were characterized by two alleles (at the Adh and Sdh loci) previously found only in T. europaea. The skulls of the specimens with introgressed alleles showed features intermediate between those typical of T. romana and T. europaea. However, the intermediate skull shape of the introgressed specimens did not correspond to an intermediate size between T. romana and T. europaea. The occurrence of individuals with introgressed alleles, and the lack of F1 hybrids or backcrossed individuals suggest that at present free interbreeding between the two species is unlikely, but that hybridization and backcrossing has occurred, probably when the species first came into contact.

Tropical seabirds have evolved a wide range of breeding regimes to fit with their local environment. The western Indian Ocean shows various oceanic situations, providing opportunities to link variations in breeding phenology with variations of the environment. The breeding seasons of seabirds at Europa Island (Mozambique Channel, western Indian Ocean) are analysed. Three oceanic, tuna-associated species (the sooty tern Sterna fuscata, the red-footed booby Sula sula, and Audubon's shearwater Puffinus lherminieri) breed during austral winter (June–October), whereas the red-tailed tropicbird Phaethon rubricauda breeds during austral summer (November–April). During winter, sea-surface temperatures are the lowest, subtropical waters are the closest to the island, and long-line catches of tunas are important. Thermal fronts occur during winter, in relation to the northward shift of subtropical waters. This is known to be favourable to tunas, and I suggest that the winter breeding of sooty terns, red-footed boobies and Audubon's shearwaters is because of an increase in the abundance of tunas. Geographic variations in the breeding phenology of sooty terns in the western Indian Ocean largely support the hypothesis that sooty terns take advantage of cool subtropical waters, when those waters are within their foraging range. The red-tailed tropicbird is a solitary forager, not associated with tunas. During the chick-rearing period, 40% of the mass of food brought to the chicks consists of dolphin-fishes Coryphaena spp. Those warm water, surface dwelling fishes are known to migrate in relation to sea-surface temperatures. Seasonal changes in the occurrence or vulnerability of dolphin-fish in the Mozambique Channel may have favoured a summer breeding regime in red-tailed tropicbirds at Europa Island. Further studies of the marine life of seabirds are needed to test these hypotheses and to learn more about the foraging ecology of tropical seabirds.

We describe the age structures of two neighbouring terrestrial salamander populations. The skeletochronological method was also used on larvae in utero and on new-born individuals. The age of adults was 8–24 years in population A, while males reached maturity at 3–5 years old and the youngest females were 6 years old in population B. Males and females from population B were also larger than those in population A. For the first time, lines of arrested growth (LAGs) were also found in the humerus of intra-uterine larvae and new-born individuals, indicating that young can spend up to 3 years in utero (population B) and up to 4 years (population A) before hatching. Growth of adults (fitted by the Bertalanffy model) also exhibited differences in growth coefficient (k) and mean asymptotic length (SVLmax) between sexes and populations. Local climatic conditions differed between the two areas of these populations and we hypothesize that the number of rainy days directly influences foraging during the short period of activity (< 3 months), leading to a delay in age at maturity, smaller length and growth rate, and increased gestation duration in the drier environment. The discussion is focused on proximate environmental influences on the variation of length and associated life-history traits in ectotherms, especially in terrestrial salamanders.

We studied the postnatal body weight gain and development of 11 male and nine female giant panda Ailuropoda melanoleuca cubs born at Beijing Zoo from 1985 to 1998. Growth rates of the cubs appeared to be sexually dimorphic from the fourth month after birth; the male grew slightly faster than the female cubs. Growth rates between artificially fed and naturally fed cubs were significantly different from the fourth month after birth. The growth rate of the artificially fed cubs was slightly higher than that of the cubs fed by their mothers, indicating that the substitute milk satisfied the nutrient needs of the cubs. The body length of the cubs increased rapidly after birth; 8-month-old cubs were three times longer than newborn cubs. Chest circumferences of 8-month-old cubs also increased to twice that of newborn cubs. Tail length relative to body length was reduced from 14.9% at birth to about 8.6% in 8-month-old cubs. Cubs started to grow teeth when they were 3 months old. By the age of 1 year, the cubs had fully grown deciduous teeth. The teeth formula of one 1-year-old cub was 2·1·3·0/2·1·3·0=24. We recorded the changes in fur colour, development of the sense organs and limbs of the giant panda cubs. Finally, we compared the body weight and life-history parameters of giant pandas with those of bears and raccoons and discussed the management regime for the care of captive-born giant panda cubs.

Lactating New Zealand sea lions (Phocarctos hookeri) have recently been reported to be the longest and deepest-diving otariid. An unusually large proportion of dives exceeded a theoretical aerobic dive limit, predicted from estimated oxygen stores and measurements of diving metabolic rate. We investigated swimming speed, a key variable in both the management of oxygen stores and foraging strategies, and its relation to diving behaviour in New Zealand sea lions. Diving behaviour was nearly continuous with short inter-dive intervals. Mean diving swimming speeds ranged from 1.6 to 2.4 m/s. Mean surface swimming speeds ranged from 0.9 to 1.8 m/s and were significantly lower than diving speeds in all subjects. New Zealand sea lions spend significant but variable amounts of time resting at the surface. Diving and swimming speed patterns were consistent with foraging on the benthos. Time in the foraging zone was maintained in deeper dives by increasing dive duration. This increased duration cannot be accounted for by a decreased metabolic rate resulting from slower swimming speeds, as speeds increased with the maximum depth of dives. Patterns of swimming speed and acceleration suggest the use of a gliding phase during descent. For most females, the extended duration of deeper dives did not impact on surface times, suggesting the use of aerobic metabolism. Females exhibited significantly slower swim speeds during the bottom segments of foraging dives than during descent or ascent. These findings suggest that swimming behaviour should be considered a critical component when modelling energetic costs for diving animals.