Observations of the rooting activity of wild boar in a holly-oak grove showed that in March–April the decrease of acorns in the diet (31%) was lower than their availability (82%). Moreover the occurrence of deep rooting events remains high despite the low occurrence of grass roots in the diet. These observations suggested that wild boar may exploit hoards of acorns collected by small mammals living in the study area (mainly wood mice Apodemus sp.). In order to test this hypothesis two experimental trials were set up to: (1) investigate whether wild boar were able to locate acorns buried in the ground (range 0–30 cm) and (2) establish if mouse burrows were more likely to be excavated than locations without burrows. The results clearly show that wild boar actively search for buried acorns, mainly in March (59% vs 31% in April and nothing in May) and that burrows are excavated significantly more than locations without burrows (ratio 2:1, respectively). Moreover, locations with burrows are characterized by a decline of rooting activity as a function of the distance from their centre (P = 0.02), which is absent in the control locations (P = 0.74). Our results show that wild boar are able to partly compensate for a reduced above-ground availability of acorns by predating on hoards collected by small mammals. Since this occurs during a critical period for female wild boar when they are giving birth and lactating, this behaviour may strongly influence the population dynamics of both wild boar and small mammals.

This study describes and quantifies the microsculpture and ultrastructural design of the neck membrane of adult Odonata using scanning and transmission electron microscopy. The membranous cuticle has a complex pattern of microfolds, which appear to have a specialized mechanical function. The membrane has two layers of cuticle: the epicuticle and exocuticle. The outermost layer is the electron-opaque epicuticle, which repeats the shapes of the microfolds. The epicuticle has no fibrillar elements. The exocuticle is electron-lucent and rather thin (0.5–1.5 μm) compared with the sclerite cuticle. The cuticle microfibrils in successive lamellae are at angles to each other. The epidermal cells underlying the membrane have an electron-lucent matrix filled with electron-opaque spherical vesicles of 0.1–0.4 μm in diameter. The behaviour of the membrane folds under loading was studied by shock-freezing experiments; these showed that the shape of the folds changed in response to head movements, and stretched under loading. A comparison of the surface patterns of the membrane in 10 odonate species from seven families (Zygoptera: Coenagrionidae, Lestidae, Megapodagrionidae; Anisoptera: Cordulegastridae, Aeshnidae, Corduliidae, Libellulidae) had not revealed any correlation of the measured parameters with the size, sex or systematic position of species studied.

This paper reports the capture of seven adult Pipistrellus nathusii including a lactating female mist-netted in July 1997 in Varese province (northern Italy). This record represents the first identification of a breeding female Nathusius' pipistrelle in the south part of the Alps. Other data on the reproduction of this species in Europe are discussed in order to reconsider its distribution and breeding sites.

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.

Seasonal regression of testes and epididymides is described for 161 mature harbour porpoises Phocoena phocoena, L. from the Bay of Fundy and Gulf of Maine from June to December 1984–1995. Based on histological appearance and size of gonads, testes are fully active from late June until at least the end of July, spanning the estimated period of conceptions. During testicular regression, spermatocytes and round spermatids disappeared first from the lumina of seminiferous tubules, followed by the gradual disappearance of spermatozoa. Ultimately, all signs of spermatogenesis were absent, but tubules retained an alternating lining of Sertoli cells and spermatogonia. Testicular and epididymal mass, testicular length and seminiferous tubular diameter decreased approximately 3.5, 1.5 and 1.5 times, respectively, from peak production to full regression and this decrease was best described by a quadratic function. During early July when most females are ovulating, all males had active testes; variation in the degree of regression among males increased as the season progressed. This may reflect a trade-off between the costs of maintaining active testes at 4% body mass and the probability of successful fertilization. Testes are completely regressed during the winter, suggesting that few reproductive opportunities exist during this season. Unlike some other odontocete species, testicular mass of porpoises is a good indicator of breeding season.

Diets of the Eurasian badger Meles meles were studied by scat analysis in three localities of eastern and central Poland, representing pristine forests and rural landscapes with little wood cover. In spring, earthworms constituted 82–89% of biomass consumed by badgers in all localities. In summer and autumn, the proportion declined to 56% in the pristine forest, and to 24% in the mosaic of forests, fields, and orchards. Supplementary resources at this time were amphibians (in forests) or garden fruits (in a rural landscape). Literature on badger diet composition in Europe showed that earthworms and vegetable matter were the dominant food types of badgers, but their roles changed with latitude. The share of earthworms grew from nil at 37–40°N to 40–70% at 55–63°N; the opposite trend was observed for vegetable food. Also, of two major supplementary resources, vertebrates were taken by badgers more often at northern latitudes, and insects in the south. In consequence, the food niche of badgers was broadest at 45–55°N and became narrow at both lower and higher latitudes. Moreover, in the temperate zone of Europe, the degree of habitat transformation by humans significantly affected badger feeding habits. In forests, badgers relied predominantly on earthworms (on average, 62% in diets). In farmlands and pastures, earthworms and plant material (usually garden fruit and cereals) played equally important roles (34% each). This biogeographical pattern of feeding habits can be explained by variation in abundance and availability of earthworms.

The habitat-related microgeographical body size variations in red foxes Vulpes vulpes living in two separated areas of Mediterranean Spain, the Central Ebro Valley (CEV) and Doáana National Park (DNP) are analysed. In both areas, samples taken from good and bad fox-habitats were compared regarding body weight and head and body length. In the Ebro Valley, foxes collected in the good habitat were heavier (14%, P < 0.001 for males; 9%, P < 0.01 for females) and larger (4%, P < 0.01 for males; 1%, P < 0.05 for females) than those collected in the bad habitat. In Doáana, males from the good habitat were 19% heavier (P < 0.01) and 3% longer (P < 0.05) than those from the poorer one. The average weight and size of DNP vixens did not show significant differences, although both are higher in the good habitat. It is shown that body size of adult foxes can vary, linked to habitat change even across short geographic distances. Some tentative explanations for these results are discussed.

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.

We examined intra- and inter-litter variation in larval life-history traits in relation to maternal weight and date of larval deposition in a population of fire salamanders Salamandra salamandra terrestris in north-western Switzerland. We also examined whether the timing of larval deposition by female fire salamanders is an adaptive strategy to the changing conditions of a temporary brook. Litters differed in mean weight at birth, weight at metamorphosis, and duration of the larval period. Mean weight at birth tended to be larger in litters deposited later in the season than in those deposited earlier. Large neonates reached metamorphosis more rapidly than small ones. A short larval period resulted in a small size at metamorphosis, indicating a fitness trade-off between duration of the larval period and size at metamorphosis. Within litters, successively-born larvae tend to decrease in body size, especially in litters with a relatively large variation in weight at birth. The results suggest that environmental factors such as floods or drying out of the brook may influence the timing of larval deposition.

During locomotion, lizards and crocodilians generally use a more sprawling limb posture than most mammals and experience substantial axial rotation of the femur. Consequently, the limb bones of most mammals are loaded predominantly in bending, but the limb bones of lizards and crocodilians are loaded primarily in torsion. As body size increases, torsional shear stress in limb bones is expected to increase more than bending stress; therefore, limb bone diameters of lizards and crocodilians might be expected to scale with relatively greater positive allometry than limb bone diameters of mammals that use upright posture. To test this hypothesis, scaling patterns of the femur and tibia in lizards (iguanians and varanids) and crocodilians were compared with patterns in felid and canid mammals, using both non-phylogenetic statistical methods and phylogenetically independent contrasts. Comparisons with theoretical models indicate that size-related changes in limb bone geometry do not completely compensate for size-related increases in limb bone stress in the lizard or crocodilian lineages examined. Unless lizards and crocodilians compensate for size-related increases in limb bone stress through other mechanisms (e.g. changes in limb kinematics or the mechanical properties of limb bones), limb bone stresses are predicted to be relatively greater among larger species of these lineages. However, limb bone diameters appear to scale with greater positive allometry (relative to body mass) in varanids than in iguanians, suggesting that larger lizard lineages might compensate for increased stress through changes in bone geometry to a greater degree than smaller lineages. Allometric scaling patterns for many limb bone diameters among iguanians are more similar to those of felids and canids than to those of varanids; thus, sprawling locomotor habits do not correlate clearly with a particular pattern of limb bone scaling. This suggests that similarity of interspecific scaling patterns of limb bone lengths and diameters is not sufficient to justify inferences of similar locomotor function.

Population dynamics of the spiny country rat Niviventer coxingi were studied by mark–recapture methods from January 1982 to May 1983 in a subtropical montane forest at Chitou, central Taiwan. The population density was < 8 rats/ha. The annual pattern of population fluctuation was characterized by summer increase, autumn peak and spring decline. Adult recruits occurred mostly in summer and autumn 1982, whereas young rats joined the population as three cohorts: winter 1981, summer 1982 and winter 1982. Growth patterns differed between winter and summer cohorts, which was attributed mainly to the slow body weight increase in summer cohort males. Males, either adult or juvenile, survived the winter better than females, resulting in the shorter lifespans and the lower number of females in the population. Life-history traits in female N. coxingi, i.e. short reproductive lifespan, few litters per life time and prolonged maternal care, along with the low breeding intensity, rendered the number of females the limiting factor for population increase. However, females may improve the survival and maturation of their offspring by prolonged maternal care.

Analysis of early development of the head of the Australian lungfish Neoceratodus forsteri indicates that no mesenchyme cells in this species enter the embryo as neurectoderm cells, originally positioned between presumptive ectoderm and primordial neural tissue of the embryo. Neural tissue in N. forsteri forms initially as a plate of columnar cells, flanked by raised folds of ectoderm, that sinks below the level of the ectoderm and forms a deep trough. Neural tissue separates from ectoderm, and fuses below the ectoderm to form a neural tube with cells arranged around a small central cavity. Subsequently, ectoderm unites to form a complete cover over the neural tissue. No migrating cells leave the ectodermal–neural junction during this process. No unsegmented column of cells appears dorsal to the neural tissue, before migration, as in teleosts and lampreys of equivalent stages. Neuromeres and tracts of cells leaving the central nervous tissues can be demonstrated in the developing neurula, but these are derived from neural tissue alone and appear after the formation of the neural keel is complete and neural structures have begun to develop. Mesenchyme cells are already present in large numbers, and are apparently derived from enterotomy or enter the embryo by involution at the blastopore. This finding explains previous experimental results in embryos of N. forsteri, which demonstrated that removal of cells from the margin of the neural folds, where higher vertebrate neural crest cells appear, apparently has little influence on the development of pigment cells or of skeletal and dental structures of the head.

In this study 529 fallow deer fawns were captured and weighed at Doñana National Park, Spain. An annual index of male-biased maternal investment (MBMI) was calculated, and this index was found to vary in relation to environmental factors. Thus, the level of MBMI was sensitive to fluctuations of autumn rainfall and the male-biased maternal investment carried out by mothers in the previous year (MBMIP). Our results reveal that those factors related to the female's body condition at the beginning of gestation have a high contribution to the variation of differential pre-natal maternal investment. It has been hypothesized by other authors that male-biased maternal investment is limited by the level of total maternal expenditure and these authors classified the fallow deer as a species near to its maximum reproductive effort, in which no sex-biased maternal investment exists. Our study reveals that male-biased maternal investment in fallow deer does exist and supports the hypothesis that sensitivity of maternal investment to environmental conditions could be expected to occur in species with high reproductive effort and sex-biased maternal investment.

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.

Caviomorph rodents stand out by showing long gestation periods and by producing few, extremely precocial young. This study compares the energy cost of gestation vs lactation in the guinea pig Cavia porcellus. It tests whether the long gestation period (68 days) relative to the total period of maternal care (88 days) of this species results in a high overall energetic efficiency of reproduction. Although maternal net production during gestation was as high as during lactation, the net energy cost of gestation was much lower than the energy cost of lactation. Mothers' average increase in energy intake (above the non-reproductive level) was only 16% during gestation, but 92% during lactation. Similarly, the peak in maternal energy intake was low during gestation (2.4 times basal metabolic rate) compared to the peak during lactation (3.7 times basal metabolic rate). Consequently, the efficiency of energy conversion into offspring tissue during gestation (62%) was almost twice as high as the efficiency during lactation (35%). The results agree with the hypothesis that a prolonged gestation period increases the overall energetic efficiency of reproduction.

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.

In the Canary Islands five extant and two extinct giant lacertid lizards belonging to the endemic genus Gallotia are known. A comparative study of the living and subfossil specimens from the Western Canary Islands demonstrates that the extinct giant species Gallotia goliath and Gallotia maxima are synonymous with the living Gallotia simonyi. Characters formerly used in the diagnosis of the extinct species and subspecies fall within the range of intraspecific variation (ontogenetic and individual) of the living species. The only significant difference between living and subfossil populations of G. simonyi is size, and there is strong evidence to suggest that the reduction in size in living populations reflects shorter life expectancy, a factor that should be taken into account in the current conservation projects on this species.

An alternative to the cold-climate model for the evolution of viviparity is that the impetus for the initial transition from oviparity to viviparity is not an increase in the duration of egg retention but a shift in the location of nests to more superficial and thus warmer locations in the soil profile as temperature declines with increasing altitude or latitude. Shallower nest placement, however, would lead to increased egg mortality as a result of physiological stress or predation, and enhanced egg mortality would thus provide the initial benefit of extended egg retention. To test this hypothesis, I examined the thermal biology of three species of Sceloporus lizards living at high altitudes: S. virgatus (1800 m), S. aeneus (2800 m), and S. bicanthalis (3200 m). The oviparous S. virgatus and S. aeneus females laid eggs at depths of 6 and 2 cm, and mean body/nest temperatures were 24.6/25.2 °C and 19.9/20.8 °C, respectively. Because the initial increment in the duration of egg retention is presumably short, females of these oviparous species cannot initially keep their eggs appreciably warmer than they would be in nests. In contrast, mean temperatures of simulated nests (17.6 °C) of the viviparous S. bicanthalis were similar to the 17 °C low temperature threshold for development, and temperatures in some nests fell below freezing at night and rose to lethal levels during the day. Mean body temperatures of S. bicanthalis females were 20.1 °C; eggs retained during the entire developmental period would hatch 17 days sooner than they would if laid in a nest. Extended egg retention at the highest elevation site would thus provide two benefits: reduced mortality of eggs and accelerated development relative to that in a nest. These benefits, however, accrue because of the initial shift of nests from deeper to more superficial depths in the soil profile.

The use of a seaweed habitat by red deer Cervus elaphus L. on the Isle of Rum, Scotland, was examined in detail. New information is provided on diet selection, timing of seaweed use relative to tides, inter-individual differences in seaweed use, and sex differences in site use within the seaweed habitat (‘site segregation’). Interestingly, seaweed use by adult males and females was closely correlated to that of their mothers. This implies that deer ‘learn’ early in life to include seaweed into their diet. Formerly, it has been suggested that male inferiority in indirect competitive ability relative to females causes site segregation in dimorphic ungulates (‘indirect competition hypothesis’). The observed pattern of site segregation within the seaweed habitat was used to test the hypothesis, which predicts that males should be found at sites where they can achieve higher intake rates, but where forage quality is lower than at female sites. With respect to seaweed use, the hypothesis further predicts that segregation should be lower within the seaweed habitat than within terrestrial vegetation communities, and that males should time seaweed use earlier (relative to the tide) than females. This is because seaweed availability is more subject to tidal rhythm than to indirect competition in comparison to terrestrial habitats. Males and females used different bays, and within bays they used different fractions of seaweed. However, male-preferred sites did not yield higher intake rates and were not of lower forage quality than sites preferred by females. Moreover, segregation was not lower within the seaweed habitat than within terrestrial vegetation communities, and males did not time their seaweed use earlier relative to the tide than did females. The indirect competition hypothesis could not explain the observed pattern of site segregation. Other factors, such as sex differences in sheltering or anti-predator behaviour, or social harassment, could be responsible instead.