The effects of mountain lion Puma concolor predation on guanaco Lama guanicoe mortality was investigated during the historically severe winter of 1995 in Torres del Paine National Park, Chile. The 45 guanaco carcasses located represented 3% of the entire guanaco population of which 74% were mountain lion kills, 13% died from malnutrition, 2% died from fence entanglement and 11% died from unknown causes. Depleted bone marrow fat was observed in 20% of all carcasses. The number of guanaco deaths differed among sex and age classes, particularly in juveniles (< 1 year of age), which died more often than expected (P < 0.001). Fresh guanaco carcasses (n = 19) killed by mountain lions were located in tree and shrub habitats 79% of the time and were significantly greater than expected values based on the relative availability of these habitats (P < 0.001). Observations of the spatial distribution of mountain lion kills and guanaco mixed-sex groups were similar (P = 0.10), suggesting that mountain lions responded to winter migratory movements made by guanacos. Overall, adult guanacos experienced surprisingly lower levels of mortality (adult male = 1%, adult female = 2%) than expected, despite the severe winter conditions, while juveniles experienced higher levels of mortality (13%) than expected. In comparison to other years (1991–96), the severe winter of 1995 (i.e. this investigation) had the greatest total mortality for juveniles, although the proportion of deaths caused by mountain lion predation for juveniles was greatest during other winters.

This study investigated species recognition based on bark calls and full threat calls (FTCs) in three fur seal species, Antarctic Arctocephalus gazella, subantarctic A. tropicalis and New Zealand A. forsteri, that breed sympatrically and hybridize at subantarctic Macquarie Island. Bark calls, which are produced by males in male–female interactions, were more species-specific than their full threat calls, suggesting that bark calls could be used in species recognition and female mate choice. Further, the bark calls of A. tropicalis were more species-specific than those of A. gazella and A. forsteri, suggesting that divergence of calls between species is a consequence of phylogenetic distance, or has resulted from sexual selection through female mate choice. We believe the latter is more probable as we did not observe similar divergence in the FTCs of males. As such, the highly divergent bark calls of A. tropicalis may have resulted from sexual selection that has promoted pre-mating isolation via the process of reinforcement.

Through interspecific hybridization and subsequent backcrossing, genes and genomes may be transferred over the species barrier. In Sweden, the introduced brown hare Lepus europaeus hybridizes with the native mountain hare L. timidus. To investigate the direction and the extent of transfer of mitochondrial DNA (mtDNA) between the species, the mtDNA haplotypes were screened in 522 brown hares and 149 mountain hares from areas of sympatry and allopatry. A total of 51 brown hares with mountain hare mtDNA, but no mountain hares with brown hare mtDNA were detected. Thus, mtDNA transfer over the species barrier is directed from mountain hares to brown hares. We argue that frequency-dependent hybridization and/or interspecific male competition mediates this directionality. Further, the percentage of brown hares with transmitted mountain hare mtDNA was lower in areas of former species sympatry (0.6%) compared to areas of current sympatry (15%). Thus, the transferred mtDNA may disappear from brown hare populations if there is no continuous input through hybridization. We suggest that specimens with an alien mtDNA experience a fitness reduction as a result of a functional incompatibility between the cytoplasmic mitochondrial genomes and the cell nucleus.

In southern Norway, population fluctuations of the herbivorous bank vole Clethrionomys glareolus and the granivorous wood mouse Apodemus sylvaticus were analysed in relation to mast seeding of bilberry Vaccinium myrtillus, sessile oak Quercus petraea and Norway spruce Picea abies. Bilberries ripen in August, acorns are dispersed in September, whereas spruce seeds are usually dispersed during winter or spring. The bilberry index of both the current and previous year contributed significantly to explain the population growth indices of bank vole. The spruce seed index significantly influenced only the bank vole, whereas the acorn index significantly influenced only the wood mouse, apparently through increased winter survival. Because of the lack of significant responses to bilberry masting by granivorous wood mice, we conclude that the most likely explanation for the observed peak populations of bank voles in post-mast years of bilberry is that high seed crops have a positive influence on the chemical composition of bilberry plants, which are important as food for bank voles during winter.

In recent years, laboratory measurements of locomotor performance of small organisms have been used increasingly to study questions in behavioural, physiological, and evolutionary ecology. Although a valuable tool that can provide insight into organismal function, behaviour, and adaptation, this approach is potentially limited by the quality of the data collected. Using the study of maximum sprint speed in lizards as an example, common problems in methodology that may confound interpretation of performance studies are discussed.

Senescence is the internal physiological deterioration that accompanies advancing age. Evolutionary hypotheses predict that rates of senescence should vary directly with extrinsic mortality and inversely with fecundity. If so, naked mole-rats (Heterocephalus glaber) should live a long time (senesce slowly) because in nature they inhabit heavily protected burrows, and large, old breeding females make disproportionate reproductive contributions. In addition H. glaber has an exceptionally low metabolic rate, which may reduce oxidative stress. We have maintained naked mole-rats in captivity since 1974. Here we report that individuals can live a very long time: many are alive after more than 20 years and some are 26 years old (and counting). Although we do not yet know how long naked mole-rats can live, they already are older than the maximum longevity of all but one of 156 rodent species that have been maintained in captivity from birth to death.

Using a porthole camera the architecture of the warrens of the southern hairy-nosed wombat Lasiorhinus latifrons was examined at two sites in southern Australia. The complexity of warrens varied from simple, single-entrance warrens to a system 89 m long with 28 entrances. Logging of deep tunnel temperatures showed daily ranges of < 1 °C over periods in which surface temperatures ranged up to 24 °C, but mean tunnel temperatures varied 15.9 °C between winter and summer. Humidity gradients were maintained between the tunnel and the surface and depended on the length and depth of the tunnel. Oxygen and carbon dioxide levels were similar to those in free atmospheric air in unoccupied tunnels, but in occupied tunnels reached 16.3% and 3%, respectively. There is no specific orientation of tunnel entrances or defined mound shape. Wombat warrens ameliorate surface conditions in habitats of low humidity and high temperatures while humidity advantages promote the construction of warrens beyond the requirements for temperature modulation.

This work examines whether stepwise discriminant function analysis of a suite of craniodental variables enables feeding behaviour and habitat preferences to be identified in fossil ungulates. There are several morphological features of the ungulate skull, mandible and dentition that are well correlated with dietary adaptations, and thus can be used for estimating the feeding ecology of extinct taxa. However, most studies have followed an univariate approach for characterizing the relationship between diet and craniodental structure in extant ungulates (but see Pérez-Barberia & Gordon, 2001), even though such a relationship has been revealed to be complex because of functional, phylogenetic and biomechanical constraints. In this paper a multivariate perspective is followed, developing quadratic discriminant functions for pairwise comparisons of dietary/habitat groups in modern species. Given that the stepwise method for selecting the morphological variables to be included in the algorithms was used, alternative discriminant functions are provided. Results obtained show that these algorithms reclassify correctly the species according to their feeding and habitat ecology, and thus may be useful for obtaining reliable palaeoautecological inferences (i.e. those related to the life style of extinct species, such as feeding ecology and habitat preferences) when applied to extinct ungulate taxa.

Although most snake species are tropical, very little is known about their biology. We monitored reproductive histories of individually marked natricine colubrid snakes (keelbacks, Tropidonophis mairii) for 18-months in a tropical Australian floodplain. Our data provide the first unambiguous records (for any snake species) of individual females in a natural population producing multiple clutches of eggs during a single breeding season. The snakes bred throughout drier months of the year. The mean size of reproducing females decreased over the season, whereas relative clutch mass increased significantly over the same time period. Larger females produced eggs that were not only larger, but also shorter and wider, than those of smaller females. Despite producing two clutches in short succession, female keelbacks grew over the intervening period. Thus, they switch from ‘capital breeding’ (building up stores of energy during the wet season to use for reproduction in the dry season) to ‘income breeding’ (relying on recently ingested energy to support both growth and reproduction during the dry season). Two females marked at hatching were recaptured as breeding adults <12 months later, confirming that maturation is attained more rapidly in this species than in temperate-zone natricines.

This study assesses the pattern of occurrence of a generalist species, the Eurasian badger Meles meles, in forest fragments located in agricultural landscapes of central Spain with a coarse-grained pattern of fragmentation (<20% forest cover in the landscape). Four forest regions (n = 139 forest fragments) were sampled. Badger presence/absence in forest fragments was studied in relation to: forest size, isolation and vegetation structure. Badgers were tested to see if, despite their habitat generalism, they were negatively affected by forest fragmentation in this type of fragmented landscape. Results indicated a strong and significant effect of fragment size on badger occurrence (presence was rare in forest fragments <100 ha) and an important effect of isolation at a local scale. The response of badgers to forest fragmentation in Spain is quite different to the response in other European landscapes. In Spain, badgers cope with a divided coarse-grained landscape where suitable habitats are embedded in a largely unsuitable matrix (cereal croplands). In contrast, in Britain or central Europe, badgers may be benefited by forest clearances in a heterogeneous but non-divided landscape where small woodlots are separated by a matrix of good quality (mainly pastures) and fragmentation produces fine-grained mosaic landscapes where food and den sites are simultaneously enhanced. Species' response to forest fragmentation may strongly depend on the pattern of fragmentation and, in coarse-grained fragmented landscapes, generalist species may be affected in the same way as specialist ones.

The resource dispersion hypothesis (RDH) proposes that in a spatially and temporally heterogeneous environment the territory size of social carnivores increases as the dispersion of limited resources is more widely spaced, whereas group size is limited, independently, by the richness or abundance of those resources or key habitats. To assess if white-nosed coatis Nasua narica behave in accordance with the RDH, the relationship between home-range size and spatio-temporal availability of resources in Mexican tropical dry forests with marked seasonal rainfall was examined. Specifically, home-range sizes were compared at two study sites that were broadly similar but contrasting in resource abundance and dispersion. Home-range estimates for seven white-nosed coati bands varied between 45 and 362 ha. Home-range size did not correlate with food resource abundance and was better explained by the dispersion of water sources during the dry season. Average home-range size was three times greater at the site where water sources were more widely separated during the dry season. These results are in accordance with the predictions of the RDH, and provide an example where the critical resource determining range size and configuration is water.

Vocalization is an important component of male reproductive behaviour in a wide range of animal taxa. In some species there is considerable intraspecific variation of call characters partitioned on a regional basis. Such ‘regional accents’ could originate from cultural or genetic evolution and have been widely studied in birds. Amphibians, however, have limited learning abilities, and where regional accents occur in this group they are primarily a consequence of genetic evolution. This raises the possibility that regional variations in anuran call characters might be informative about phylogeographic history. Microsatellite studies of the pool frog Rana lessonae have been used previously to infer patterns of post-glacial colonization in Europe, with unexpectedly complex implications for northernmost populations of this species. Therefore, regional variation in call characters of the pool frog was quantified and the pattern observed was concordant with the differentiation of a distinct northern clade as implied by the microsatellite study. We therefore conclude that regional accents in this amphibian are useful phylogeographic indicators of distribution history.

Examples of the ocular, digestive gland and brachial end-organ photophores of specimens from all 13 cranchiid genera are described. The cranchiine and taoniine subgroups have different ocular photophore morphologies, but very similar brachial end-organs in adult females. Most taoniines have ocular photophores that contain large numbers of crystalloids, but these are lacking in Helicocranchia and Sandalops. There are no crystalloids in cranchiine ocular photophores, in taoniine digestive gland photophores (Megalocranchia) or in the brachial end-organs of both groups. The cranchiine Leachia atlantica uniquely has one group of photocytes that contain aggregates with some similarities to the taoniine crystalloids. The end-organs of mature females have a glandular structure; the deciduous photocytes are structurally different from those present in the ocular or digestive gland photophores. The reflectors of Sandalops and Megalocranchia contain unusual arrangements of iridosomal platelets. End-organs lack any reflective structures. The comparative anatomy of the photophores supports the separation of the cranchiine and taoniine groups but the ultrastructural detail provides common links between the two.

In response to the interplay between variation in food quality and energetic demands, the foraging behaviour of captive green-backed firecrown hummingbirds Sephanoides sephaniodes was studied. Hummingbirds were exposed to two temperatures (25°C vs 15°C), two food qualities (0.5 vs 0.75 m sucrose solutions), and two costs of feeding (birds were provided with feeders with and without a perch). Food selection and consumption were measured, as well as time budgets and metabolic rate while feeding. We predicted that when given a choice, birds would minimize the cost of feeding by selecting feeders with a perch and with a high sugar concentration. However, rather than increasing energy consumption when energy availability was low and thermoregulatory demands were high, hummingbirds remained perched. They reduced feeding and spent most of their time perching. Our results identify a novel behavioural and physiological strategy in hummingbirds. These birds seem to shift their foraging behaviour depending on thermoregulatory and feeding costs. When these costs are high, rather than matching them with increased energy consumption, hummingbirds reduce energy costs by reducing activity. They seemed to adopt the following strategy: when food quality was high and thermoregulatory demands were low, they adopted a high-expense lifestyle. In contrast, when thermoregulatory costs were high, they adopted an energy conserving strategy even when food quality was high. We hypothesize that limitations imposed by physiological processes may explain why animals do not forage during all available time and why under some circumstances they choose foraging behaviours with lower rates of net energy gain.

Specialization for a locomotor behaviour may affect limb bone morphology throughout ontogeny. Ontogenetic development of the limb skeletons of two mammalian species, which are behaviourally specialized for the half-bounding gait (Chinchilla lanigera and Oryctolagus cuniculus), were compared to two similarly-sized species which are not specialized for half-bounding (Rattus norvegicus and Monodelphis domestica). Limb bone lengths and anteroposterior diameters (mediolateral diameters for the radius and metacarpal) were measured from radiographs taken throughout the ontogeny of each species. Body mass was also measured repeatedly during growth. Bone measurements were regressed against body mass, as well as forelimb bone length vs serially homologous hindlimb bone length, bone length vs total limb length and bone length vs width. Similar comparisons were made among adults of each species using ratios. Although there were many significant differences among species, overall there were few consistent differences in adult scaling ratios or ontogenetic allometry slopes between specialized and generalized groups. Adult specialized half-bounders had significantly narrower tibiae and metatarsals than the gait-generalized runners. Specialized half-bounders usually had similar slopes for hindlimb length vs width ontogenetic comparisons, but the non-specialized species did not group together. However, there were two patterns that occurred among all four species: (1) hindlimb bone lengths nearly always grew faster than the serially homologous forelimb bone lengths in all species; (2) proximal elements usually increased in length proportionally faster than distal elements. In conclusion, small mammals may share strong developmental constraints that govern their relative growth rates. It is also likely that there are different selective pressures on juveniles and adults, but that these selective pressures may not be different between specialized and unspecialized runners during ontogeny.

Life-history details of the live-bearing Peripatoides novaezealandiae (Hutton) were obtained by measuring and dissecting field collected animals. As in other studies, the sexes were found to have different demographics. Sex-specific weight frequency distributions and regression of weight vs length suggest sex differences in patterns of growth and/or mortality. Mature males were smaller than mature females; females apparently undergo a further period of growth between maturity and the onset of embryo production. The sex ratio of the whole sample was female biased; the sex ratio in the smallest size class was 1:1, and then oscillated from female- to male-, and then back to female-biased as size increased. Embryos were unable to be sexed. The sex ratios in individuals of mature (i.e. mating) size, and of reproductive size, were both 1:1. Females, especially but not exclusively before the onset of embryo production, had widely varying numbers of sperm in their haemolymph, indicating dermal-haemocoelic sperm transfer. These data also suggest that females are able to mate throughout life. Numbers of sperm in spermathecae of females were negatively correlated with body size. Fecundity increased with size in both sexes, somewhat more so in females. Embryo weight was correlated with maternal weight only at the beginning of the embryo's development. Rotting logs containing small populations contained a disproportionate number of large females.

Spectral and temporal features of echolocation calls emitted by 22 bat species from Italy (three rhinolophids, 18 vespertilionids and the molossid Tadarida teniotis) are described. Time-expanded recordings of calls from 950 bats of known identity were examined. Rhinolophus ferrumequinum, R. hipposideros, R. euryale and T. teniotis could be identified by measuring the call frequency of highest energy (FMAXE). Quadratic discriminant function analysis with cross-validation was applied to calls from the remaining 18 species. A function based on start frequency (SF), end frequency (EF), FMAXE and duration (D) provided a correct overall classification of approximately 82%. A classification model at genus level that also comprised middle frequency (MF) and inter-pulse interval (IPI) reached 94% correct classification. Two separate discriminant functions were devised for species emitting FM (frequency modulated) and FM/QCF calls (i.e. calls consisting of a frequency-modulated component followed by a terminal part whose frequency is almost constant) respectively. The former function included SF, EF, FMAXE and D and provided an overall classification rate of 71%; the latter comprised EF, MF, D and IPI, and reached 96%. The functions may be applied to bat habitat surveys in southern Italy since they cover most of the species occurring in the area.

We tested the hypothesis that the number of presacral vertebrae in lacertid lizards has evolved to meet requirements set by the structural habitat. The idea was that lizards from cluttered habitats (densely vegetated areas, stony walls and hills, rocks) would be aided by a flexible backbone with many vertebrae, ensuring manoeuvrability, whereas lizards from open habitats would require stiffer vertebrate columns, with relatively few vertebrae, favouring speed and acceleration capacity. In contrast to earlier findings in fishes and snakes, evolution of vertebral number and body size was uncorrelated in lacertid lizards. Body size also did not differ between structural habitat types (open areas, densely vegetated areas, vertical elements). Traditional analysis of variance suggests strong differences in vertebral counts between species from open areas and cluttered areas, the latter having higher numbers of presacral vertebrae. When adequate phylogenetic analyses are used, differences remain significant although the level of significance is considerably lower. Tests of the mechanistic relationships between vertebral number, bending ability, and manoeuvrability, and assessment of the relative importance of manoeuvrability and speed in habitats with varying degrees of impediment are needed to reveal the evolutionary path that has led to the differences in vertebral number.

Many simultaneously hermaphroditic land snails have sperm digesting glands and multiple sperm storage organs, which it is suggested give the sperm recipient control over the number of sperm accepted and hence fertilization. In order to increase fertilization success, the sperm donor should manipulate the recipient to accept more sperm, especially so in situations of sperm competition. In helicid snails, the love dart optionally pushed into the partner's body during courtship, has been suggested to be such a manipulative tool. We investigated the influence of the sperm donor's size, sperm volume transferred and dart pushing on the volume of allosperm stored by the recipient in virgin Arianta arbustorum. In addition, we were interested in sperm storage patterns within the spermathecae. Fifty per cent of the snails already possessed a dart and tried to use it. However, most of them missed the partner. The main tubule always contained more than 50% of the total amount of sperm stored. Otherwise sperm storage patterns were very variable. The volume of sperm stored was significantly influenced only by the number of spermathecal tubules. The significance of spermathecal morphology for sperm storage needs further exploration.

Patterns of reproductive phenology and temporal variation in species composition and age structure were investigated for a sample of terrestrial leaf litter frogs from a lowland tropical rainforest in north-eastern Costa Rica. Recruitment of most species showed a seasonal pattern in which the growth of juveniles occurred during the dry season. The phenology of the assemblage was also seasonal, with a peak in abundance during the dry season. Variation in abundance was driven by seasonal patterns of juvenile recruitment in one species, Eleutherodactylus brandsfordii. We suggest that the timing of reproduction and patterns of frog phenology may be tied to the availability of arthropod prey items. A comparison of our data with data collected at other rainforest sites in Central America and the Amazon basin of South America indicates that patterns of recruitment and abundance, while correlated with arthropod abundance on both continents, show divergent seasonal patterns. This and other studies indicate that peaks in abundance and recruitment of juvenile frogs are concentrated in the dry season in Central America, whereas in South American rainforests, the wet season is the period of highest abundance and juvenile recruitment. We suggest that the length and severity of dry periods in the Amazon basin limits the ability of terrestrial frogs to reproduce successfully, while in Central America a more benign dry season, while strong enough to create distinct seasonal trends in the phenology of rainforest animals, is not strong enough to prohibit frogs from recruiting juveniles during the dry season.