A new genus and species of gecko from the Lower Eocene of north-western Russia is described from a superbly preserved specimen in Baltic amber. It is the oldest gekkonid lizard to be represented by more than fragmentary skeletal remains. The digits of the specimen are mostly intact and reveal a unique combination of characters not seen in any living form. Expanded sub-digital scansors on the toes, however, are essentially similar to those of modern climbing geckos and verify the existence of a complex adhesive system 20–30 million years earlier than supported by previously discovered fossil geckos.

Population density is likely to determine the form of competition in which males are engaged for access to females. At low density, scramble competition should be of paramount importance because of the low probability of encounter between males and females. Consequently, sexual selection should favour characters that allow rapid detection of females. Conversely, at high population density, sexual selection should favour attributes that raise the fighting ability of males because of the more frequent contacts between males. These general predictions were tested in this study for the precopulatory mate-guarding isopod, Asellus aquaticus. In this species, male-biased sexual dimorphisms are reported for body size and antennae length and are, respectively, ascribed to contest and scramble competition over females. Therefore, the relative strength of sexual selection on male body size and antennae length at two different densities was experimentally assessed. Multivariate analyses indicated that density affected morphological correlates of the mating success of males, with body size being the main determinant of pairing success in males at a high density, whereas only antennae size significantly affected access to females at a low density. The antennae length of males was manipulated to examine how antennae length affects the ability of males to detect females in three experimental conditions varying in the probability of random contacts with receptive females. An advantage of having long antennae was only observed when there was an intermediate difficulty in finding females. Our results are discussed in relation to the influence of density on selective regimes in A. aquaticus.

Direct observation of Eurasian otters was used to demonstrate the characteristics and interannual use of small patches of habitats by females and litters in stretches of two rivers in north-east Spain. During censuses and other vigils, 215 otter sightings (involving 265 otters) were obtained, 14–18% of which were observations on females and litters. Thirty-five additional sightings were obtained in stretches used by litters of large cubs (47 individuals). Six small cub (2- to 6-month-old) and 15 large cub (>7-month-old) different family units (litters) were detected in both rivers as a whole. Average sizes of litters of small and large cubs were significantly similar, being respectively 1.17 (SD=0.41, range 1–2, n=6) and 1.27 (SD=0.46, range 1–2, n=15), so mortality of cubs was low at the period before dispersal. Litters were detected in significantly different patches from other otters, and litters of small and large cubs were also found in significantly different river sections. Litters of large cubs used small home ranges and core areas, and selected sections at reservoir tails, reservoirs, wider stretches, rough waters and refuges. Small cubs were found in narrow river stretches with calm waters. Selected patches had sheltered zones with abundant fish. This reduced use of space may result in the low rate of mortality.

Data from a long-term study (1993–2003) using artificial nest-boxes, were analysed to examine competition for nesting between blue tit Parus caeruleus and common dormouse Muscardinus avellanarius in Sicily. Occupation rates and the reproductive biology of the blue tit in sample woodlots outside the distribution area of the common dormouse were used as a control in sample areas where the two species were syntopic. A selection test showed that the two species, when living in syntopy, actively chose the small nest-boxes, thus overlapping in the use of the same spatial resource. The experimental exclusion of the common dormouse from nest-boxes caused an increase of blue tit occupation rate. Once the effect of nest-box density was removed, complementary density changes between the two species clearly appeared. The population cycle of both species in the areas of syntopy showed a swinging pattern, i.e. in areas or during years of common dormouse high abundance few blue tits bred and vice versa. The abundance of the blue tit was affected not only by common dormouse abundance, but also by some habitat and climate variables. Blue tits had low breeding success and a high percentage of nest failure (38% in syntopy vs 3% in control areas), owing to nest destruction and predation by common dormouse, as well as probably also by other rodents (23%) and Martes martes (15%). Another experiment, using stuffed models, showed that the blue tit recognized the common dormouse as an enemy, and behaved as if confronted by a competitor or predator species to protect their nests.

The species–area relationship was used to test the effects of habitat reduction on the proportion of tetrapod species that would be considered threatened with extinction, assuming the current estimate of 19% of remaining forest coverage in Rio de Janeiro State, Brazil. Here, species–area estimates from deforestation were compared with a Red List produced by experts. Analyses were performed with: (1) the total pool of species that occur in Rio de Janeiro State (159 amphibians, 115 reptiles, 635 birds and 157 mammals); (2) the pool of species endemic to the Atlantic forest (109 amphibians, 46 reptiles, 149 birds and 35 mammals). The sensitivity of the analyses to variations in the Z parameter of the species–area relationship was evaluated. In general, the species–area overestimated the total number of species threatened with extinction for all tetrapods, while the estimate of endemic mammals predicted to be extinct was close to the number of endemic species listed as threatened with extinction. Furthermore, changes in the Z-values did not affect those results. The species–area relationship accurately predicted the number of endemic birds assumed to be extinct since it used values of Z smaller than 0.25. The analyses with endemic species of reptiles and amphibians of Atlantic forest overestimated the number of species predicted to be extinct for both groups. In conclusion, at the considered scale, mammals and birds endemic to the Atlantic forest seem to be more affected by deforestation than reptiles and amphibians.

From 1515, the rhinoceros was well known in Europe through a woodcut by Albrecht Dürer, showing an armour-plated animal from India with one horn on the nose and a spurious ‘Dürer-hornlet’ on the shoulders. When the first reports of the rhinoceros from Africa spread in the 17th century, it was not differentiated from the prototype, although it had a smooth skin and two nasal horns. Parsons in 1739 recognized differences between rhinos in Asia and Africa, but could not clearly separate them as two forms. Linnaeus based Rhinoceros bicornis on a skull from India with a second horn added by a trader. Camper in 1780 provided first anatomical proof for the existence of two species of rhinoceros distinguished by the number of teeth and horns. In the 19th century, travellers exploring the interior of southern Africa named rhino species according to the shape and size of the two horns, known as the Rhinoceros simus of Burchell, the unicorn of Campbell, the keitloa of Andrew Smith and the Mohoohoo of Oswell. Around 1900, with an increase of observations from the entire African continent, only two species were recognized, known as black rhino Diceros bicornis and white rhino Ceratotherium simum. The black rhino was first seen in captivity in the 1870s, the white rhino in 1944. Their status in the wild is precarious primarily because of illegal hunting for the horn. Continuous protection and management in the field together with research and documentation of their biology can still achieve their long-term preservation.

Dry season diets and habitat use of increasing populations of Asian elephants Elephas maximus and greater one-horned rhinoceros Rhinoceros unicornis in the Babai Valley of Royal Bardia National Park, Nepal, are described, and an assessment is made of the potential for competition between them. The diets, analysed by microhistology, were different, with a similarity index of 37.5%, and with different grass/browse proportions: the rhino diet consisted of 63% grass and 28% browse; that of elephants was 24% grass and 65% browse. A tallgrass floodplain grass, Saccharum spontaneum, was the plant most eaten by rhinos, whereas elephants consumed a large proportion of bark of Bombax ceiba and Acacia catechu, as well as several browse species not eaten by rhino. The habitat use of elephants was determined by dung-counts within 30 km of 20-m wide belt transects, while that of rhino was taken from an earlier study. Elephants used a wider range of habitats than rhino, but two types, the tallgrass floodplain and khair–sissoo forest, were preferred by both species simultaneously. While elephants used the abundant sal forest extensively, rhino strongly avoided this habitat. Densities of both species were low at the time of study (<0.5 animals/km2), but their numbers are expected to increase markedly in coming years. Because available habitats for expansion are limited, this may lead to competition. Rhino might then become the weaker species, as elephants are more flexible in their ranging and foraging activities. The tallgrass floodplain habitat and its important forage grass S. spontaneum may then become the critical resources.

During the past 50 years the number of badgers (Meles meles) in Denmark has declined by c. 50%. To assess the genetic consequences of the demographic decline, six DNA-microsatellite loci were used to analyse 139 badger tissue-samples, which were collected in 1995–98 from three zones (1, 2 and 3) in Jutland (Denmark). Results from contemporary samples were compared to data obtained from DNA extracted from teeth belonging to 39 badgers collected from zones 1 and 2 in 1957–66. The microsatellites showed a low to moderate polymorphism, and the within area genetic diversity (HE) was relatively low (0.308≤HE≤0.441) as compared to other carnivores and mustelids. Genetic differentiation among the three recent sampling zones was significant (FST=0.072, P<0.0001). The FST values between the two recent (FST=0.092, P<0.0001) and the two historical samples (zones 1 and 2; FST=0.073, P<0.0001) were significant and similar. The HE and FST of the recent and historical zones were not significantly different (P>0.05). Despite the drastic recent decline, Danish badgers did not show apparent signs of genetic bottlenecks in both recent and historical samples. The use of molecular techniques which allowed us to work with small amounts of degraded DNA extracted from old teeth, allowed us to exclude the hypothesis that genetic differentiation between zones 1 and 2 was owing to a barrier, which has appeared in the last 50 years. Furthermore, the low genetic variability and therefore the relatively high genetic differentiation shown by Danish badgers were also shown not to be the result of the recent drastic population decline.

The allometric relationship between body mass and burrow cross-sectional area for burrowing animals holds across greater than six orders of magnitude variation in body mass, and includes species separated by >500 million years of evolution from two phyla (Arthropoda and Chordata), seven classes (Arachnida, Insecta, Malacostraca, Osteichthyes, Amphibia, Reptilia, and Mammalia) and both terrestrial and marine habitats. Only birds, which construct relatively large burrows, and vermiform animals, which construct relatively narrow burrows, are separated from the remaining burrowing species. No difference is found between fossorial (burrowing animals that forage beneath the soil surface) and semi-fossorial (burrowing animals that forage terrestrially) mammals, suggesting that subterranean foragers do not modify burrow cross-sectional area to increase energy yields. However, solitary fossorial mammals do construct significantly larger nest chambers than semi-fossorial and colonial fossorial mammals. These large nest chambers probably assist in maintaining body temperature by providing a better thermally insulated microenvironment. This offsets the thermoregulatory problems faced by these animals, which are characterized by low, labile body temperatures and poor thermoregulatory ability. Colonial fossorial mammals, on the other hand, construct nest chambers that are the same relative size as those constructed by semi-fossorial mammals and probably maintain homeothermy by huddling with endothermic nest-mates.

The European mink Mustela lutreola is the focus of extensive conservation programmes whereas the American mink M. vison is exotic in Europe and a possible cause of European mink decline. Since both species, together with the European polecat M. putorius have similar hair and produce similar faeces, molecular techniques are essential for reliable species identification when disturbance is not appropriate. In this report a simple, cheap and reliable molecular method for the genetic distinction of mink is provided based on the amplification of the microsatellite locus Mel08 that results in a longer PCR product (436 bp) in American mink than in other mustelid species, such as the European mink (221 bp) and the European polecat (221 bp). Sequencing these PCR products revealed, in the microsatellite-flanking region of American mink, a CAN-SINE insertion of 213 bp that was absent in 22 species of the Canoidea superfamily tested. When the Mel08 PCR product is cut with restriction enzyme AciI and then run in an agarose gel, the restriction pattern observed is different in the three Mustela spp. The method was successfully tested with DNA amplified from a large sample of hair roots, thus making it suitable for non-invasive sampling.

The timing of implantation, duration of gestation and energetic costs associated with foetal development were examined in the north-west Atlantic grey seal Halichoerus grypus. Implantation occurs between 5 and 8 May. Active gestation lasts for 259–272 days and the duration of suspended development is 78–91 days. The duration of active gestation was slightly shorter among north-east Atlantic grey seals (238–255 days), while suspended development was longer (95–112 days). The rate of foetal growth increased in August, 3 months after attachment, until mid December when it began to slow once again, c. 1 month before parturition. During August, the placenta to foetus mass ratio was about 0.3, but declined to around 0.07 near birth. Foetal energy density increased rapidly reaching asymptotic levels of 22.6 kJ g−1 (dry weight) 3–4 months after implantation. Energy density of the placenta changed only slightly throughout gestation increasing from c. 21.7 to 23 kJ g−1 (dry weight) by the autumn. Energy costs associated with foetal growth are c. 648 MJ.

Several hypotheses about changes in adult survival of European storm-petrels Hydrobates pelagicus and predation by yellow-legged gulls Larus michahellis at Benidorm Island (western Mediterranean) during 1993–2003 were assessed. Two approaches were used: analysis of pellets containing remains of predated petrels from two caves, and multistate capture–recapture models using recaptures of breeders together with recoveries only from one of these caves. These models were used to estimate separately adult storm-petrel survival and a minimum probability of being killed by gulls. At least 11–14% of the storm-petrels killed had been ringed as breeders. Local adult survival varied greatly among years, from 0.701 (SE=0.095) to extremely high values (0.951, SE=0.031) for such a small species (0.833 on average for the whole period). Nevertheless, it was not possible to assess whether this variation was influenced by inter-annual differences in gull predation. The peak of predation occurred in June, when maximum numbers of prospecting petrels visit the colonies. Predation was much higher at the cave that received stronger illumination from Benidorm city. Minimum predation probabilities estimated from capture–recapture varied with time from 0.022 (SE=0.011) to 0.040 (SE=0.016), and increased significantly after the powering of light received from the city in 1997. In these years, predation by yellow-legged gulls accounted for a large percentage of mortality of storm-petrels at Benidorm Island (up to 33%). Both methodological approaches confirmed that predation was carried out by specialist gulls, and that neither the size of the gull colony nor its food availability influenced predation on petrels. Management might reduce predation rate by removing gulls that nest in the caves, since these individuals tend to kill most storm-petrels.