The legally endangered Cape Sable seaside-sparrow (Ammodramus maritimus mirabilis) is restricted to short-hydroperiod, marl prairies within Florida's Everglades National Park and Big Cypress National Preserve. Marl prairies are typified by dense, mixed stands of graminoid species usually below 1 m in height, naturally inundated by freshwater for 3–7 months annually. Water levels affect the birds directly, by flooding their nests, and indirectly by altering the habitat on which they depend. Managed redistribution of water flows flooded nearly half of the sparrow's geographical range during several consecutive breeding seasons starting in 1993. Furthermore, these high water levels rapidly changed plant communities, so jeopardizing the sparrow's survival by reducing the availability of nesting habitat.

Genetic variation was measured in 105 African buffalo from four populations in South Africa to investigate the effects of habitat fragmentation. Levels of heterozygosity, allelic diversity and genetic differentiation among populations were quantified using seven polymorphic microsatellite markers. There was a significant correlation between the amount of genetic variation and population size, and differentiation was detected among all populations measured by FST and RST. We used likelihood analysis to infer the effective population sizes of each population and to determine whether the fragmented populations were historically differentiated from one another. The genetic estimates of census size were consistent with historical records, and no historical genetic differentiation could be inferred in the original population before fragmentation. These results are discussed in the light of conservation management of fragmented buffalo populations, particularly where natural gene flow is no longer possible.

Insular breeding seabirds are likely to be particularly vulnerable to introduced mammalian predators because they often lack behavioural, morphological and life-history defenses against predation. We studied the life-history of the black-vented shearwater (Puffinus opisthomelas) on Natividad Island, Baja California Sur, Mexico, to examine its vulnerability to introduced feral cats. Using an allometric equation, we estimated that feral cats consumed 328 g of food day-1 to satisfy their nutritional requirements. We used stable isotope analysis of cat scat to estimate that 90% of the cats' diet was composed of shearwaters. Using data from our focal species and from the closely related manx shearwater (Puffinus puffinus), we created a demographic model to evaluate the effects of cat population size on the annual growth rate (λ) of the shearwater. The annual growth rate for black-vented shearwaters was estimated to be 1.006 in the absence of cat predation. With predation, we estimated that annual growth rate declined approximately 5% for every 20 cats in a population of 150,000 birds. Persistence times of bird colonies decreased both with an increase in the size of the feral cat population and with a decrease in the size of the initial bird population.

Successful management of endangered species may be greatly facilitated by the ability to monitor population trends. The Australian northern hairy-nosed wombat (Lasiorhinus krefftii) is one of the world's most endangered mammals, but precise abundance estimation by trapping surveys has proven exceedingly difficult. A mark-recapture study was conducted in the sole remaining L. krefftii population, based on microsatellite identification of individuals and their gender from DNA in remotely collected single hairs. Population size was estimated to be 113 (95% confidence interval of 96 to 150). This suggests an increase in population size over the previous estimate of 65 (95% CI 42-186) in 1993, although the estimates did not differ significantly. There was a significant male bias in the sex ratio (2.25 males:1 female), in agreement with recent trapping surveys. The non-invasive approach used here is vital for estimating population size and trends, and hence it is the most important recent advance in the conservation management of the northern hairy-nosed wombat.

In rural New England, forest fragmentation is caused by housing developments in forested areas. To evaluate the effects of these changes on forest birds, we compared bird assemblages between forests with different housing densities in western Massachusetts. Species occurrences and relative abundances were determined from systematic point count surveys and mist-netting at three plots in forest of low housing density (0–0.05 houses/ha) and of moderate housing density (0.60–6.70 houses/ha) in 1993 and 1994. Among guilds, Neotropical migrants and forest-interior species had significantly lower abundances in forests of moderate housing density. Abundances of ground/shrub nesting birds as a group, and of individual species such as veery (Catharus fuscescens), ovenbird (Seiurus aurocapillus) and wood thrush (Hylocichla mustelina), were greater in forest of low housing density, but blue jays (Cyanocitta cristata) were more abundant in forest of moderate housing density. Although the abundances of ground/shrub nesting birds were positively related to ground cover, this vegetation structure did not differ between forest types. Avian and mammalian nest predators may be responsible for the trends in bird abundance. Avian nest predators may recognize forest of moderate housing density as edge habitat, and this rural development may also support relatively high densities of mammalian nest predators. These trends suggest that birds of New England's relatively extensive forests may be subject to greater fragmentation effects than generally thought, as a result of increasing rural housing development within forests.

A recent estimate suggests that the Scottish wildcat may be critically endangered. Nevertheless, there is still no uncontroversial method for diagnosing the Scottish wildcat. We analysed morphological differences between wild-living cats in Scotland on the basis of 20pelage characters, scoring from 1 (domestic cat) to 3 (wildcat), in combination with 40skull parameters and intestinal length. A cluster analysis, based on Principal Components derived from the scores for pelage characters, showed that the wild-living cats fell into three main groups without any a priori classification. Each group corresponds well to the traditional characteristics of wildcats, hybrids and domestic cats, respectively, and the former two each show higher levels of morphological homogeneity compared with the third group. The three groups are most significantly differentiated by seven pelage characters: (1) extent of dorsal stripe, (2) shape of tail tip, (3) distinctness of tail bands, (4) presence/absence of broken stripes and (5) spots, on flanks and hindquarters, (6) shape and number of stripes on nape and (7) on the shoulders. Most Group-1 cats (75.6%, n=74), but none of the other two groups, score more than 2 for all seven characters. All Group-3 cats (n=35) and some Group-2 cats (19.2%, n=26), but no Group-1 cats, scored 1 for one or more of the seven characters. We propose that Group-1, which is the furthest from the domestic cat in all criteria, should be used to define the Scottish wildcat. However, in practice, if a wild-living cat does not score 1 for any of the seven characters it should be treated as a wildcat in the field. These definitions provide a simple way of diagnosing a Scottish wildcat scientifically, as well as practically, which will effectively facilitate conservation action and the enforcement of protective legislation.

Five out of 169 fertile California condor (Gymnogyps californianus) eggs laid in captivity have exhibited chondrodystrophy, a lethal form of dwarfism. Pedigree records indicate that this chondrodystrophy, like similar conditions in chickens, turkeys and quail, is probably inherited as an autosomal, recessive allele. We estimate that the frequency of this putative allele is about 9%. This high frequency is probably due to a founder effect. We consider three management options for the allele: ignoring it, eliminating it by selection and minimizing its phenotypic manifestation by avoiding matings between possible carriers. We recommend minimizing its phenotypic expression because an unacceptably large proportion of condors (up to 78 out of 146) would be prevented from breeding under a selection strategy designed to eliminate the allele. We predict that many captive populations will prove similar to the California condor population in that it will prove inadvisable or impractical to select against one or more deleterious alleles detected in the population.

Populations established with a small number of founders are thought to have a high risk of extinction due to allee effects, demographic stochasticity, inbreeding and reduced genetic variation. We tested whether the initial number of birds released was related to persistence in reintroductions of saddlebacks (Philesturnus carunculatus) and robins (Petroica australis) to New Zealand offshore islands. Data were analysed for 31 populations that had been observed for at least 3 years since reintroductions. The numbers released ranged from 5–188. Most of the populations (26) survived and grew, including five from less than 15 founders, and four out of the five extinctions were attributable to introduced mammalian predators. The number of individuals released did not significantly affect extinction probability. The ability of these small releases to establish populations can be attributed to the closed nature of the islands (allowing birds to find mates), low mortality rates following release and high growth rates at low density. Stochastic simulation models based on data from two reintroduced populations suggested that populations with four founders (two male, two female) would have a negligible chance of extinction through demographic stochasticity and would be able to grow even if there were high rates of egg failure through inbreeding.

The number and extent of human settlements around the world are increasing as the human population grows and people move from rural to urban areas. The decline and ultimately the local extinction of many indigenous species from a range of taxonomic groups within urbanised areas is a recurring theme from cities around the world. However, determining whether a species has become extinct can be difficult because sufficient survey effort may be too costly and expert opinion may involve considerable subjective bias. In this study, we compared the results of four quantitative assessments of the probability of persistence of indigenous mammals within Melbourne, Australia. Our comparisons were methodological, taxonomic and spatial. Less than half (26) of the original 54 species that occurred in Melbourne prior to European settlement have a greater than 95% probability of being extant at the end of 2000. Mammals occurring in local government areas (LGAs) within 10km of the central business district of Melbourne were less likely to be extant, with 29% of species having a greater than 95% probability of persisting, compared to 48% in the outer LGAs. The group of species most negatively affected by urbanisation were the small, ground-dwelling mammals, with just two out of 15 species having a greater than 10% probability of persisting. All four methods gave broadly similar results, with the Bayesian approach consistently suggesting higher probabilities of species persistence. The decline in the number of species is likely to continue with the ongoing expansion of Melbourne. The greatest opportunity to conserve the maximum number of species of mammal within Melbourne is in the outer LGAs where they remain extant. We recommend that state and local governments design and adopt a comprehensive strategy for managing habitat networks that cross jurisdictional boundaries and encompass the greater Melbourne area to enhance prospects for the survival of mammals.

In this study, non-invasive molecular methods were used to investigate the abundance and spatial organisation of otters (Lutra lutra) in Kinmen. DNA samples were extracted from fresh spraints collected seasonally along two streams from February to November 2001 and genotyped using a panel of 7 microsatellites and the SRY gene. Out of 343 spraints, 222 were successfully genotyped and 38 different genotypes (19 females and 19 males) were identified. Thirteen of these were residents that were identified in more than one season and 25 were floaters that were only identified in a single season. The average number of otters per km found along the two streams (1.5–1.8 for all otters, or 0.8–1.1 for residents only) was higher than that estimated in other studies. Female residents lived in exclusive group ranges and the ranges of male residents overlapped with no more than one group range of female residents. Otters appearing in the same range tended to be more closely related to each other. This study demonstrates that non-invasive molecular methods can be used to reveal a more comprehensive estimation of size and structure in an otter population.

Many species are currently undergoing reductions in population size due to widespread habitat loss and expanding human activities. Because interspecific hybridization is often a consequence of population decline and fragmentation, identification of individuals or populations with hybrid ancestry is an increasingly important issue in conservation biology. In many wild cattle and bison species, the problem of natural hybridization has been compounded by indiscriminate crossbreeding with domestic cattle for the purpose of improving domesticated stocks. Therefore, a genetic test using the polymerase chain reaction was developed so that wild cattle and bison with domestic cattle mitochondrial DNA (mtDNA) haplotypes could be rapidly identified. Using this genetic test, domestic cattle mtDNA haplotypes were detected in Bos grunniens (yak), Bison bonasus (European bison), and 6 out of the 15 (40%) Bison bison (North American bison) populations tested. In total, 30 out of the 572 (5.2%) North American bison tested, were found to have domestic cattle mtDNA. The hybrid origin of these mtDNA haplotypes was verified in a phylogenetic analysis using the parametric bootstrap. These results are discussed in terms of their implications for the conservation status and future management of wild cattle and bison species.

Population structure of the threatened long-tailed bat (Chalinolobus tuberculatus) was studied over five summers between 1993 and 1998, in temperate Nothofagus rainforest in Fiordland, New Zealand. Composition of 95 communal groups was sampled and spatial distribution of individually marked bats investigated. Individual C. tuberculatus moved to new roost sites virtually every day. Long term non-random associations among individuals were found by a cluster analysis that revealed three distinct social groups. Groups contained on average 72.0 (± 26.0) (mean ± SD), 99.3 (± 19.0) and 131.7 (± 16.5) marked individuals/year. Collective foraging ranges of the three groups overlapped but roosting occurred in three geographically distinct adjacent areas. Only 1.6% of individuals switched between groups. Non-reproductive females and males switched between groups more often than reproductive females but individuals switched only once or twice during the study and then just for one night. Juveniles of both sexes were associated with their natal group as 1 year-olds and then later when breeding. Social groups were cryptic because foraging ranges of groups overlapped, bats belonging to each group spread over many roosts each day, and these roost sites changed from day to day. Bats moved infrequently between groups, potentially linking the local population assemblages. Future research should explore whether the population is structured in demes. Population structure did not conform to traditional metapopulation models because groups occurred in homogeneous habitat extending over a large geographical area. Conserving bat populations should entail preserving a representative number of subgroups but development of models for predicting minimum number of effective local populations is still required.

Conventional census techniques are inappropriate for estimating numbers of nocturnal animals such as the spotted hyaena (Crocuta crocuta). A technique based on attracting animals by taped sounds to calling stations is described. A simple independent experiment to estimate the probability of response to the sounds, as well as a probability model for estimating the population size in a given habitat based on the response counts, is proposed. The model allows for the possibility that some animals may not respond to sounds. The estimate of the population size has a simple form and the sensitivity of the estimate to changes in the response probability can be assessed. The model allows statistical comparisons to be made between different habitats or different times. Likelihood-based confidence intervals can be found for all estimates. The results of surveys in the Kruger National Park illustrate the technique which can be applied in different areas and possibly to other species.

Species with ecological (habitat, dietary) specialization and low reproductive output may be at particular risk from anthropogenic habitat disturbance. We studied growth, reproduction and diet of the threatened broad-headed snake (Hoplocephalus bungaroides), a small nocturnal elapid from sandstone habitats in south-eastern Australia. Our data suggest that the life-history traits and diets of broad-headed snakes contribute to their vulnerability. Rather than searching actively for prey (like most sympatric elapids), broad-headed snakes wait under rocks to ambush prey. In consequence, these snakes feed infrequently, grow slowly, mature late and reproduce infrequently (compared with other sympatric snake species). Because of an ontogenetic shift in food habits, populations of broad-headed snakes require access to high densities of velvet geckos (in rock outcrops) as well as small mammals (in adjacent woodland). The specialized diet, reliance upon two distinctive habitats, low rate of growth, delayed maturation and low reproductive output may have exacerbated the vulnerability of broad-headed snakes to habitat destruction. All of these traits may be due to the species' reliance upon ambush predation rather than active foraging. A broader analysis supports the hypothesis that foraging mode may contribute to endangerment: a disproportionate number of ‘threatened’ species of Australian elapid snakes rely on ambush predation.

Understanding livestock grazing impacts on native wildlife is difficult when grazing is pervasive and has a long history. Spiti Valley in the Indian Trans-Himalaya is characterized by overstocking of rangelands and a grazing history of over 3 millennia. An intriguing aspect of the wild large-herbivore assemblage in Spiti Valley is its low diversity. In the present theoretical exploration, data on body masses of wild large-herbivore species in the Trans-Himalaya are examined against the backdrop of competition theory, to evaluate the possible role of competition in structuring the herbivore assemblage. The analysis is then expanded to include the livestock assemblage, and the possibility of the low wild herbivore diversity in Spiti Valley being a consequence of the high livestock diversity is explored. Null model analyses suggest that competitive interactions may have played a role in structuring the Trans-Himalayan wild herbivore assemblage. This is reflected in a proportional regularity in species body masses, with each species, on average, being a constant proportion larger than the nearest smaller one. Such a proportional regularity is absent in the livestock assemblage. The analyses make a case for the competitive exclusion of at least four wild grazers in Spiti over the last 3 millennia. The present grazer assemblage conforms reasonably to the theoretical predictions - these four species are among the six wild herbivores presently missing from Spiti. The implications of the analyses for conservation management in the Trans-Himalaya are discussed.

We examined how several ecological factors influenced home-range size for 57 mountain lions inhabiting three regions of California. Our specific objectives were to investigate: (1) the relationship between home-range size and sex, age and reproductive status; (2) how broad-scale habitat differences and prey relative abundances influenced home-range size; (3) how seasonality, within these habitats, affected home-range size; (4) whether there was a significant relationship between body mass and home-range size. Results indicate that the effects of season on home-range size influenced the study areas differently. Both intrinsic factors, such as sex and body mass, and extrinsic factors, such as deer relative abundance and study site, influenced home-range size for mountain lions in this analysis. Linear relationships, however, between body mass and home-range size were not evident for any of our study locations. Curvilinear relationships, in contrast, existed between body mass and home-range size for all study areas during particular seasons, influenced strongly by animal sex. Conservation strategies designed to protect mountain lions and their habitats should reflect the above balance between intrinsic and extrinsic factors which influence home-range size.

Fitness and rates of extinction were compared among populations of the housefly, Musca domestica L., kept either at constant effective sizes of 50, 500 or 1500 or passed through extreme founder events reducing effective size to 5. Populations were maintained for 24 generations, which for small to medium-sized mammals would be less than the 200 years suggested by Soulé et al. (1986) as necessary for maintaining viable populations of endangered species. The results demonstrate that effective population sizes have to be greater than the 50 individuals suggested by Franklin (1980) to retain fitness and escape extinction, even in the short term. In contrast to populations of constant size that exhibited monotonic decreases in fitness through time, populations established with few founders rebounded from initial inbreeding depression. However, they were less adaptable to environmental stress than constant size populations, suggesting that populations founded with few numbers may do well within a single environment but may do far less well if they are reintroduced to natural environments or exposed to rapid environmental changes.

We sought to assess the effects of forest fragmentation, introduced Rattus rattus, exotic tree plantations and secondary vegetation on the endemic rodent Eliurus webbi (Nesomyinae) and the lemur Microcebus murinus in the littoral forests of southern Madagascar. For E. webbi the number of individuals caught, the body mass of males and the percentage of females in the population were positively correlated with the size of the forest fragments. Capture rates and population characteristics of the other two species were uncorrelated with fragment size. None of the endemic species was caught outside the native forest while R. rattus inhabited all vegetation formations except for a newly planted corridor of tree saplings. Capture rates of both endemic species were uncorrelated with the number of R. rattus caught at the same site and thus did not indicate replacement of native species by R. rattus. The study demonstrated negative effects of fragmentation on capture rates of E. webbi and changes in their population characteristics. Exotic tree plantations or secondary vegetation seem to represent unsuitable or marginal habitats for the endemic species.

We radio-tracked 24 Myotis daubentonii and 35 Myotis nattereri during the swarming season to determine the catchment area of a swarming site and to study habitat preferences of the bats so that important foraging habitats within the catchment area could be identified. Sixty-one percent of individuals were relocated and 39 day roosts were found for 31 bats. Maximum range from the swarming site was 26.7 km for M. daubentonii and 24.8 km for M. nattereri. Minimum convex polygons depicting the minimum catchment area of the swarming site measured 254 km2 for M. daubentonii and 497 km2 for M. nattereri. Including recoveries of ringed bats increases the area enclosed by the maximum range to at least 4118 km2. Compositional analysis of habitat used in relation to that available suggested selection of mixed agricultural areas by M. nattereri. Broad-leaved woodland was preferred for foraging. Parkland, woodland and open-water habitats were common around roosts of M. daubentonii. Such habitats should be conserved and enhanced to protect these species. Some individuals of both sexes returned to the swarming site of capture, but none visited another swarming site. Bats may be faithful to only one site and may be inflexible should that site be destroyed. Because the catchment area of swarming sites is large, such sites are probably important centres of outbreeding. Protection of these mating sites should be a conservation priority, and key habitats should be protected over a large area around swarming sites.

Because of the difficulties encountered in detecting many large tropical forest-dwelling species in their natural habitat, precise figures concerning the distribution, number and trends of many populations remain deficient. In tropical forests, ground surveys are generally carried out by counting objects along straight lines. These counts require a strict compliance with the line-transect methodology before (proper design of the census), during (careful data collection) and after (accurate and correct data processing and analysis) the census itself. In addition, the major source of bias when estimating population size and/or trends comes from the extrapolation of estimates obtained in small sampling areas to the larger, and often incompletely known, distribution of the population. In the Kinabatangan floodplain (Sabah, Malaysia), helicopter surveys were useful in directly assessing the distribution of orang-utans and were a major advantage in the precise estimation of the size of the orang-utan population surviving in this region. Our survey showed that about 1100 orang-utans remain in the multiple-use forests of the Kinabatangan floodplain. These results provide new evidence on orang-utan adaptation to habitat disturbance and indicate the potential of the Kinabatangan multiple-use forests for orang-utan conservation. Helicopter surveys appear to be a promising alternative to ground survey for precise distribution assessment and for monitoring population trends of apes throughout their entire range in Asia and in some parts of Africa.