Theoretical estimates of long-term minimum viable population (MVP) sizes for mammals indicate MVPs of tens of thousands, even a million. However, data to test the theoretical estimates are effectively non-existent. I here use information on distributions of primates on islands of southeast Asia to provide empirical estimates of the size of multi-millennial MVPs following the post-Pleistocene insularization in the Sunda region. Small Sunda region islands have fewer taxa than do large ones. Assuming extinction on the small islands, the MVP size is somewhere between the population size on the smallest island on which the taxon is extant and that on the largest island on which the taxon no longer exists (population size calculated as density of taxon by area of land available). Results for eight to ten genera (depending on the taxonomy) on 35 islands indicate MVPs of perhaps a few score for Nycticebus (loris) and Macaca (macaque) to several thousands, or scores of thousands, for Pongo (orang-utan) and Symphalangus (siamang). Large-bodied taxa have significantly larger MVPs than do small-bodied taxa. Only four protected areas in southeast Asia are large enough to conserve the smaller MVPs of the siamang and orang-utan.

As metapopulation dynamics is thought to play an important role in the conservation of mammals, mainly owing to the fragmentation process, a Population Viability Analysis (PVA) was used to evaluate the role and importance of individual patches to the metapopulation persistence of the long-furred wooly mouse opossum, Micoureus demerarae, a neotropical arboreal marsupial. The metapopulation under study comprises eight small Atlantic Forest patches at Poço das Antas Biological Reserve, southeastern Brazil. The analysis indicates that the local populations may be divided into three groups: (1) in the smallest and most isolated patches, where they are the most endangered, (2) in five circular-shaped and relatively well-connected patches and (3) in the largest patch with the most persistent local population. Knowledge of how specific patches influence metapopulation dynamics is an important tool in guiding management strategies, and dynamics can be affected by factors like patch size and relative position. It seems that for this particular case, probability of metapopulation extinction, mean metapopulation size, heterozygosity and mean growth rate were the most informative measures to evaluate a patch's contribution to metapopulation persistence. Despite all controversies, metapopulation theory, when carefully and properly applied, is a valuable tool in conservation biology.

Bat activity was quantified in 15 historic landscape parks in England to assess the importance of habitat features within them for foraging bats. Unimproved grassland, water and plantation woodland were selected (used more than expected based on availability) by all bat species. Pipistrellus pipistrellus selected unimproved grassland and areas around water; Pipistrellus pygmaeus selected semi-natural woodland and tree lines; ‘Myotis group’ bats, (including Myotis spp., Plecotus spp. and Barbastella barbastellus) selected water and plantation woodland; and ‘Nyctalus group’ bats (including Nyctalus spp. and Eptesicus serotinus) selected unimproved grassland and parkland. The relative area of watercourses and tree lines in the landscape parks was the best predictor of bat activity. Landscape parks including unimproved grassland, water, parkland, semi-natural woodland, plantation woodland and tree lines have the most potential for foraging bats, and may form favourable ‘islands’ in intensively managed agricultural landscapes. To maximize the conservation value of historic landscape parks for bats, these habitats should be conserved or created.

Most species-specific conservation efforts require estimates of population size to establish priorities and to monitor management activities. Yet obtaining reliable estimates of animal populations is often difficult, especially given time and funding limitations experienced by many research programmes. Consequently, there is a great need for practical methods to provide indices of animal density. Ideally, accurate estimates of populations would be obtained through mark-recapture data collected from recognizable individuals over multiple censuses that cover the entire population range. Such data are rarely available, so conservation biologists have no alternative but to resort to analyses of less perfect data, ranging from permanent-point censuses from cameras through to transect data on sightings and spoor encounters. The importance of census and monitoring data makes the development, and validation, of new techniques a priority. Because we do not live in a perfect world, there is a need to develop methods that can give an estimate of population sizes. It would be naïve to assume that these will give hugely accurate estimates of population size, but these techniques can prove useful in identifying areas that are likely to benefit from conservation action.

Inbreeding depression is a critical phenomenon for conservation of small populations, especially concerning the captive breeding of endangered animals whose effective population size may be very low. In order to manage such captive populations on a long-term basis, assessment of the interactions between demographic and genetic parameters and their consequences on the population survival probability is essential. Therefore, we examined (1) the relative importance of initial population size and carrying capacity on the survival probability of a population, (2) the impact of a bottleneck in an already inbred population. For this purpose, a stochastic model taking into account the effect of genes responsible for inbreeding depression was built. It was concluded that the population survival probability is very sensitive to the carrying capacity. Moreover, in inbred populations, a large increase in the extinction rate results from a second bottleneck. With two founders, survival is high as long as the carrying capacity is not very small (above a few decades), whereas a second bottleneck has a dramatic effect, even when the carrying capacity approaches 100. Consequently, previous inbreeding should be considered in the case of reintroduction. Reason for reintroduction failure could be successive bottlenecks, with the associated deleterious effects of inbreeding.

Maximum likelihood mixed stock analysis was used to identify the natal origin of immature loggerhead turtles (Caretta caretta) in a tropical developmental habitat in Caribbean Panamá. Approximately 65-70% of the loggerhead turtles in Chiriquí Lagoon originate from South Florida nesting beaches, and the other 30-35% originate from Mexico. Haplotype frequencies of the Chiriquí Lagoon loggerhead population are significantly different from those observed in the pelagic environment in the eastern Atlantic, and estimated nesting beach contributions to Chiriquí Lagoon are significantly different from values expected if recruitment were based solely on the size of nesting populations. These observations suggest that dispersal of loggerheads into benthic developmental habitats from the pelagic environment is not random. The occurrence of US and Mexican loggerheads in tropical developmental habitats has not been previously recognized. Exploitation and other mortality factors operating in the Caribbean area must be taken into account in demographic models and management plans for these two populations. This exploitation could be particularly important for the small, demographically vulnerable Mexican population and for other small populations for which no genetic data are currently available.

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.

To ensure the effective conservation of biodiversity the distribution of species needs to be accurately characterized and areas of high species richness located. For many taxa this can be achieved only by experienced taxonomists. Taxonomic research has a large input from non-professional or amateur researchers, in addition to professionals working at museums or universities. The decline of taxonomy and the number of taxonomists within the professional community has been widely publicized, but the trends in the activities of amateur taxonomists are unclear. Because amateurs contribute many valuable records of species occurrence this may have a disproportionate impact upon the information available for conservation planning and represents an underappreciated threat to conservation planning. We use taxonomic research by UK entomologists in order to evaluate the changing role of both amateur and professional taxonomists. We reviewed contributions by British-based authors to Entomologist's Monthly Magazine over the past century. Our results show that both amateur and professional taxonomy have undergone a long and persistent decline since the 1950s, in terms of both the number of contributors and the number of papers contributed. It is argued that the conservation community needs to help try and reverse the decline of taxonomy.

Species diversity and community structure indices (richness, diversity and evenness) are typically derived from contemporary biological survey atlases to identify conservation areas or to determine macroecological-environment relationships. Surprisingly, there are few studies based on national taxa surveys that describe and measure the influence human disturbance patterns may have on these ecological measures. This study uses various spatial statistical methods to examine and model large-scale spatial structure in diversity, structure indices derived from a comprehensive bird atlas, and composite variables of environment and human land transformation. Data were derived from an atlas of South African birds and segregated into five vegetation biomes. For each sample location, environmental and land-use data were used to calculate composite environmental gradients in climate, topography and human land transformation. Semivariograms were used to detect large-scale trends and spatial scale, and Moran's I statistic correlograms to test for large-scale spatial autocorrelation in detrended diversity indices. Ordinary least squares regressions for all biomes indicated a significant positive relationship between high levels of human transformation and species diversity, whereas high transformation had a significant negative influence on evenness. These same relationships held for the majority of biomes after the effects of environmental gradients were removed. The analysis also shows that in areas with favourable environmental resource levels, diversity for birds increases. These areas also tend to contain a large proportion of highly transformed land, and evenness decreases in the woodland, grassland, Karoo and fynbos biomes. This suggests that high-intensity transformation may bring in novel resources for birds not normally found in some of the biomes, with some species adept at exploiting these changes and reaching high densities with a tendency for assemblage structure to drift towards single species dominance. The results imply that species data derived from contemporary atlases may begin to demonstrate the effects of human influence on ecological measures rather than only indicating the effects of environmental variation on community structure.

Australian mammals have one of the world's worst records of recent extinctions. A number of studies have demonstrated that red foxes (Vulpes vulpes) have a profound effect on the population biology of some species. However, not all species exposed to fox predation have declined. We studied the antipredator behaviour of a species that has not declined - the red-necked pademelon (Thylogale thetis), and contrasted it with previous studies on a species that has declined - the tammar wallaby (Macropus eugenii), to try to understand behavioural factors associated with survival. We focused on two antipredator behaviours: predator recognition and the way in which antipredator vigilance is influenced by the presence of conspecifics. We found that predator-naïve pademelons responded to the sight of certain predators, suggesting that they had some degree of innate recognition ability. However, pademelons responded similarly to a broad range of acoustic stimuli, including dingo howls, wedge-tailed eagle calls, foot-thumps - a predator-elicited sound - and a control sound, suggesting that they did not specifically recognize predator vocalizations. Unlike a number of other macropodid marsupials, including tammars, pademelons did not modify time allocated to antipredator vigilance as group size increased. Taken together, these results suggest that red-necked pademelons independently assessed and managed their predation risk whereas tammars relied more on conspecifics to assess and manage risk. We suggest that these factors may have been important determinants of species survival. More generally, we suggest that a fundamental understanding of antipredator behaviour can enlighten conservation efforts.

Recent studies have suggested that contemporary losses of species are unevenly distributed over phylogenies. Here, we show that species of Australian marsupials are at higher risk if they belong to genera that are species-poor, old or phylogenetically distinct. Extinction risk in this group is also related to habitat and body size, being higher for species from non-forested habitats and of intermediate body size. We tested the extent to which the phylogenetic selectivity of extinction was explained by this ecological pattern. We found that while genus size and distinctiveness explain no variation in extinction risk that is not accounted for by habitat and body size, there is a significant residual association of genus age with extinction risk. This suggests that while species in small and distinctive genera are at high risk because they are overrepresented in non-forested habitats and intermediate body size classes, species in old genera are at higher risk over the range of body sizes and habitats and may be intrinsically vulnerable to extinction.

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.

Products from the protected East Sea/Sea of Japan (‘J’ stock) minke whales (Balaenoptera acuturostrata) are sold widely on the commercial markets of Japan and Korea despite the protection of this stock since 1986. To determine the minimum number of individual whales for sale, genotypes from six microsatellite loci were used to profile North Pacific (NP) minke whale products purchased on these markets between December 1997 and October 1999. Genotype differences showed that 99 NP minke whale products from the Japanese market represented 86 unique individuals. Of these, 33.7% were of likely J-stock origin based on mitochondrial (mt) DNA haplotypes. In Korea, genotyping showed that 23 NP minke products from March 1999 represented 18 individuals, and 19 products from October 1999 represented 16 individuals. No matches were found between the two sampling periods, giving a total of 34 unique individuals. A frequency-of-capture model suggests that 98 minke whales were present on the Korean market over the two brief sampling periods. No genotype matches were confirmed between the two countries, indicating that undocumented exploitation of this depleted stock must be additive, and greater than previously assumed.

Estimating the risk of extinction or decline requires estimates of the variability in vital rates, such as survival and fecundity. This paper describes a method for estimating variance of survivals and fecundities from census data. The method involves calculating an estimate of the variance in survival and fecundity due to demographic stochasticity and subtracting this estimate from an estimate of total variance. The method is demonstrated by applying it to the data set on acorn woodpeckers by Stacey & Taper (1992), and tested in a series of simulations. The results show that the method can estimate the environmental variance with no bias. The main advantages of this method are its simplicity, its independence of the underlying distribution, and its applicability to estimating the variance of fecundity as well as of survival.

Approximately 40% of the world's leatherback marine turtles (Dermochelys coriacea) nest in Suriname and French Guiana. Trends in nest numbers reconstructed for the last 34 years indicate several up and down events. We undertook computer simulations to determine whether a density-dependent phenomenon might be involved because the period of high-density nesting coincides with a high level of nest destruction by nesting females. The parameters of density-dependent nest destruction were calculated for the Yalimapo-Awala beach. We show that: (1) density-dependent nest destruction occurs, but (2) it promotes a density-dependent feminization of hatchling sex ratio, and consequently (3) the global production of juveniles continues to increase in relation with the increasing number of deposited nests even for the highest densities observed at that beach. Mean annual production of female hatchlings per adult female, although density dependent, is less than two juveniles even at the lowest densities of nesting females.

We develop a stochastic model of population viability which explicitly links demography and genetics in order to examine the consequences for extinction dynamics of different levels of heritable fitness variance within a population. We particularly focus on situations in which a local small population is artificially built with individuals that were taken from several large source populations. Our results suggest that different levels of fitness variability within a population (due to partially recessive deleterious alleles rather than local adaptation) have a large influence on its viability. Moreover, the optimal level of fitness variance for maximizing population persistence is a function of the species life-cycle. Two mechanisms with opposite effects are mainly responsible for the different patterns of extinction obtained depending on the life-cycle, (1) purging of deleterious alleles, (2) demographic stochasticity. For high growth rate or long-lived species, a high fitness variance decreases short-term viability and increases long-term viability. In contrast, for other cases, a high fitness variance increases both short- and long-term viability.

In recent decades, the abundance of otter, Lutra lutra, decreased in many European countries. This study aimed at determining if varying occurrence of otters is related to land features and if this occurs at many spatial scales. Values of landscape features were compared among three categories of otter occurrence, i.e. absent, sporadic and common, for 25 European countries, for 19 regions and 22-40 departments in France. At all scales, significantly higher human and road densities were detected in areas where otters are absent, which illustrates the pervasive impact of human presence on otter population fragmentation. Moreover, particular natural features (‘percentage other use’ defined as non-agricultural and non-forested) may also limit otter populations at the scale of Europe. Our study failed to detect significant differences in landscapes occupied by common or sporadic otter populations, probably owing to a limited sample size, or to the resilience of otters. The conservation of the European otter in Europe would benefit from an improved list of common large-scale land descriptors, the recognition of large gaps of naturally unsuitable habitats, and the development of international large-scale conservation studies to support existing regional otter conservation efforts.