Rare bouts of extreme environmental perturbations (catastrophes) have been predicted to have a major influence on the probability of extinction. Yet very little information is available on the frequency and severity of catastrophes. Improving the available information concerning catastrophe parameters would allow for an evaluation of their effect and a start towards understanding their causes. We used the Global Population Dynamics Database to determine the frequency and severity of die-offs in 88 species of vertebrates. We define a catastrophe as any 1-year decrease in population size of 50% or greater. The data yielded three findings. (1) The frequency of severe die-offs in vertebrate populations is strongly related to the generation length of the organism. (2) The probability of a severe die-off for a particular population is approximately 14% per generation. (3) The frequency of die-off severity can be modelled as a modified power function with the frequency of die-offs decreasing with increasing magnitude of effect. The distribution is not consistent with catastrophes stemming from environmental sources different than those responsible for smaller fluctuations, but seems to represent the tail of a continuous distribution of environmental perturbations.

Introduced species can compete with, prey upon or transmit disease to native forms, resulting in devastation of indigenous communities. A more subtle but equally severe effect of exotic species is as a supplemental food source for predators that allows them to increase in abundance and then overexploit native prey species. Here we show that the introduction of feral pigs (Sus scrofa) to the California Channel Islands has sustained an unnaturally large breeding population of golden eagles (Aquila chrysaetos), a native predator. The resulting increase in predation on the island fox (Urocyon littoralis) has caused the near extirpation of three subspecies of this endemic carnivore. Foxes evolved on the islands over the past 20,000 years, pigs were introduced in the 1850s and golden eagles, historically, were only transient visitors. Although these three species have been sympatric for the past 150 years, this predator-prey interaction is a recent phenomenon, occurring within the last decade. We hypothesize that this interaction ultimately stems from human-induced perturbations to the island, mainland and surrounding marine environments.

The success of captive-breeding and release programmes is often compromised by predation of released individuals, which are naïve about predators. Pre-release behavioural preparation of release candidates in the form of anti-predator training has been attempted infrequently, usually using models of predators, but success was most often measured in terms of improved behavioural responses rather than survival to breeding age after release. Here we report that post-release survival of captive-reared houbara bustards (Chlamydotis [undulata] macqueenii) was improved through exposure to a live predator before release: a result with possible applications for a wide range of species currently the focus of reintroduction projects. We also show that rearing houbara with minimal human contact and training with a model of a predator had no effect on post-release survival. Moreover, neither pre-release behavioural responses to a model predator nor the degree of tonic immobility were predictors of post-release survival.

Carnivore translocations are usually risky and expensive, and a number of biological and non-biological factors can influence success. Biological considerations include knowledge of genetics, demographics, behavior, disease, and habitat requirements. This information is critical for determining if the translocation should be attempted, if it could be successful, and how it could be implemented in an efficient and effective manner. We stress that individual species will vary in their responses, and ideas should be tested scientifically. The technical considerations of translocation are closely related to the biological questions. They include legal framework, fiscal and intellectual resources, monitoring capacity, goals of the translocation, logistic challenges, and organizational structure of decision-making. We do not discuss socio-economic aspects of translocation because those challenges require detailed discussion in a separate paper. We suggest that because large carnivores often play key roles in regulating ecological interactions between trophic levels, restoring them is more than a single-species activity. By restoring carnivores in viable numbers, we can take a large step toward recovering ecological integrity of geographically extensive landscapes.

With increasing awareness of disease as an endangering process, an assessment of which pathogens might pose a problem and their patterns of infection in natural hosts is necessary. This paper examines the exposure of sympatric Ethiopian wolves (Canis simensis) and domestic dogs to canine distemper virus (CDV), canine adenovirus (CAV) and canine parvovirus (CPV) in the Bale region, Ethiopia and then relates these data to population trends of wolves. Wolves (n = 30) sampled between 1989 and 1992 had been exposed to CDV, CAV and CPV, but only CAV might be able to persist in this wolf population. Anecdotal and serological evidence suggested that an epidemic of CDV occurred in the dog population of the Bale Mountains National Park (BMNP) in 1992–93. All park dogs born since this time were seronegative to CDV, although some young dogs in the nearby urban population were seropositive. Despite evidence of CAV infection in wolves, none of the dogs sampled in the park were CAV seropositive, although this virus appeared highly seroprevalent and endemic in urban dogs. All dogs tested for CPV antibodies were seropositive. The BMNP wolf population declined in the late 1980s and early 1990s, with rabies responsible for a dramatic population reduction between 1990 and 1992. Although the population declined further up until 1995, it is not possible to assess whether the concurrent canine distemper epidemic in park dogs also affected wolves. Nevertheless, with evidence of rabies, CDV, CAV and CPV infections in sympatric domestic dogs and Ethiopian wolves, canid diseases clearly pose a significant threat to the future persistence of this Ethiopian wolf population.

The detection of reductions in effective population size (Ne) or census size (Nc) is essential for conservation. Recent developments allow wildlife researchers to obtain genetic material via non-invasive sampling techniques that may provide the large sample sizes necessary for precise estimates of Ne and Nc. Population genetic theory provides several methods to estimate Ne from allele frequency data: including temporal change in allele frequencies, gametic disequilibrium and heterozygote excess methods. Modification of capture–mark–recapture methods for use with multi-locus genotype data provides new means for estimating Nc. The combination of new DNA sampling techniques, polymerase chain reaction-based DNA markers and analytical methods may provide unprecedented power to detect reductions in Ne and Nc of endangered populations. However, these genetic methods are largely untested in the field. We review some relatively unexplored, but promising ways that multi-locus genetic data can be used to provide important genetic and demographic information and suggest avenues for further research in this area.

It has been documented that certain types of shade coffee plantations have both biodiversity levels similar to natural forest and high concentrations of wintering migratory bird species. These findings have triggered a campaign to promote shade coffee as a means of protecting Neotropical migratory birds. Bird censuses conducted in the El Triunfo Biosphere reserve in southern Mexico have confirmed that shade coffee plantations may have bird diversity levels similar to, or higher than, natural forest. However, coffee and forest differed in species composition. Species with a high sensitivity to disturbance were significantly more diverse and abundant in primary ecosystems. Neotropical migratory birds, granivorous and omnivorous species were more abundant in disturbed habitats. Insectivorous bird species were less abundant only in shaded monoculture. Foraging generalists and species that prefer the upper foraging stratum were more abundant in disturbed habitats, while a decline in low and middle strata foragers was found there. Findings suggests that shade coffee may be beneficial for generalist species (including several migratory species), but poor for forest specialists. Although shade coffee plantations may play an important role in maintaining local biodiversity, and as buffer areas for forest patches, promotion of shade coffee may lead to the transformation of forest into shade coffee, with the consequent loss of forest species.

The current decline of the highly endangered African wild dog (Lycaon pictus) may be partly due to the population dynamics induced by their social system. African wild dogs are obligate co-operators, and their need for helpers could generate inverse density dependence at the pack level. We show, through a mathematical model, that this can create an Allee effect, leading to a lower population size and a higher risk of population extinction, compared to populations with direct density dependence. This is due to three different processes. All three processes can increase population extinction individually and probably occur simultaneously in African wild dogs. First, inverse density dependence causes significantly higher rates of pack extinction. Second, it also increases the probability of failure to colonize territories by founders. Third, the Allee effect at the pack level (with a critical number of individuals), generates an Allee effect at the population level (with a critical number of packs). These three processes are likely to apply to other obligate co-operative breeders. Furthermore, our results suggest that habitat fragmentation and destruction, as well as increased human pressure, increase the effects of inverse density dependence. Direct and indirect anthropogenic effects may thus be more detrimental to obligate co-operative breeders than to other species.

Flagship species are charismatic species that serve as a symbol and rallying point to stimulate conservation awareness and action but are often used synonymously as de facto umbrella species to delineate reserve boundaries. We tested the extent to which the presence of a flagship species would protect other ‘background species’ at the local scale at which practical decisions about small reserves are often made. Using long term sightings, we identified four 1 km2 sites that are frequently visited by jaguars and by tapirs (flagship species), and by white-lipped peccaries and spider monkeys (non-flagship species) in neotropical rainforest in Belize. We then made inventories of five vertebrate taxonomic groups at each site. We found no consistent differences in species richness or abundances of frogs, phyllostomid bats, terrestrial mammals, scansorial mammals or birds across the four sites, except that frog diversity and abundance was higher close to a river at the flagship site where tapirs were found. Since these classic Latin American flagship species fail to encompass particularly high numbers or abundances of vertebrate species at a local scale, they appear to be a poor conservation tool when co-opted as umbrella species for delineating the location of very small reserves in the neotropics.

Conservation programmes increasingly involve the translocation of animals to reinforce failing populations or establish new ones. To help guide translocation programmes of swift foxes (Vulpes velox) or other imperilled species, we aimed to discern factors affecting translocation success among reintroduced swift foxes in Canada. Post-release movements characterized three stages. In the initial acclimation phase, foxes moved erratically and quickly distanced themselves from release sites. During the establishment phase, distances from the release site did not change significantly but daily movements were more wide-ranging than those of concurrently tracked, resident swift foxes. In the final settlement phase, movements of translocated foxes reflected those of resident individuals. Radio-telemetry showed that survival and reproductive success were highest for swift foxes with small dispersal distances, suggesting that measures should be taken to acclimatize animals to release sites. Since females had lower survival rates than males, translocations should also use a greater proportion of females to establish balanced sex ratios in the population. Translocated juveniles dispersed less far but survived and reproduced as well as translocated adults, suggesting that juveniles can be used to establish translocated foxes in small, protected areas, while minimizing demographic effects on source populations. The fact that survival rates and litter sizes of translocated foxes were similar to those of resident animals indicates that translocation can be an effective reintroduction tool for this endangered species, and possibly other foxes.

In recent years, it has become apparent that introduced or novel pathogens or parasites may have a significant negative impact on endangered species. Here we examine experimentally the effect of an exotic fluke from guppies on the endangered Gila topminnow. Populations from different sources showed variable responses (although statistically non-significant) to the fluke and, in particular, the most homozygous population had high fluke infections and high subsequent mortality. Homozygotes for a MHC (major histocompatibility complex) gene had lower (although statistically non-significant) survival when infected with flukes than did heterozygotes. An inbred line from one of the populations had statistically significant lower survival and higher fluke infection than did a simultaneous outbred control. Overall, Gila topminnows appear quite susceptible to infection by the non-native fluke compared to other related species. In addition, it was shown that Gila topminnows can be infected by casual contact with infected guppies. This is another example of the potential detrimental effects of a parasite on an endangered species, a threat that may constitute a particular problem for species with low genetic variation, either in general, for important MHC genes, or for populations with a past history of inbreeding.

African wild dogs (Lycaon pictus) always live at low population densities relative to sympatric large carnivores. This suggests that there are basic ecological reasons for the wild dog's endangered status. We examined the effects of intraspecific and interspecific competition, infectious diseases, foraging success, genetics and human activities on wild dogs. We present data from wild dogs in the Selous Game Reserve, and make comparisons with other populations to identify the limiting factors that are broadly important. The high density of wild dogs in Selous (40 adults/1000 km2) is associated with weak competition from lions and spotted hyenas. Across ecosystems, population density is negatively related to the intensity of interference competition with larger carnivores. Predation by lions and hyenas accounted for 13% of known-cause deaths in Selous and 33–50% in other populations. Intraspecific competition caused 69% of known-cause deaths in Selous, through infanticide and fights between packs, although most of the victims were juveniles with low reproductive value. Infectious diseases had little apparent impact in Selous (4% of deaths) or Kruger National Park (5%), but did play a role in the extinction of a small population in Serengeti. Infectious diseases and competition will generally interact because competitors harbor and transmit the diseases that affect wild dogs. Human activities caused 12% of deaths in Selous, even though it is large (43 000 km2) and does not border large human or livestock populations. Humans were the major agent of mortality in some populations. Foraging success varied little across ecosystems and was not apparently limiting. Mitochondrial DNA (mtDNA) genotypes revealed clinal variation between Selous and distant populations (rather than geographically isolated subspecies, as previously suggested). All wild dog populations have a genetically effective size (Ne) less than 500, so gene flow is necessary to maintain genetic diversity within populations.

Sequences from complete mitochondrial control regions (mtDNA CR) were used to infer phylogenetic relationships in 25 Cervinae taxa. Cervus splits into clades that are partially discordant with current species delimitations. Nominate Cervus elaphus includes two divergent clades that must be referred to as species elaphus (European elaphoid deer) and canadensis (Eurasian and North American wapitoid deer). Cervus nippon splits into Japanese and continental plus Taiwan sika. Père David's deer is nested within Cervus, suggesting that Elaphurus should be merged with Cervus. European and Persian fallow deer are genetically divergent and distinct species. Sequence length varied due to a CR-I insertion, tandemly repeated twice in rusa and sambar deer, sika and wapiti, and repeated up to six times in a clade of Japanese sika. Variable copy numbers of this repeat are also fixed in different sika subspecies, and could be used as a diagnostic marker for subspecies. Sequence variability at the mtDNA CR is informative for defining species and subspecies boundaries, and for locating the geographical origin of captive-reared stocks. Natural and farmed populations of some species have been deeply affected by human management and the conservation of deer populations would be aided by the appropriate identification of the different evolutionary and taxonomic units.

Cheetahs (Acinonyx jubatus) held ex situ can provide an important resource for obtaining new biological information that usually cannot be gleaned from free-living individuals. However, consistent captive propagation of the cheetah, a prerequisite for establishing a self-sustaining population, has not been accomplished so far. This study examined the effect of a husbandry regimen commonly used in ex situ facilities on female cheetahs. Although generally solitary in the wild, zoos frequently house cheetahs in pairs or groups. Using non-invasive hormone monitoring and quantitative behavioural observations, we studied the impact of such enforced social conditions on behaviour and ovarian/adrenal activity. Eight female cheetahs were evaluated for two consecutive 6-month periods, first while maintained in pairs and then as individuals. Subsequently four females were regrouped into two new pairs and monitored for another 6 months. Females in five of six pairings demonstrated prolonged anoestrus and displayed agonistic behaviours. After pair separation all females rapidly resumed oestrous cyclicity. Females in the sixth pair continued cycling throughout the year while consistently displaying affiliative grooming and no agonistic behaviours. Faecal corticoid patterns varied significantly among individuals, but appeared unrelated to behavioural or ovarian hormone patterns. Thus, data appear to indicate that same-sex pair-maintenance of behaviourally incompatible female cheetahs may lead to suppressed ovarian cyclicity. This suppression appears linked to agonistic behaviours but not to any particular adrenal hormone excretion pattern. Results clearly demonstrate the value of applying knowledge about in situ social behaviour to ex situ management practices. Conversely, however, non-invasive hormone monitoring conducted ex situ may help us to identify physiological phenomena of potential relevance for future in situ studies.

Large carnivores are of vital importance to the stability and integrity of most ecosystems, but recent declines in free-ranging populations have highlighted the potentially devastating effect of infectious diseases on their conservation. We reviewed the literature on infectious diseases of 34 large (maximum body mass of adults >20 kg) terrestrial carnivore species, 18 of which are considered to be threatened in the wild, and examined reports of antibody prevalence (seroprevalence) and cases of infection, mortality and population decline. Of 52 diseases examined, 44% were viral, 31% bacterial and the remainder were protozoal or fungal. Many infections were endemic in carnivores and/or infected multiple taxonomic families, with the majority probably occurring via inhalation or ingestion. Most disease studies consisted of serological surveys for disease antibodies, and antibody detection tended to be widespread implying that exposure to micro-organisms was common. Seroprevalence was higher in tropical than temperate areas, and marginally higher for infections known to occur in multiple carnivore groups. Confirmation of active infection via micro-organism recovery was less common for ursids than other taxonomic groups. Published descriptions of disease-induced population decline or extinction were rare, and most outbreaks were allegedly the result of direct transmission of rabies or canine distemper virus (CDV) from abundant carnivore species to less-common large carnivores. We conclude that the threat of disease epidemics in large carnivores may be serious if otherwise lethal infections are endemic in reservoir hosts and transmitted horizontally among taxa. To prevent or mitigate future population declines, research efforts should be aimed at identifying both the diseases of potential importance to large carnivores and the ecological conditions associated with their spread and severity.

We tabulate three measures of rarity: local abundance, breeding range size and elevational extent for the passerine birds of the New World. We determine what fraction of species is threatened with extinction within the combinations of these three measures. Species with smaller ranges, lower abundances and narrower elevational bands suffer higher levels of threat across lowland, montane and island species. For a given range size, lowland species suffer higher levels of threat than island or montane species. (This is counter to the intuition that island species — and those isolated on mountain tops — might be ecologically naïve.) When all three factors are considered together, there is only a slight tendency for lowland species to be disproportionately more threatened. Simply, island and montane species tend to be relatively common within their restricted ranges and their increased abundance reduces their likelihood of being threatened. Elevation is a consistent but relatively unimportant factor in determining threat; abundance and range size are much more important, and have an interactive effect on threatened status. We calculate the number of humans with which each species shares its breeding range, and find that this number does not aid in predicting threat status.

There have been few contemporary extinctions in the sea, which suggests marine species are either less vulnerable to extinction than terrestrial species, or marine extinctions may have gone unnoticed. We consider whether a large conspicuous reef fish, the giant humphead parrotfish (Bolbometopon muricatum), is likely to have declined across much of its geographical range. Informal knowledge was used to determine the status of the giant humphead parrotfish. We first surveyed fishers' knowledge of this parrotfish at 12 lightly exploited islands in the Lau group, Fiji and then compiled a global inventory of available information. In the Lau islands, Fiji, fishers reported this parrotfish as previously abundant, but it had not been caught at six islands since at least 1990 and was considered rare at another four islands. The parrotfish had been captured recently (since the 1990s) at three islands where fishers did not target parrotfishes regularly. A compilation of giant humphead parrotfish records provided by local scientists at 39 locations in 31 Indo-Pacific nations suggested this fish is locally common only inside areas where fishing is prohibited and that it is currently globally rare. Local densities of the giant humphead parrotfish were negatively correlated to a categorical scale of fishing pressure across six Indo-Pacific locations. The retrospective discovery of local disappearances and global rarity of a distinctive and formerly prominent reef fish is consistent with the hypothesis that the capacity to detect disappearances of exploitation-vulnerable species in the sea is lower than expected.

Management of marine species has increasingly focused on key site protection. Initiatives to protect bottlenose dolphins, Tursiops truncatus, under the EU Habitats Directive reflect this trend. The boundaries of the Moray Firth candidate Special Area of Conservation (cSAC) were intended to include the main Scottish population's core range, following research conducted in the 1980s and early 1990s. However, during implementation, anecdotal sightings increased outside the cSAC. Here, the authors examine existing datasets to identify whether these reports reflect simply elevated awareness among public observers or real changes in distribution. Dolphins photo-identified in areas originally considered to be outside the population's range confirmed they originated from the protected population. These individuals became rarer within the cSAC during the 1990s. Scottish bottlenose dolphins kill harbour porpoises, Phocoena phocoena, and carcasses from these interactions also became more frequent outside the cSAC during the 1990s. These results indicate mobility of this ‘resident’ dolphin population on a timescale similar to that of the implementation of the European Directive designed to protect it. Consequently, this and other similar designations, may afford less protection than originally envisioned and the authors recommend, therefore, that the potential for long-term mobility should be actively incorporated into such management structures from the outset.

Translocation is an important tool in conservation biology. However, translocation success is generally low for numerous animal species, therefore experiments are required for improvement. We carried out an experimental translocation of European wild rabbits (Oryctolagus cuniculus). The results may be of great interest for conservation biology, although we used a common species. As rabbits are known to experience a high mortality during the first days following release, it was necessary to assess the influence of handling trauma and environment novelty, respectively, and ways of suppressing them. Both tranquillization treatment during handling and a ‘soft’ release protocol (acclimatization pens in the new territory) were tested. Tranquillization did not increase survival, while the effect of acclimatization depended on sex. Females survived better when acclimatized, while males showed the opposite tendency. This difference is discussed in terms of sex-specific social behaviour, which is possibly an important correlate of translocation success. Finally, environmental stress seemed to override handling stress in determining the level of early survival for translocated wild rabbits.

The present study reports the first population genetic analysis of Arapaima gigas, an important but critically over-exploited fish species of the Amazon basin. We sequenced two discontinuous mitochondrial DNA regions of 1204 base-pairs (bp) (NADH1 segment) and 1143bp (ATPase segment) from 139 individuals of A. gigas representing eight localities spanning the Amazon basin from Iquitos, Peru to Macapá, Brazil. We discovered 34 haplotypes separated by 44 segregating sites. The two most common haplotypes are shared among all populations and isolation-by-distance appears to be the most important population dynamic, although there is no significant association between geographical distance and genetic differentiation. Observed patterns of differentiation appear to be attributable largely to anthropogenic factors associated with over-exploitation. Greatest haplotypic diversity exists upstream of Manaus and in areas away from large centres of population. The female variance and inbreeding effective population sizes are approximately 150000 individuals and localities in the Amazon basin are connected by gene flow. Naturally low levels of population differentiation and relatively high between-population connectivity is encouraging for the conservation and management of A. gigas. If strategically placed biological reserves were created throughout the Amazon basin to act as sources of emigrants within a source–sink metapopulation model, we believe locally depleted populations can be re-populated and maintained by individuals immigrating from these reserves.