Many species modify their behaviour in response to the scents of their predators, but species or populations living without predators may lose such abilities. This loss has been suggested to be irreversible, and to constitute a significant hurdle in restoring historical ecosystems. Olfactory predator recognition was studied in two macropodid marsupials - the tammar wallaby (Macropus eugenii) and the red-necked pademelon (Thylogale thetis). Both species are in the ‘critical weight range’ of Australian native mammals that have been negatively affected by the introduction of novel predators since European settlement. Predator-naïve animals were tested by exposing subjects simultaneously to two feeders with either a predator or a herbivore faecal or urine sample beneath the food tray. The presence of predator olfactory cues beneath the feeder did not affect foraging behaviour or feeder use when compared to control stimuli (herbivore faeces or urine). Previous studies have found that predator-experienced herbivorous marsupials modify their behaviour in the presence of predator scents. In contrast, our studies of predator-naïve individuals found no evidence of such selectivity, suggesting that marsupial herbivores may have to learn to modify their behaviour in response to olfactory cues from predators. This implies that the loss of olfactory predator recognition may not be irreversible. Animals translocated from predator-free areas could potentially be trained to recognise the smells of their predators.

A population and habitat viability analysis (PHVA) was carried out for the Malagasy giant jumping rat (Hypogeomys antimena), one of the key species of the highly threatened dry deciduous forests on the western coast of Madagascar. The occurrence of H. antimena is now confined to 200 km2 of fragmented but relatively undisturbed forest remnants, divided in northern and southern subpopulations. Since 1985 the habitat has declined by about 52% (1985: 42,000 ha; 2000: 20,000 ha). The annual rate of habitat decline increased from 3.9% between 1985 and 1995 to 4.4% between 1995 and 2000. Within a study area (Kirindy Forest/CFPF) in the southern subpopulation, the Hypogeomys population collapsed during the decade 1990-2000, as well as over its remaining range. An ongoing population decline within the next 100 years is predicted even if further habitat decline can be stopped within the next 5 years and no additional mortality by roaming dogs is considered. Thereby, the outcomes of two different individual-based simulation approaches, one that was explicitly written to reflect Hypogeomys life history and VORTEX, one of the most common software packages used for this purpose, were compared. The results of the Hypogeomys model were more pessimistic, but were within the range of predictions of the VORTEX model which calculated larger standard deviations of the mean values. In both subpopulations, a slight increase in the mortality caused by roaming dogs resulted in a predicted decline to an average population size of maximal 170 individuals within 100 years with a high risk of extinction. However, the simulations indicated that the most important factor is reduction in habitat. If the actual annual rate of habitat lost continues, the extinction of the both subpopulations and therefore the entire species is predicted within 24 years.

El Salvador has the smallest protected areas system in Central America. High levels of habitat destruction and disturbance throughout the country make the reserve system especially important for conservation of biodiversity. I used complementarity approaches to assess the relative conservation importance of ten reserves in El Salvador. The principal criterion was presence of nationally threatened and endangered bird species. Additional criteria included residency status (resident species were more important than migratory non-breeding species) and regionally endemic species. Montecristo National Park was the most important area, with 42% of all nationally threatened birds present. El Imposible National Park, El Salvador's largest park (5000 ha), scored second, followed by Laguna El Jocotal wildlife refuge and Barra de Santiago wildlife refuge. In all, these four areas provide refuge for 83% of El Salvador's 268 nationally threatened bird species in less than 7600 ha of natural habitat. Because of small reserve sizes, all of El Salvador's threatened birds may need additional protection.

The demographic relationship between life-history variation and environment may form a foundation for developing conservation strategy. We predicted that grouping 52 North American carnivore species based on life-history modules (reproductive output and reproductive chronology) would highlight differences in adaptations to particular environments. We tested whether differences among life histories related to particular environments classified according to primary productivity and seasonality into a 2 × 2 table. We found that bet-hedgers (e.g., bears, martens, fishers) have evolved life history adaptations to unpredictable environments, marine carnivores (e.g., seals) have evolved highly competitive abilities, and other terrestrial carnivores show adaptations to high reproduction (e.g., neotropical felids and procyonids) or survival (e.g., foxes and skunks). For example, ‘reproducers’ lived in environments with low seasonality and high primary productivity and were characterized by high reproductive output (long gestation, large neonates and small litters), short chronology of reproductive events (early age at maturity and short life), small home ranges and high population density. Conservation measures to promote carnivore populations should differ relative to the type of life history, emphasizing adult survival for bet-hedgers and survivors, and juvenile survival for reproducers and competitors.

The extant genetic variation of a population is the legacy of both long-term and recent population dynamics. Most practical methods for estimating effective population size are only able to detect recent effects on genetic variation and do not account for long-term fluctuations in species abundance. The utility of a maximum likelihood estimator of long-term effective population size based upon the coalescent theory of gene genealogies is examined for three endangered Colorado River fishes: humpback chub (Gila cypha), bonytail chub (Gila elegans) and razorback sucker (Xyrauchen texanus). Extant mitochondrial DNA (mtDNA) variation in humpback chub suggests this species has retained its historical equilibrium genetic variation despite recent declines in abundance. The mtDNA variation in razorback suckers indicates the population was quite large and expanding prior to recent declines and that rare alleles still survive in the remnant populations. The remaining mtDNA variation in bonytail chub indicates that dramatic, recent declines may have already obliterated a substantial portion of any historical variation. The results from long-term effective population size analyses are consistent with known natural history and illustrate the utility of the analysis for endangered species management.

Field ecologists in Everglades National Park know that the dynamics of water flow affect the breeding success of wading birds. A number of recent studies have suggested foraging success as the primary causal link. Data on the number and location of foraging birds are available from the Systematic Reconnaissance Flights, monthly aerial surveys of wading birds and surface water condition. A set of regression models were developed that predict the number of foraging birds observed in the Park at the beginning of May, a crucial period in the breeding season of almost all wading birds in this area. Predictor variables were obtained by converting the observations of surface water condition into three indexes that describe (1) the amount of surface water in the Park in January (near the beginning of the ‘dry’ season), (2) the rate at which it dries over the subsequent months, and (3) the amount of disruption to that drying process. An information-theoretic measure, ICOMP(IFIM), was used to choose on the basis of parsimony between the large set of possible models that incorporate these predictors. Most species were best predicted by the same few models, and the fitted model parameters were also similar, indicating that the same pattern of surface water dynamics was optimal for most species. The optimal pattern was: intermediate water levels at the beginning of the dry season, a rapid rate of drying, and no disruption in the drying process. A number of disruptions in drying since 1985 have been the result of releases of water from the flow-control structures at the northern boundary of Everglades National Park. Reducing or eliminating these unnatural hydrological events should help wading bird populations to increase.

There is considerable interest in the use of assisted breeding techniques as a component of conservation programmes for a variety of macropods threatened with extinction. While cross-fostering is being conducted in some programmes in captivity, little is known about the best techniques for carrying this procedure out from wild populations. In this study we compare the success of various procedures for isolating small tammar wallaby (Macropus eugenii) and brush-tailed rock wallaby (Petrogale penicillata) pouch young (0.4 g–410 g) for short periods (6 hours) as a first step towards establishing a methodology for recruiting endangered macropod pouch young directly from the wild for foster-rearing in captivity. Pouch temperature and humidity were determined. Pouch young from females in experimental groups were weighed, measured and then isolated, at 30°C, 27°C or 23°C, and 100% humidity. After isolation the weight of pouch young maintained at 30°C and 27°C had declined significantly (2–17% of body weight), whereas those held at 23°C and 100% humidity lost less than 0.5% of body weight. All young were reattached to the active teat of their mother following pouch isolation and their survival and growth monitored. Pouch young from the control group and those isolated at 23°C and 100% humidity survived and grew at normal rates. Only the largest pouch young maintained in isolation at either 30°C or 27°C survived to day 7 following reattachment. Data indicated that the proportion of weight lost by pouch young as a result of isolation decreased with increasing size and age of the pouch young. These trials indicate that it would be possible to harvest very small macropod pouch young from a species in the wild with a very high probability that they would survive short-term isolation from the pouch and reattachment to the teat. The use of this procedure in combination with cross-fostering techniques will allow small pouch young from threatened macropod species to be recruited directly from the wild into captivity, for captive breeding or to improve genetic diversity in captive colonies. It should also act to reactivate diapause embryos in these animals and hence may accelerate breeding in wild-based mothers.

Manipulating family sex ratio is often possible, either through non-invasive methods like changing sex-determining ecological or social factors, or through more invasive methods such as hormone treatment of embryos or sperm sexing prior to using assisted reproductive technologies. If the number of available eggs limits population growth, the production of relatively more daughters than sons may eventually lead to increased population growth in terms of absolute numbers. However, any deviation of the effective sex ratio from equality increases the rate of inbreeding and the loss of genetic variance in the next generation. I show here that there is a range of female biased sex ratios where increased population growth outweighs the effect of an enhanced inbreeding rate during the first generation or the first few generations after the start of a sex ratio manipulation programme. This is especially so in small and declining populations, where some sex ratio manipulations not only increase the effective population number Ne, but also shift the population quickly into population numbers that are safe against the Allee effect. Consequently, an optimal sex ratio manipulation with respect to the genetic quality of a population means sending an endangered population first through a genetic bottleneck to achieve increased Ne, and hence decreased rates of inbreeding, in the long run.

The Montagu's harrier (Circus pygargus) is a ground-nesting raptor that breeds mainly in cereal crops in western Europe. We evaluate how the use of agricultural habitats may affect population sustainability in this species, based on simulation analyses, and explore how conservation measures could be optimized. Probability of extinction increased with decreasing harrier productivity, and this trend was accentuated when the carrying capacity (maximum number of breeding pairs) decreased. Harrier productivity in agricultural habitats is strongly affected by harvesting activities. An average of 60% of nestlings in agricultural areas of France and the Iberian Peninsula would perish in the absence of conservation measures. These losses would make populations unsustainable, if no immigration occurred. Simulation analyses showed that connectivity between populations through natal dispersal could allow persistence of threatened populations even in the absence of conservation measures. The probability of extinction of four hypothetical populations connected through natal dispersal would be lowest if one of those populations were fully protected (or fully productive), even if the other ones were unprotected. Montagu's harriers are semi-colonial, and populations could be considered as a compound of subpopulations (the colonies). Additionally, Montagu's harriers bred more frequently in areas where food abundance was high, and where the number of fledglings produced in the previous reproductive attempt was high. These factors could be used to develop sustainable and efficient conservation plans, identifying and protecting the most productive and stable colonies in agricultural areas, and further exploring experimentally factors that are likely to attract and maintain harriers in protected areas.

A supplementary feeding and predator removal experiment was conducted on the hen harrier population on West Mainland, Orkney, to test whether increased predation pressure or shortage of food was responsible for the poor breeding success and potentially the decline of this population. Although numbers of crows appeared to have increased since 1983, the removal of hooded crows from breeding territories of male harriers had no detectable effect on any of the breeding parameters measured. The provision of supplementary food to male harriers significantly increased their numbers of breeding females, but had no detectable effect on either lay date, clutch size or hatching success. Results suggest that the current low levels of polygyny are a consequence of a shortage of food during the pre-lay period. Conservation management for this species should therefore be directed towards increasing the harriers' food supply, especially during the pre-lay period.

This study examined the effects of alteration of tropical rainforest vegetation structure and composition on bird community structure and the influence of life-history traits on species persistence in the Kalakad-Mundanthurai Tiger Reserve, Western Ghats. Systematic sampling for vegetation and point count surveys for birds were carried out in cardamom plantations abandoned for 5 and 15 years, plantation-rainforest edges, a selectively logged forest patch and adjoining undisturbed rainforest sites. Principal components analysis of vegetation variables revealed clear differences between undisturbed and altered sites in woody plant and cane densities, canopy cover and vertical stratification. Bird species richness was lowest in cardamom plantations abandoned for 5 years and highest in logged and undisturbed forest. Bird species richness and similarity with undisturbed forest were significantly positively related to the vegetation component representing woody plant and cane (Calamus spp.) densities. Sites that were more similar in tree species composition had more similar bird communities whereas similarity in foliage profile between sites did not influence bird community similarity. Birds that were rare, were large-bodied and belonged to the carnivore, omnivore, bark-surface feeder and terrestrial insectivore guilds were adversely affected by habitat alteration. Restoring woody plant and cane densities and rainforest floristic composition in disturbed habitats may be required for management and conservation of bird communities typical to the region.

Vocal individuality is widely suggested as a method for identifying individuals within a population. But few studies have explored its performance in real or simulated conservation situations. Here we simulated the use of vocal individuality to monitor the calling corncrake (Crex crex), a secretive and endangered land rail. Our data set contained 600 calls from 30 individuals and was used to simulate a population of corncrakes being counted and monitored. We tested three different neural network models for their ability to discriminate between and to identify individuals. Neural networks are non-linear classification tools widely applied to both biological and non-biological identification tasks. Backpropagation and probabilistic neural networks were used to simulate the reidentification of members of a known population (monitoring) and a Kohonen network was used to simulate the counting of a population of unknown size (census). We found that both backpropagation and probabilistic networks identified all individuals correctly all the time, irrespective of sample size. Kohonen networks were more variable in performance but estimated population size to within one individual of the actual size. Our results indicate that neural networks can be used effectively together with recordings of vocalizations in census and monitoring tasks.

In the UK, hen harriers (Circus cyaneus) are illegally killed on moorland that is managed for red grouse (Lagopus lagopus scoticus), and they produce fewer young per female on grouse moorland than on either unmanaged moorland or forestry. However, those breeding attempts on grouse moorland that escape nest destruction produce more young than in other land-use classes. One explanation for this difference is that food is more available to harriers on managed moorland than elsewhere. To examine this hypothesis, we compared the capture rates of hunting male harriers on sites across Scotland. Four of these sites were managed for grouse whilst the remaining three consisted of either unmanaged moorland or a mixture of unmanaged moorland and young forestry plantations. We found a significant difference in capture rates, with harriers on managed grouse moorland capturing prey at a greater rate than elsewhere, supporting the idea that prey were more available on grouse moorland. However, there was no difference in strike rates between the land-use classes, suggesting that prey were not necessarily more abundant on grouse moors. Males on unmanaged moorland tended to catch larger prey, though this was insufficient to compensate fully for the reduced capture rates. The improved hunting success on grouse moorland means that this habitat is likely to be more attractive to breeding harriers, thereby increasing the conflict between those interested in maximizing grouse numbers and those interested in conserving rare raptors.

Numbers of free-ranging dogs (Canis familiaris) have reached unprecedented levels in Zimbabwean communal lands (agropastoralist rural areas). This study examined the potential competitive interactions between dogs and wild scavengers on the boundary of Gokwe Communal Land (GCL) and the Sengwa Wildlife Research Area (SWRA) in 1995-96. Dietary studies showed that dogs were primarily scavengers of human waste and animal carcasses. Twelve experimental carcasses indicated that dogs were the most successful species in the vertebrate scavenger guild, consuming 60% of available biomass and finding 66.7% of carcasses. Dogs monopolized the supply of domestic animal carrion within GCL, but also consumed wild carrion up to 1 km within the SWRA, and were seen 3 km inside the reserve. Their principal competitors for carcasses were vultures, and to a lesser degree lions (Panthera leo), leopards (P. pardus) and spotted hyaenas (Crocuta crocuta). Dogs outcompete vultures on wildlife reserve boundaries owing to their high densities, nocturnal and diurnal activity, physical dominance and greater tolerance of human disturbance. With a population growth rate of 6.5% per annum the influence of dogs will intensify on the peripheries of reserves, exacerbating their existing threat to wild scavengers. This scenario is probably occurring in many other African countries.

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.

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.

Heaviside's dolphin, Cephalorhynchus heavisidii, is endemic to coastal waters of the western seaboard of South Africa and Namibia. The inshore habitat of the species places it at risk from commercial fishing operations and has led to concerns that the depletion of regional populations may result in loss of locally adapted genetic variation. To determine the geographic population structure of the Heaviside's dolphin, we obtained control region sequence (HVR1) from 17 specimens collected along the South African west coast and 18 animals taken along the Namibian coast. We identified 17 unique haplotypes within these 35 specimens which were aligned to 18 HVR1 sequences available from 40 specimens deposited in Genbank. A total of 20 maternal haplotypes was detected in the combined sample of 75 animals, of which ten were singletons. Neighbour joining and parsimony methods showed an absence of correspondence between group structure and geographic locality. Analysis of molecular variance (AMOVA) showed that almost all of the genetic variation is attributable to variation within geographic regions. This low level of differentiation between South Africa and Namibia is further underscored by an extremely low ϕST value suggestive of genetic homogeneity within the species. However, we caution that the failure to detect unambiguous population structure genetically does not necessarily mean that the population should be considered one panmictic unit for management purposes. Our genetic results should not be viewed in isolation but be considered in combination with information from nuclear markers, morphometrics, pollutants and tagging studies.

Logging and poaching have dramatically reduced chimpanzee density and distribution in the Republic of Congo. Most chimpanzee translocations attempted in the past failed because a number of biological and non-biological factors can influence success. Biological considerations include knowledge of behaviour, disease, habitat requirements and genetics. We critically review genetic considerations in pre- and post-release phases of translocations and apply them to a welfare-based chimpanzee release project in the Republic of Congo which aimed to re-establish orphan chimpanzees in the wild with a native chimpanzee population. We analyze genetic diversity and relatedness in released animals and devise a genotyping strategy for monitoring of released individuals and their future offspring. Fifty-nine confiscated chimpanzees from different areas of the Republic of Congo were typed for 20 microsatellites using plucked hair as the DNA source. Genetic diversity was high, with an average expected heterozygosity of 81%, and three to 18 alleles per locus. Between 1996 and 1998, 19 individuals were released, and genetic analysis showed that these are unrelated (mean r ± jack-knifed SD = −0.014 ± 0.001). Using FST and population admixture analysis, we identified population structure in wild chimpanzees. For long-term genetic monitoring of released and native chimpanzees, we identified a set of six informative markers, which are easy to score using basic techniques.

The search for easy-to-use indices that substitute for direct estimation of animal density is a common theme in wildlife and conservation science, but one fraught with well-known perils (Nichols & Conroy, 1996; Yoccoz, Nichols & Boulinier, 2001; Pollock et al., 2002). To establish the utility of an index as a substitute for an estimate of density, one must: (1) demonstrate a functional relationship between the index and density that is invariant over the desired scope of inference; (2) calibrate the functional relationship by obtaining independent measures of the index and the animal density; (3) evaluate the precision of the calibration (Diefenbach et al., 1994). Carbone et al. (2001) argue that the number of camera-days per photograph is a useful index of density for large, cryptic, forest-dwelling animals, and proceed to calibrate this index for tigers (Panthera tigris). We agree that a properly calibrated index may be useful for rapid assessments in conservation planning. However, Carbone et al. (2001), who desire to use their index as a substitute for density, do not adequately address the three elements noted above. Thus, we are concerned that others may view their methods as justification for not attempting directly to estimate animal densities, without due regard for the shortcomings of their approach.

The Mexican gray wolf appears to be extinct in the wild and exists now only in captivity and as a reintroduced population in southeast Arizona and southwest New Mexico. A recent study did not find evidence for inbreeding depression in juvenile viability or litter size in captive animals. Here we found that captive wolves with little or no known inbreeding had lower body size than wild-caught wolves. In addition, captive wolves with higher inbreeding had lower body size than captive wolves with little or no inbreeding. The captive population was descended from three founders until two other lineages, each descended from two founders, were recently added to the population. There has been concern that the offspring from matings between these lineages may differ from the individuals in the original lineage so we examined the potential statistical power to detect differences between body size for animals from cross-lineage matings and other matings. In endangered species there are often limited opportunities to obtain sample sizes large enough to detect statistically significant differences because of the extensive resources needed to produce and maintain captive animals. In this case, however, it appears from our examination that in the next few years there will be an adequate sample size to evaluate statistically the differences in body size between these groups.