We studied the influence of vegetation structure and tree phenology on bird communities along a gradient of tropical forest degradation in NW Madagascar. Birds were censused by point counts at Ankarafantsika, one of the largest remnants of the severely reduced dry deciduous forest. The original forest was dominated by foliage insectivores. A few years after wildfire, regrowth was dense, most forest bird species were still present and additional understorey species appeared. As a result, species richness and abundance per point count increased. In contrast, when forest was transformed into savanna, the avian assemblage became poor, dominated by granivores and aerial insectivores, with only seven species shared with the original forest. Foliage volume, grass volume and bare ground cover explained most of the bird community variation by means of canonical correspondence analysis. Birds tended to increase their habitat breadth along the forest–savanna gradient. An index of bird conservation value, including abundance, endemism and the threatened status of the species, was highest in burned forests (1.12), intermediate in unburned forests (1) and lowest in savanna (0.44). The results emphasise the urgent need to protect not only the undisturbed fragments, but also the burned dry forests, because of their high value for biodiversity.

Many diurnal raptors are vulnerable to modern forestry and areas surrounding individual raptor nests are often strictly protected. This study compared random forest plots and nest sites of five species of forest-dwelling raptors in Estonia to explore whether timber harvesting per se reduces the probability of raptor nesting when controlling for the effect of nest tree availability and stand structure. Medium-sized species – the honey buzzard (Pernis apivorus), goshawk (Accipiter gentilis), common buzzard (Buteo buteo) and lesser spotted eagle (Aquila pomarina) – preferred natural to managed forests but the preference, when controlling for other stand characteristics, was not significantly related to the incidence of cutting. Instead, the presence of nests depended on structural features of old growth, even for the sparrowhawk (Accipiter nisus), which preferred young secondary forests. The sparrowhawk was the only species for which thinning had an independently negative influence on nest presence. The results stress the importance of structural diversity of forest stands in multiple-use forestry and indicate that if natural stand structure is preserved and disturbance avoided in buffer zones around the nests of medium-sized raptors, some non-commercial cutting (firewood collecting, sanitary cutting) may be allowed there outside the breeding season.

During the 1990s, populations of two species of griffon vulture, the Indian white-backed Gyps bengalensis and the long-billed Gyps indicus, declined by more than 90% throughout India. These declines are continuing and are due to abnormally high rates of both nesting failure and adult, juvenile and nestling mortality. Affected birds exhibit signs of illness (neck drooping syndrome) for approximately 30 days prior to death. Epidemiological observations are most consistent with an infectious cause of this morbidity and mortality. To investigate the cause of these declines, 28 vulture carcases, including adults and juveniles of both species, were examined in detail. Significant post-mortem findings included visceral gout, enteritis, vasculitis and gliosis. Although we have not yet been able to identify the causative agent of the declines, the results of our pathological studies are most consistent with those for an infectious, probably viral, aetiology. We examine hypotheses for the cause of the declines and, based on our epidemiological and pathological findings, we show infectious disease to be the most tenable of these.

The extent of inbreeding and outbreeding depression is thought to be a fundamental factor influencing the long term persistence of an endangered species. However, there have been no comprehensive examinations of either factor in an endangered species, except for a mouse species. Here we examined both the extent of inbreeding and outbreeding depression for five traits related to fitness in populations from the four watersheds in which the endangered Gila topminnow (Poeciliopsis o. occidentalis) still exists in the USA by making experimental matings with replicate samples and simultaneous controls. There was generally high survival, similar body size, and little bilateral asymmetry for all the inbred and outbred matings for all populations, i.e. there was no evidence of either inbreeding or outbreeding depression for these traits. Similarly there was no evidence of inbreeding or outbreeding effects for fecundity or sex ratio except for the sample from Monkey Spring, which had highly skewed (female-biased) sex ratios after one generation of inbreeding. In addition, brood sizes for Sharp Spring declined over time in inbred lines maintained by full-sib mating. These results further support the suggestion, based on molecular genetic analysis and considerations of habitat differences, that Monkey Spring be considered an evolutionarily significant unit, distinct from the remainder of existing populations. Potential explanations for the results and their implications for conservation are discussed.

To achieve long-term viability of hunted puma (Puma concolor) populations (even at historically low densities), we propose a management plan based on the metapopulation concept that designates source areas (closed to hunting) and sink areas (open to hunting). We use 11 years of data from Idaho and Utah to demonstrate how the proposed management plan might be implemented. We use minimum and maximum densities of resident animals to calculate minimum and maximum effective population sizes, neighbourhood areas (regional management units) and usable habitat within the units. We designate sink and source areas based on their size, accessibility to hunters and juxtaposition. We show that closing 63% of puma habitat to hunting would ensure long-term puma population viability while permitting traditional hunting levels in other areas. This system could be adapted to existing state (and interstate) hunting management units, and we outline several steps by which wildlife agencies might set up a process (including public participation) to manage puma hunting.

Giant tortoises once thrived throughout the Galápagos archipelago, but today three island populations are extinct, only one individual survives from the island of Pinta, and several populations are critically endangered. We established the geographic origin of 59 captive tortoises housed at the Charles Darwin Research Station in the Galápagos Islands in an effort to find a mate for the sole survivor from Pinta (‘Lonesome George’) and to augment the number of breeders in other imperilled populations. By comparison with an extensive database of mtDNA control region (CR) haplotypes and nine microsatellites, we determined the geographic and evolutionary origin of the captive individuals. All individuals had CR haplotypes and multilocus microsatellite genotypes identical to or closely related to known haplotypes from natural populations. No obvious mate was found for Lonesome George, although we found several captive individuals carrying an evolutionarily close but geographically distinct mtDNA haplotype. Tortoises with mtDNA haplotypes closely related to another at-risk population (San Cristóbal) were also identified. These individuals could be considered as candidates for augmentation of natural populations or captive-breeding programmes and exemplify how molecular techniques can provide insights for the development of endangered species management plans.

As a signatory of the Convention on Biological Diversity, the United Kingdom (UK) Government is obliged to conserve and enhance biodiversity. One step towards addressing this goal is to determine the level of biodiversity conservation already achieved within the current array of protected areas. We used national distribution data for ten taxonomic groups, and location information for three reserve networks, to assess the contribution of nature reserves to biodiversity conservation in Great Britain at the 10 km square (=100 km2) resolution. For several taxonomic groups, 10 km squares containing nature reserves had a significantly greater overlap than random networks with both hotspots (areas of high species richness) and complementary areas (sets of sites within which all species are represented). In addition, more than 94% of species from each taxonomic group have been recorded within the 10 km squares of the three reserve networks. These results provide some encouragement in terms of the UK meeting its commitment to conserve biodiversity.

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.

Faecal oestrogen and progestin analyses were used to assess ovarian activity in non-pregnant scimitar-horned oryx (Oryx dammah) during a 13-month interval. Mean (± SE) luteal phase, interluteal phase and oestrous cycle duration were 18.8 (± 0.5), 5.1 (± 0.2) and 23.8 (± 1.3) days, respectively. All females exhibited a synchronized anovulatory period that ranged from 36–95 days during spring. Short ovarian cycles (10.6 (± 0.8) days) were observed intermittently throughout the year and before the spontaneous resumption of oestrous cyclicity. Periovulatory peaks in oestrogen concentrations were detected for 42.5% (31/73) of ovarian cycles. A parallel analysis of reproductive data from the North American studbook (1985–1994) revealed that captive-held scimitar-horned oryx gave birth throughout the year. Sex ratio at birth was male-biased (54.4%), and 19.1% of all calves failed to survive to 6 months of age (220 out of 1149 births). Only 0.7% of births resulted in twins. Median interbirth interval was 277 days, and 75% of these intervals were less than 332 days. Interbirth interval was extended (P < 0.05) if parturition occurred from January through May. In summary, the scimitar-horned oryx is a seasonally polyoestrous species that experiences a distinct anovulatory period during spring in north-east America.

In Asia, subtropical tall grasslands and their associated fauna are mostly confined to the floodplains of the large rivers draining the Himalayan range. In recent decades, cultivation and hydroelectric dam construction have severely reduced their spatial abundance. During 1998–2000, we conducted a detailed study of the habitat use of hog deer, Axis porcinus, an important prey species of tiger, Panthera tigris, in the floodplains of the large Karnali river in Royal Bardia National Park, Nepal. Strong preference for tall grass and avoidance of the successional stages following riparian forests throughout the year was revealed by analyses of tracking data from 18 radio-collared deer and from density estimates from block counts (n=46) in different habitat types. Continuously strong selection for tall grass despite the reduced availability of this habitat type during the monsoonal flooding indicated an insignificant effect of density-dependent factors in habitat selection. Reduced availability of cover following traditional cutting and burning of the tall grasslands by local villagers did not produce changes in habitat use or an increase in daily movements, indicating an absence of trade-offs between habitat preference for food and for predator avoidance. By regulating fluvial action, hydroelectric power development will lead to the loss of tall grasslands due to accelerated secondary succession, which will therefore adversely affect the viability of local populations.

Male fiddler crabs have one of their feeding claws greatly enlarged, which may comprise up to 40% of their weight. In southern Portugal (Ria Formosa) the major claw of the fiddler crab Uca tangeri is a local delicacy. Fishermen break off the male major claw and throw the crab back into the mudflat to regenerate a new one. Approximately 38 % of the males sampled had a missing or a regenerating claw. Although individuals are not removed from the population the operational sex ratio is biased towards females since other males and females behave towards clawless males as if they were females. Moreover, removing the major claw from males prevents them from signalling (waving display) to females to attract them to their breeding burrows and it also places them at a disadvantage if they have to defend their burrows from males with intact claws. Thus, the harvesting of male fiddler crab claws has potential consequences at the population level. In this paper we investigated these potential consequences by comparing an exploited population of fiddler crabs at Ria Formosa with a remote population at the Mira estuary that is not under human exploitation. The unexploited population has significantly larger males and a significantly higher density of burrows. The operational sex ratio is also significantly different between the two populations with a female-biased sex ratio in the exploited population. These preliminary results suggest that claw harvesting in fiddler crabs has a measurable effect at the population level. The consequences of this type of fishery in which the individuals are not removed from the population but the population structure is potentially affected need further investigation.

We assessed the genetic status of two endangered subspecies of the northern flying squirrel (Glaucomys sabrinus) that are restricted to isolated stands of high elevation spruce-fir and adjacent spruce-fir-hardwood ecotonal habitat in the Appalachian Mountains of eastern North America. We used mitochondrial DNA (mtDNA) and allozyme data to estimate levels of genetic variability in the two subspecies of interest and then evaluated this information in the context of large-scale phylogeographical structure and overall genetic variability for the entire species and for the closely related and partially sympatric southern flying squirrel (Glaucomys volans). This broader analysis involves much of North America's northern coniferous forest biome, together with the deciduous forest biome of eastern North America. Our results support the evolutionary distinctness of the endangered Appalachian populations of G. sabrinus. These populations possess several private alleles and have levels of genetic variability that are substantially lower than those observed in conspecific populations found elsewhere. However, the endangered Appalachian populations of G. sabrinus have higher levels of genetic variability than those observed in populations of G. volans from across eastern North America. These results highlight the utility of evaluating the conservation genetics of small and isolated populations within a broad-scale comparative evolutionary and biogeographical framework.

Digital maps and a dated supertree of global carnivore species were used to assess the distribution of American carnivores' phylogenetic diversity (PD, measured in millions of years) both from a geopolitical perspective (‘evolutionary heritage’ or EH) and on the basis of species' range size and conservation status. A new measure, range-weighted EH, is introduced. This measure partitions the total PD of the tree between countries based on the proportion of species' ranges within each country. Sociopolitical correlates of these measures were explored. Only 3% of the total PD in the Americas is endemic to any one country. As expected, the measures of PD are positively correlated with each other and with species richness. The USA contains the most species, the most EH and the second most range-weighted EH after Brazil. Indeed, larger and richer countries, and those with the lowest state-corruption-rate hold most EH. No significant differences were observed in the amount of PD remaining if species are removed at random, or following more plausible sequences based on IUCN conservation status and range size. Eighty percent of the American carnivores' PD would remain safe if only the set of not threatened species were to remain. Roughly the same is true if only the 50% most widespread species were to persist. Samples of wide-ranging species represent more of the entire tree than do samples of narrow-ranging species, highlighting the importance of the former for conservation strategies. We suggest that similar approaches be applied to more groups across the globe to assess which countries and areas steward the most PD, as well as which species and taxa do, in order to plan conservation actions consequently.

A set of priority sites for wildfowl conservation in Mexico was determined using contemporary count data (1991–2000) from the U.S. Fish & Wildlife Service mid-winter surveys. We used a complementarity approach implemented through linear integer programming that addresses particular conservation concerns for every species included in the analysis and large fluctuations in numbers through time. A set of 31 priority sites was identified, which held more than 69% of the mid-winter count total in Mexico during all surveyed years. Six sites were in the northern highlands, 12 in the central highlands, six on the Gulf of Mexico coast and seven on the upper Pacific coast. Twenty-two sites from the priority set have previously been identified as qualifying for designation as wetlands of international importance under the Ramsar Convention and 20 sites are classified as Important Areas for Bird Conservation in Mexico. The information presented here provides an accountable, spatially-explicit, numerical basis for ongoing conservation planning efforts in Mexico, which can be used to improve existing wildfowl conservation networks in the country and can also be useful for conservation planning exercises elsewhere.

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.

I used VORTEX to make a prior evaluation of the planned reintroduction project of the endangered bearded vulture (Gypaetus barbatus) in the mountains of southern Spain. The minimum size of a captive population needed to ensure the release of two bearded vulture fledglings per year is 30 individuals. If breeding success was improved, this minimum captive population could be reduced to 10 individuals. As the cost of the project is proportional to the size of the captive population, some research effort should be devoted to improving breeding success in captivity. The current size of the captive population — four individuals — is not enough to start the releases, even if the vultures were already breeding. The first step for the project should be to increase the size of the captive population. If on average one individual per year was added to the captive population, it would take 15 years to reach 30 individuals. If breeding in captivity was improved, it would take only three to seven years to reach the minimum captive population of 10 individuals. Once releases were started, the project would need on average 20 years to reach a goal of 15 adult pairs in the Cazorla mountains. Both the success of the project and the time necessary to reach this stated goal are very sensitive to the mortality rates in the wild. There is little known about these rates, and better estimates are urgently needed to improve the predictions of the models.

The Bahamian Andros iguana (Cyclura cychlura cychlura) is an endangered lizard threatened by habitat loss, illegal hunting, impacts from historic large-scale logging practices and predation by feral animals (e.g. cats, dogs and hogs). There is interest by local and national conservation organisations to demarcate protected areas for the iguana in the southern portion of its range. However, no life history information is available for the lizard. In order to provide data that can be applied in a science-based management strategy for the Andros iguana, we investigated seasonal variation in home-range size and habitat selection of the iguana using radio telemetry. Home ranges were the largest reported to date for free-ranging Cyclura iguanas (Fixed 95% Kernel maximums: 30.58 ha for males, 5.63 ha for females). Habitat selection using the Euclidean Distance method revealed that open pine was the only habitat type out of four where iguanas occurred more than expected by chance. However, the pair-wise comparisons of habitat types reveal that iguanas were found significantly closer to open pine and shrubland than to closed pine. We failed to uncover selection of cumulative home-range placement throughout our multi-habitat study areas. Conservation implications of the dynamic seasonal home-range fluctuations and habitat usage are discussed and recommendations are offered for establishing protected areas.

Studies on the effects of nonindigenous invasive species and habitat fragmentation on native ecosystems have become priorities for conservation biologists. This is relevant particularly for islands with high degrees of endemism. In the present paper the role of fragmentation and possible effects of introduced Rattus rattus on endemic rodents (Macrotarsomys bastardi and Eliurus spp.) and the gray mouse lemur (Microcebus murinus) were assessed for dry deciduous forests in Madagascar. Capture rates of endemic rodents declined significantly with declining fragment size. Macrotarsomys bastardi was never caught in primary forest fragments < 600 ha or outside the primary forest but captures of M. bastardi were correlated to changes in vegetation structure associated with fragmentation rather than to fragment size per se. Eliurus spp. were also found in small primary-forest fragments and in secondary forests close to primary forests, suggesting that secondary forests can serve as buffer zones or corridors for this species. The lemur M. murinus was caught in all types of primary and secondary forest. This species did not seem to respond to fragmentation of primary forests. Even though it was found in most secondary-forests, capture rates declined as these secondary forest formations increased in size. This indicates that secondary forests are suboptimal habitats for M. murinus. Rattus rattus were caught in all vegetation formations except for the open savanna. Their capture rates increased as forest fragments became smaller, indicating that mosaics of different habitat types are beneficial for introduced rats. There was no significant relation between capture rates of R. rattus and the endemic species. In conclusion, these results suggest that (1) native Malagasy rodents of the dry deciduous forest are more sensitive towards forest disturbance than M. murinus; (2) there is no indication for negative interactions between introduced rats and the native small-mammal fauna.

This study reports the population responses of the lizard Psammodromus algirus to forest fragmentation by comparing its distribution in two contrasting situations of habitat conservation: a well connected mosaic landscape (forest patches larger than 2000 ha and/or connected by corridors that prevent their isolation), and an archipelago of forest remnants embedded within a matrix of cereal fields. The frequency of occurrence of P. algirus was larger in the unfragmented habitats (14 out of 19 censused plots) than in the fragments (two out of of 21 wood-lots). Vegetation structure was a good predictor of lizard occurrence under conditions of no fragmentation, but not in the fragments, where high plant cover seemed a necessary, but insufficient, condition for the survival of lizard populations, and where remnant size was the only variable that differed significantly between wood-lots with and without lizards. Historical fragmentation of the habitat is also crucial for understanding the current distribution of lizards, as shown by their absence from a large forest that was highly fragmented in the past but which has been regenerating for decades. It is hypothesized that the combined effects of fragmentation and predation in small remnants have led to the extinction of P. algirus in fragments smaller than c. 90 ha, recolonization being prevented by the very limited dispersal abilities of these forest lizards.

The roan antelope (Hippotragus equinus) population inhabiting the Kruger National Park, South Africa, declined from 450 animals in 1986 to around 25 free-ranging animals subsequent to 1994. A computer simulation model was developed to: (1) evaluate likely contributions of low rainfall, habitat deterioration, population fragmentation and predation to the observed population decline; (2) project future likelihood of persistence of the population remnant, under various scenarios. Direct consequences of severe drought and habitat deterioration alone were inadequate to explain the observed decline, unless effects were more severe than assumed in the model. An increased predation loss to around 30% per year was needed. Persistence probability over 50 years was less than 0.5 if the predation loss remained above 20% per year. Models that take into account only stochastic uncertainty in demography and environmental variability are of limited reliability if potential changes in predation risk are not also accommodated.