Rates of biodiversity loss are clearly associated with a reduction in the extent of original habitat. The most frequently used method to derive such estimates comes from the well-known species–area relationship. We explored the relationship between habitat loss and area for the Brazilian mammal fauna on a biome level (Atlantic Forest, Cerrado and the Brazilian portion of the Amazon basin), as well as on a smaller regional scale (the Rio Doce Valley of the Atlantic Forest). Habitat loss overestimates the number of threatened species when the entire species pool is considered (endemics and wide-ranging species). Restricting the analyses to the endemic species, the predicted extinction as a function of habitat loss in the Atlantic Forest and in the Cerrado is found to be greater than the number of taxa actually listed as threatened. This relation is reversed in the Amazon. When considering only the localized species pool for the Rio Doce Valley region of the Atlantic Forest, the function accurately predicts the number of extinctions resulting from habitat loss. We suggest that there is both theoretical and empirical evidence to suggest that threat analysis will generate more accurate estimates of species loss when conducted on a more local scale, particularly for the fauna of non-insular, continental regions. Furthermore, other phenomena affecting the likelihood of extinction of certain groups of species, such as hunting, need to be taken into account in order to better understand the dynamics of biodiversity loss.

Darwin's fox (Pseudalopex fulvipes) is known to survive only on Chiloé Island off the coast of southern Chile and in Nahuelbuta National Park, 600 km to the north in mainland Chile. The Valdivian coastal forest, in which the Darwin's fox lives, historically spanned from Nahuelbuta National Park southward past Chiloé Island on the mainland. Furthermore, the forest on Chiloé Island was connected to the mainland forest by a land bridge for much of the Pleistocene. Thus, the distribution of Valdivian forest suggests that the historic range of Darwin's fox may have been much larger. We searched the remnant pockets of coastal forest on mainland Chile using live traps, non-invasive techniques and interviews to look for new populations of the critically endangered Darwin's fox. Although no Darwin's fox was captured, evidence of a new population near Punta Chanchán was found.

Species conservation may be complicated in symbiotic interactions. Sub-lethal impacts of human activities on one species may be lethal to other species on which they depend. We investigated the impact of two aspects of eutrophication – changes in phytoplankton and oxygen levels – on the interaction between a freshwater fish that is endangered in several countries, the European bitterling, Rhodeus sericeus, and the unionid mussel hosts that they require for spawning. Reduced concentrations of algae and oxygen each led to a greater proportion of bitterling embryos being ejected prematurely from the mussel hosts. Reduced algal concentrations also led to reductions in mussel ventilation rates and to mussels spending less time with their valves open. Bitterling mortality may have been due to three causes: direct effects of environmental conditions on embryonic survival, active expulsion by mussels when stressed and through responses by mussels that created internal conditions that bitterling embryos could not survive. Our study shows that the sub-lethal effects of pollution on one species can have lethal effects on another species with which it interacts. Such interactions need to be considered in conservation programmes.

As effective population size (Ne) decreases, genetic factors may become relatively important to a population's or species' persistence. Conservation biologists should be aware of anything that can potentially cause a sudden reduction in Ne. I used simple models to illustrate how certain types of female mating preferences combined with certain types of male traits may lead to a sudden and substantial decrease in Ne. Specifically, if and when there is a sudden ‘downward’ shift in the expression of condition-dependent male traits, females using fixed-threshold mate choice criteria might find fewer acceptable males. While mechanisms of female choice remain elusive, a variety of sexually selected traits may be condition dependent. Because the expression of condition-dependent traits is likely to be impacted by natural or human-induced environmental changes, behavioral and conservation biologists should pay special attention to them around the mating season. Armed with knowledge of condition-dependent male traits, it may be possible to minimize the impact on condition-dependent traits while planning translocations or reintroductions.

Translocation is increasingly used in conservation to re-establish or augment populations of threatened species or to remove individual animals from areas of human-wildlife conflict. We assess the feasibility and utility of translocating hen harriers (Circus cyaneus) in the UK to enhance their distribution and abundance whilst simultaneously reducing the impact of harrier predation on red grouse (Lagopus lagopus scoticus) populations and shooting bags. Current knowledge of hen harrier feeding ecology, dispersal, survival and recruitment suggests that they would be suitable subjects for translocation with the aim of increasing their distribution in the UK. Assessment of habitat and food availability suggest that there are suitable recipient sites beyond the current range of the hen harrier in the UK. However, translocation would not be a sustainable method of reducing predation on grouse moors because it would have to continue indefinitely as long as grouse moors attracted harriers. Translocation of harriers to grouse moors where they have been locally extirpated would not be appropriate until levels of illegal control are reduced. Establishing new harrier populations through translocation away from grouse moors may become desirable if initiatives to reduce human-raptor conflicts on grouse moors are unsuccessful, or as an interim measure to accelerate the recovery of hen harriers in the UK.

The Cape Sable seaside sparrow (Ammodramus maritimus mirabilis) is Federally protected under the Endangered Species Act of the United States of America. This legislation prohibits direct or indirect take - the killing or harming - of the protected species. In 1993 and 1995, the opening of floodgates into Everglades National Park during the normal dry season resulted in a direct take of the sparrow. The argument was also made that there was indirect take through destruction of the habitat upon which the sparrow depends. Using a combination of fieldwork and satellite image analysis, we show that the floods did damage to the habitat of the sparrow. Moreover, they did so for a period longer than the actual flooding, further increasing the sparrow's extinction risk. Recovery of the sparrow population to pre-flood levels will require an adequate and stable amount of habitat. We now have a technique for monitoring that habitat and ensuring that poor water management does not threaten it. More broadly, this technique has the potential for monitoring the habitat of many other species and avoiding another situation such as the sparrow faces.

Effective representation of all species in local conservation planning is a major challenge, particularly in poorly known but highly fragmented biological ‘hotspots’. Based on 105 months of studies over 49 years, we reviewed the status of 915 species and 910 subspecies of butterflies known in the Philippines. We identified 133 globally threatened and conservation-dependent endemic Philippine taxa. The current system of 18 priority protected areas provides at least one protected area for 65 of these but no areas for 29 species and 39 subspecies. Of the 133 taxa, 71% do not have a stable population inside a priority site. A total of 29 taxa is endangered or critically endangered; 83% of these do not occur within a priority site. Least protected are the lowland taxa. The minimum network required to include each threatened and conservation-dependent taxon of butterfly within at least one area would comprise 29 sites. The Sulus and Mindanao hold disproportionate numbers of threatened butterflies. Our findings suggest limited cross-taxon congruence in complementarity-derived priority sets. A large proportion of the priority areas for Philippine butterflies do not coincide with known priority areas for mammals and birds. We demonstrate that a better resolved species level classification could reveal numerous ‘new’ priority areas. In tropical island and mountain regions where the distinctiveness of butterfly subspecies is high, significant evolutionary units may be lost unless fine-scale conservation planning pays attention to well-defined subspecies.

Rana iberica is an Iberian endemic with populations mainly distributed in northwestern Iberia, but with scattered populations along the Sistema Central in central Spain. These latter populations inhabit mostly mountain areas and are endangered due to habitat loss and fragmentation. At present, no information about genetic variability and gene flow patterns between populations is available and, consequently, it is unknown to what extent geographical fragmentation might have caused restrictions to gene flow. We used six microsatellite loci to characterise genetic variability in R. iberica populations from the Sistema Central. We analysed samples of 142 specimens from 15 populations in this region and another two from additional locations in the Iberian Peninsula. The number of alleles per locus observed ranged from four to 15. Allelic richness, percentage of private alleles and gene diversity was significantly lower in populations from the Sistema Central, where inbreeding coefficients were relatively high. Analysis of molecular variance (AMOVA) and estimated FST values indicated the existence of genetic substructuring within this region and suggested the existence of restrictions to gene flow in geographically close populations. Low heterozygosities and a trend towards lower values of genetic variability from western to eastern populations within the Sistema Central suggest that R. iberica has colonised this region recently. We hypothesise that the observed pattern is due to the interaction of both historical (reduced genetic variability in peripheral populations) and present-day (anthropogenic habitat loss) factors that confirm the vulnerable status of populations of R. iberica in central Spain and point to the need for adopting measures directed towards the preservation of existing habitat.

Maritime ringlet butterflies (Coenonympha tullia nipisiquit McDunnough) are rare, endangered salt marsh butterflies with larvae that survive periodic tidal submergence. Only six disjunct populations are known to exist. First-instar larvae were released and monitored in seven microhabitats within a salt marsh in Bathurst, New Brunswick, Canada. From resighting data, microhabitat-specific daily death rates were estimated with maximum likelihood. The survival of the larvae released in groups was compared by calculating minimum number of larvae known to be alive (MNKA). Death rates were low in microhabitats with the larval host plant, salt meadow cordgrass (Spartina patens (Aiton) Muhl.) and the major nectar source, sea lavender (Limonium carolinianum (Walter) Britton), a habitat with a moderate frequency of flooding. Because microhabitats have a large effect on the survival rate of young larvae, use of microhabitat profiles in salt marshes as habitat-quality indices is recommended in critical-habitat assessment and reintroduction efforts.

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.

The sarus crane (Grus antigone) ranges across two continents and is the only species of crane (Gruidae) that breeds in India and Southeast Asia. Four subspecies, the Indian sarus (G. a. antigone), the eastern sarus (G. a. sharpii), the Australian sarus (G. a. gillae) and the extinct Philippine sarus (G. a. luzonica) were originally described through morphological, plumage, and/or geographical differences. The ranges of the Indian and eastern sarus converge in eastern India and Myanmar, but the Australian sarus has a disjunct Australian distribution. This study assesses population genetic structure of the current sarus populations utilising 13 DNA microsatellite loci. Population structure within this species was investigated utilising traditional FST and Bayesian clustering methods. While significant divergence was observed among populations when individuals were assigned to geographical populations, analyses based solely on individual genotypes demonstrated a clinal nature to the variation. The results of this study suggest that the Indian and eastern sarus cranes represent two major breeding groups within Asia and that the birds from Myanmar probably reside in an introgression zone between them. Lastly, because of genetic similarities shown to the eastern sarus, the results support recent theories contending that the Australian sarus was derived from mainland Asian birds.

The Belding's yellowthroat (Geothlypis beldingi) is an endemic species of Baja California Sur confined to the edge vegetation of freshwater at several oases. Information on its current status, distribution and habitat selection, and an analysis of the human-related threats that the species faces at 10 oases are given here. Belding's yellowthroats have disappeared from three historical sites, Santiago, Miraflores and El Triunfo, where they were recorded in the early 1900s. Belding's yellowthroats forage mainly in reed grass and cattails in all oases and were never recorded > 50 m outside the edge vegetation of the water. The main threats we detected to their habitat were cutting of reed grass for rural home construction, burning vegetation, opening trails to the water for cattle, overgrazing of reed grass by horses and burros, and using up the water for agricultural and tourism purposes. Although local populations of the species seem to be common, they are vulnerable because the distribution of the species in southern Baja California is patchy. Populations are in general small and isolated, the bird has habitat-specific requirements, and human-related activity is putting pressure on the habitat of this endemic species. A Multidimensional Scaling Analysis showed that southern populations are likely to be more severely affected than northern ones.

Wildlife capture and trade for traditional use in Papua New Guinea has led to the extirpation of cassowary in some areas and increasing pressure for trade from areas where they remain. We tested a village-based monitoring programme to evaluate sustainability of wildlife capture and trade by households in the Crater Mountain Wildlife Management Area. We monitored the type and number of wildlife species captured and traded. For the most heavily traded species, dwarf cassowary, we compared estimated annual offtake of live cassowary to maximum sustainable offtake and also compared change in hunter effort over time. We found that live offtake rates of 0.06–0.07/km2 were unsustainable in one village catchment and on the threshold of unsustainable use in another. Extirpation of cassowary will probably occur in the management area unless the location or quantity of the harvest can be restricted and the husbandry of captive birds improved. Results indicate that village monitoring of cassowary offtake is feasible when done in collaboration with outside, trained observers. Such monitoring should be encouraged as a means for landowners and management agencies to collectively evaluate the sustainability of the cassowary harvest in Papua New Guinea. This study provides an example of how scientists working with local communities in tropical forests can contribute to systematic monitoring and evaluation of wildlife offtake for sustainable use.

Baird's tapir, Tapirus bairdii, is an endangered, large, Central American mammal whose shy behaviour, solitary social structure and preference for deep tropical forests make it difficult to study using traditional field biology techniques. Despite great concern regarding its conservation status, very little is known about its population structure, mating system or dispersal patterns, information needed for designing appropriate management plans. Molecular genetic approaches can be of use in obtaining such information. In this study, we developed six polymorphic microsatellite genetic markers from genomic libraries of T. bairdii and T. terrestris. Using these markers, we completed the first assessment of genetic variability and population genetic structure in Baird's tapirs. Populations from southern Costa Rica and southern Panama were found to have low levels of genetic variability (allelic content, heterozygosity) but no indication of a recent population bottleneck. Bayesian and standard (F-statistic) analyses of genotype data indicate that the southern Costa Rican and southern Panamanian populations of Baird's tapirs were connected by some (at least one migrant per generation) gene flow prior to the destruction of intermittent habitat. These results indicate that the connection of these two populations by a MesoAmerican Biological Corridor (MBC) would be appropriate.

As large-bodied mammals become restricted to progressively smaller fragments of former habitat, competitive interactions and interspecies aggression are likely to intensify. Data on the outcomes of 159 encounters between endangered African pachyderms revealed that: (1) female elephants (Loxodonta africana) dominated both sexes of black rhinos (Diceros bicornis); and (2) rhino males but not females displaced elephant bulls. The results of an additional 127 interactions involving pachyderms and 12 additional mammals ranging in size from cheetahs (Acinonyx jubatus) to giraffe (Giraffa camelopardalis) indicates that females of either pachyderm deny immediate access to limited resources. Although the evolution of gender-specific asymmetries in interspecific dominance has received little formal study, it may best be explained by understanding patterns of parental investment; however, from a conservation perspective, one consequence of size-related dominance is that with continued containment of elephants and rhinos in managed reserves, the most handicapped species are likely to be the smaller ones.

Branching (birth–death) models are used to project the time to extinction for bird and mammal orders. While such projections are very coarse, they provide information on how long fundamental units of biodiversity, as represented by such higher taxa as orders, will persist at specified rates of species extinction. The results of a basic decay model indicate that, if all threatened species in each order go extinct within the next 100 years, and this species extinction rate continues indefinitely, then half the species in most orders will disappear in a few hundred years or less. This result is robust and is in agreement with other estimates. A more detailed branching model indicates that most bird and mammal orders will become 100% extinct in a few thousand years if current extinction trends are extrapolated. This projection is also relatively robust, as it is consistently produced using a number of different methods and estimates of future species extinction rates. Mammal orders generally have substantially shorter half-lives and time to 100% extinction than bird orders because of a combination of fewer species per order and higher species extinction rates.

Demographic analyses suggest that chelonians will have a low ability to withstand harvesting, although most have been based on stationary or declining populations. In contrast to this prediction, a population of Testudo graeca grew at the instantaneous rate r = 0.137 from 1980–1990, with a doubling time of 5 years. r was similar in both adult and 10 cm animals, showing that this high rate was not due to changes in population structure, and may thus be taken as an intrinsic rate of increase (rm). rm was higher than that of most large mammals, and suggests that sustainable harvesting would be a viable conservation strategy for chelonians if tightly regulated. Ranching or farming operations for chelonians would be even more likely to succeed, given their high fecundity. A resumption of trade in Mediterranean tortoises is, however, unlikely to be economically sustainable.

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.

Between 1959 and 1968 the entire world population of Seychelles warblers (Acrocephalus sechellensis) comprised only 26–29 individuals entirely confined to Cousin Island (26 ha). Through conservation actions the island population has reached a carrying capacity of ca 320 birds since 1982. The warbler population has significantly lower levels of genetic variation, as determined by multilocus DNA fingerprinting, compared with its mainland relative, the Australian warbler (Acrocephalus australis) and other outbred natural bird populations (mean band sharing coefficients are 0.50, 0.22 and 0.21, respectively), and has a very low annual reproductive rate of 0.28 yearlings per breeding pair. Therefore some degree of inbreeding may have occurred in this population.

The relatively low level of genetic variation is not directly responsible for this low reproductive output since breeding pairs that were transferred to the islands of Aride (68 ha) and Cousine (29 ha) with similar vegetation and climate, but with higher year-round insect food abundance, had significantly higher fecundity and survival. In contrast, no difference in reproductive success was observed between incestuous breeding pairs and non-incestuous breeding pairs.

In addition, annual production of yearlings by pairs on Aride was on average 44 times higher than that by the same pairs on Cousin before the transfer. Annual production of yearlings by pairs on Cousine, that were as inbred as those on Aride, was on average five times higher than that by the same pairs on Cousin before the transfer. Eight years after translocation, the Aride population had grown to over 1000 birds, and six years after translocation, the Cousine population had grown to 186 birds.

The experiments, controlled for group size, breeding partner, breeder age and experience, showed that the differences in reproductive success by warblers on the three islands cannot be due to genetic differences because of similar band-sharing similarities, but seem entirely accounted for by differences in food supply. Although the amount of genetic variation in the Seychelles warblers is relatively low, the demographic parameters do not indicate apparent signs of inbreeding depression in these populations.