The archaeological record indicates that guanacos inhabited the Patagonia of Chile and Argentina about 13,600 years ago, but were unable to migrate further south owing to the presence of glacial and water barriers that covered much of southern South America including the island of Tierra del Fuego. As environmental and ecological conditions improved, guanacos, along with other large mammals including horses, colonized the area. As a result of continued world-wide glacial melting, ocean levels rose and Tierra del Fuego became isolated from the mainland approximately 8000 years ago. Although island populations generally exhibit lower levels of genetic variation than their counterpart mainland populations, it is difficult to predict how much less variation island populations will exhibit. An analysis of mitochondrial cytochrome b and ATPase-8 sequences and 15 nuclear microsatellite loci revealed that both populations retained appreciable genetic diversity. The island population, however, exhibited much less variation than the mainland population. Measures of genetic variation revealed modest, but significant genetic differentiation, consistent with separation of the two populations approximately 8000 years ago. The assessment of levels of genetic diversity and population differentiation among populations of the wild South American camelids is becoming increasingly important as interest mounts in their utilization as a renewable resource.

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.

The Shenandoah salamander (Plethodon shenandoah) is restricted to three isolated talus outcrops in Shenandoah National Park, VA, USA and has one of the smallest ranges of any tetrapod vertebrate. This species was listed as endangered under the US Endangered Species Act in 1989 over concern that direct competition with the red-backed salamander (Plethodon cinereus), successional habitat changes, and human impacts may cause its decline and possible extinction. We address two issues herein: (1) whether extensive introgression (through long-term hybridization) is present between the two species and threatens the survival of P. shenandoah, and (2) the level of population structure within P. shenandoah. We provide evidence from mtDNA haplotypes that shows no genetic differentiation among the three isolates of P. shenandoah, suggesting that their fragmentation is a geologically recent event, and/or that the isolates are still connected by occasional gene flow. There is also no evidence for extensive introgression of alleles in either direction between P. cinereus and P. shenandoah, which suggests that P. shenandoah may not be in danger of being genetically swamped out through hybridization with P. cinereus.

Habitat clearance generally produces fragmented landscapes. A major consequence is the creation of large amounts of new ‘edge habitat’, often of a kind not previously existing, such as abrupt forest- agricultural land interfaces. Much work from around the world suggests that proliferation of edge habitat seriously affects birds reliant on large forest blocks to persist, and the intrusion of edge specialists into areas they did not previously occupy. These processes often generate avifaunal gradients in which assemblages change from the interior to the edge. This effect is explored in the largest remnant block of box-ironbark forest of central Victoria, Australia (about 30,000 ha). Eight radially oriented survey lines were established around the periphery of the block. Along each survey line, five transects with long axes oriented parallel to the edge were positioned with midlines at 40 m, 160 m, 280 m and 400 m into the forest, and one transect 80 m into the agricultural land, yielding a total of 40 transects. Six identical transects were located deep within the forest (> 2 km). There was little evidence of a change in the avifauna from interior to edge, although mean richness was depressed in the edge habitats compared with forest interior transects. These results were essentially the same for ‘all species’ or ‘forest dependent’ species. Thus, there is little evidence for marked edge effects on the avifauna of these large forest blocks, although work in intermediate sized remnants (100-1000 ha) is needed to identify thresholds at which edge effects begin to be manifested.

Between the years 1994 and 2000, we assessed the mortality rate of adult-sized, migrant Asian houbara bustards (Chlamydotis [undulata] macqueenii) via banding and satellite tracking programmes. The birds were captured either on their breeding grounds in Kazakhstan (Taukum desert and Buzachi peninsula) and in China (Jungar basin) or on their wintering grounds in Pakistan (Cholistan desert) and in the United Arab Emirates (Baynunah area). For the banding programme, 104 houbara bustards were marked and statistical analysis was performed on the number of transmitters and rings returned by falconers. This allowed us to calculate a 0.045 (SD 0.061) annual mortality rate attributable to hunting activities. The tracking programme analysed the fate of 41 houbara bustards equipped with satellite transmitters (PTTs). Overall, the satellite-tracked birds were followed for 10,965 days and had travelled all over the distribution range of the species in Asia. The causes of mortality were assessed from the interpretation of the ARGOS data relayed by the sensors embarked on the PTTs. The annual mortality rate was derived from the calculation of the average finite daily survival rate using the Trent & Rongstad (1974) method. With this method, the overall annual mortality rate in adult-sized houbara bustards migrating through Asia was 0.283 (95%lcl 0.186-95%ucl 0.404). The hunting and poaching pressure could explain 73.5% of the observed mortality. The mortality rate during winter, when the houbara is under severe hunting pressure, was 11.2 times higher than during the breeding season. Houbara appear to be especially at risk in Pakistan, Afghanistan and Iran. A VORTEX simulation showed that under current hunting and poaching pressures, the probability of extinction of the houbara population modelled can be anticipated at 50 years with a 94% probability. The maximum sustainable yield was estimated at 7.2% of the adult-sized population whereas as much as 20.8% is currently taken. This work stresses the need for conservationists and Arab falconers to take appropriate concerted measures as soon as possible.

Microhabitat use studies of translocated species are crucial to assess their adaptation to the new environment. A total of 42 St Lucia whiptail lizards (Cnemidophorus vanzoi), an endemic to two islets (Maria Major, 10.2 ha and Maria Minor, 1.8 ha) off St Lucia in the Lesser Antilles, were translocated from Maria Major to Praslin Island (1.1 ha) in 1995. Three years after the release, we studied the abundance, density and distribution of the translocated lizard population in the prevailing five habitat types on the island. Habitats varied from more exposed open grasslands to tall, continuously canopied woodlands. Although lizards were distributed throughout the island, some habitats were used more than predicted with respect to availability. Habitat utilization showed a seasonal shift in distribution. Line transect sampling estimated a population of 145 ± 23 lizards on Praslin Island. There were significant seasonal differences in estimated lizard abundance indicating a change in activity during the dry season. Lizard density was significantly correlated with general habitat characteristics, rather than with any specific microhabitat variable measured. Factors affecting distribution (thermo-regulation, food resources and competitive exclusion) are discussed and it is suggested that habitat use during the dry season may be best explained by thermal constraint. These results will help managers choose future translocation sites.

We present a case study of the use of simulation modelling to develop and test strategies for managing populations under uncertainty. Strategies that meet a stock conservation criterion under a base case scenario are subjected to a set of robustness trials, including biased and highly variable abundance estimates and poaching. Strategy performance is assessed with respect to a conservation criterion, the revenues achieved and their variability. Strategies that harvest heavily, even when the population is apparently very large, perform badly in the robustness trials. Setting a threshold below which harvesting does not take place, and above which all individuals are harvested, does not provide effective protection against over-harvesting. Strategies that rely on population growth rates rather than estimates of population size are more robust to biased estimates. The strategies that are most robust to uncertainty are simple, involving harvesting a relatively small proportion of the population each year. The simulation modelling approach to exploring harvesting strategies is suggested as a useful tool for the assessment of the performance of competing strategies under uncertainty.

Although the massive organized slaughter of African wild dogs, Lycaon pictus, largely ended several decades ago, this endangered canid continues to decline and faces extinction. Several lines of evidence suggest that this arises from obligate cooperative breeding, which makes Lycaon more sensitive to anthropogenic mortality. A number of behaviours in this species are characterized by a reliance on helpers. These include cooperative hunting, defence from kleptoparasitism, pup feeding and baby-sitting. As a result, there are strong, positive relationships between pack size and the production and survival of pups, and pairs of wild dogs are often unsuccessful at raising offspring without the assistance of helpers. Consequently, a pack in which membership drops below a critical size may be caught in a positive feedback loop: poor reproduction and low survival further reduce pack size, culminating in failure of the whole pack. Here, we review the literature to reveal the importance of pack size in the African wild dog. Most importantly, we argue that there is a critical minimum threshold, below which packs face an increasing probability of extinction - an Allee effect with consequences for the conservation of this species, and of other obligate cooperators.

We sought to assess the effects of forest fragmentation, introduced Rattus rattus, exotic tree plantations and secondary vegetation on the endemic rodent Eliurus webbi (Nesomyinae) and the lemur Microcebus murinus in the littoral forests of southern Madagascar. For E. webbi the number of individuals caught, the body mass of males and the percentage of females in the population were positively correlated with the size of the forest fragments. Capture rates and population characteristics of the other two species were uncorrelated with fragment size. None of the endemic species was caught outside the native forest while R. rattus inhabited all vegetation formations except for a newly planted corridor of tree saplings. Capture rates of both endemic species were uncorrelated with the number of R. rattus caught at the same site and thus did not indicate replacement of native species by R. rattus. The study demonstrated negative effects of fragmentation on capture rates of E. webbi and changes in their population characteristics. Exotic tree plantations or secondary vegetation seem to represent unsuitable or marginal habitats for the endemic species.