Systematics and conservation of the swift fox,Vulpes velox,in North America

Two subspecies of swift fox have been described for North America, Vulpes velox velox and Vulpes velox hebes, but the latter northern subspecies is no longer recognised as endangered due to controversy over systematic status. We analyse morphological variation in these North American foxes, and conclude that subspecific status for northern populations is probably not justified, even though there is significant geographic variation. Because geographic variation may reflect genetic variation, we feel it should be the object of conservation effort. Although taxa may receive variable conservation attention due to the existence of arbitrary subspecies classifications, such preservation efforts may be desirable.The Canadian Wildlife Service has initiated a swift fox rehabilitation project in Alberta, Saskatchewan, and Manitoba, where foxes are re-introduced from Colorado stock. We urge extreme caution in such programmes because of risk of interbreeding with rare swift foxes known to exist in northern Great Plains states and potential loss of genetic adaption to the rigours of northern environments.     

Predation determines the outcome of 10 reintroduction attempts in arid South Australia

Ten reintroduction attempts were conducted in and around the Arid Recovery Reserve in northern South Australia between 1998 and 2008. Five locally-extinct mammal species and one reptile species were reintroduced into a fenced Reserve where cats, foxes and rabbits were excluded. Reintroductions of the nationally threatened greater stick-nest rat, burrowing bettong, greater bilby and western barred bandicoot were all considered successful based on short and medium-term success criteria. These criteria included continued survival after 8 years, increased distribution across the large Reserve and, most importantly, recovery after a drought event. The trial reintroductions of the numbat and woma python into the Reserve were unsuccessful due to predation by native avian and reptilian predators respectively. Outside the Reserve, where cats and foxes were present but controlled through poison baiting, reintroduction attempts of the greater bilby and burrowing bettong were unsuccessful. High mortality was attributed to cat and fox predation with dingoes also contributing to post-release mortality in bettongs. However, a reintroduction of burrowing bettongs into a fenced area with low rabbit and cat abundance has, to-date, met short-term and medium-term success criteria. Results suggest that the absence or severe restriction of exotic mammalian predators was the critical factor responsible for the success of the mammal reintroductions. Determining thresholds of predator activity below which successful reintroduction of threatened species can occur, are needed to improve the science of reintroduction biology in Australia.     

Pathogen exposure in endangered island fox (Urocyon littoralis) populations: Implications for conservation management

Island fox (Urocyon littoralis) populations on four California Channel Islands have declined severely since 1994. Canine distemper (CDV) was suspected to be responsible for the decline of the Santa Catalina Island fox, so knowledge of infectious disease exposure in the remaining island fox populations was urgently needed. This study reviewed previous pathogen exposure in island foxes and investigated the current threat by conducting a serologic survey of foxes on all islands and sympatric feral cats on three islands from 2001 to 2003 for antibodies against canid pathogens. Before the decline, foxes had evidence of exposure to CDV, canine adenovirus (CAV), canine parvovirus (CPV), and Toxoplasma, with exposure to these five pathogens differing greatly by island. Exposure to canine coronavirus (CCV), canine herpesvirus (CHV), and Leptospira was rare. In 2001-2003, wild-born foxes had evidence of exposure to CDV (5.2-32.8%) on 5 of 6 islands, CPV (28-100%) and CAV (4.7-100%) on five islands, and Toxoplasma gondii (2.3-15.4%) on four islands. Exposure to CCV, CHV and Leptospira was less common. Sharing of infectious agents between sympatric foxes and feral cats appeared minimal, but CDV exposure was detected in two cats on Santa Catalina Island. Domestic dogs have historically been present on the islands, but it is not known if canine diseases can be maintained in fox populations without the continual presence of dogs. Targeted vaccination programs against the most virulent pathogens and continued intensive disease surveillance may help protect the critically small remaining fox populations from disease outbreaks that could threaten the success of ongoing conservation efforts.     

Is the endangered Fennoscandian arctic fox (Alopex lagopus) population genetically isolated?

The arctic fox population in Fennoscandia is on the verge of going extinct after not being able to recover from a severe bottleneck at the end of the 19th century. The Siberian arctic fox population, on the other hand, is large and unthreatened. In order to resolve questions regarding gene flow between, and genetic variation within the populations, a 294 bp long part of the mitochondrial hypervariable region 1 was sequenced. This was done for 17 Swedish, 15 Siberian and two farmed foxes. Twelve variable nucleotide sites were observed, which resulted in 10 different haplotypes. Three haplotypes were found in Sweden and seven haplotypes were found in Siberia. An analysis of molecular variance showed a weak, but significant, differentiation between the populations. No difference in haplotype diversity was found between the populations. A phylogenetic analysis revealed that the three Swedish haplotypes were not monophyletic compared to the Siberian haplotypes. These results indicate a certain amount of gene flow between the two populations, both before and after the bottleneck. Restocking the Fennoscandian population with arctic foxes from Siberia might therefore be a viable option.     

Are Canadian foxes swift enough?

In 1983, the swift fox Vulpes velox was reintroduced to the Canadian prairie, after an absence of 45 years. We counter recent criticism of our efforts by Stromberg & Boyce (1986). Our initial breeding stock originated from Colorado and South Dakota. From those animals we have developed a successful captive breeding programme in Canada. The goal of our captive breeding programme is to maximise genetic heterogeneity. Once animals are released, natural selection over subsequent generations will produce locally adapted genotypes. Contrary to Stromberg and Boyce, we feel that our reintroduction programme is based on principles of sound genetic management. We do not believe that our efforts will diminish the genetic composition of what appears to be rare populations of swift fox in the northern United States.     

Ecology and use of arctic fox Alopex lagopus dens in Norway: tradition overtaken by interspecific competition?

Arctic fox Alopex lagopus dens in Norway are mostly large and well-defined structures of great age. Examinations of these dens have been used in surveys of the breeding and population status of the arctic fox in Fennoscandia. In this study, dens all over north Norway and in some parts of south Norway were surveyed (n=214), and several aspects of den characteristics, localisation and use were recorded. Red fox Vulpes vulpes dens were also recorded whenever found, including red fox use of arctic fox dens (total n=211). Most of the arctic fox dens were of the “classic” type dug out in sandy soil (n=210). The average number (±1 SD) of open entrances (at least half open) was 27.4±19.0, and the average size was 363.1±288.7 m². Regional variation was found in both these measurements, as well as in two variables classifying the vegetation at the den. However, no consistent south-north gradient was found, although the most southern and the most northern regions were extremes in several respects. A positive correlation was found between den size and the number of entrances, as well as between these two variables and the two vegetation variables. For each arctic fox den, height above the tree line, distance to the tree line, distance between arctic fox dens, distance to the nearest red fox den, distance to a main road and distance to other human activity were estimated. Regional variation was found in all these variables, but no consistent south-north gradient. Again, the most southern region deviated most. There were large differences in the proportion of dens used by arctic foxes between the nine regions, with one region outstanding in its production of arctic fox litters and paucity of red foxes. The proportion sum of arctic fox entrances to sum of red fox entrances reliably, but not perfectly, identified the best arctic fox regions. Arctic fox dens that were known to have produced litters at least once during 1980-2001 had about twice as many entrances as dens without pups, were 32% larger and had a more lush vegetation. They were also situated further from a red fox den. Distance to red fox dens and height above the tree line were the most important factors regarding arctic fox use of dens. Thus, the red fox was identified as a threat to the arctic fox population.     

Threats from overhunting to the flying fox, Pteropus tonganus, (Chiroptera: Pteropodidae) on Niue Island, South Pacific Ocean

Flying fox fruit bats are hunted in an annual 2-month season in Niue, a small and isolated South Pacific island nation. The sustainability of this hunt has been questioned because of an obvious recent decline. We estimated the island-wide flying fox population to be between 2040 and 4080 bats, 2 months prior to the 1998-1999 hunt. Sixty hunters interviewed after the hunt had shot 1555 bats, an unsustainable number. Many Niueans believe that an infinite quantity of flying foxes live in two small taboo or forbidden areas that originally acted as wildlife sanctuaries to safeguard animal resources for times of famine. However, our surveys suggest only a small colony roosts in one taboo area. Niueans' belief that taboo areas shelter an unlimited number of bats cannot be refuted as the areas may not be visited. Consequently, few people believe that the population is being overharvested.     

Hunting of flying foxes and perception of disease risk in Indonesian Borneo

Widespread hunting of flying foxes has generated concern regarding population declines and the spread of emerging infectious diseases. To investigate the potential impacts of this trade, we conducted questionnaires in 45 settlements across 12 population centres within Central Kalimantan, Indonesia, a region previously identified as a hunting hotspot. By combining results from 63 hunter and 88 vendor interviews, we highlight two population centres (Palangka Raya and Buntok/Tamiang Layang) with higher hunting rates than other areas, which act as flying fox trading hubs. Flying fox populations were perceived to be declining province-wide: declines in captures and sales were reported by 81% of hunters and 60% of market vendors, who also reported availability as the key factor underlying temporal variations in trade. There was substantial risk of zoonotic disease transmission between bats, hunters and traders: the vast majority of respondents were unaware that flying foxes carry potentially fatal viruses, and so few people protected themselves from physical contact. Moreover, both hunters and vendors were frequently bitten and the majority of bites drew blood. Most hunters (58%) also reported unintentional by-catches that included keystone bird species and slow lorises. The scale of hunting over Central Kalimantan represents a serious threat to the long-term viability of flying fox populations (and potentially those of other species), and could have serious public health implications. Reducing or eliminating hunting and trade would mitigate the risk of disease transmission, while maintaining the economic and ecosystem benefits that flying foxes provide, in terms of pollination and seed dispersal.     

Establishment success of 25 rare wetland species introduced into restored habitats is best predicted by ecological distance to source habitats

In response to ongoing local extinction of species and the current biodiversity crisis, the number of reintroduction programs aiming to establish new populations of rare species in the wild has increased. However, only a small proportion of these programs has been planned and monitored scientifically and comparative multi-species studies are missing in this context. Therefore, the relative importance of factors involved in reintroduction success is poorly known. In 2007, we assessed population growth since introduction as a measure of establishment success of 25 wetland species (rare or extinct in the wild nationwide) and a total of 50 populations in Switzerland that had been introduced at seven restored sites with apparently adequate environmental conditions between 1997 and 2005. We related establishment success to 32 life-history traits of these species obtained from the BiolFlor database, to initial number of introduced plants (propagule pressure with 1–130 individuals introduced per population), and to the ecological distance between source sites and restored sites based on vegetation records. Our results clearly showed the importance of close ecological similarity between source and introduction sites for successful establishment of wetland species into restored pond habitats. In contrast, neither life-history traits nor propagule pressure were related to establishment success in our study. Based on our results, we strongly recommend enforcing ecological studies prior to reintroduction to accurately assess the suitability of restored sites. To unambiguously assess the key determinants of successful establishment, future reintroduction programs should be set-up according to experimental designs.     

Factors associated with survival of reintroduced riparian brush rabbits in California

The riparian brush rabbit (Sylvilagus bachmani riparius) is an endangered species found in dense, brushy habitat in the California’s Central Valley. We implemented a reintroduction program to bolster populations at a Federal Wildlife Refuge and to assess factors influencing mortality and subsequent survival of released individuals. Between July 2002 and July 2005, we reintroduced 325 captive-bred individuals to unoccupied habitat within their historic range using a soft-release strategy and monitored their subsequent survival with radiotelemetry. Longer time in soft-release pens resulted in increased monthly survival. Rabbits were most susceptible to post-release mortality during the first 4 weeks following reintroduction and both body mass and length of time in the soft-release enclosure influenced this relationship. When we controlled for release mortality during this acclimation period, subsequent monthly survival probabilities were most strongly influenced by release year (year 1 vs. years 2 and 3) and by a catastrophic flooding event; length of time in the soft-release enclosure remained an important variable in longer-term survival. Cause of mortality was unknown for the majority of deaths (61.9%), but predation (including presumptive predation) was the greatest known cause of death in translocated rabbits (26.4%). Reintroduction programs should employ an adaptive management approach with ongoing monitoring of target animals and concurrent analysis to allow managers to adjust methods as conditions dictate.     

How successful are plant species reintroductions?

Reintroduction of native species has become increasingly important in conservation worldwide for recovery of rare species and restoration purposes. However, few studies have reported the outcome of reintroduction efforts in plant species. Using data from the literature combined with a questionnaire survey, this paper analyses 249 plant species reintroductions worldwide by assessing the methods used and the results obtained from these reintroduction experiments. The objectives were: (1) to examine how successful plant species reintroductions have been so far in establishing or significantly augmenting viable, self-sustaining populations in nature; (2) to determine the conditions under which we might expect plant species reintroductions to be most successful; (3) to make the results of this survey available for future plant reintroduction trials. Results indicate that survival, flowering and fruiting rates of reintroduced plants are generally quite low (on average 52%, 19% and 16%, respectively). Furthermore, our results show a success rate decline in individual experiments with time. Survival rates reported in the literature are also much higher (78% on average) than those mentioned by survey participants (33% on average). We identified various parameters that positively influence plant reintroduction outcomes, e.g., working in protected sites, using seedlings, increasing the number of reintroduced individuals, mixing material from diverse populations, using transplants from stable source populations, site preparation or management effort and knowledge of the genetic variation of the target species. This study also revealed shortcomings of common experimental designs that greatly limit the interpretation of plant reintroduction studies: (1) insufficient monitoring following reintroduction (usually ceasing after 4 years); (2) inadequate documentation, which is especially acute for reintroductions that are regarded as failures; (3) lack of understanding of the underlying reasons for decline in existing plant populations; (4) overly optimistic evaluation of success based on short-term results; and (5) poorly defined success criteria for reintroduction projects. We therefore conclude that the value of plant reintroductions as a conservation tool could be improved by: (1) an increased focus on species biology; (2) using a higher number of transplants (preferring seedlings rather than seeds); (3) taking better account of seed production and recruitment when assessing the success of reintroductions; (4) a consistent long-term monitoring after reintroduction.     

Sampling on private property to evaluate population status and effects of land use practices on the gopher tortoise, Gopherus polyphemus

Although private properties are predicted to play an increasingly significant role in conservation, surveys of species of special concern are rare on these lands. We created a template for a multi-county survey of randomly selected sites and sampled for burrows of the gopher tortoise (Gopherus polyphemus) in south-central Georgia, USA. Current land use was strongly correlated with tortoise population condition. The highest densities of tortoise burrows were found on lands with open-canopied pine stands that were managed with prescribed fire, a practice associated with types of selection forestry and/or wildlife management. Agricultural sites and unburned areas provided poor habitat and pine plantations were only slightly better. Our estimates of tortoise population densities indicated that the current landscape supports less than 20% of the animals present before implementation of modern land use practices. In addition, our estimate for density of active burrows was approximately one third of that projected for the entire state range 20 years ago by Auffenberg and Franz [Auffenberg, W., Franz, R., 1982. The status and distribution of the gopher tortoise (Gopherus polyphemus). In: Bury, R.B. (Ed.), North American Tortoises: Conservation and Ecology (US Fish and Wildlife Service Wildlife Research Report 12). pp. 95-126]. However, some good sites for gopher tortoises remain in south Georgia and our data also suggested that extraordinary conservation actions may not be required if ways can be developed to retain traditional land management practices on private property.     

The control of fox movement by electric fencing

On the Sands of Forvie National Nature Reserve, Aberdeenshire, Scotland, a low electric fence was tested as a barrier to foxes preying on sandwich terns and eiders. The fence was an effective deterrent, reducing fox visits to the general area by over two-thirds and turning back about 60% of those which did visit. Fox activity beyond the fence was thus reduced to about 16% of that expected without the fence. Crossing of the fence was rare (6% of encounters) but foxes were able to pass round the ends of the fence on unprotected intertidal areas. Where this became common and predictable it enabled selective removal of an individual fox causing damage, since the fence steered the animal to a predictable place.     

Generations in captivity increases behavioral variance: considerations for captive breeding and reintroduction programs

Long-term maintenance of captive populations followed by release of captive animals into the wild is one of many approaches to endangered species conservation. To assess captivity's effects on behavior, a simulated predator was presented and response behaviors measured in oldfield mice, Peromyscus polionotus subgriseus. The animals tested were from four populations collected from Ocala National Forest, Florida, and held in captivity for varying numbers of generations: 35, 14, 2, and 0 (wild caught). Results show (1) that the more generations a population has been in captivity, the less likely an individual is to take cover after seeing a predator and (2) variance in predator-response behaviors increases with generations in captivity. These results point to two ways in which captivity can compromise animal behavior and, in turn, the success of reintroduction programs. First, because individuals from populations that have been in captivity for multiple generations seek refuge less often than their wild counterparts, they might experience increased mortality in the wild due to predation. Second, increased behavioral variance could translate into decreased survivorship upon reintroduction. Therefore, more individuals will need to be released to reach the targeted wild population size.     

Evidence-based decisions on the use of predator exclosures in shorebird conservation

Conservation practitioners often rely on experience rather than scientific evidence when making management decisions. These experience-based measures can waste limited time and funding if the given conservation practice is ineffective. Unanalyzed conservation strategies may negatively impact the species that is being protected. The use of predator exclosures to increase hatching success in ground-nesting shorebirds has been studied for almost two decades, yet their effectiveness is still debated. In ecosystems where predation pressure is particularly strong, electrified exclosures have been adopted; however, there are no studies on their efficacy or potential negative impacts. We conducted a nest survival analysis for 10 years (1998-2007) of piping plover monitoring data to determine: 1) the effectiveness of predator exclosures and electrified predator exclosures, and 2) conditions associated with nest abandonments at electrified exclosures. We found that predator exclosures significantly increase nest hatching success. Electrified exclosures can also be very effective at increasing hatching success under certain conditions, but at sites with high human disturbance and red fox densities, the proportion of exclosed nests that are abandoned by parental adults becomes sizeable. The direct cause of nest abandonments remains unclear since fox behavior on beaches and the dynamics of foxes and plovers at exclosures have not been studied. Our results suggest that such information is necessary if conservation practitioners can make more informed use of this direct management measure.     

Reintroduction and establishment of the western barred bandicoot Perameles bougainville (Marsupialia: Peramelidae) at Shark Bay, Western Australia

The western barred bandicoot was reintroduced to the Australian mainland in 1995 after an absence of at least 60 years. The new population was derived from 14 animals, reintroduced to Heirisson Prong from Dorre Island in Shark Bay, Western Australia. Introduced predators (the European red fox and the feral cat) were controlled at the reintroduction site, but European rabbits were not. A large fenced area of natural vegetation within the reintroduction site was used as a secure refuge from mammalian predators. Bandicoots were released from this predator refuge to the 12 km² conservation site. Dispersal from the point of free release was minimal. The reintroduced population has persisted for 4 years and increased, with at least 175 bandicoots recruited to the population in this time. The recapture rate of marked bandicoots was low, suggesting that adult mortality was high. Reproductive output at Heirisson Prong appeared greater than that of the two surviving wild populations on Bernier and Dorre Islands. Litter size was similar, but there was an extended annual breeding season at the reintroduction site. Body condition of reintroduced and wild bandicoots were similar, although there was some indication that reintroduced males may have been in poorer condition than their island counterparts. The litter size of bandicoots increased with a decrease in rabbit abundance, however, bandicoots were able to reproduce, maintain condition, and sustain recruitment to allow the population to increase despite the presence of rabbits. Two fox incursions occurred during the 4-year period of establishment, and feral cats were present on occasion in low numbers. Feral cats may be responsible for a lower rate of population increase than that observed on predator-free Dorre Island. Ongoing predator control is essential for any mainland reintroduction of bandicoots.     

The importance of thinking big: Large-scale prey conservation drives black-footed ferret reintroduction success

Objective evaluations of wildlife reintroductions are vital for increasing the success of future efforts to re-establish endangered species. Attempts to reintroduce one of the most endangered mammals in North America, the black-footed ferret (Mustela nigripes), have been ongoing for 18 years with no quantitative assessment of factors related to reintroduction success. We examined relationships between ferret reintroduction success and factors associated with disease outbreaks, release strategies, and the distribution and abundance of their primary prey, prairie dogs (Cynomys sp.), at 11 reintroduction sites. The most important factor related to ferret reintroduction success was a cumulative metric incorporating both size of the area occupied by prairie dogs and density of prairie dog burrows within that area. Each of the four successful sites had prairie dog populations that occupied an area of at least 4300 ha. No sites with <4300 ha of prairie dogs were successful in maintaining ?30 adult individual ferrets over multiple years without augmentation even if they had a high prairie dog burrow density. The overarching importance of the availability of high-quality habitat suggests managers should prioritize actions that maintain and enhance the availability of large areas with high prairie dog burrow density, which are becoming increasingly rare due to anthropogenic impacts and disease outbreaks.     

Structural characteristics of a low Arctic tundra ecosystem and the retreat of the Arctic fox

We conducted a large-scale, campaign-based survey in Finnmark, northern Norway to evaluate the proposition that declining Arctic fox populations at the southern margin of the Arctic tundra biome result from fundamental changes in the state of the ecosystem due to climatic warming. We utilized the fact that the decline of the Arctic fox in Finnmark has been spatially heterogeneous by contrasting ecosystem state variables between regions and landscape areas (within regions) with and without recent Arctic fox breeding.Within the region of Varanger peninsula, which has the highest number of recorded dens and the most recent breeding records of Arctic fox, we found patterns largely consistent with a previously proposed climate-induced, bottom-up trophic cascade that may exclude the Arctic fox from tundra. Landscape areas surrounding dens without recent Arctic breeding were here more productive than areas with recent breeding in terms of biomass of palatable and climate sensitive plants, the number of insectivorous passerines and predatory skuas. Even the frequency of unspecified fox scats was the highest in landscape areas where arctic fox breeding has ceased, consistent with an invasion of the competitively dominant red fox. The comparisons made at the regional level were not consistent with the results within the Varanger region, possibly due to different causal factors or to deficiencies in Arctic fox monitoring at a large spatial scale. Thus long-term studies and adequate monitoring schemes with a large-scale design needs to be initiated to better elucidate the link between climate, food web dynamics and their relations to Arctic and red foxes.     

Behavioural response of a trophic specialist, the Iberian lynx, to supplementary food: Patterns of food use and implications for conservation

Prey scarcity compromises population survival, especially for specialist predators. Supplementary feeding is a management tool that can be applied to reverse the decline of food-limited populations. We analyse how a population of Iberian lynx, a threatened food specialist, initially reacted to, and subsequently used, supplementary food. Twenty-seven feeding stations (FS) with domestic rabbits were placed in the Doñana Biological Reserve, SW Spain, between 2002 and 2005. We recorded lynx tracks inside and around stations to analyse spatio-temporal patterns of use, as well as the performance of several station designs. Iberian lynx used 62% of the FS installed, and consumed most of the supplied food. All station designs were used and food provision apparently covered the energetic needs of the lynx inhabiting the reserve. There was spatial aggregation in the use of the FS. Fourteen weeks were needed on average for lynx to become familiar with feeding stations and making a regular use of the supplementary food. Seasonal variations in consumption frequency appeared to be modulated by fluctuations of wild rabbit numbers throughout its annual cycle as well as by variation in energy demand of breeding females. The Iberian lynx responded positively to our supplementary feeding programme. We show that this technique allows the persistence of lynx populations during long periods in areas where wild rabbits are extremely scarce. Supplementary food may be used to sustain lynx whenever rabbit populations need recovery, as well as in the context of lynx restocking or reintroduction programmes.     

The grey fox Canis griseus (gray) in Chilean Patagonia (Southern Chile)

During May 1982 a total of 2235 km² of land was surveyed in Southern Chile to estimate grey fox Canis griseus density. An area of 28 310 km² was judged to be potential habitat for populations in the continental area including Riesco Island. The total number of grey foxes was estimated as 65 835, that is 1 fox per 43 ha.Despite the generally good habitat conditions and the lack of both disturbance and pollution, there is no certainty that the relatively good population level can be maintained in the future due to illegal hunting. An adequate management programme could couter this threat, not only for this species but for all wildlife in the area.