Creating Larger and Better Connected Protected Areas Enhances the Persistence of Big Game Species in the Maputaland-Pondoland-Albany Biodiversity Hotspot

The ideal conservation planning approach would enable decision-makers to use population viability analysis to assess the effects of management strategies and threats on all species at the landscape level. However, the lack of high-quality data derived from long-term studies, and uncertainty in model parameters and/or structure, often limit the use of population models to only a few species of conservation concern. We used spatially explicit metapopulation models in conjunction with multi-criteria decision analysis to assess how species-specific threats and management interventions would affect the persistence of African wild dog, black rhino, cheetah, elephant, leopard and lion, under six reserve scenarios, thereby providing the basis for deciding on a best course of conservation action in the South African province of KwaZulu-Natal, which forms the central component of the Maputaland-Pondoland-Albany biodiversity hotspot. Overall, the results suggest that current strategies of managing populations within individual, small, fenced reserves are unlikely to enhance metapopulation persistence should catastrophic events affect populations in the future. Creating larger and better-connected protected areas would ensure that threats can be better mitigated in the future for both African wild dog and leopard, which can disperse naturally, and black rhino, cheetah, elephant, and lion, which are constrained by electric fences but can be managed using translocation. The importance of both size and connectivity should inform endangered megafauna conservation and management, especially in the context of restoration efforts in increasingly human-dominated landscapes.     

Conservation implications of prey responses to wild dogs Lycaon pictus during the denning season on wildlife ranches

The spread of game ranching in southern Africa provides opportunities for the reestablishment of populations of endangered wild dogs extirpated by livestock ranchers. However, this potential has not been realized, partly because of negative rancher perceptions. Some ranchers believe that wild dogs impart costs by killing wildlife that could be utilized consumptively. Others complain that wild dogs make ungulates 'skittish' and cause local reductions in prey densities while denning. We compared the skittishness and density of prey species inside and outside the denning home ranges of nine wild dog packs in Zimbabwe. Wild dogs had no impact on prey skittishness, but prey species did occur at lower densities inside denning home ranges. In some scenarios, and particularly on fenced game ranches, wild dogs could cause prey population declines during denning. On small game ranches, the use of fences as a tool by wild dogs during hunting can increase the proportion of large prey species in their diet by up to 11 times, and thus increase the minimum area required to support that diet. In addition, game fencing is typically permeable to wild dogs but not their prey, preventing the recovery of prey populations through the natural influx of prey animals into the denning area following departure of the dogs. Wild dogs could thus impose significant financial costs to game ranchers hosting denning packs. Our findings emphasize the importance of promoting the formation of conservancies, where neighbouring landowners remove boundary fences to create larger contiguous wildlife areas.     

Exclosure fences around nests of imperiled Florida Grasshopper Sparrows reduce rates of predation by mammals

Increasing nest survival by excluding predators is a goal of many bird conservation programs. However, new exclosure projects should be carefully evaluated to assess the potential risks of disturbance. We tested the effectiveness of predator exclosure fences (hereafter, fences) for nests of critically endangered Florida Grasshopper Sparrows (Ammodramus savannarum floridanus) at a dry prairie site (Three Lakes; 2015–2018) and a pasture site (the Ranch; 2015–2016) in Osceola County, Florida, USA. We installed fences at nests an average of 8 days after the start of incubation, and nest abandonment after fence installation was rare (2 of 149 installations). Predation was the leading cause of failure for unfenced nests at both sites (48–73%). At Three Lakes, nest cameras revealed that mammals and snakes were responsible for 61.5% and 38.5% of predation events, respectively, at unfenced nests. Fences reduced the daily probability of predation (0.016 for fenced nests vs. 0.074 for unfenced nests). The probability that a fenced nest would survive from discovery to fledging was more than double that of unfenced nests (60.4% vs. 27.7%). However, we found no difference in daily nest survival at the Ranch between the year before nests were fenced (2015; 0.874) and the year when all but one nest were fenced (2016; 0.867) because red imported fire ants (Solenopsis invicta) were responsible for 86% of predation events at fenced nests at the Ranch. The use of cameras at fenced nests revealed that site‐specific differences in nest predators explained variation in fence efficiency between sites. Our fence design may be useful for other species of grassland birds, but site‐specific predator communities and species‐specific response of target bird species to fences should be assessed before installing fences at other sites.     

Electric Fencing as a Measure to Reduce Moose-Vehicle Collisions

Abstract: We tested the effectiveness of electric fences to reduce moose (Alces alces)-vehicle collisions in 2 fenced sectors (5 km and 10 km) using weekly track surveys and Global Positioning System telemetry. Number of moose tracks along highways decreased by approximately 80% following fence installation. Only 30% (16/53) of moose tracks observed on the road side of the fence were left by moose that crossed an operational fence; moose mostly entered the fenced corridor through openings (e.g., secondary roads) or at fence extremities. Electric fences also prevented 78% (7/9) of collared moose from crossing the highway in fenced sectors. Fences were less effective during occasional power failures. We suggest that circuit breakers should be used to prevent power failures and that there should be no opening along the fence line unless anti-ungulate structures are used.     

One‐way gates successfully facilitate the movement of burrowing bettongs (Bettongia lesueur) through exclusion fences around reserve

When native herbivores are enclosed in fenced reserves without predators or dispersal options then overgrazing can occur, leading to damage to vegetation and co‐occurring fauna species. One‐way gates that allow medium‐sized herbivores to exit fenced reserves may be an effective management tool to address overabundance or facilitate population expansion. We tested the use of one‐way gates to facilitate the movement of the reintroduced burrowing bettong (Bettongia lesueur) from inside to outside a fenced reserve in arid South Australia. One‐way gates were installed in the exterior fence of the reserve and assessed using remote motion‐sensor cameras. The influence of gate position (dune, swale or corner) and provision of food were assessed in relation to gate visits and exits. Animals were trapped inside and outside the gates to determine any population bias in gate exits. Baited gates recorded significantly more exits than unbaited gates and dune gates had higher exit rates than interdunal swale gates. When gates were unbaited, those installed in corners of the reserve showed significantly higher visitation by bettongs and a non‐significant trend towards more exits compared to gates placed in straight sections of fence along dunes or swales. There was no sex or age bias of burrowing bettongs using the gates and bettongs travelled between 75 m and 1535 m from their warrens to use the gates. No non‐target species gained access to the reserve through the one‐way gates and only two non‐target animals used the gates to exit the reserve confirming gate specificity for bettongs. During the same period, 96 burrowing bettongs exited the reserve through the one‐way gates. One‐way gates may be a management strategy for facilitating passive movement of medium‐sized herbivores outside of fenced reserves for the purposes of reducing overpopulation or facilitating population expansion outside reserves.     

Are predator-proof fences the answer to New?Zealand?s terrestrial faunal biodiversity crisis?

A review of pest-exclusion fences throughout New?Zealand shows that the goals of fence projects are frequently not achieved and cost-benefit analyses often do not adequately quantify ongoing costs. The creation of these sanctuaries enclosed by predator-proof fences often creates small expensive zoos surrounded by degraded habitat that will never be able to sustain the animal and plant species contained within the fence. We examine what fence proponents and conservation trusts believe they are achieving and ask whether the evidence available demonstrates that fenced areas are capable of fulfilling these objectives.     

卧龙自然保护区野生动物肇事农地特征及影响机制

野生动物肇事是保护区内部和周边地区的普遍现象,严重影响了保护区生物多样性保护的有效性,是当前保护区管理面临的新问题。以四川卧龙国家级自然保护区为例,于2014年7—8月以问卷调查方式获取了170个农地的野生动物肇事信息,建立了野生动物肇事与不同农地特征之间的二元logistic回归模型,并通过赤池信息量准则筛选出3个拟合优良的回归模型。研究结果表明,野生动物肇事与农地特征之间存在密切关系,其中农地种植作物类型、农地与森林、公路的距离、围栏的使用等农地特征意义显著(P值均小于0.01)。进而探讨了上述农地特征对野生动物肇事的影响机制及原因,并据此结果提出了野生动物肇事地的评价和管理、调整作物种植结构、统一规划和管理防护措施、减轻当地居民对农业的依赖等缓解人与野生动物冲突的对策。     

Development of a bait and baiting system for delivery of oral rabies vaccine to free-ranging African wild dogs (Lycaon pictus)

The objective of the study was to develop a bait and baiting system capable of delivering one effective dose of oral rabies vaccine to each member of a free-ranging African wild dog (Lycaon pictus) pack. Trials were conducted between June and October 2000. The results of cafeteria-style bait preference trials testing seven candidate baits in captive wild dogs revealed a significant preference for chicken heads (June trials: P = 0.023, September trials: P = 0.021). Trials using a topical biomarker (rhodamine B) showed that chicken head baits were sufficiently chewed on most occasions to rupture the vaccine container. Free-ranging wild dogs and young pups ingested chicken head baits. Significant dominance of bait intake by a single individual was seen in four of six study packs and in the three packs in which an alpha pair could be distinguished, the dominant feeder was an alpha animal. Pattern of bait distribution and degree of satiation had no effect on pack coverage (proportion of pack ingesting at least one bait). Pack coverage was significantly related to trial number (r = 0.71, P < 0.001), with pack coverage increasing with increased exposure of the pack to the baits. During 46 hr of diurnal observations of free-ranging wild dogs only two baits were lost to non-target species. A baiting system for the oral vaccination of captive and free-ranging wild dogs is proposed.     

No sitting on the fence: protecting wetlands from feral pig damage by exclusion fences requires effective fence maintenance

Feral pigs damage the significant ecological and cultural values of tropical Australian wetlands. Control measures such as culling, baiting, and trapping can reduce overall pig populations, but do not eliminate the substantial physical damage to wetlands that can occur from just a few individuals. Exclusion fences have been adopted as a potential technique to prevent damage to selected wetlands. To test the effectiveness of exclusion fences we measured the physical damage caused by pigs to multiple wetlands in the Archer River catchment of tropical northern Australia. Wetlands were fenced using a typical cattle exclusion fence, a specific pig exclusion fence or had no fence. Initial analyses of these fence treatments showed no significant difference in the intensity of physical pig damage to exposed wetland sediments and fringing vegetation. However, several of the pig exclusion fences were found to have been compromised. Reanalysis indicated wetlands with functioning pig exclusion fences had no physical pig damage and this was significantly less damage than in all other treatments. In contrast, wetlands with compromised pig exclusion fences had damage that was statistically equivalent to sites without fences or with cattle exclusion fences, but in individual cases had the worst damage recorded in any of the treatments. Compromised pig exclusion fencing of wetlands can thus be worse than having no fencing at all. This suggests that the successful prevention of pig damage to wetlands by exclusion fences requires ongoing and effective fence monitoring and maintenance regimes.

     

Fence-Line Contact Between Wild and Farmed Cervids in Colorado: Potential for Disease Transmission

Abstract: Direct and indirect contact between wild and farmed cervids along perimeter fences may play a role in transmission of diseases like chronic wasting disease (CWD), but no studies have quantified such interactions. At 9 high-fenced commercial elk (Cervus elaphus) farms in Colorado, USA, during October 2003 to January 2005, we used animal-activated video to estimate rates of fence-line use by wild cervids, rates of direct contact between farmed and wild cervids, and probability of direct contact when wild cervids were present. We recorded 8-fold-more wild elk per unit time than mule deer (Odocoileus hemionus) at fence lines. Depending on site, we recorded 0.66 to 46.90 wild elk per 1,000 hours of camera monitoring. We documented 77 interactions between wild and farmed elk involving naso-oral contact and no contact between wild mule deer and farmed elk. Rate of direct contact ranged from 0.00 to 1.92 direct contacts per 1,000 hours of camera monitoring among sites. Given recorded presence of wild elk, estimated probability of observing direct contact during a 2-minute video recording ranged from 0.00 to 0.11 among sites. Risk of direct contact was about 3.5 times greater for single woven-wire fence compared with offset electric fence attached to a single woven-wire fence. We observed no direct contact through double woven-wire fences. Because little is currently known about infection rates associated with infection mechanisms, we cannot infer a level of CWD infection risk from our results, but some form of double fencing should reduce potential for direct and indirect transmission of disease into or out of elk farms.     

Differential response of mammals to agricultural fences — The effects of species vagility and body size

An increase in wolf populations during the 1990s in North-Eastern Israel compelled livestock growers to establish fenced calving enclosures to minimize cattle predation. We hypothesized that such fences form barriers to animals traversing the landscape, to which various wildlife species may respond differentially. In order to test this, an array of line transects were established near six enclosures at which scat pellets were monitored for 23 months. We identified 1496 pellets, belonging mainly to medium or large mammal species. To estimate pellet abundance and quantify mammal activity levels we used N-mixture models. We tested the performance of seven models assuming two abundance distribution functions: Poisson and zero-inflated Poisson (ZIP) distribution models which evaluated different combinations of explanatory variables: effects of time, enclosure and transect. Model selection was performed using the Akaike Information Criterion (AIC). Pellet counts and mean estimated abundance were greater in transects external to the enclosures, for all species combined, mountain gazelle (Gazella gazella) and wild boar (Sus scrofa). Additionally, two behavioral responses to the presence of protective fences were observed. Outside the enclosures a U-shaped response of decrease in abundance at a distance of 50 m from the fence followed by an increase towards the distant transects at 200–700 m from the fence. Inside the calving enclosures a decreasing abundance response was observed, which was negatively correlated with distance from the fence. This study identifies the spatial effects emerging from the presence of protective fences as habitat-fragmenting agents. It suggests that a protective fence imposes a habitat-independent behavioral filter at the landscape level which could be related to species vagility and body size. Inconsistent activity responses of the different species to the presence of fences are repeatedly observed, providing support for our initial hypothesis.     

Reserve Size,Conspecific Density,and Translocation Success for Black Rhinoceros

Abstract: Fighting and accidental injury commonly cause black rhinoceros (rhino; Diceros bicornis) death after release. Smaller reserves and higher conspecific density after release (release density) might increase a rhino's encounter rate with hazards like fenced boundaries and conspecifics. We conducted a science-by-management experiment on the influence of reserve size and release density on rates of movement, association, and injury and death amongst 39 black rhinos during the first 100 days after their release into 4 Namibian and 8 South African reserves ranging in size from 670 ha to 45,000 ha. Association rates were negatively related to reserve size and positively correlated with release density. There was also a negative relationship between the proportion of the reserve traversed by individual rhinos and reserve size. In reserves ≥18,000 ha association rates were consistently zero but became elevated in reserves ≤11,500 ha and at release densities ≤9 km²/rhino. Daily displacement did not increase with increasing reserve size >8,500 ha but in smaller reserves daily displacements indicated higher encounter rates by released rhinos with fenced boundaries. Three rhinos received fight-related injuries requiring intervention and 2 of 4 deaths were fight-related. All injuries and 3 deaths occurred in reserves ≤11,500 ha. Model selection based on Akaike's second-order Information Criterion indicated that the parameter release density alone best explained mortality risk. Traditionally considered risk factors, rhino sex, age, and presence of resident conspecifics, were superseded by the risk posed by releases into smaller reserves. Reserves ≤11,500 ha and release densities ≤9 km²/rhino pose an increasing risk to rhino survivorship and so larger reserves and lower densities than these should be favored as release sites.     

Characteristics of insect populations on habitat fragments: A mini review

Modern human-dominated landscapes are typically characterized by intensive land-use and high levels of habitat destruction, often resulting in sharply contrasted habitat mosaics. Fragmentation of remaining habitat is a major threat to biodiversity. In the present paper, we focus on the different features of habitat fragmentation. First we discuss the importance of pure habitat loss, fragment size, fragment isolation and quality, edge effects, and the importance of landscape structure. Second, we characterize life-history features of fragmentation-sensitive species, showing that rare, specialized, little dispersing species are most affected, as well as species characterized by high population variability and a high trophic position, while the effect of body size is unclear. Third, we discuss the conservation value of habitat fragments. The question arises how to relate studies on population survival to those of community structure and studies on biodiversity to those on ecologicalal functions. Despite the general superiority of large to small reserves, only small or medium-sized reserves are available in many human-dominated landscapes. A great number of small habitats covering a wide range of geographic area should maximize beta diversity and spreading of risk and may be very important for the regional conservation of biodiversity, in contrast to the prevailing arguments in favor of large habitats. Finally, landscape context influences community structure of fragments, and communities are composed of species that experience the landscape on a broad range of spatial scales. Spatial arrangement of habitat fragments in a landscape appears to be important only in simple, not complex landscapes.     

Foraging costs,hunting success and its implications for African wild dog (Lycaon pictus) conservation inside and outside a protected area

When selecting a habitat, animals utilize habitat in which they yield the highest rate of energy. Differences in foraging costs and hunting success are therefore likely to affect habitat choice. In a previous study, we showed that African wild dog (Lycaon pictus) packs with territories inside Hwange National Park (HNP), over the course of several years, moved their territories into the buffer zone outside HNP, where reproductive success was higher but anthropogenic mortality exceeded natality. In this study, based on long‐term radio‐telemetry data from 22 African wild dog packs, we analysed whether differences in foraging costs and hunting success could have contributed to this territorial drift. Taking seasonality and pack size into account, we determined foraging costs (foraging distance and chase distance) and hunting success (successful or failed chase) inside and outside HNP. Although we observed no difference in foraging costs, hunting success was higher outside HNP, which is likely to have contributed to the territorial drift into the buffer zone outside the protected area. This study shows the importance of taking factors affecting hunting success into account in the conservation strategy of African wild dogs.     

Effects of marine reserve characteristics on the protection of fish populations: a meta-analysis

Meta-analyses of published data for 19 marine reserves reveal that marine protected areas enhance species richness consistently, but their effect on fish abundance is more variable. Overall, there was a slight (11%) but significant increase in fish species number inside marine reserves, with all reserves sharing a common effect. There was a substantial but non-significant increase in overall fish abundance inside marine reserves compared to adjacent, non-reserve areas. When only species that are the target of fisheries were considered, fish abundance was significantly higher (by 28%) within reserve boundaries. Marine reserves vary significantly in the extent and direction of their response. This variability in relative abundance was not attributable to differences in survey methodology among studies, nor correlated with reserve characteristics such as reserve area, years since protection, latitude nor species diversity. The effectiveness of marine reserves in enhancing fish abundance may be largely related to the intensity of exploitation outside reserve boundaries and to the composition of the fish community within boundaries. It is recommended that studies of marine reserve effectiveness should routinely report fishing intensity, effectiveness of enforcement and habitat characteristics.     

Environmental factors affect swing gates as a barrier to large carnivores entering game farms

Burrowing animals such as warthog (Phacochoerus africanus), Cape porcupine (Hystrix africaeaustralis) and aardvark (Orycteropus afer) are able to compromise the integrity of fenced‐in farmlands by digging holes under game fences. These holes provide access for predators to enter the farm where they can kill livestock or captive game animals. Data collected from the use of swing gates (n = 263) installed along a 23.93 km game fence in the Otjozondjupa region of Namibia was analysed to determine the factors that influenced their efficacy at reducing hole creation along the fence by digging animals. Statistical analyses revealed that soil substrate, grass height, vegetation density, distance to the nearest permanent water source and season influenced digging activity along the fence line. The number of holes created and reopened decreased over time from the start of the study period, probably demonstrating that burrowing animals had learnt to use the swing gates rather than dig holes under the fence. These factors can inform the correct future usage of swing gates as a large predator exclusion method to ensure that they do not enter game farms, which will reduce the need to lethally control carnivores and burrowing animals.     

Achilles' heel of sociality revealed by energetic poverty trap in cursorial hunters

This study empirically tests two foundation ecological theories: (1) pack hunting is a driver for the evolution of sociality; and (2) species have a finite energy potential, whereby increased maintenance costs result in decreased reproductive effort. Using activity and prey data from 22 packs of African wild dogs (Lycaon pictus), we parameterized a model detailing the energetic cost/benefit of cooperative hunting. Larger pack size increased foraging time, prey size, and capture probability while reducing chase distance, resulting in a rapidly increasing net rate of energy intake up to a pack size of five, which peaked at 10 individuals and then declined. With a streamlined body plan necessary for hypercursoriality limiting stomach capacity in smaller packs, it was demonstrated that the group hunting benefit will rather accrue to widely foraging predators than to "sit-and-wait" ones. Reproductive effort, measured by the number of pups born, revealed smaller litters with decreasing pack size, validated finite energy theory, and highlighted a "poverty trap" where smaller groups have lower foraging gains, smaller litters, and increased vulnerability to extirpation. Consequently, these results demonstrated a mechanistic example of pervasive selection for maximal body size (Cope's rule), leading to a macroevolutionary ratchet, where sociality linked to hypercursoriality is betrayed by an Achilles' heel.     

Rabies outbreak in African Wild Dogs (Lycaon pictus) in the Tuli region,Botswana: Interventions and management mitigation recommendations

We describe an outbreak of rabies in a pack of African wild dogs (Lycaon pictus) in the Limpopo-Lipadi Private Game and Wilderness Reserve in the Tuli region of south-eastern Botswana. We define the pack’s behavioural response to the disease, clinical signs, and management interventions undertaken and make recommendations to mitigate against future disease outbreaks of this nature. The outbreak, which occurred in late 2014 and early 2015, resulted in the death or disappearance of 29 individuals out of a pack of 35 wild dogs. The disruption to the social structure within the pack, the behaviour of the animals and clinical signs were similar to that documented during previous rabies outbreaks amongst African wild dogs in Southern and East Africa in recent years. Management interventions taken during the outbreak were aimed at preventing extirpation of the pack and reducing the risk of further disease spread to other mammals in the reserve.     

Training cattle to control by electric fences

Since cattle learn respect for electric fences, it may be possible to use single electric wires as permanent fences on beef-cattle properties. Two experiments are reported in this paper. The first investigated a method of training inexperienced cattle in a small yard before release to paddocks fenced with a single wire. The training yard consisted of a strong conventional fence with a single electric wire attached. It confined animals in a small area, thus encouraging them to investigate, receive shock and learn respect. After a day of such training, the animals were automatically photographed at each approach to a single wire in a test paddock and compared with an untrained group in a similar test paddock. Although no animals broke through in either group, it is clear that trained animals more quickly recognized the wire and showed respect by not touching it.The second experiment demonstrated the great respect cattle had for a single electrified wire after training, because it prevented hungry heifers from going to eat hay which they had been conditioned to eat.It is concluded that training is simple and provides a controlled learning period to give increased respect for electrified wires and to minimize the risk of animals breaking through when first released to paddocks with electrified boundaries.     

Effects and Mitigation of Road Impacts on Individual Movement Behavior of Wildcats

ABSTRACT Roads can affect the persistence of wildlife populations, through posing mortality risks and acting as barriers. In many countries, transportation agencies attempt to counterbalance these negative impacts. Road mortality is a major threat for European wildcats (Felis silvestris); therefore, we tested the effectiveness of a newly developed wildcat-specific fence in preventing wildcat mortality along a new motorway. We hypothesized that such a fenced motorway would at the same time be a significant barrier to wildcats and may at worst result in 2 isolated populations. We used radiotracking data of 12 wildcats, resulting in 13,000 fixes, to investigate individual movement behavior during and after construction of a new motorway in southwestern Germany. The motorway was fenced with the wildcat-specific fence and included crossing structures, not especially constructed for wildlife. Additionally we collected road kills on stretches of the same motorway with various types of fencing. A rate of 0.4 wildcat kills/km/year on the motorway, which was traveled by 10,000 vehicles/day and fenced with a regular wildlife fence, was reduced by 83% on stretches with wildcat-specific fencing. Of the available crossing structures, wildcats preferred open-span viaducts. Road underpasses were used but hold a mortality risk themselves. As opposed to our expectations, the fenced motorway (fenced with wildcat fence) posed only a moderate barrier to wildcats. Individuals were hindered in their daily routine and some stopped crossing completely but others continued crossing regularly. The adaptation of spatial and temporal behavior to traffic volume and location of crossing structures has an energetic cost. Hence, we suggest that only a small number of major roads can be tolerated within a wildcat's home range. To meet the demands of the European Habitats Directive, we recommend installing the wildcat fence in wildcat core areas along motorways to reduce wildcat mortality. We suggest that fences should incorporate safe crossing structures every 1.5-2.5 km. Our findings in terms of fencing design and crossing structures can be used by transportation agencies for an effective reduction of road mortality and barrier effect for carnivores.