Fencing affects African wild dog movement patterns and population dynamics
H ELEN M. K. O’ N EILL,SARAH M. DURANT S TEFANIE S TREBEL and R OSIE W OODROFFE
Abstract Wildlife fences are often considered an important Introduction tool in conservation. Fences are used in attempts to pre- vent human–wildlife conflict and reduce poaching, despite abitat fragmentation is a leading threat to global bio- known negative impacts on landscape connectivity and ani- Hdiversity (Millennium Ecosystem Assessment, ). mal movement patterns. Such impacts are likely to be par- As habitats become increasingly fragmented, wildlife pop- ticularly important for wide-ranging species, such as the ulations also become fragmented in smaller, genetically African wild dog Lycaon pictus, which requires large areas isolated, subpopulations that will be at greater risk of of continuous habitat to fulfil its resource requirements. extinction (Lande, ). This is of particular concern for Laikipia County in northern Kenya is an important area wide-ranging species that are reliant on accessing large for wild dogs but new wildlife fences are increasingly areas to fulfil their resource requirements, meaning that being built in this ecosystem. Using a long-term dataset fragmentation can lead to such species being extirpated, from the area’s free-ranging wild dog population, we evalu- even when habitat may remain (Løvschal et al., ). Frag- ated the effect of wildlife fence structure on the ability of mentation often increases the cost incurred by wildlife wild dogs to cross them. The extent to which fences im- in obtaining vital resources and may even cut access off en- peded wild dog movement differed between fence designs, tirely (Epps et al., ; Løvschal et al., ). Fragmentation although individuals crossed fences of all types. Purpose- can occur as a result of habitat loss, but is also associated built fence gaps increased passage through relatively imper- with the erection of barriers to movement such as fences meable fences. Nevertheless, low fence permeability can lead (Clevenger & Waltho, ). to packs, or parts of packs, becoming trapped on the wrong Fences have been employed in attempts to mitigate – side of a fence, with consequences for population dynamics. numerous conservation issues, including human wildlife Careful evaluation should be given to the necessity of erect- conflict, invasive species control, prevention of disease ing fences; ecological impact assessments should incorpo- transmission and delineation of protected area bound- rate evaluation of impacts on animal movement patterns aries (Hayward & Kerley, ; Gadd, ; Hayward & and should be undertaken for all large-scale fencing inter- Somers, ; Beale et al., ). In some cases fences have ventions. Where fencing is unavoidable, projects should led to positive conservation outcomes such as reductions in – use the most permeable fencing structures possible, both human elephant conflict (Knickerbocker & Waithaka, ), in the design of the fence and including as many purpose- protection of threatened native species from invasive spe- built gaps as possible, to minimize impacts on wide-ranging cies in New Zealand (Burns et al., ), or, in the case of wildlife. the Critically Endangered hirola antelope Beatragus hunteri in Kenya, from native predators (Ali et al., ). However, Keywords African wild dog, connectivity, fence, Lycaon although fences can have positive impacts, the effects are pictus, movement ecology, wide-ranging often mixed. Building and maintaining fences is costly, Supplementary material for this article is available at and the associated habitat fragmentation can require the doi.org/./S use of expensive, complex conservation management strate- gies, including translocations, to maintain genetic diversity across metapopulations (Davies-Mostert et al., ; Buk et al., ). There are also reports of negative impacts, in- cluding mortalities, as a result of fencing preventing animals HELEN M. K. O’NEILL*† (Corresponding author, orcid.org/0000-0002-9458- from accessing vital resources, and of individuals becom- 4494), SARAH M. DURANT and ROSIE WOODROFFE Institute of Zoology, Zoological Society of London, London, UK. E-mail h.o’[email protected] ing entangled or being electrocuted by fences (Gadd, ; Pietersen et al., ). However, although there are multiple STEFANIE STREBEL Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland examples where fences have restricted the access of wild *Also at: Centre for Biodiversity and Environment Research, Division of animals to vital resources (Gadd, ), thereby negatively Biosciences, University College London, London, UK affecting populations, the impact of such barriers on the † Current address: Durrell Institute of Conservation and Ecology, School of movements of individual animals is poorly understood. Anthropology and Conservation, University of Kent, Canterbury, UK Some fencing projects have sought to minimize harmful Received September . Revision requested November . Accepted April . effects by using fences with different levels of permeability,
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, Downloadeddistribution, from https://www.cambridge.org/core and reproduction in any medium,. IP address: provided 82.26.43.192 the original work, on 10 is properlyAug 2021 cited. at 14:35:52, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/termsOryx, Page 1 of 9 © The Author(s),. https://doi.org/10.1017/S0030605320000320 2021. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605320000320 2H.M.K.O’Neill et al.
which block the passage of certain key species but allow also presented, to provide context for the quantitative other species to cross. Semi-permeable fence structures may analyses. be high enough for species to pass below, or low enough for species to jump over, but act as barriers to the movement Study area of less agile species such as the elephant Loxodonta africana, the white rhinoceros Ceratotherium simum or the black The study area lies in Laikipia County in northern Kenya; a rhinoceros Diceros bicornis. Similarly, purpose-built gaps, wooded savannah landscape (mean annual rainfall mm; which permit the passage of some species but prevent the Woodroffe, ). Laikipia supports the second highest movement of others, are sometimes included in the structure density of large terrestrial mammalian wildlife in Kenya of a fence to increase permeability (Dupuis-Désormeaux et al., (Kinnaird & O’Brien, ) and is an important area for a). These gaps may allow animals to pass through the many threatened species. fence, but if there are few gaps then animals may have The landscape is divided into privately and community to move a considerable additional distance to use them. owned properties of , – km , with land uses including Fence gaps may also have impacts on the movement of traditional pastoralism, commercial livestock ranching, sub- wildlife species as they are likely to funnel them into sistence agriculture, large-scale farming, and tourism (Ulrich certain areas (Little et al., ), thereby affecting species’ et al., ). The amount of wildlife fencing in Laikipia has distributions across a landscape (Dupuis-Desormeaux et al., increased since . Many of the properties in Laikipia are b). fenced to demarcate their boundaries (Evans & Adams, ; The African wild dog Lycaon pictus is an extremely Yurco, ); fencing is also used in an attempt to reduce wide-ranging species (Woodroffe, ), categorized on human–wildlife conflict and to reduce rhinoceros poaching the IUCN Red List as Endangered (Woodroffe & Sillero- by containing animals within protected reserves (Dupuis- Zubiri, ). The species is threatened by habitat loss and Désormeaux et al., a; Blair & Meredith, ). fragmentation; it is estimated to have been extirpated from We focused on the effects of the fences of two of the largest up to % of its former range (IUCN/SSC, , , ). wildlife properties in Laikipia, referred to here as Property A and Wild dogs need access to large, continuous areas of wildlife- Property B. These properties are used by wild dog packs (Sup- friendly habitat to persist; increases in fencing would be plementary Fig. ) and employ three types of fencing (Fig. ). expected to affect wild dogs negatively because they will Property A comprises two sections. The property’sranch- fragment the landscape and confine packs to smaller areas. ing and tourism businesses are based in the western part In South Africa, where wild dogs live in fenced reserves, the (hereafter Property A), which supports a wide variety of metapopulation has to be actively managed using trans- wildlife. Property A ( km ) is fenced with a low-level, locations and reintroductions (Davies-Mostert et al., ), electrified Type A fence, which is raised from the ground although some positive impacts of fencing have been (Fig. a). The fence is . km long and intended to restrict found within this metapopulation as individuals have been the movement of elephants and rhinoceroses. This fence has shown to suffer lower mortality when released with an five purpose-built gaps (Fig. d, Supplementary Figs & ) established social group into securely fenced reserves (Gusset that allow the passage of most wildlife species but prevent et al., , ). Wild dogs have also been recorded using rhinoceroses moving off the property. The eastern part of fences to their advantage in catching larger prey, reducing Property A ( km ; hereafter Property A) is set aside for their hunting effort (Davies-Mostert et al., ). However, wildlife. It is separated from Property A by a public road as other large carnivores, including lions Panthera leo, and is surrounded by a . km long Type A fence often reach higher population densities within fenced (Fig. b). This fence is also electrified but is intended as a reserves, wild dogs may be vulnerable to the negative barrier to medium and large bodied species. When first impacts of increased interspecific competition, kleptopar- erected, the Type A fence had no gaps, but two gaps asitism and predation (van Dyk & Slotow, ;Darnell (Fig. d) have since been added. et al., ). Property B ( km ) has a Type B fence (Fig. c) that Here we explore the impacts of different fence designs on is electrified and . km long. The fence was erected to animal movements using data from a free-ranging popula- try and reduce conflict with local communities by restricting tion of African wild dogs in Laikipia, Kenya. We investi- the movement of all medium and large bodied mammals gate whether fence structure affects wild dog movement out of the property. It was erected in with three pur- patterns and crossing ability, whether purpose-built fence pose-built gaps (Fig. d, Supplementary Figs & ). These gaps are used by wild dogs to cross fences and if fence gaps are clustered in the north-west of the property, where gaps affect their spatial distribution. Incidences of observed it borders an area of wildlife-friendly habitat, away from negative interactions between wild dog packs and fences are human settlements.
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FIG. 1 The three fence structures used on two wildlife properties in Laikipia County, northern Kenya, referred to here as Property A and Property B: (a) Type A fence, which surrounds Property A; (b) Type A fence, which surrounds Property A; (c) Type B fence, which surrounds Property B; and (d) design of the fence gaps.
Methods The effect of fence structure on wild dog movement
Wild dog data To analyse the effect of fence structure on fence crossing success by wild dogs, we compared the rate they crossed The wild dog population of Laikipia has been continually real fences with the rate they crossed simulated fence monitored since ; each study pack had at least one in- lines. Locations from the GPS collars were plotted and the dividual fitted with a VHF or GPS collar. Packs were visually number of times each wild dog successfully crossed a observed at least once every – weeks. During observations, fence was counted. An individual was considered to have data were collected about pack size, behaviour and the re- crossed a fence when a location was recorded on one side productive and social status of pack members, providing of a fence and the subsequent location was on the other a long-term demographic dataset (Woodroffe, ). The side of the fence. Each record was checked to ensure it population’s main prey species are Kirk’s dikdik Madoqua was a true crossing event and could not be a result of the in- kirkii and impala Aepyceros melampus, which are abun- dividual circumnavigating the fence (Supplementary Fig. ). dant throughout the study area (Woodroffe et al., ; A step was defined as the movement between one loca- Shorrocks et al., ). tion and the next; steps had both length (the straight-line We used data from GPS collars to investigate the effects distance in metres between consecutive locations) and dur- of fencing on wild dog movement behaviour. Wild dogs ation (the difference in minutes between consecutive loca- were immobilized and collared as described by Woodroffe tions). The step lengths for each wild dog’s movement (). This study uses data collected during –, pathway were calculated from the collar data. The number when wild dogs from packs were fitted with GPS of steps that were close to a fence, and therefore could have collars (GPS-Posrec, Televilt, TVP Positioning AB, Lindes- resulted in a crossing, was also counted. Step durations var- berg, Sweden, and GPS-Plus, Vectronic Aerospace GmbH, ied with time of day, and between individuals, as the fre- Berlin, Germany). Of the GPS-collared wild dogs, indivi- quency of GPS data recording was not the same for all duals from nine packs interacted with at least one of the collars. The shortest step duration was – minutes. We fences surrounding Properties A and B. calculated the mean step length for the shortest step duration GPS collars were programmed to record the wild dog’s for each wild dog; there was no correlation between the location – times per day. No pack had two individuals length of time and mean step length for that time period fitted with GPS collars concurrently. Wild dogs are highly (Pearson’s product-moment correlation: t = .,df=, crepuscular (Woodroffe et al., ), and so the collars were P=.). To define the areas close to the fences within programmed to collect locations more frequently during which steps could have resulted in a crossing, we drew buffers dawn and dusk (Rabaiotti & Woodroffe, ). around each fence for each wild dog; the buffer width was
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equal to that individual’s mean step length at the shortest from each of these random points to the nearest gap was step duration (range: .–. km; mean step length across also calculated. The distances between the wild dog loca- all individuals: . km). tions and the fence gaps were compared with those of the We created simulated fence lines in areas close to the real random points using a Welch two sample t test. fences to generate a baseline fence crossing probability; i.e. the rate of crossing that would be expected if a fence did not Direct observations of interactions between wild dogs present a movement barrier. By randomly creating two and fences points at least km apart and joining them with a straight line, fences were simulated that were randomly orientated To provide insight into the impacts of fences on wild dog in areas close to the real fences (within km) but where packs, we collated incidents of observed interactions be- no fences, or other potential movement barriers (e.g. major tween wild dogs and fences in Laikipia in which packs’ roads and rivers), actually existed. We followed the same pro- movement or dynamics were clearly affected by fences. cess as described above for the real fences to establish a base- line measurement of crossing success. These data were analysed using a generalized linear mixed model (GLMM) with bino- Roadkill mial distribution. Fence crossing success as a binary response Vehicle collisions can be an important cause of mortality for variable (crossed successfully vs failed to cross) was compared wild dogs (van der Meer et al., ). Information on cause for fence type (A,A or B), with individual wild dog identity of death has been collected for all dead wild dogs (collared as a random variable. and uncollared) found in Laikipia since project inception in . We used data collected on roadkilled individuals to evaluate whether there may be higher rates of roadkill on Use of purpose-built fence gaps by wild dogs roads close to fences. To determine whether wild dogs used fence gaps to cross fences, we estimated the proportion of successful crossings Results that occurred in the vicinity of the gaps. Steps that crossed the fence and had at least part of their length within km of The effect of fence structure on wild dog movement a fence gap location (hereafter referred to as the fence gap buffer) were assumed to have made use of the gap. A buffer The per cent of wild dog steps close to a fence that resulted distance of km was chosen as it approximated the mean in fence crossings varied significantly with fence type. For step length of . km for the GPS-collared wild dogs. the simulated fences, . % of steps within the buffer dis- The number of crossings in the fence gap buffer was then tance resulted in a crossing. The crossing frequency of the compared with the expected number of crossings using a Type A fence was . % and was not significantly different χ test. For each fence type, a × contingency table was from that of the simulated fences (Table , Supplementary used with the expected number of crossings calculated as Table ). The Type A fence had a crossing success of the total number of fence crossings multiplied by the pro- . %, significantly lower than for the simulated fences portion of the fence that fell within the fence gap buffer. (Table , Supplementary Table ). The Type B fence pre- For properties where wild dogs preferentially used fence sented the greatest movement barrier: only . % of the gaps to cross fences, we investigated the impact of the fence steps within the buffer resulted in a crossing (Table , gaps on the spatial distribution of wild dog locations. To Supplementary Table ). capture the effects of the gaps on the wild dogs’ distribution beyond their immediate passage though the gaps, a km Use of purpose-built fence gaps by wild dogs wide buffer was created around the property’s fence line and wild dog locations within this buffer used for the ana- Successful crossings of the Type A and A fences by col- lysis. Data from denning wild dog packs were not included lared wild dogs did not have part of their length within in the analysis because during denning movement patterns , m of a purpose-built fence gap more often than are restricted to areas close to the den. Using only locations would be expected by chance (Table ). The majority of the recorded at . (n = from individuals: WDF, successful crossings of Property B’s fence (.%) had part WDM and WDM), when the wild dogs were likely to of their length within the fence gap buffers (P , .; be resting (Woodroffe et al., ) and therefore not in the Table ). As only the Type B fence had a significantly greater process of travelling through the fence gaps, the distance than expected number of crossings close to fence gaps, the from each location to the nearest gap was calculated. An effect of fence gaps on wild dog distribution was only inves- equal number (n = ) of random points was generated tigated in relation to this fence. Wild dog resting locations within the km buffer for comparison, and the distance were found to be closer to the gaps than would otherwise
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TABLE 1 GLMM of the effect of fence structure (Fig. ) on fence TABLE 3 Number of occurrences of five impacts of fences observed crossing success by African wild dogs Lycaon pictus. The model in- during the course of this study. cluded individual ID as a random effect, which was not significant. No. of Fence type Coefficient ± SE P Incident type occurrences Fences involved A1 vs simulated 0.059 ± 0.09 0.52 Dispersal group split 2 Property B A2 vs simulated −0.36 ± 0.12 0.003 Permanent pack 2 Property B vs simulated −2.10 ± 0.17 , 0.001 separation B + other Roadkill 4 Property A2 Livestock depredation . 10 Property B Pack extinction 1 Property B TABLE 2 Use of purpose-built fence gaps by wild dogs. The expected number of crossings was calculated as the total number of fence crossings multiplied by the proportion of the fence line within the next months, although the number of individuals the fence gap buffer. seen declined from the original to . Two animals, Total no. of No. of crossings including the alpha female, eventually returned to the , ’ successful 1,000 m from pack s core territory but a small group, believed to be all fence gap fence male and including the alpha male, remained trapped inside Property crossings Observed Expected χ2 P the fence. A1 411 85 67.22 2.08 0.15 A2 175 26 22.21 0.34 0.56 B 52 32 2.20 25.96 , 0.001 Livestock depredation A pack of wild dogs (hereafter PB pack) whose territory was centred on Property B became sep- arated by the fence, with four individuals inside the fence on be expected. Locations randomly generated within the km Property B, and individuals outside, on neighbouring fence buffer were on average . km from the fence gaps. community land. It is likely that the individuals had used Wild dog locations were an average distance of . km one of the purpose-built gaps to cross the fence and had then from the fence gaps (number of wild dogs = ; t = −., moved away from the gaps and were unable to find their way P , .). back. During the time the pack was separated there were several reports of depredation of sheep and goats by the wild dogs outside the property and the pack was threat- Direct observations of interactions between wild dogs ened with being poisoned. After several weeks, staff from and fences PropertyBwereabletocutpartofthefence,toreunitethe pack, after which there were no more depredation reports. Although interactions with fences are rarely observed, there have been at least incidents since that have had tan- gible impacts on wild dog movement and pack dynamics. Pack extinction The PB pack was seen near the Property B The recorded encounters observed between wild dogs and fence soon after the death of the pack’s alpha female. The fences within the study area are summarized in Table . alpha male was calling and looking at a lone, unrelated young female from a nearby pack, who was on the other Dispersal group split Two VHF-collared wild dogs from side of the fence, calling and looking towards the PB pack the same natal pack dispersed from their pack’s territory but unable to reach them (Supplementary Plate ). The PB in the north of Laikipia. The wild dogs travelled south and pack had no female members unrelated to the alpha male separated while close to the Property B fence. One of the that could take the place of the deceased alpha female. collared dogs entered Property B, and the other continued Packs in this situation often leave their territories in search south. It is unusual for single sex dispersal groups to sepa- of new females, and may split up (Woodroffe et al., a). rate. Since , natal dispersals have been recorded in- Soon after this encounter, the PB pack left Property B and volving collared wild dogs (Woodroffe et al., b); only moved into community areas where there were several two groups are known to have separated during dispersal, reports of livestock depredation. The alpha male died both in association with fences. during this time; the rest of the pack split and were lost to monitoring. After the encounter the young female returned to her pack, and soon afterwards the alpha male of this pack Pack separation A resident pack made an excursion be- was killed in retaliation for the pack’s livestock depredation. yond the eastern bounds of their normal territory and It is not known what happened to the rest of the pack, were subsequently seen separated by a wildlife fence. VHF including the young female, but it is likely they were tracking and sighting reports of the pack continued over also killed.
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FIG. 2 Part of the Property B fence showing the , m buffer around three fence gaps, and where tracks of GPS- collared wild dogs Lycaon pictus crossed the fence within and beyond these buffers.
Roadkill Type A fence had higher permeability than the Type B fence despite the similarity in their structures; this may Since , wild dogs have been recorded killed on the reflect this fence’s state of repair. Fences are expensive and roads in Laikipia, four of which ( . %) were on the stretch difficult to maintain (Hayward & Kerley, ); this fence of road next to the Type A fence. Laikipia has c. . km is substantially older than the fence around Property B and of main roads; the stretch of road next to the Type A fence holes have been observed, which are likely to be used by an- is c. . km in length ( . %). imals, such as wild dogs, to traverse the fence. This higher level of overall permeability also probably explains the rela- Discussion tively low levels of fence gap use observed for this fence. Despite its relative permeability, the Type A fence may Our findings suggest that fences can affect wild dog move- have had demographic consequences for the wild dog popu- ment and population dynamics. Based on the wild dog lation, as several wild dogs have been killed by vehicle colli- movement patterns observed, the fences in this study ap- sions on the road that runs along one side of the fence peared to be broadly successful in their designs. The aim (Table ). It is not possible to discern whether these fatalities of the Type A fence is to restrict movement of megaherbi- were a direct result of the fence, as wild dogs are susceptible vores but not smaller species, and our analyses found no to being killed on roads regardless of the presence of fences evidence that the fence affected wild dog movement or (Woodroffe & Ginsberg, ). However, we have observed population dynamics. The aim of the Type A fence is to re- individuals from another threatened species, the cheetah strict the movements of medium and large bodied species: Acinonyx jubatus, being chased along this road by people although wild dogs crossed the fence at a reduced rate, in vehicles whilst attempting to cross the fence between they were still able to cross, although there was no evidence the road and Property A. they used the fence gaps. The Type B fence is intended to The movement behaviour and crossing ability of wild restrict the movements of medium and large bodied species: dogs suggest that the design of fence structures and/or the wild dogs had significantly lower numbers of successful inclusion of fence gaps are vital for maintaining landscape crossings than would be expected if the fence was complete- connectivity. Fence A had no detectable impact on the ability ly permeable; the analysis also suggested that wild dogs were of wild dogs to cross, whereas the Type B fence was relatively reliant on using purpose-built gaps to cross this fence. The impermeable, with most crossings probably involving the use purpose-built gaps in the Type B fence had a significant of fence gaps. Our analysis used a buffer distance of km effect on wild dog spatial distribution, with daytime resting around the fence gaps, assuming all crossings within this locations clustered close to the gaps; suggesting the gaps are distance used them, although it is possible that some cross- at least partly successful at channelling animals into certain ings within the buffer did not use the gaps, and some outside areas. Although the fences were, overall, largely successful the buffer did use the gaps. Most of the crossings of the Type B at achieving their intended impacts, there have nonetheless fence were clustered around the fence gaps (Fig. ), although been numerous negative impacts on the wild dog population not all were within the buffer distance, suggesting that the use observed as a result of the barrier effects of these fences, and of the gaps could be greater. The importance of the fence gaps others in Laikipia, including permanent social group separa- is also indicated by the wild dogs’ GPS collar locations being tions, livestock depredation, retaliatory killings and roadkill. significantly closer to the gaps than would be expected by These results show that some fences within the study area chance, suggesting that gaps channel wild dogs into specific have had important effects on one of the threatened species areas. living there; however, in addition to structure playing an im- As fence gaps appear to channel wild dog movement and portant role, maintenance is also likely to be important. The affect spatial distribution, careful consideration should be
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given to both their location and the number incorporated positive impact on elephant and rhinoceros conservation, into a fence. An aim of the fence around Property B is to the increased costs to other threatened but non-target spe- prevent medium and large bodied wildlife from moving cies also need to be evaluated. onto community land, to try to reduce conflict with local The methodologies used here could be used more widely communities; the fence gaps are in areas of wildlife-friendly to assess permeability of fence types for a range of species, as habitat, away from human settlements and agriculture. The well as the extent to which purpose-built gaps and other gaps appear successful in channelling movement of species mitigation methods are successful. As fences have been into certain areas, away from local communities, as the wild identified as a key cause of the loss of large-scale migrations dogs tended to stay in areas close to the gaps. However, be- (Harris et al., ), these methodologies could be used to cause the gaps are close to each other (Fig. ) there are long evaluate the level of impact that fences are having on the stretches of the fence that are almost completely imperme- movements of animals and help identify the mitigation able. This has inadvertently caused problems when indivi- methods required. This information could be used in envi- duals or packs have left the property, then moved away ronmental impact assessments, which should be conducted from the gaps and have been unable to return. before fences are erected, and could also be used after con- The African wild dog is an obligate social species. struction to evaluate impacts and inform future modifications. Resident packs have a strong group bond, and therefore Our findings show that relatively impermeable fences when packs are separated by a fence the two groups will usu- can have effects on long-term connectivity levels across a ally remain close to each other over many days rather than landscape for wide-ranging species, with short-term im- splitting immediately. When this happened with the PB pacts on the population. Where fencing is considered essen- pack, the result was that the individuals on the outside of tial, preference should be given to the building of more the fence were left in an area with little wild prey, where permeable fences. Where less permeable fencing is consid- they were reported attacking livestock. Instances of wild ered necessary, careful consideration should be given to dogs being effectively stuck on the apparent wrong side of planning how to react if animals (including parts of social a fence may therefore have led to human–wild dog conflict, groups) become stranded on the wrong side of the fence, have been associated with the death of individual wild dogs, so that rapid mitigation is possible, as well as to the techni- and contributed to the loss of entire packs. It is important to ques for mitigating long-term habitat fragmentation and consider what to do when animals become trapped on the connectivity loss. wrong side of a fence. There is a contradiction between erecting a barrier to separate wildlife from local communi- Acknowledgements We thank the landowners and communities within our study site for hosting our research, Kenya Wildlife Ser- ties and then building a hole into it. Planning appropriate vice for collaboration, and the Kenya National Council for Science management strategies is important because, as we found, and Technology (permit NACOSTI/P/14/9920/1659) for research intervention may be required when animals have crossed permission, and funders and research assistants too numerous to list to the wrong side of a fence and are unable to return individually. (Krebs et al., ; Sinclair, ). Author contributions Study design: HMKON, SMD, RW; collection Fences are widely recognized as causing landscape frag- of field data: RW, HMKON, SS; long-term field data: RW; analyses, mentation and reducing connectivity, and have contributed writing: HMKON; editing: RW, SMD, SS. to the loss of large terrestrial mammal migrations (Harris et al., ). This has prompted the Convention on Mi- Conflicts of interest None. gratory Species to develop guidelines to address the impact of fences and other linear movement barriers on migratory Ethical standards Wild dogs were captured and handled as de- scribed by Woodroffe (2011) in collaboration with the Kenya species (Wingard et al., ). The evidence from our study Wildlife Service, with permission from the Kenyan Ministry of suggests it may be possible to design fences that restrict the Science and Technology, according to guidelines of the IUCN/ movement of certain groups of species, without reducing Species Survival Commission Canid Specialist Group and in confor- landscape connectivity for others. However, although these mity with the guidelines of the American Society of Mammalogists fences do not appear to measurably affect connectivity for (Gannon et al., 2007), following a protocol approved by the Ethics Committee of the Zoological Society of London. This work abided wild dogs, and thus probably also other similarly sized by the Oryx guidelines on ethical standards. species, they are likely to affect other non-target species. Although intended primarily to prevent rhinoceros move- ment and channel elephant movement, these fences prob- ably also affect the movements of other, non-target, mega- References herbivores such as the giraffe Giraffa camelopardalis,as ALI, A.H., KAUFFMAN, M.J., AMIN, R., KIBARA, A., KING, J., MALLON, they are not able to cross the fence freely and therefore D. et al. () Demographic drivers of a refugee species: large-scale must also use the purpose-built gaps to move on and off experiments guide strategies for reintroductions of hirola. Ecological the properties. Thus although these fences may have had a Applications, , –.
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