Forest expansion is a major current land use change across Europe. How this will affect the forest use of the most common European wild ungulate species, roe deer (Capreolus capreolus), and associated forest ecosystem services and disservices is poorly understood. Using a forest-agricultural mosaic landscape in northeast Scotland, we selected forests across a size and connectivity gradient as a proxy of expansion. We predicted that roe deer forest use estimated using camera traps would be driven by: i) higher structural and functional forest connectivity at a landscape scale, ii) within-forest structural characteristics including higher shrub density, deciduous cover and lower canopy cover, and iii) lower human usage. In line with predictions, roe deer preferred more connected forests and smaller forests in areas of the landscape with higher forest edge density. Within forests, roe deer preferred forest edge, and usage increased with higher tree density and variation in tree diameter, supportive of a preference for structurally complex forests. Human usage of forests was associated with lower roe deer use. This study has implications for current and future forest management. Firstly, targeted monitoring of forest patches predicted to have high roe deer usage for impacts could inform priorities and approaches to deer management. Secondly, as forest configuration changes with expansion policies, this study provides insights into how deer usage may change. We highlight how this knowledge can be used in forest planning to optimise deer management to minimise disservices to forestry, biodiversity and human and livestock health.

During their free-living stage, gastrointestinal nematode (GIN) eggs and larvae may encounter environmental and biomechanical perturbations, such as dung beetle (Coleoptera: Scarabaeidae, including Aphodiinae, Scarabaeinae and Geotrupidae) activity, that could alter their survival. However, dung beetles' influence in promoting or suppressing nematodes' survival is poorly understood. Past work suggests that the burial of dung underground by dung beetles may either suppress nematode infections, limiting larval emergence above ground, or enhance nematode infections by creating favourable microclimates for eggs and larval development. We examined the effect of simulated burial of wildebeest dung at four soil depths on the density of infectious third-stage larvae (L3) on herbage over a 42-day window in the Serengeti ecosystem. GIN larval density was highest from dung buried at 5 and 10 cm depths below the soil surface, and lowest at 0 cm (on the surface) and 15 cm depths. This suggests that dung beetles may facilitate L3 survival and emergence by creating favourable conditions at shallow depths (5-10 cm), protecting them from disturbances (e.g., desiccation) on the surface. Deeper burial depth (15 cm) by dung beetles, however, appears to suppress the emergence of L3 by creating a physical barrier to upward migration. Across burial depths, L3 density peaked on Day 14 and declined on Days 28 and 42, with no evidence that deeper burial led to a prolonged emergence period. These results reveal dung beetles' complex role in parasite ecology, not merely as suppressors of these free-living stages but also as facilitators of their survival through burial activities that vary with depth. Incorporating this knowledge into pasture and insect management could support the use of dung beetles as potential biological control agents against gastrointestinal nematodes.

Migratory wildlife plays an outsized role in disease transmission. Transmission risk is often assumed to be scaled with migratory host density through parasite transport effects, but in environmentally transmitted parasites, migratory hosts can also influence parasite availability via trophic effects. Trophic effects can either amplify or dampen transport effects, making the net impact of migratory hosts on resident hosts difficult to predict. We propose that the net effect is shaped by two attributes of migrant movement: intensity of use (i.e., number of migrants) and duration of use (i.e., length of stay). Using gastrointestinal nematodes (GIN) as a model, we experimentally varied transport and trophic effects of a migratory grazer wildebeest (Connochaetes taurinus) by manipulating the intensity and duration of dung addition and grazing across five treatment combinations in replicated plots, and measuring their effects on the density of infective third-stage GIN larvae in pasture. We found that: (1) higher dung addition increased GIN larvae density, (2) simulated grazing reduced the density of GIN, particularly in treatments with high dung addition, and (3) longer duration and lower intensities of use reduced GIN density for the subsequent hosts compared to treatments with single bouts of dung addition and grazing. Our results indicate that migratory hosts directly facilitate parasite spread via transport effects, while infection risk tends to decline with increasing intensity and duration of trophic interactions. Our results highlight the underappreciated role of transport and trophic interactions in shaping parasite spread in migrant-resident systems.

Fencing is one of the most widely utilized tools for reducing human-wildlife conflict in agricultural landscapes. However, the increasing global footprint of fencing exceeds millions of kilometers and has unintended consequences for wildlife, including habitat fragmentation, movement restriction, entanglement, and mortality. Here, we present a novel and quantitative approach to prioritize fence removal within historic migratory pathways of white-bearded wildebeest (Connochaetes taurinus) across Kenya's Greater Masai Mara Ecosystem. Our approach first assesses historic and contemporary landscape connectivity of wildebeest between seasonal ranges by incorporating two sets of GPS tracking data and fine-scale fencing data. We then predict connectivity gains from simulated fence removal and evaluate the impact of different corridor widths and locations on connectivity and removal costs derived from locally implemented interventions. Within the study system, we found that modest levels of fence removal resulted in substantial connectivity gains (39%-54% improvement in connectivity for 15-140 km of fence line removed). By identifying the most suitable corridor site, we show that strategically placed narrow corridors outperform larger, more expensive interventions. Our results demonstrate how and where targeted fence removal can enhance connectivity for wildlife. Our framework can aid in identifying suitable and cost-effective corridor restoration sites to guide decision-makers on the removal of fences and other linear barriers. Our approach is transferable to other landscapes where the removal or modification of fences or similar barriers is a feasible mitigation strategy to restore habitat and migratory connectivity.

Migratory animals can bring parasites into resident animal (i.e., non-migratory) home ranges (transport effects) and exert trophic effects that either promote or reduce parasite exposure to resident hosts. Here, we examine the importance of these transport and trophic effects and their interactions for resident parasite dynamics. We propose that migrant transport and trophic effects are impacted by the number of migratory animals entering a resident's home range (migration intensity), the amount of time that migrants spend within a resident's home range (migration duration), and the timing of migrant-resident interactions. We then incorporate migration intensity, duration, and timing into a framework for exploring the net impact of migrant trophic and transport effects on resident animal parasite prevalence.

Competition, facilitation, and predation offer alternative explanations for successional patterns of migratory herbivores. However, these interactions are difficult to measure, leaving uncertainty about the mechanisms underlying body-size-dependent grazing—and even whether succession occurs at all. We used data from an 8-year camera-trap survey, GPS-collared herbivores, and fecal DNA metabarcoding to analyze the timing, arrival order, and interactions among migratory grazers in Serengeti National Park. Temporal grazing succession is characterized by a “push-pull” dynamic: Competitive grazing nudges zebra ahead of co-migrating wildebeest, whereas grass consumption by these large-bodied migrants attracts trailing, small-bodied gazelle that benefit from facilitation. “Natural experiments” involving intense wildfires and rainfall respectively disrupted and strengthened these effects. Our results highlight a balance between facilitative and competitive forces in co-regulating large-scale ungulate migrations.

RATIONALE:Metabolism and diet quality play an important role in determining delay mechanisms between an animal ingesting an element and depositing the associated isotope signal in tissue. While many isotope mixing models assume instantaneous reflection of diet in an animal- tissue, this is rarely the case. Here we use data from wildebeest to measure the lag time between ingestion of 34 S and its detection in tail hair. METHODS:We use time-lagged regression analysis of δ34 S data from GPS-collared blue wildebeest from the Serengeti ecosystem in combination with δ34 S isoscape data to estimate the lag time between an animal ingesting and depositing 34 S in tail hair. RESULTS:The best fitting regression model of δ34 S in tail hair and an individual- position on the δ34 S isoscape is generated assuming an average time delay of 78 days between ingestion and detection in tail hair. This suggests that sulfur may undergo multiple metabolic transitions before being deposited in tissue. CONCLUSION:Our findings help to unravel the underlying complexities associated with sulfur metabolism and are broadly consistent with results from other species. These findings will help to inform research aiming to apply the variation of δ34 S in inert biological material for geolocation or understanding dietary changes, especially for fast moving migratory ungulates such as wildebeest.

QuestionsHow does the grass layer affect seedlings across large environmental gradients in savannas?LocationSavanna sites in Argentina, Tanzania, and South Africa.MethodsWe carried out a joint analysis of three grass removal experiments in which seedlings of various Fabaceae species were transplanted into plots with native grass and companion plots where grass had been removed. First, we estimated the effect of grasses on tree seedling mortality and seedling growth rate at each site. Then, we used the resulting coefficient estimates from site-level models to examine the impact of two climate (monthly precipitation and aridity index) and two soil (soil organic carbon content and clay content) variables on the direction and magnitude of the grass effects.ResultsGrasses increased the risk of mortality, but there was no evidence for a global effect of grasses on tree seedling rate of height growth. The best model fit indicated a high mortality risk of tree seedlings in response to grasses at intermediate aridity index values. No other climate or soil variable influenced tree seedling survival or growth (monthly precipitation, soil organic carbon content and clay content).ConclusionsOur results support the notion that the grass layer consistently creates a bottleneck to tree seedling establishment in African and South American savannas beyond climate and soil conditions, mainly by affecting tree seedling survival. The negative effect of grasses on seedling survival was lower in dry conditions compared to intermediate aridity levels. These results suggest that grass-seedling interaction is less intense in drier conditions, possibly due to reduced total grass biomass, which leads to decreased site evapotranspiration and improved soil water retention capacity. This study presents a joint analysis of field research in African and South American savannas. We assessed the effect of grasses on tree seedling survival and growth across a gradient of climate and soil variables. Grasses reduced tree seedling survival with no consistent global effects on growth. The influence of grass on seedling mortality was higher at moderately arid sites.image

Site fidelity-the tendency to return to previously visited locations-is widespread across taxa. Returns may be driven by several mechanisms, including memory, habitat selection, or chance; however, pattern-based definitions group different generating mechanisms under the same label of 'site fidelity', often assuming memory as the main driver. We propose an operational definition of site fidelity as patterns of return that deviate from a null expectation derived from a memory-free movement model. First, using agent-based simulations, we show that without memory, intrinsic movement characteristics and extrinsic landscape characteristics are key determinants of return patterns and that even random movements may generate substantial probabilities of return. Second, we illustrate how to implement our framework empirically to establish ecologically meaningful, system-specific null expectations for site fidelity. Our approach provides a conceptual and operational framework to test hypotheses on site fidelity across systems and scales.

Understanding animals' habitat selection and movement behaviours relative to human activities is important for evaluating resource requirements and ensuring effective conservation management. The world's largest remaining population of Kordofan giraffe ( Giraffa camelopardalis antiquorum) reside in Zakouma National Park, Chad. However, it is unclear whether the park boundaries sufficiently encompass the full range of this population's preferred habitats. We used GPS telemetry data from 17 female giraffe over multiple years to better understand landscape and seasonal factors that influence their home range patterns and habitat preferences at multiple spatial scales. Kordofan giraffe seasonal ranges and core seasonal ranges were larger during the wet season and core utilization distributions had greater overlap with the national park in the dry season. The importance of shifts in seasonal habitat use, attributed to the flooding and drying that occurs within the park, necessitates Kordofan giraffe to move beyond the park's boundaries. Kordofan giraffe selected for open grasslands (mean coefficient = 0.48, 95% CI [0.22,0.74]), and increased their tortuosity of movement in these areas (mean coefficient = -0.18, 95% CI [-0.23,-0.14]). Conversely, with Vachellia savannas as the reference level for land-cover variables, the giraffe avoided anthropogenic areas, barren lands, Combretaceae savannas and forests. We advise increased community-based co-learning projects and awareness of giraffe outside the park. In addition, by identifying key habitat types that giraffe selected, we advise enhanced monitoring in preferred giraffe habitats during the wet season to protect these areas from being encroached by human settlement or agricultural expansion, with the support of the legal framework of the Bahr Salamat Wildlife Reserve and other agreements that protect wet season wildlife corridors.

Fires in grassy ecosystems consume vegetation and initiate high-quality regrowth, which results in pyric herbivory when mammalian grazers concentrate feeding in recent burns. For environmentally transmitted parasites with transmission mechanisms linked to vegetation structure, fire should exert direct effects on parasites, as well as indirect effects resulting from subsequent enhanced herbivory, which can affect parasite input and exposure to environmental conditions.We combined an experimental manipulation with observational data in the Serengeti National Park to investigate the direct and indirect effects of fire on parasites. We assessed the direct effects of fire by measuring changes in parasitic nematode larvae in the grass layer before and after fire on paired experimental burned and control plots. To investigate indirect effects linked to pyric herbivory, we sampled herbivore dung, grass biomass, ground temperature and larval densities every month for 5 months following fire in seven pairs of burned and unburned monitoring plots. Finally, to assess if fire-driven changes to larval densities affected host infection burdens, we collected faecal samples from a key host, Grant's gazelle (Nanger granti), each month for 5 months to estimate within-host parasite burdens.Fire killed all larvae and increased grazer dung inputs by 40% for 2 months following fire. Dung inputs after fire led to larval parasite recolonization of burned patches, but intense herbivory kept grass short and larval densities were associated with changes in ground temperature linked to grass biomass and ambient temperature. Grant's gazelles had lower parasite burdens when sampled in areas with higher compared to lower burned area fraction.Fire and pyric herbivory change the densities of larval parasites in the environment and divide the landscape into burned and unburned regions with distinct infection risks for local herbivores.The indirect effects quantified here represent a novel finding with major implications for all grazing systems impacted by fire. Mioto katika mifumo ikolojia yenye nyasi nyingi humaliza mimea na kuanzisha uotaji upya wa malisho yenye virutubisho jambo ambalo husababisha ulaji mwingi wa nyasi baada ya moto wakati mamalia walao nyasi wanapokusanyika katika sehemu zilizoungua hivi karibuni. Kwa vimelea vinavyosambazwa katika mazingira vilivyo na njia za uambukizaji zinazohusishwa na muundo wa uotaji wa mimea, moto unapaswa kuwa na athari za moja kwa moja kwa vimelea, pamoja na athari zisizo za moja kwa moja zinazotokana na wanyama kula mimea, ambapo inaweza kuathiri uingizaji na mfichuo wa vimelea katika mazingira.Tuliunganisha majaribio na takwimu za uchunguzi katika Hifadhi ya Taifa ya Serengeti ili kuchunguza athari za moja kwa moja na zisizo za moja kwa moja za moto kwa vimelea. Tulitathmini athari za moja kwa moja za moto kwa kupima mabadiliko ya idadi ya mabuu ya vimelea vya minyoo kwenye safu ya nyasi kabla na baada ya moto katika jozi ya viwanja vilivyochomwa na visivyochomwa. Ili kuchunguza athari zisizo za moja kwa moja zinazohusishwa na ulaji wa mimea baada ya moto, tulichukua sampuli za vinyesi vya wanyama walao nyasi, uzito wa nyasi, jotoridi la ardhini, na msongamano wa mabuu ya vimelea kila mwezi kwa muda wa miezi mitano kufuatia moto katika jozi saba za maeneo ya ufuatiliaji yaliyoungua na ambayo hayajachomwa. Hatimaye, ili kutathmini kama mabadiliko yanayotokana na moto kwa msongamano wa mabuu ya vimelea yaliathiri kiwango cha maambukizi kwa wanyama, tulikusanya sampuli za vinyesi kutoka kwa Swala Granti (Nanger granti), kila mwezi kwa miezi mitano ili kukadiria kiwango cha vimelea ndani ya mnyama.Moto uliua mabuu yote ya vimelea na kuongeza kiwango cha vinyesi vya wanyama kwa 40% kwa muda wa miezi miwili baada ya moto. Ongezeko la vinyesi baada ya moto lilisababisha kurudi upya kwa mabuu ya vimelea kwenye sehemu zilizoungua, lakini ulaji wa nyasi kwa wingi ulipelekea nyasi kuwa fupi na msongamano wa mabuu ulihusishwa na mabadiliko ya jotoridi la ardhini yanayohusishwa na kiwango cha nyasi na halijoto iliyopo. Swala Granti walikuwa na kiwango cha chini cha vimelea walipochukuliwa sampuli katika maeneo yaliyoungua sana ukilinganisha na maeneo yaliyoungua kidogo.Moto na ulaji wa nyasi baada ya moto hubadilisha msongamano wa mabuu ya vimelea katika mazingira na kugawanya mandhari katika maeneo yaliyochomwa moto na yasiyochomwa moto yenye hatari tofauti za maambukizi kwa wanyama walao nyasi wanaopatikana katika eneo husika.Athari zisizo za moja kwa moja zilizohesabiwa hapa zinawakilisha matokeo mapya yenye athari kubwa kwa mifumo yote ya malisho iliyoathiriwa na moto. Previous work on fire effects on parasites have focused on the direct impact of fire on parasite survival. Here, we show that concentrated herbivory following fire can lengthen the effects of fire on free-living parasites, and create divided landscapes with burned and unburned areas that have distinct infection risks.image

Abstract Human activities are transforming landscapes and altering the structure and functioning of ecosystems worldwide and often result in sharp contrasts between human‐dominated landscapes and adjacent natural habitats that lead to the creation of hard edges and artificial boundaries. The configuration of these boundaries could influence local biotic interactions and animal behaviours. Here, we investigate whether boundaries of different degrees of ‘hardness’ affect space utilization by migratory species in Serengeti National Park, Tanzania. We deployed camera traps along transects perpendicular to the national park boundary at three different locales. The transects were located in areas that consisted of two types of human–wildlife interface: a sudden transition from the national park into agro‐pastoral land use (termed a ‘hard’ boundary) and a more gradual transition mediated by a shared usage area (termed a ‘soft’ boundary). Camera traps were placed at 2 km intervals along each 10 km transect from the edge towards the core of the park and were programmed to collect images hourly between dawn and dusk between June 2016 and March 2019. We used a deep neural network to detect the presence of wildlife within images and then used a Bayesian model with diffuse priors to estimate parameters of a generalized linear model with a Bernoulli likelihood. We explored the binomial probability of either wildebeest or zebra presence as a function of distance to the boundary, the rate of grass greening or drying (dNDVI) and the concentration of grass protein. There was a strong negative effect of distance to boundary on the probability of detecting wildebeest or zebra; however, this was only observed where the transition from human‐dominated landscape to protected areas was sudden. Conversely, soft boundaries had little to no effect on the probability of detecting wildebeest or zebra. The results suggest that boundary type affects migratory species occurrence. The implications of these findings suggest that hard boundaries reduce the effective size of conservation areas; for many species, the area used by wildlife is likely less than the gazetted area under protection. The impacts may be severe especially for narrow protected areas or dispersal corridors.

The ability to move is essential for animals to find mates, escape predation, and meet energy and water demands. This is especially important across grazing systems where vegetation productivity can vary drastically between seasons or years. With grasslands undergoing significant changes due to climate change and anthropogenic development, there is an urgent need to determine the relative impacts of these pressures on the movement capacity of native herbivores. To measure these impacts, we fitted 36 white-bearded wildebeest ( Connochaetes taurinus ) with GPS collars across three study areas in southern Kenya (Amboseli Basin, Athi-Kaputiei Plains, and Mara) to test the relationship between movement (e.g., directional persistence, speed, home range crossing time) and gradients of vegetation productivity (i.e., NDVI) and anthropogenic disturbance. As expected, wildebeest moved the most (21.0 km day –1 ; CI: 18.7–23.3) across areas where movement was facilitated by low human footprint and necessitated by low vegetation productivity (Amboseli Basin). However, in areas with moderate vegetation productivity (Athi-Kaputiei Plains), wildebeest moved the least (13.3 km day –1 ; CI: 11.0–15.5). This deviation from expectations was largely explained by impediments to movement associated with a large human footprint. Notably, the movements of wildebeest in this area were also less directed than the other study populations, suggesting that anthropogenic disturbance (i.e., roads, fences, and the expansion of settlements) impacts the ability of wildebeest to move and access available resources. In areas with high vegetation productivity and moderate human footprint (Mara), we observed intermediate levels of daily movement (14.2 km day –1 ; CI: 12.3–16.1). Wildebeest across each of the study systems used grassland habitats outside of protected areas extensively, highlighting the importance of unprotected landscapes for conserving mobile species. These results provide unique insights into the interactive effects of climate and anthropogenic development on the movements of a dominant herbivore in East Africa and present a cautionary tale for the development of grazing ecosystems elsewhere.

A fundamental condition for maintaining viable populations of wildlife is to ensure that animals can access resources. In landscapes where the boundaries of protected areas encompass only a fraction of annual home ranges, animal movement is often curtailed by human activities, often with negative population consequences. In the Tarangire Ecosystem (TE), wildlife generally aggregates in three main protected areas during the dry season (Tarangire and Lake Manyara National Parks, and Manyara Ranch Conservancy) and disperses to several other areas during the wet season. Connectivity between and within seasonal ranges in the ecosystem has generally become more restricted over time, though the apparent effects of these changes have been species-specific. Historical accounts of wildlife movement suggest that animals once moved over much larger areas than they do currently. In this chapter, we review historical information on wildlife movement and distributions in the TE and synthesize data on population genetic structure and individual movements from studies of elephants, giraffes, lions and wildebeests conducted over the past 25 years. Given the continued expansion of agricultural and urban areas, there is a need to coordinate efforts across land management agencies and local governments to ensure that wildlife can continue to move across the landscape.

Our understanding of ungulate migration is advancing rapidly due to innovations in modern animal tracking. Herein, we review and synthesize nearly seven decades of work on migration and other long-distance movements of wild ungulates. Although it has long been appreciated that ungulates migrate to enhance access to forage, recent contributions demonstrate that their movements are fine tuned to dynamic landscapes where forage, snow, and drought change seasonally. Researchers are beginning to understand how ungulates navigate migrations, with the emerging view that animals blend gradient tracking with spatial memory, some of which is socially learned. Although migration often promotes abundant populations-with broad effects on ecosystems-many migrations around the world have been lost or are currently threatened by habitat fragmentation, climate change, and barriers to movement. Fortunately, new efforts that use empirical tracking data to map migrations in detail are facilitating effective conservation measures to maintain ungulate migration.

Malignant Catarhal Fever (MCF), caused by a virus transmitted from asymptomatic wildebeest, is a lethal disease in cattle that threatens livestock-based livelihoods and food security in many areas of Africa. Many herd owners reduce transmission risks by moving cattle away from infection hot-spots, but this imposes considerable economic burdens on their households. The advent of a partially-protective vaccine for cattle opens up new options for disease prevention. In a study of pastoral households in northern Tanzania, we use stated preference choice modelling to investigate how pastoralists would likely respond to the availability of such a vaccine. We show a high probability of likely vaccine uptake by herd owners, declining at higher vaccine costs. Acceptance increases with more efficaceous vaccines, in situations where vaccinated cattle are ear-tagged, and where vaccine is delivered through private vets. Through analysis of Normalized Density Vegetation Index (NDVI) data, we show that the reported MCF incidence over 5 years is highest in areas where the mean and interannual varibility in vegetative greeness is relatively low and where herds sizes are smaller. Trends towards lower rainfall and greater landscape-level constraints on cattle movement suggest that MCF avoidance through traditional movement away from wildebeest will become more challenging and that demand for an MCF vaccine will likely increase.

Limited mapping of migrations hampers conservation

While the tendency to return to previously visited locations - termed 'site fidelity' - is common in animals, the cause of this behaviour is not well understood. One hypothesis is that site fidelity is shaped by an animal's environment, such that animals living in landscapes with predictable resources have stronger site fidelity. Site fidelity may also be conditional on the success of animals' recent visits to that location, and it may become stronger with age as the animal accumulates experience in their landscape. Finally, differences between species, such as the way memory shapes site attractiveness, may interact with environmental drivers to modulate the strength of site fidelity. We compared inter-year site fidelity in 669 individuals across eight ungulate species fitted with GPS-collars and occupying a range of environmental conditions in North America and Africa. We used a distance-based index of site fidelity and tested hypothesized drivers of site fidelity using linear mixed effects models, while accounting for variation in annual range size. Mule deer Odocoileus hemionus and moose Alces alces exhibited relatively strong site fidelity, while wildebeest Connochaetes taurinus and barren-ground caribou Rangifer tarandus granti had relatively weak fidelity. Site fidelity was strongest in predictable landscapes where vegetative greening occurred at regular intervals over time (i.e. high temporal contingency). Species differed in their response to spatial heterogeneity in greenness (i.e. spatial constancy). Site fidelity varied seasonally in some species, but remained constant over time in others. Elk employed a 'win-stay, lose-switch' strategy, in which successful resource tracking in the springtime resulted in strong site fidelity the following spring. Site fidelity did not vary with age in any species tested. Our results provide support for the environmental hypothesis, particularly that regularity in vegetative phenology shapes the strength of site fidelity at the inter-annual scale. Large unexplained differences in site fidelity suggest that other factors, possibly species-specific differences in attraction to known sites, contribute to variation in the expression of this behaviour. Understanding drivers of variation in site fidelity across groups of organisms living in different environments provides important behavioural context for predicting how animals will respond to environmental change.

In Africa, livestock are important to local and national economies, but their productivity is constrained by infectious diseases. Comprehensive information on livestock movements and contacts is required to devise appropriate disease control strategies; yet, understanding contact risk in systems where herds mix extensively, and where different pathogens can be transmitted at different spatial and temporal scales, remains a major challenge. We deployed Global Positioning System collars on cattle in 52 herds in a traditional agropastoral system in western Serengeti, Tanzania, to understand fine-scale movements and between-herd contacts, and to identify locations of greatest interaction between herds. We examined contact across spatiotemporal scales relevant to different disease transmission scenarios. Daily cattle movements increased with herd size and rainfall. Generally, contact between herds was greatest away from households, during periods with low rainfall and in locations close to dipping points. We demonstrate how movements and contacts affect the risk of disease spread. For example, transmission risk is relatively sensitive to the survival time of different pathogens in the environment, and less sensitive to transmission distance, at least over the range of the spatiotemporal definitions of contacts that we explored. We identify times and locations of greatest disease transmission potential and that could be targeted through tailored control strategies.

Background Current animal tracking studies are most often based on the application of external geolocators such as GPS and radio transmitters. While these technologies provide detailed movement data, they are costly to acquire and maintain, which often restricts sample sizes. Furthermore, deploying external geolocators requires physically capturing and recapturing of animals, which poses an additional welfare concern. Natural biomarkers provide an alternative, non-invasive approach for addressing a range of geolocation questions and can, because of relatively low cost, be collected from many individuals thereby broadening the scope for population-wide inference. Methods We developed a low-cost, minimally invasive method for distinguishing between local versus non-local movements of cattle using sulfur isotope ratios (δ 34 S) in cattle tail hair collected in the Greater Serengeti Ecosystem, Tanzania. Results We used a Generalized Additive Model to generate a predicted δ 34 S isoscape across the study area. This isoscape was constructed using spatial smoothers and underpinned by the positive relationship between δ 34 S values and lithology. We then established a strong relationship between δ 34 S from recent sections of cattle tail hair and the δ 34 S from grasses sampled in the immediate vicinity of an individual’s location, suggesting δ 34 S in the hair reflects the δ 34 S in the environment. By combining uncertainty in estimation of the isoscape, with predictions of tail hair δ 34 S given an animal’s position in the isoscape we estimated the anisotropic distribution of travel distances across the Serengeti ecosystem sufficient to detect movement using sulfur stable isotopes. Conclusions While the focus of our study was on cattle, this approach can be modified to understand movements in other mobile organisms where the sulfur isoscape is sufficiently heterogeneous relative to the spatial scale of animal movements and where tracking with traditional methods is difficult.