IntroductionThe overall aim of this project is to investigate the role of spotted hyaena in the Okavango Delta ecosystem of northern Botswana. Previous studies have shown that this species exhibits extensive flexibility across populations in certain aspects of their behaviour, yet there is relatively little known about spotted hyaena in this ecosystem. They interact frequently with other large predators (lion, leopard, cheetah and wild dog) due to their abundance and opportunistic nature. Therefore, it is important to understand how hyaena behave and coexist naturally with other species in order to effectively conserve the ecosystem as a whole.
Researcher: Jessica VitaleRegion: Moremi Game Reserve, Okavango Delta, Botswana
BackgroundUnderstanding coexistence between predators is critical for effective conservation of intact ecosystems. Groups of species within an ecosystem that compete over shared resources are termed “guilds”. Within much of sub-Saharan Africa, the large carnivore guild consists of five species: lion, leopard, cheetah, spotted hyaena and African wild dogs. Interactions between guild members can impact their distribution and abundance, and these effects can vary significantly between populations. Identifying and quantifying these interspecies relationships is directly relevant to the development of appropriate and effective conservation and management strategies for large carnivores.
The spotted hyaena is a nocturnal, social carnivore and the most abundant member of the large carnivore guild. Hyaena are highly intelligent and opportunistic predators, performing vital ecosystem functions that are amplified by their widespread distribution and comparatively high densities.
Previous studies of hyaena have shown that they exhibit enormous flexibility in certain aspects of their behaviour including activity patterns, territoriality, feeding, and clan sizes. This extensive behavioural plasticity observed across multiple ecosystems can also influence interactions between hyaena and their competitors. Hyaena can interact with sympatric carnivores through direct competition for resources (i.e. dietary overlap, stealing food) and intra-guild predation. The proportion of kills that hyaena make themselves, rather than scavenge from competitors, ranges from 43% – 95% across ecosystems. For ecosystems in which hyaena behavioural ecology is relatively unknown, such as the Okavango Delta, it is essential to investigate their role within an intact guild system, in order to develop effective conservation initiatives.
Objectives1. To determine the group size, composition, territories, and subgrouping patterns of spotted hyaena clans inhabiting the study area.
2. To investigate how communal latrines relate to hyaena territories and subgrouping patterns.
3. To investigate how spotted hyaena naturally interact with sympatric predators (lion, cheetah, African wild dog, and leopard).
4. To investigate how spotted hyaena respond to olfactory cues (i.e. scent marks) from sympatric predators.
MethodologyField research will be conducted in association with the Botswana Predator Conservation Trust (BPCT) at an established field site. This project involves three main activities: population monitoring, observations of natural encounters between hyaena and other carnivores, and experimental presentations.
Objective 1 will be accomplished through population monitoring and the use of both remote and direct observations. As spotted hyaena live in fission-fusion societies, clan membership will be determined through repeated sightings of associations between individuals, which are each identified by their unique spot pattern. Direct observations will be combined with sightings of identified individuals from remote camera traps placed at dens, latrines, and large carrion sites. All identifiable individuals encountered at the study site will be photo catalogued on a database, which already includes 307 individuals.
Monitoring hyaena communal latrines (Objective 2) will provide further insight into the social networking and territory use of Okavango hyaena. Latrines are found due to the conspicuous white scats left by hyaena. At the start of the project, there were 106 known latrine sites in the study area and approximately 75 of these sites are checked each month to record changes over time. Latrine visitation is also monitored through the use of remote camera traps to determine how visitation rate is influence by latrine size, location in relation to territories and habitat type.
Observation of natural encounters between hyaena and other guild species will continue to contribute to our understanding of how hyaena respond to other predator species in this ecosystem (Objective 3 and 4). The BPCT research team monitors all five species of the large predator guild, which provides a unique opportunity to investigate intra-guild interactions with detailed understanding about all individuals involved. Investigations into whether hyaena respond to, and possibly discriminate between olfactory cues of sympatric predators will take place through olfactory presentations at latrines.
Annual Report, February 2016
After 20 months of fieldwork, substantial progress has been made in the investigation of spotted hyaena behaviour in the Okavango Delta ecosystem. Research thus far has provided insight into variable behaviours such as clan size, territoriality, scent marking, and interactions with other predator species. Three experiments are being conducted to investigate olfactory eavesdropping by hyaenas and sympatric heterospecifics.
Five hyaena clans are being monitored in the study area by visual observation, recording the GPS location and taking photographs to identify individuals and determine clan membership. A database is cataloguing all individuals, which currently contains 463 individuals. Determining clan membership is an ongoing process, but clans in this ecosystem are likely comprised of 30-40 individuals.
Hyaena latrines – sites at which individuals deposit scent marks including faeces, urine, and secretions from anal and interdigital glands – contain information on the presence and movement of individuals, and are used in territorial defence by clans. Latrines are being monitored with remote cameras to collect data on the identity of visitors, rate of hyaena visitation, and responses by sympatric carnivores. Since monitoring began in 2012, 215 latrine sites have been identified in the study area and changes over time are being investigated. Data analysis will relate latrine size and growth to factors such as visitation rate, spatial patterning, habitat type, and rainfall.
Spotted hyaenas interact with all members of the large predator guild in this ecosystem, and data on these encounters are collected continuously through the research programme. At the time of this report, there have been 105 observed intra-guild interactions involving hyaenas: 32 lion, 16 leopard, 46 wild dog, and 11 cheetah. Continued field observations will increase this dataset, and analyses will investigate the factors that influence the outcomes of these interactions.
Urine samples collected opportunistically are deployed in the environment, and camera traps are monitoring any responses to these. The study includes responses from hyaenas as well as from sympatric carnivores, mesocarnivores, and herbivores.
The first two months of the year were spent analysing data from spotted hyaena communal latrines at the University of Nottingham in the United Kingdom. Since latrine monitoring began at the study site in 2012, 159 latrine sites and 168 single scats have been discovered in the area. Latrines are used extensively by hyaena in the ecosystem, with seasonal changes and roads seeming to have the largest influence on latrine behaviour.
The second field season began in March 2015 and will continue through to December. The main goal will be to increase sample sizes for the three olfactory experiences, which will examine both intra- (with hyaenas) and inter-specific (between hyaenas and other large predators) olfactory communication.
The photo identification database is now up to 394 individuals.
One of the main achievements of the first phase of this study has been a vast improvement in hyaena population monitoring in the Okavango Delta region. At the start of the project, in March 2014, 183 individuals had been identified in the study population. After only eight months of research, the number has more than doubled to 378 individuals, providing a much-improved overall picture of the hyaena population. This provides a solid foundation for the further study of hyaena behaviour, including intraspecific interactions, habitat use, prey preferences and intraguild encounters.
The average clan size is approximately 30 – 40 adults, however further study is required to confirm this finding. Sightings revealed that territorial boundaries are not strictly maintained, and individuals will often leave their clan territory, particularly when large carcasses are present elsewhere.
Hyaena subgrouping patterns directly influence their ability to interact and compete with sympatric carnivores, and sightings indicate that in this ecosystem, hyaena most often travel alone. Data on intraguild interactions between spotted hyaena and other predators are collected continuously, through the Botswana Predator Conservation Trust research programme. At the time of this report, there have been 122 observed intraguild interactions involving hyaena: 36 lion, 19 leopard, 56 wild dog, and 11 cheetah. Continued field observations will increase this dataset.
Hyaena communal latrine sites are being monitored to investigate how latrines are involved in territorial defence by hyaena, and whether sympatric predators respond to their presence. To date, there are 159 known latrine sites since monitoring began in 2012, with 120 of these sites containing scats in 2015. Month-long monitoring by camera has been completed on 25 latrines.
Several olfactory experiments are being conducted to investigate whether hyaena respond to scent marks from sympatric predators. Urine samples collection from lion, leopard, and wild dog in the study area are placed at hyaena latrine sites and monitoring using remote camera traps. A second scent experiment investigates whether hyaena respond differently to predator scents in the presence of a prey resource by placing urine samples at carcasses. Additional trials need to be conducted to increase the sample sizes for these experiments.