Grevy's Zebra Equus Grevyi Research Articles

Population and habitat connectivity of Grevy's zebra Equus grevyi, a threatened large herbivore in degraded rangelands

Land degradation, competition with livestock, infrastructure development, and climate change have reduced habitat availability and reduced population connectivity for many wildlife species. Large herbivores are particularly vulnerable, and approximately 90 % of global large herbivore diversity is in Africa. The endangered Grevy's zebra illustrates the decline and fragmentation of large mammalian herbivore populations, with extensive population loss across their range in northern Kenya and Ethiopia. A better understanding of the factors influencing population connectivity and movement patterns of Grevy's zebra, highlighted in national strategies, offers valuable insights for other threatened species.Using location and movement data for Grevy's zebra from GPS collars deployed between 2010 and 2017, seasonally-explicit landscape resistance was modelled as a function of water availability, vegetation, cattle density, topography and proximity to roads and settlements. Maximum entropy models identified habitat suitability during wet and dry seasons respectively. Population connectivity analyses using least-cost paths and circuit theory determined landscape resistance to movement and highlighted linkage pathways. Movement was modelled over a range of distances, using GPS data.Grevy's zebra reliance on water was confirmed, with an apparent trade-off between habitat suitability and proximity to people. Connectivity models highlighted potentially isolated populations, with reduced seasonal connectivity being most apparent between north to south distribution areas. These results can inform sustainable land management planning in northern Kenya and offer support for Grevy's zebra conservation actions. These results also provide insights that can be applied to other large herbivores occurring in this region and in arid or degraded environments elsewhere.

The forgotten Grevy's zebra Equus grevyi population along the Kasigau Corridor ranches, SE Kenya: recent records and conservation issues

AbstractSince the 1970s, the globally endangered Grevy's zebra Equus grevyi has suffered a substantial reduction in range and population size. Grevy's zebra was introduced into the Tsavo ecosystem in two translocations: 22 individuals released in Tsavo East National Park in 1964 and 30 individuals released in Tsavo West National Park in 1977. This study focuses on the Tsavo East subpopulation within the Kasigau Corridor REDD+ Project Area. Data were collected from 2011 to 2014 using systematic and ad lib methods, while vegetation stratification was based on tonnes of CO2e per hectare. Cumulatively, 785 Grevy's zebra were seen in 210 encounters. The largest single group comprised of 24 individuals; mean group size was 4 ± 3. Foals comprised 10% of all individuals seen and were recorded across most months, suggesting year‐round breeding. The range core for the Grevy's zebra in this area was estimated to be 400 km2. Its density was estimated at 0.09 ± 0.038 individuals per km2, translating to a population of 36 ± 15 individuals (range: 6–67) based on the estimated core range. Grasslands and sparse Acacia–Commiphora vegetation strata were used significantly more than expected. Despite constituting only about 2–3% of the global Grevy's zebra population, this subpopulation could still play a role as a – disconnected – reserve population.

Utilizing Zoos Victoria's Connect‐Understand‐Act model to enable social and biological gains in northern Kenya

As human populations grow, wildlife across the globe is increasingly threatened. As a zoo‐based conservation organization, Zoos Victoria (ZV) in south‐east Australia is dedicated to fighting wildlife extinction locally and globally. Our international partnerships work with local communities, governments and non‐governmental organizations. The focus of the ZV conservation programmes is on alleviating threats to wildlife while addressing the needs of the community. The shared vision of a partnership with the Melako Community Conservancy (MCC) in northern Kenya is to foster sustainable development that allows communities to live in balance with wildlife. In 2011, an opportunity arose to trial ZV's Connect‐Understand‐Act (CUA) model for influencing visitor behaviour change, and this led to the first practical application of this model in Kenya. The model utilizes best‐practice conservation, education and social science to shape wildlife‐friendly values and behaviours. The impact of this model is now being trialled in situ through a conservation‐based sports programme called ‘Kicking Goals for Wildlife’. After conducting a conservation‐needs assessment in 2010, the community identified human–wildlife conflict as an issue negatively impacting species such as the Beisa oryx Oryx gazella beisa and Grevy's zebra Equus grevyi. The Kicking Goals for Wildlife programme is targeted at morans (initiated youth ranging from 15 to 30 years of age, and also referred to as warriors), filling their ‘idle time’ with football as an alternative to harming wildlife or engaging in intertribal conflict. The outcomes of the programme will be measured through changes in warrior attitude, knowledge, behavioural efficacy, reduction in biological threat and social change. Preliminary feedback is showing positive progress across all aspects. An additional measure, in an effort to assess the programme's impact on target species, was distance sampling to monitor the changes in flight distance. This paper outlines the theoretical framework underpinning the model, using the Kicking Goals for Wildlife programme in the MCC as a case study for what is involved in planning, designing and implementing a conservation‐education programme in the field.

Monitoring an Endangered savannah ungulate, Grevy's zebraEquus grevyi: choosing a method for estimating population densities

AbstractMethods that accurately estimate animal abundance or density are crucial for wildlife management. Although numerous techniques are available, there have been few comparisons of the precision and cost-effectiveness of different approaches. We assess the precision and cost of three methods for estimating densities of the Endangered Grevy's zebraEquus grevyi. We compare distance sampling and photographic capture–recapture, and a new technique, the random encounter model (REM) that uses camera-trap encounter rates to estimate density. All three methods provide comparable density estimates for Grevy's zebra and are preferable to the common practice of raw counts. Photographic capture–recapture is the most precise and line-transect distance sampling the least precise. Line transects and photographic capture–recapture surveys are cost-effective in the first year and REM is most cost-effective in the long-term. The methods used here for Grevy's zebra may be applied to other rangeland ungulates. We suggest that for single species monitoring programmes in which individuals can be identified, photographic capture–recapture surveys may be the preferred method for estimating wildlife abundances. When encounter rates are low, distance sampling lacks the precision of the other methods but its cost advantage may make it appropriate for long-term or multi-species monitoring programmes. The REM is an efficient and precise method of estimating densities but has high initial equipment costs. We believe REM has the potential to work well for many species but it requires independent estimates of animal movements and group size.

Effect of social system on allosuckling and adoption in zebras

AbstractAlthough nursing non‐filial offspring (allonursing) represents costly behaviour to the female, it occurs in a variety of taxa, including ungulates. The only three currently existing species of zebra differ in their ecology and social system. In the wild, mountain zebra Equus zebra and Grevy's zebra Equus grevyi live in arid environments, while plains zebra Equus quagga inhabit savannahs. Mountain and plains zebra mares form long‐term stable herds associated with a social hierarchy, whereas Grevy's zebra mares form loose associations of short duration. In this study, we investigated the occurrence of allosuckling in three zebra species at the Dvůr Králové Zoo, Czech Republic, during 1626 h of observation. We recorded no successful allosuckling bouts and only 1 and 22 attempts to allosuckle by foals of mountain and plains zebra, respectively, whereas we observed 117 attempts and 13 successful allosuckling bouts by Grevy's zebra foals. Moreover, more than half of all observed Grevy's zebra foals succeeded in allosuckling at least once. When rejecting an allosuckling attempt, Grevy's zebra mares were less aggressive than mountain and plains zebra mares. When a Grevy's zebra mare allowed occasional allosuckling by a non‐filial foal, the probability of long‐term allosuckling was smaller than that in mountain and plains zebra. We also present the first evidence of adoption in Grevy's zebra. We suggest that higher tolerance towards non‐filial offspring, including the occurrence of allosuckling in Grevy's zebra, was affected by the different social systems of zebra species.

Is the endangered Grevy's zebra threatened by hybridization?

AbstractHybridization between an abundant species and an endangered species is cause for concern. When such hybridization is observed, it is both urgent and necessary to assess the level of threat posed to the endangered species. We report the first evidence of natural hybridization between two equids: the endangered Grevy's zebra Equus grevyi and the abundant plains zebra Equus burchelli. Grevy's zebra now number <3000 individuals globally, and occur only in northern Kenya and Ethiopia. In recent years, Grevy's zebra have become increasingly concentrated in the south of their range due to habitat loss in the north. Both species are sympatric in the Laikipia ecosystem of northern Kenya, where we have observed purportedly hybrid individuals. Using mitochondrial and Y chromosome DNA, we confirmed the hybrid status of the morphologically identified hybrids and demonstrate conclusively that all first‐generation hybrids are the offspring of plains zebra females and Grevy's zebra males. Behaviorally, hybrids integrate themselves into plains zebra society, rather than adopting the social organization of Grevy's zebra. Two hybrids have successfully raised foals to over 3 months in age, including one which has reached adulthood, indicating the fertility of female hybrids and viability of their offspring. We hypothesize that hybridization occurs due to (1) skewed sex ratios, in favor of males, within Grevy's zebra and (2) the numerical dominance of plains zebra in the region where hybridization is occurring. Stakeholders have discussed hybridization as a potential threat to Grevy's zebra survival. We argue, however, based on behavioral observations, that hybridization is unlikely to dilute the Grevy's zebra gene pool in the short term. As a conservation concern, hybridization is secondary to more direct causes of Grevy's zebra declines.

Fecal glucocorticoid metabolite analysis as an indicator of stress during translocation and acclimation in an endangered large mammal, the Grevy's zebra

AbstractFecal glucocorticoid metabolite (FGM) analysis provides a non‐invasive method for studying the physiological response of wildlife to a variety of stressors and is a ground‐breaking monitoring technique in wildlife management and conservation. The conservation benefits of successful wildlife translocation restocking efforts are significant but understandably stressful for the animals being captured, removed from familiar habitat, held in captivity in many cases and subsequently released into an unfamiliar environment. It is imperative that we identify non‐invasive methods for evaluating stress in translocated animals, especially in endangered species. Twenty Grevy's zebra Equus grevyi were translocated to Meru National Park as part of a Kenya Wildlife Service re‐population initiative. FGMs were monitored from the time of capture, during captivity and post‐release as an indicator of the stress of translocation and acclimation to the new environment. FGMs from representative non‐translocated zebra were used as a further control. When held in pens at Meru Park 3–4 and 5–6 weeks after capture, the zebra had higher FGMs (25.1±1.2 and 23.4±1.3 ng g−1) than either at the time of capture (14.6±2.1 ng g−1) or non‐translocated controls (16.2±1.2 ng g−1). This suggests that the stress of captivity elevated FGMs. FGM concentrations returned to pre‐capture concentrations c. 11–18 weeks after the zebra were released into Meru Park. The return of FGM concentrations to baseline suggests successful acclimation to the new environment. This study supports the use of FGM analysis as an assessment technique in wildlife management projects involving the movement of endangered large mammals with application for monitoring stress in a wide array of conservation projects involving translocation, reintroduction and rehabilitation.

An analysis of the population of Grevy's zebra Equus grevyi in Dvur Kralove Zoo

An analysis of the population of Grevy's zebra Equus grevyi in Dvur Kralove Zoo