In many African savanna landscapes, domestic and wild herbivores cooccur across different land-use systems, but the role of land-use in shaping their spatial relationship is poorly understood. We evaluated the spatial relationship between cattle and wild herbivores categorized by body sizes and feeding habits across different land-use types, namely, private ranches (PR), transitional lands (TRL), and pastoral grazing areas (PGA), in Laikipia County, Kenya. Cattle and wild herbivores spatial distribution data were obtained from Kenya’s Department of Resources Survey and Remote Sensing (DRSRS). Spatial relationships between cattle and different wild herbivore guilds were analyzed using Ripley’s bivariate
Savannas are the most widespread ecosystems in the tropics and subtropics. The tropical and subtropical savannas cover nearly a third of the world’s land surface and over 50% of Africa [
Conversion of grassland ecosystems into croplands, afforestation, urbanization, and other detrimental human activities is a global problem [
Habitat sharing between domestic and wild ungulates may result in different kinds of ecological interactions between these two herbivore guilds, including competition [
We investigated the influence of land-use system on spatial relationship between cattle and wild mammalian herbivores in Laikipia County, Kenya. The study area is a typical example of a tropical savanna which is of profound socioeconomic and ecological significance. Laikipia was ideal for the study because it hosts a mixture of livestock and a diverse assemblage of wild herbivores. Domestic and wild herbivores commonly share habitats across much of the Laikipia landscape because only approximately 2% of the landscape is formally protected exclusively for wildlife conservation [
In this study, we compared the spatial relationship between herds of cattle and mammalian herbivores among three land-use types, namely, private ranches (PR), transitional lands (TRL), and pastoral grazing areas (PGA). Considering the varying densities of cattle and wild herbivores, management regimes, and forage resources availability in the three land-use types, we expected that the spatial relationship between these herbivore guilds would vary among land-use types. Additionally, we expected that the strength of these effects would vary depending on wild herbivore body size (megaherbivores and medium-sized herbivores) and feeding habits (grazers, browsers, and mixed feeder).
The research was conducted in Laikipia County, Kenya. The county covers approximately 9666 km2 [
Laikipia county broad land-use types (equator: 0°0′0″). Source: LWF, 2012.
The study area is located in the central part of Kenya, where it largely falls on the northern side of the equator (0°). To the southwest are the Aberdare highlands and to the southeast is the Mt. Kenya. A climatic gradient occurs longitudinally in Laikipia due to the presence of Mt. Kenya (5199 m) and Aberdare ranges (3999 m). Laikipia experiences a mean annual rainfall range of between 300 mm and 750 mm with a weak trimodal distribution. Long rains fall between March and June, continental rains occur between August and September, and short rains fall between October and December [
Laikipia is a species-rich savanna rangeland in both animal and plant life-forms. It harbors over 95 mammal species of which 25 are ungulate species, 540 bird species, and close to 1000 species of invertebrates [
Habitat types in Laikipia are largely characterized by the dominant plant community or plant species. In the grassland and open woodlands, several species of
Laikipia County communities engage in various socioeconomic activities; agriculture in various forms dominates. In the northern part of the county where rainfall is scarce, pastoralism is the dominant economic activity being practiced on communally owned land. Agropastoralism and small scale mixed farming dominate the rest of the county especially in areas where land ownership is small-holding and rainfall permits arable farming. Agropastoralism refers to land-use where a parcel of land is either on crop farming (during wet season) or on livestock (during dry periods). Where land owners or government entities have large tracts of land, cattle ranching, game ranching, and tourism are practiced [
In this study, we assessed the spatial relationship between cattle and wild herbivores of different feeding habits and body sizes (Table
Categorization of Laikipia wild herbivores based on body size and feeding habits.
Wild herbivore species | Body size | Feeding habits | |||
---|---|---|---|---|---|
Megaherbivore | Medium-sized | Grazers | Browsers | Mixed-feeders | |
African elephant | Yes | Yes | |||
Rhino | Yes | Yes | |||
Giraffe | Yes | Yes | |||
Burchell’s zebra | Yes | Yes | |||
Grevy’s zebra | Yes | Yes | |||
Thomson’s gazelle | Yes | Yes | |||
Grant’s gazelle | Yes | Yes | |||
Hartebeest | Yes | Yes | |||
Impala | Yes | Yes | |||
Cape buffalo | Yes | Yes | |||
Eland | Yes | Yes | |||
Warthog | Yes | Yes | |||
Beisa oryx | Yes | Yes | |||
Greater kudu | Yes | Yes | |||
Lesser kudu | Yes | Yes | |||
Waterbuck | Yes | Yes | |||
Reedbuck | Yes | Yes | |||
Gerenuk | Yes | Yes |
Source: author, 2017.
Land-use was classified based on
This land-use type comprises large scale land holdings which are acquired or leased to individuals or private entities by the government. The private proprietors manage these properties which can either be fenced or unfenced. The “owners” of these properties utilize the land primarily for wildlife conservation while at the same time keeping livestock as a secondary utility for varied reasons; therefore wildlife density is usually higher compared to livestock density [
These are properties which are registered under a limited number of families from the local pastoral community who communally own and manage their land. Unlike the private ranches where property management is centralized, some group ranches have a much decentralized land management system where each group ranch elects a committee which manages grazing, tourism, and other land utilization activities [
These are lands which have been subdivided into small plots (1–10 ha) and are owned by the small scale holders by way of having free-hold title deed. Land owners manage their individual properties. Occupants practice mixed farming or agropastoralism when rain permits; in the unoccupied plots, the pastoral communities dominate with their livestock thus displacing wildlife in those areas. There are also some large scale farms and ranches which may or may not tolerate wildlife but do not actively favor wildlife conservation; as a result, wildlife densities are varied in these transitional properties [
Livestock and wild ungulates spatial data collected during November 2012 aerial census was obtained from the Department of Resources Survey and Remote Sensing (DRSRS), a Kenyan government department mandated with collecting, storing, analyzing, updating, and disseminating geospatial information on natural resources. DRSRS has over the years conducted aerial surveys for both wildlife and livestock in Laikipia where each detected group of either livestock or wild ungulates is mapped using the Global Positioning System (GPS) and the individuals counted. The spatial data was processed based on species and the land-use type in which the species occurred; individual species vector data (points) were then grouped according to the respective wild ungulate category based on feeding habit or body size. Spatial analysis was done using
Ripley’s bivariate
The corresponding linearized
Cattle and wild herbivore events in different land-use systems.
Ungulate guild | Land-use type | ||
---|---|---|---|
PR | TRL | PGA | |
Cattle | 212 | 399 | 22 |
Wild grazers | 1025 | 379 | 23 |
Browsers | 271 | 28 | 6 |
Mixed feeders | 564 | 57 | 24 |
Megaherbivores | 460 | 45 | 22 |
Medium sized ungulates | 1431 | 421 | 31 |
Source: author, 2017.
Cattle and wild grazers showed a significant attraction towards each other up to approximately 700 m and from approximately 1400 m to 5000 m in PR (Figure
Spatial relationship between cattle and wild grazers across land-use types: (a) private ranches (PR), (b) transitional lands (TRL), and (c) pastoral grazing areas (PGA). Green solid line
Cattle and browsers exhibited both attraction and repulsion in the PR; at short distances of up to approximately 700 m, there was significant attraction between the two guilds. From 700 m up to 5000 m, the
Spatial relationship between cattle and wild browsers across land-use types: (a) private ranches (PR), (b) transitional lands (TRL), and (c) pastoral grazing areas (PGA). Green solid line
Cattle and mixed feeders exhibited two different departures from independence across all the three land-use systems unlike in the cases of cattle and grazers and cattle and browsers. In the PR, significant attraction was observed up to approximately 700 m followed by a weak repulsion up to around 1200 m. A weak attraction was observed from 1200 m to 5000 m, the observed spatial relationships between cattle and mixed feeders in PR conspicuously oscillated very close to complete spatial randomness (Figure
Spatial relationship between cattle and mixed feeders across land-use types: (a) private ranches (PR), (b) transitional lands (TRL), and (c) pastoral grazing areas (PGA). Green solid line
A weak significant attraction existed between cattle and megaherbivores in PR at distances less than approximately 700 m. Weak repulsion was exhibited between 700 m and 3300 m, followed by weak oscillations of attraction and repulsion up to around 3900 m. Further, a weak attraction was observed up to 5000 m (Figure
Spatial relationship between cattle and megaherbivores across land-use types: (a) private ranches (PR), (b) transitional lands (TRL), and (c) pastoral grazing areas (PGA). Green solid line
A significant positive dependence between cattle and medium-sized ungulates was observed throughout all the scales of distances in the PR; however, the strength of the relationship weakened towards the 5000 m mark (Figure
Spatial relationship between cattle and medium-sized ungulates across land-use types: (a) private ranches (PR), (b) transitional lands (TRL), and (c) pastoral grazing areas (PGA). Green solid line
The wild grazers largely exhibited significant attraction to cattle in PR and TRL unlike in PGA where they showed both repulsion and attraction. In a parallel study, mean NDVI in PR and TRL (excluding forested areas) was higher than in PGA (excluding forested areas) indicating higher forage availability (G.W. Kinga, unpublished data). The observed attraction between cattle and wild grazers in PR and TRL is consistent with previous studies where niche overlap between cattle and some wild grazers has been reported especially when forage resources are abundant [
Browsers had a significant attraction to cattle at distances (≤700 m) in PR; however, they largely exhibited negative dependence in PR and TRL. Conversely, they generally exhibited attraction in PGA which was significant at distances (approximately ≤500 m). The observed repulsion between cattle and browsers in both PR and TRL could be due to lack of dietary niche overlap as the two guilds have exclusively different feeding styles as was observed in some browser species [
Mixed feeders exhibited both departures from CSR in all the three land-use types considered in this study. This is presumed to be due to their dynamic feeding style allowing them to conveniently adjust their spatial interaction with cattle. Attraction, independence, and repulsion at different scales of distance were evident (Figures
Megaherbivores exhibited attraction towards cattle at short distances (≤700 m and ≤500 m) in PR and TRL, respectively, possibly due to habitat niche overlap as compared to dietary niche overlap. This is more so because no pure grazer was in this ungulate guild (megaherbivore). The spatial repulsion observed at fairly short to moderate distances in PR (≈700 m to ≈3300 m) and short to larger distances in TRL (≈600 m to 5000 m) broadly conforms with previous studies indicating that particular species of megaherbivores (elephants) segregate with cattle even at larger scales of distance [
The medium-sized ungulates broadly indicated attraction to cattle at nearly all scales of distance in all the three land-use types (Figures
The observed spatial relationships (attraction, independence, and repulsion) between cattle and different wild herbivore guilds in the three different land-use types can largely be attributed to pasture resources availability and the density of cattle and wild herbivores in the specific land-use types. Pasture resource availability is a requisite conditional requirement for interspecific competition to occur between sympatric populations [
The five wild ungulate guilds considered in this study exhibited varying spatial relationships with cattle at different scales of distance, a phenomenon which is possibly attributed to habitat and/or dietary niche overlap amidst other possible biotic and abiotic factors. Stronger attractions were exhibited in PGA than in TRL and PR. Moreover, most important is the consistent observation that the variation of the observed spatial relationship
The authors declare no conflicts of interest regarding publishing this paper.
The authors acknowledge the Department of Resources Survey and Remote Sensing (DRSRS) for making the data used in this study available besides allowing access to the library resources.