Comparative changes in density and demography of large herbivores in the Masai Mara Reserve and its surrounding human-dominated pastoral ranches in Kenya

Abstract

Wildlife habitats in pastoral lands adjoining protected areas in east African savannas are getting progressively degraded, fragmented and compressed by expanding human populations and intensification of land use. To understand the consequences of these influences on wildlife populations, we contrasted the density and demography of 13 wild and three domestic large herbivores between the Masai Mara National Reserve and the adjoining pastoral ranches using aerial surveys conducted in the wet and dry seasons during 1977-2010. Species of different body sizes and feeding styles had different densities between landscapes and seasons. Small-sized herbivores, requiring short, nutritious grasses, and browsers were more abundant in the ranches than the reserve in both seasons.Electronic supplementary material The online version of this article (Medium-sized herbivores moved seasonally between landscapes. Larger-bodied herbivores, requiring bulk forage but less susceptible to predation, were more abundant in the reserve than the ranches. The proportions of newborn warthog (Phacochoerus africanus) and juvenile topi (Damaliscus korrigum) were higher in the ranches, with shorter grasses and lower predation risk than in the reserve. These results suggest that pastoral lands adjoining protected areas in African savannas are important as seasonal dispersal and breeding grounds for wild herbivores. However, human population growth and dramatic land use changes are progressively degrading wildlife habitats in pastoral areas, thus restricting the seasonal wildlife dispersal movements between the protected areas and adjoining pastoral lands. Conservation efforts should focus on (1) creating and maintaining functional heterogeneity in protected areas that mimic moderate pastoral grazing conditions to attract small and medium-bodied grazers and (2) securing dispersal areas, including corridors, to ensure continued seasonal large herbivore movements between protected and pastoral systems.

Changing Wildlife Populations in Nairobi National Park and Adjoining Athi-Kaputiei Plains: Collapse of the Migratory Wildebeest

“…The catastrophic range contractions and reductions in ungulate numbers currently underway in the Athi-Kaputiei ecosystem is extremely worrisome because it corroborates an alarming general pattern that has been documented for many species in the Maasai Mara region [13,66], Lake Nakuru National Park [24], previously for this ecosystem [26] and most other protected and unprotected lands in Kenya [67,68,69], as well as in large parts of Tanzania [14,70,71]. Wildebeest are especially at risk when their seasonal migrations take them well beyond protected area boundaries [10,72].…”

Co-existence of wildlife and pastoralism on extensive rangelands: competition or compatibility?

“…Competition occurs when large numbers of wildlife remove large masses of growing forage in the lean season, as happens when wildlife avoid pastoral areas in the dry season of the Mara ecosystem of Kenya (Bhola et al 2012). Borana pastoralists of Ethiopia recognize that heavy grazing by their cattle can 'overgraze' their pasture, promoting the spread of shrubs and reducing pasture productivity (Desta and Coppock 2004).…”

Population regulation of African buffalo in the Mara–Serengeti ecosystem

“…It is noteworthy that buffalo occurred in sizable numbers in the pastoral ranches adjoining the MMNR through the 1970s and 1980s. However, by 1990s and 2000s they were almost completely excluded from the ranches and became largely confined to the MMNR by competition with livestock for forage, human population growth, settlements, cultivation and other land use changes (Serneels et al 2001;Sitati 2003;Lamprey and Reid 2004;Ogutu et al 2009;Bhola et al 2012aBhola et al , 2012b. , n = 49).…”

“…Livestock from the ranches are grazed illegally in the MMNR, especially during droughts, a phenomenon that has become more frequent and acute since 2006, when conversion of large parts of the pastoral ranches adjoining the MMNR into communal wildlife conservancies with controlled livestock access began (Butt et al 2009;Ogutu et al 2009Ogutu et al , 2011. Apart from livestock numbers, livestock distribution, human population, settlements, fences and cultivation have also expanded in the Mara ranches, resulting in progressive habitat degradation and fragmentation and intensification of land use (Serneels et al 2001;Sitati 2003;Lamprey and Reid 2004;Ogutu et al 2009;Bhola et al 2012aBhola et al , 2012b.…”

“…We expected buffalo to compete with livestock and migratory wildebeest in the dry season and the intensity of the competition to increase over time because of increasing livestock numbers, expansion of their spatial distribution in the Mara pastoral ranches and increasing illegal incursions into the Masai Mara National Reserve. Moreover, gradual exclusion of buffalo from the pastoral ranches by rapid expansion of settlements and intensification of livestock grazing linked to sedentarisation of the formerly semi-nomadic Masai pastoralists (Bhola et al 2012a(Bhola et al , 2012b should further aggravate the competition. H 4 : Predation hypothesis.…”