First, Amboseli, a 10,000 km² area, provides habitat for several thousand elephants, hundreds of lions, and thousands of wildebeest and zebra. Private land in this area is now heavily fenced (21,150 km) with a median fence line density of 1.78 km.km^-2 ( Figures 1 , 2 ). In addition to high densities of livestock enclosures, agriculture covers 428.09 km²or 3.4% of the area ( Figure 1 ). This proliferation of fencing, sedenterization, and land transformation has fragmented the ecosystem, with severe implications for pastoral livelihoods (Kimiti et al., 2018) and the connectivity of wildlife populations (Groom and Western, 2013; Osipova et al., 2018). Yet, considerable areas of very low-density fencing remain around the Amboseli National Park ( Figures 1 , 2 ), especially in areas where communities have set aside parts of their land for conservation. Many of these communities are paid annual lease fees by conservation NGOs, supporting wildlife’s persistence around the National Park, although subdivision and fencing are also underway here.

Second, the South Rift Valley, an 8,000 km² area, is primarily under communal ownership with a diverse and abundant wildlife community. Here, private land in parts of the ecosystem has high densities of livestock enclosures and fences (1.3 km.km^-2 median, 11,152 km in total: Figure 1 ) but areas in the south and west remain with very low-density settlement and fencing, including community conservation areas ( Figures 1 , 2 ). In these areas, wildlife and livestock still maintain considerable mobility, which is vital for their long-term survival (Tyrrell et al., 2017). The arid climate of the southern and western parts of the South Rift Valley makes them unsuitable for rainfed agriculture and the local community maintains traditional governance structures that manage the landscape for extensive pastoralism (Brehony, 2020). These factors have prevented land subdivision and conversion to cropland (presently only 0.9% of total area) or urban development (Western et al., 2020).

Third, the Loita ecosystem (~3,000 km²) has undergone considerable fencing (3,029 km total, 0.901 km km^-2), sedentarization, and conversion to agriculture (80.06 km², 2.3% of total area; Figures 1 , 2 ), which now limits the mobility of large mammals between the Maasai Mara and South Rift Valley. The Loita Forest is a vital part of this ecosystem, where considerable areas remain with very low-density fencing and settlement (adjacent to the South Rift Valley). It is an important water source for both the Mara-Serengeti and South Rift Valley ecosystems, a central connection for large mammal movement across the greater Kenya-Tanzania borderlands region, a critical area for carbon sequestration, and a biodiversity hotspot (Broekhuis et al., 2018).

Finally, the Maasai Mara ecosystem (~7,000 km²), world-renowned for its large wildlife populations, still has a comparatively low intensity of fencing (3,039 km total, 0.477 km.km^-2 median) and livestock enclosures due to the Maasai Mara National Reserve and the surrounding conservation areas, supported by eco-tourism lease fees. However, as reported by Løvschal et al. (2017), there has recently been a rapid expansion of fencing around the Maasai Mara National Reserve and within surrounding ‘conservation areas’ ( Figures 1 , 2 ), with associated wildlife declines including the near complete collapse of the Loita Plains migration of >300,000 wildebeest (Løvschal et al., 2018). Large-scale conversion to agriculture has occurred in key wet season grazing areas for wildlife, extending south from private lands in the north (8.3% of the ecosystem; 579.74 km²; Figures 1 , 2 ).

Fencing has escalated most rapidly in areas with increasing land prices ( Figure 3 ), driven by proximity to Kenya’s capital, Nairobi, and agricultural potential (Tyrrell et al., 2021). These factors encourage the transfer of land from traditional communities to urban speculators and its eventual transformation into agricultural, industrial, or urban land-uses ( Figure 3 ) (Rutten, 1992; Tyrrell et al., 2021). The Nairobi National Park and Athi-Kapiti ecosystem, adjacent to Nairobi, are now almost completely fragmented with a collapse of the previously rich migratory system of wildlife and pastoralism (Said et al., 2016; Nkedianye et al., 2020). Economically, subdivision into private parcels may empower landowners, at least in the short-term, allowing them entry into the cash economy through land sales, loans on title deeds, and subsistence agriculture. However, land sales are often driven by wealthy and powerful investors external to the local community (Rutten, 1992). Without access to grazing land, pastoralists will eventually be forced to abandon their traditional lifestyle and culture, risking a poverty trap (Rutten, 1992). Poor planning and weak local leadership during the subdivision process itself, often led by local elites or government officials, can exacerbate inequalities within communities and worsen the ecological impacts of fencing and land conversion (Galaty, 1999; Mwangi, 2007).

The density of livestock enclosures was lowest in protected areas followed by conservation areas, community land, and private subdivided land ( Figure 4 ). Rainfall and land tenure both explained the distribution of livestock enclosure density (PPM, df= 4, p-value < 0.0001). Private land in Amboseli, the South Rift, and the Mara ecosystem showed some of the highest average densities ( Figure 4 ) whereas the largest spaces between livestock enclosures were predictably in conservation areas ( Figure 4 ). On the other end of the spectrum, private subdivided land had the least open space between livestock enclosures, which is related to the sedentarization of pastoral households during privatization and has worrying implications for rangeland sustainability (Groom and Western, 2013).

Fencing and land conversion alter the mobility of wildlife and livestock, including their access to vital resources such as water and seasonal forage, which are patchily distributed in rangeland ecosystems (Western and Gichohi, 1993; Homewood et al., 2001; Hobbs et al., 2008; Said et al., 2016; Jakes et al., 2018; McInturff et al., 2020). In addition, these changes limit connectivity between wildlife sub-populations thereby preventing wildlife from moving between seasonal ranges, restricting genetic exchange, exacerbating human-wildlife conflict, squeezing wildlife and livestock into smaller areas, altering ecosystem function, and hampering adaptation to climate change (Western and Maitumo, 2004; Newmark, 2008; Western et al., 2015a; Jakes et al., 2018; Osipova et al., 2018; Veldhuis et al., 2019; McInturff et al., 2020). Sedentarization results in a homogeneous year-round spread of livestock enclosures, reducing livestock mobility and increasing local livestock density and grazing pressure, which creates deeper annual and seasonal deficits in grass biomass than would occur from rainfall-induced droughts alone (Groom and Western, 2013; Western et al., 2015b; Western et al., 2021). Locally high stocking rates with low mobility alter the species composition, height, productivity, and nutritional content of forage resources, with ramifications for wildlife and livestock composition and productivity (Augustine et al., 2003; Boone et al., 2005; Western et al., 2009; Groom and Western, 2013; Young et al., 2013). Moreover, the combination of land privatization, sedentarization, and fencing endangers pastoral livelihoods by reducing resilience to drought and diminishing livestock holdings per person (Boone et al., 2005; Bedelian and Ogutu, 2017; Kimiti et al., 2018). These negative trajectories are likely to steepen with continued global climate change (Funk, 2020)

To maintain social-ecological systems with land-sharing between wildlife and local communities, land use planning for the remaining areas, particularly those currently undergoing subdivision, is vital and pressing. This must allow for people to equitably benefit from their land while maintaining the space and mobility required for livestock and wildlife (Western et al., 2020). In Amboseli, a comprehensive ecosystem management plan and a locally developed subdivision plan are indeed guiding the process of subdivision to ensure equitable allocations of land, and the maintenance of important wildlife corridors. ² In the community-owned and fertile Loita ecosystem, where conversion to private title is underway, bottom-up processes are also being incorporated into regional land-use planning. In the longer term, however, the response to these changes must be driven by regional (county) governments in collaboration with local communities, with significant support from the national government, local and international civil society stakeholders, and where relevant, tourism stakeholders (like the lucrative Mara). This support includes policy reforms to curtail land speculation and mitigate the impact of fencing and land subdivision, coupled with economic incentives for local landowners to maintain open rangelands, ensuring the social-ecological sustainability of these ecosystems (Norton-Griffiths and Said, 2009; Lindsey et al., 2020). Without such incentives, the current situation will continue with ad hoc propagation of fences encircling subdivisions of commodified land into small parcels.

The highest costs of wildlife conservation are ultimately borne by local communities (Norton-Griffiths and Said, 2009; Weldemichel and Lein, 2019). Solutions to offset these costs could include recognition by national and regional governments of the culturally important practice of pastoralism and local livelihoods, and the cultural and economic value of protecting it to avoid a poverty trap for a significant segment of the human population. Increased efforts are needed to develop payments for ecosystem services, to restructure and expand a potentially lucrative post-COVID eco-tourism industry, and to ensure an equitable distribution of benefits to local communities (Lindsey et al., 2020; Western et al., 2020). In some areas, there is evidence that removal of fencing and prevention of sedentarization can be incentivized (Western et al., 2020), but reducing the direct and indirect costs of co-existing with wildlife is also critical (Norton-Griffiths and Said, 2009).

Immediate investment could be required to support leases and purchases by conservation organizations of ecologically critical areas under imminent threat of fragmentation and conversion. There would also have to be co-created, long-term solutions for the people living in and off such areas. However, the level of investment needed is ominously high (Norton-Griffiths and Said, 2009). For example, in the private land around the Maasai Mara Reserve, over US$6,000,000 is already invested in conservation areas through land leases to offset the opportunity costs of conservation, although in some areas this still might not be enough to ensure equitable and sustainable livelihood options for the local community (Bedelian and Ogutu, 2017). Any support garnered would need to be underpinned by strong and accountable local leadership and governance, along with devolved benefits and decision-making rights to local people, in order to ensure its ultimate sustainability (Western et al., 2020). Kenya does have proactive policies for devolving the benefits and management rights of natural resources, including wildlife (Western et al., 2015b), but more is needed to ensure sustainability, fairness, and effectiveness at the landscape scale (Weldemichel and Lein, 2019). For the remaining areas not yet subdivided, there is a need to maintain and empower community tenure and governance systems, including adopting the recent Community Land Act, allowing for an alternative to uncontrolled and unequitable subdivision.