Traditional grazing grounds near Amboseli National Park (Kenya) are rapidly converted to cropland - a process that closes important wildlife corridors. We explore the scope for introducing a "payments for ecosystem services" scheme to compensate pastoralists for spillover benefits associated with forms of land use that are compatible with wildlife conservation. Our results indicate that such a scheme likely enhances global welfare, but that (i) 'leakage' through excessive stocking rates warrant close scrutiny and (ii) that payments increase the risk of overstocking during droughts.