Ecology and conservation of sympatric tropical deer populations in the Greater Calakmul Region, south-eastern Mexico

Abstract

The conservation and management of tropical deer populations need both knowledge of the ecology and natural history of deer and an understanding of the utilization of deer populations by humans. The south-eastern portion of the Yucatan Peninsula in Mexico is the region with the largest ungulate diversity in Mesoamerica, including three of the five species of deer found in Mexico. For centuries, human populations have been harvesting deer for subsistence in this region. Little is know on the ecology and conservation of ungulate populations undergoing subsistence harvesting in Mesamerica. This thesis is the result of a long-term study (1996-2001) on the population, community ecology and sustainable management of the Yucatan Peninsula brown brocket deer (Mazama pandora), red brocket deer (Mazama americana) and white-tailed deer (Odocoileus virginianus) in the Greater Calakmul Region՝ (GCR), south eastern Mexico. Chapter two addresses the estimation of deer abundance, densities, population structure and habitat use of sympatric populations of these three species of deer. Chapter three outlines the relationships of the deer diet with aspects of habitat ecology such as fruit phenology, availability and seasonality. Chapter four describes the spatial and temporal patterns of subsistence hunting of tropical deer populations with the use of a novel technique incorporating both GIS/GPS technologies and participatory research. The abundance of deer in the GCR remained stable during a continuous monitoring period of five years and no effects of hunting were detected in the populations of the two Mazama species. A steady decline was detected in the populations of white-tailed deer that might be attributed to over-harvesting by subsistence hunters. Densities of the three species of deer are similar or higher that those reported elsewhere in the Neotropics. Mazama americana presented strong preferences in habitat use for the Tall Perennial Forest, while M pandora and o. virginianus used habitats in relation with availability. The population structure of the three species of deer resembles a stable population with the majority of individuals found in younger age classes but older individuals still found in ages above 12 years old (the cementum annuli technique for age determination was used for the first time in a tropical deer population). Mazama americana is a frugivore deer with its diet composed of up to 80% fruits year-round, while M. pandora and o.virginianus are both frugivores and browsers. Fruit availability for deer was strongly linked with fruit phonological patterns of the major planit species composing the deer diet year-round. A critical period with low fruit availability and potential dietary stress for deer was found during the dry season (April-May). The Zapote tree {Manilkara zapota) might be a keystone plant resource in the region. Subsistence hunting of deer is widespread in the GCR region, but deer hunting seems to be sustainable in part due to the dynamic patterns in spatial and temporal location of hunters in the landscape. The spatial and temporal patterns of deer hunting might be responsible for the creation of natural refuges and source/sink areas for deer populations. The conservation and management of tropical deer populations in the GCR and Meso-America are discussed in the light of these findings. [brace not closed]