Abstract

MANDUJANO, S.; GALLINA, S.; ARCEO, G.  and  PEREZ-JIMENEZ, L. A.. Variación estacional del uso y preferencia de los tipos vegetacionales por el venado cola blanca en un bosque tropical de Jalisco. Acta Zool. Mex [online]. 2004, vol.20, n.2, pp.45-67. ISSN 2448-8445.

The white-tailed deer (Odocoileus virginianus) inhabits the tropical forest of Chamela in the Pacific coast of the state of Jalisco, Mexico. In this region the dominant vegetation is the tropical dry forest which settles down in the hills and it is characterized because in the arboreal stratum and understory dominate species that lose its leaves during six to seven months in the dry season. In contrast, the vegetation that is along the streams and rivers is the tropical semi-evergreen forest in which dominate species with leaves non deciduous. Therefore, in this region a remarkable contrast exists in the food availability, sources of water, covering against the climate and predators. The objective of the present study was to analyze the seasonal variation of the use and the preference that the white-tailed deer has for the two main communities in Chamela. The results are discussed in function of two hypothesis which predict bigger preference of the tropical dry forest during the rainy season, and bigger preference of the tropical semi-evergreen forest during the dry season. The study was carried out from 1989 to 1993, using the methods of direct count of active deer along the year and the count of fecal groups during the dry season. The understory of both plant communities were described for each season of the year quantifying the total number of arboreal species, shrubs and herbaceous, and it was expressed as density of the number of species for square meter; also was estimated the production of biomass to foliage potentially of the parts consumable for the deer like leaves and tender branches, and it was expressed as gram of dry weight by square meter; finally was estimated the relative availability of food in the dry season. As a result it was found that in the rainy season the density of species and the biomass of foliage was bigger in comparison to the dry season (T test of ranges of Mann-Whitney, P <0.01). In particular, in the rainy season the density of species was higher in the tropical dry forest, while in the dry season both the density of species and the biomass was higher in the tropical semi-evergreen (T, P <0.01). They were also significant differences in the density of species and biomass among years (H test of Kruskal-Wallis, P <0.01). Therefore, there was significant positive correlation among the quantity of rain with the density of species and biomass to foliage of the species in both types of forests (r², P <0.001). During the dry season the relative availability of food was higher in the tropical dry forest than in the tropical semi-evergreen forest (X², P <0.01). Regarding the use of the habitat, higher number of deer was observed during the period of fawning (July to October), smaller during the period of mating (November to February), and an increase during the period of gestation (March to June) (X², P <0.01). The deer used both types of vegetable communities the whole year, but preferred the tropical dry forest during the rainy season (X², P <0.01) as area of forage, rest and fawning, because it offers a higher availability of food of high quality nutritional, and bigger protection against predators. During the dry season the deer not prefer the tropical semi-evergreen forest (X², P> 0.05) nevertheless that this type vegetacional offers higher density of species and biomass in the understory in comparison to the tropical dry forest. This could be due to that the tropical semi-evergreen forest has smaller availability of the plants that consumes the deer to that the plants probably have a high contained of fiber, and to that has bigger predators presence and hunters. On the contrary, nevertheless the drop density of species and biomass of the plants in the tropical dry forest, the deer used it preferably in the dry time (X², P <0.01 ) because it has bigger quantity of food, the trees of the plum tree (Spondias purpurea) establish mainly in this type of vegetation and its fruits represent a important resource that provides with water to the deer during this period, the covering of the understory and the topography diminish the predation risks, and the hillsides with north exhibition have better thermal covering being more humid.

Keywords : tropical dry forest; tropical semi-evergreen forest; understory; wet and dry seasons; use-preference; temporal-spatial variation; white-tailed deer; Odocoileus virginianus, Chamela; Mexico.