Ocelot (Leopardus Pardalis) Food Habits in a Tropical Deciduous Forest of Jalisco, Mexico

Article excerpt

ABSTRACT.-Few studies have been conducted on the food habits of the ocelot (Leopardus pardalis), considered an endangered feline in Mexico. Past studies showed that rodents were the main component of ocelot diet. In our study ocelot prey consumption was measured as frequency of occurrence of prey in scats and then converted to biomass. The spiny-tailed iguana (Ctenosaura pectinata) was the most important prey of ocelots, followed by the spiny pocket mouse (Liomys pious). Other rodents and some birds were also present in the scats, although representing only a minor proportion of the ocelot's diet. Evidence of subadult white-tailed deer (Odocoileus virginianus) was also found in scats indicating that ocelots can either capture prey bigger than themselves or are using deer as carrion.

INTRODUCTION

Members of the family Felidae are strict carnivores and as such they confront several difficulties when they feed. First, meat is a relatively limited food resource in nature, and second, feuds generally feed on live prey, which makes acquisition of meat a highly energy-- demanding activity (Gittleman and Harvey, 1982). Hence, the anatomical structure of a felid is related to the way its prey are detected and captured, resulting in a striking similarity in body shape among the 36 species of cats in the world regardless of the habitat in which they live (Kitchener, 1991). Furthermore, all Felidae have a common predator-prey size pattern (Rosenzweig, 1966). In this sense, the ocelot (Leopardus pardalis) is a medium size feline (~10 kg) that should consume small to medium size prey (Brown, 1990; Kitchener, 1991). Studies of ocelot food habits are scarce and cover disjunct areas of its distribution. Ocelot

diets are principally comprised of small mammals, but also include medium to large mammals, reptiles, amphibians, birds, fishes and insects (Bisbal, 1986; Emmons, 1987; Konecny, 1989; Sunquist et aL, 1989; Chinchilla, 1994; Crawshaw, 1995). Based on these results some authors have suggested that ocelots are opportunistic feeders (Bisbal, 1986; Emmons, 1987). Anecdotal data for Mexico, principally in the states of Sinaloa, Nayarit and Jalisco (mangrove, coastal dunes and tropical deciduous forest, respectively) indicated that ocelot's diet includes rabbits, small mammals, birds, iguanas, frogs, fishes, crabs and small turtles (Allen, 1906). This study presents data on ocelot food habits in a tropical deciduous forest of western Mexico.

METHODS

The study was carried out in the Chamela-Cuixmala Biosphere Reserve (CCBR), which is located on the Pacific coast in the state of Jalisco and covers ca.13,600 ha. Elevation ranges from 0 to 500 m above sea level. Temperature fluctuates from 16 C to 32 C throughout the year and the average annual precipitation is 748 mm. Rainfall is seasonal, with a long dry period from October to June and a short wet period from July to October (Bullock, 1986). Seven types of vegetation are found in the Reserve (Rzedowski, 1983; Ceballos and Miranda, 1986; Lott, 1993), but tropical deciduous forest and tropical semideciduous forest are most common. Sample collection was mainly carried out at the Estacion de Biologia Chamela (EBCh). This field station, which is operated by the Universidad National Autonoma de Mexico (UNAM), has a road and trail system through both tropical deciduous forest and tropical semideciduous forest.

From March 1995 to December 1996 we spent approximately 15 d each month looking for scats along trails and creeks of the station, occasionally walking areas outside the reserve. We identified ocelot scats based on shape, color, odor and associated tracks (Aranda, 1981). Scats not associated with tracks were discarded. Ocelot tracks were distinguished from jaguar (Panthera onca), puma (Puma concolor), and jaguarundi (Herpailurus jaguarondi) by size and shape. Ocelot tracks (approximately 50 mm long x 55 mm wide) in the study area are 30% smaller than tracks of jaguars and pumas in this region (B. …