干旱区生态环境知识资源中心

Rabbit abundance patterns in the North American Southwest are poorly known, particularly relative to the potentially important influences of rainfall and plant production. We conducted a 10-year study on the comparative densities of black-tailed jackrabbits (Lepus californicus) and desert cottontail rabbits (Sylvilagus audubonii) in relation to annual rainfall and plant production in both black grama (Bouteloua eriopoda) grassland and creosotebush (Larree tridentata) shrubland habitats in the northern Chihuahuan Desert. We found that both species of rabbits were more abundant in black grama grassland than in creosotebush shrubland and that plant production was positively correlated with rainfall at both habitats. however, rabbit densities were not positively correlated with rainfall or plant production in either habitat. In fact, both species of rabbits exhibited gradual, multiyear changes in abundance rather than the patterns of high annual variation observed in desert rodent communities. Our findings of no significant relationship between plant production and rabbit densities indicate that rabbit abundance in the northern Chihuahuan Desert may not be strongly regulated by short-term, bottom-up effects of annual variation in plant production. Long-term trends indicate that other factors such as disease or predation may be equally or more important. We suggest that future research evaluate both top-down and bottom-up influences to elucidate the temporal dynamics of Chihuahuan Desert rabbit abundance.