Seasonal reproduction in Mexican cottontail rabbits Sylvilagus cunicularius in La Malinche National Park, central Mexico

Mexico has the largest number of leporid species in the world but most have been little studied. The endemic Mexican cottontail Sylvilagus cunicularius (Waterhouse, 1848) is the largest Mexican rabbit, and although not in danger of extinction, it is increasingly threatened. Since little is known about its annual pattern of reproduction, we studied this species in La Malinche National Park, central Mexico, where S. cunicularius is still common. For 7 years we trapped and marked 157 different individuals (plus 59, sometimes multiple, re-captures), determining across the year the percent of adult females that were reproductively active, the number of juveniles as a percent of total captures, and the percent of males with scrotal testes. Reproductively active females were present throughout the year but with a notable peak from March to October, juveniles were present throughout the year but with a peak from September to December, and adult males had scrotal testes throughout the year with no seasonal change in testis length. Onset of the breeding season coincided with increasing day length and temperature, and births with high rainfall. Thus, in central Mexico S. cunicularius breeds throughout the year but particularly during the warmer, wetter summer months. We therefore recommend that hunting only be permitted from November to February.