Description of the nursery burrow of the Mexican cottontail rabbit Sylvilagus cunicularius under seminatural conditions

Abstract

The rabbit Sylvilagus cunicularius is endemic to Mexico and is one of the largest, most widespread, but little studied of the country’s 10 rabbit species. As part of a project investigating its reproductive biology, we describe here for the first time the nursery burrow, vital for the survival of the altricial young. During the breeding seasons of 2008–2012, we collected data from 25 nursery burrows and 22 nests constructed by eight females (three wild caught and five captive bred) kept in enclosures within their natural habitat in the Malinche National Park in the central Mexican state of Tlaxcala. Although not a burrow-living species, several days before parturition, females dug a nursery burrow in which they constructed a nest. These burrows were short, shallow tunnels with a median length of 23 cm, typically located beneath grass tussocks or shrubs, and ending in a nest chamber a median 17 cm beneath the surface. Nests consisted of dry grass, fragments of woody plants, pine needles, and alfalfa hay and oat straw provided as supplementary food, fur pulled from the mother’s body, and her fecal pellets. Females nursed their young at the burrow entrance, and until the young were approximately 12 days old, they closed the entrance after each visit in such a way as to make it very difficult for humans to locate. Surprisingly, these nursery burrows were more similar to those of the European rabbit Oryctolagus cuniculus and the pygmy rabbit Brachylagus idahoensis than to other Sylvilagus species studied to date. As almost 50 % of burrows did not result in emergent young, present work is directed to determining what characterizes successful burrows.