Unique reproductive traits of the Amami rabbit Pentalagus furnessi: an endangered endemic species from southwestern Japan

Abstract

The Amami rabbit Pentalagus furnessi is an endangered leporid species and is endemic to the two subtropical islands (Amami-Oshima Island and Tokunoshima Island) in the Ryukyu Archipelago in southwestern Japan. In total, 11 breeding burrows of this rabbit were detected from 1994 to 2017 in Amami-Oshima Island. Breeding was observed from November to December in most cases and in May in one case. The litter size was one in most cases, except for one burrow which had two offspring. Two burrows were observed during the entire delivery and nursing period for two different years, and the duration of breeding (from estimated date of delivery to the date when the offspring leaves the burrow) in these two burrows was 38 and 43 days. The mother visited the burrow periodically on alternate nights, and the duration of maternal visit was relatively short. The time at which the mother visited the burrow became progressively earlier in the night as the offspring became older. Although some aspects of breeding behaviour are similar to those of other lagomorphs, the Amami rabbit has an extremely small litter size with few breeding seasons in a year, resulting in the lowest fecundity rate among the lagomorph species. This unique reproductive trait is considered to have evolved in the small subtropical island environment that has a relatively stable climate with no native carnivorous mammals.