Factors influencing the timing and frequency of litters in captive fennec foxes (Vulpes zerda).

Maintaining reproductive seasonality can be vital to the fitness of wild animals. Certain species, however, may display aseasonal reproduction and may produce multiple yearly litters when maintained in captivity. Wild fennec foxes (Vulpes zerda), for example, produce a single litter in March or April although their reproductive behaviors are reportedly variable in captivity. Here, we used the fennec fox studbook to extract traits related to reproductive variability in 220 captive-born litters. The captive litters in our dataset were born during every month of the year and nearly half (47%) were born outside of the expected months. The production of multiple litters in a single year was common, where 67% of the litters represented a second annual litter for a given dam. We detected several traits related to multi-litter years, including the dam's ability to habituate to the birth location, the dam's age, the dam's number of previous litters, and the dam's birth month. Although producing multiple litters within a year has been anecdotally associated with the loss of a previous litter, we did not detect a relationship between multi-litter years and the survivorship of previous litters. These findings suggest that captive populations of fennec foxes may experience a destabilization of their reproductive patterns, which may culminate in the production of multiple litters outside of the typical window of reproduction. Fennec foxes are a common captive species bred in zoos worldwide. Developing a greater understanding of their reproduction can allow for more successful captive management, which may improve future reproductive successes.