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Campus Access

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Degree Program

Wildlife & Fisheries Conservation

Degree Type

Master of Science (M.S.)

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island fox, captive breeding, aggression, compatibility, Channel Islands


These chapters were written as three separate papers for publication. After the island fox (Urocyon littoralis) underwent a period of severe population decline, the National Park Service began a captive breeding program to increase their numbers. Here, I identify the factors influencing the breeding success of pairs in captivity to formulate strategies that could increase productivity. I compiled a database of variables including litter size, reproductive success, distance to nearest occupied pen, subspecies, exposure, female age, male age, age difference, female and male origin (wild vs. captive born), years paired, previous reproductive success by the pair, previous reproductive success by the female, mate aggression related injuries reported, and previous involvement in an aggressive pair. I performed linear multiple regression to identify factors related to litter size, and logistic regression to predict the probability of reproductive success. A larger interpen distance, higher male age, less exposure, and a smaller intra-pair age difference positively affected litter size. The probabilities of reproductive success increased with interpen distance, lower female age, fewer years paired, and less exposure. Comparatively, pairs with wild born females (vs. captive born females), previously successful pairs (vs. previously unsuccessful and new pairs), and pairs with a previously unsuccessful female (vs. untried and previously successful females) were most likely to be successful. These results suggest that the ideal situation and pairing would be to pair young wild-caught females with older males in sheltered pens that are as far from other pens as possible, while maintaining successful pairs and repairing unsuccessful pairs.


First Advisor

Todd K Fuller