Effects of aggression on breeding, affiliation, and reproductive success of lsland Foxes (Urocyon littoralis) on Santa Rosa Island, CA
Karslake, Elizabeth B.
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The island fox (Urocyon littoralis) is found on the Channel Islands off the coast of Los Angeles, Califomia, and six islands each support a different subspecies. Recently, three subspecies underwent dramatic population declines due to golden eagle predation. The National Park Service began a very successful captive breeding program, and now all captive foxes have been released back into the wild. For several years, video cameras were placed in fox pens on Santa Cruz, Santa Rosa, and San Miguel Islands to monitor fox pairs during the breeding season. From these videos, I assessed the relationship between aggressive, affiliative, and sexual behaviors of fox pairs on Santa Rosa. While research has been done on factors effecting reproductive success of the island fox, none have looked specifically at effects of these behaviors. In my project, I observed no correlations between aggressive, affiliative, or sexual behaviors. The only correlations were between sexual behaviors and between aggressive behaviors. Interestingly male aggression levels in some pens increased slightly, but not statistically significant, around the copulatory tie date. As island foxes and their mainland counterparts, gray foxes, are closely related to the ancestral canid form, it may be that island foxes are induced ovulators like most other camivores. Also, I compiled the age of each fox, previous reproductive history, size of litter, and fate of pups into a table to analyze how intra-pair aggression levels for a pair affected their reproductive successes. Intra-pair aggression did not affect reproductive success, but none of the pens experienced extreme levels of aggression. It is possible that reproductive success of foxes is instead affected by other factors such as the age of the male or female or social compatibility between the pair. Although all the captive foxes on Santa Rosa were released back into the wild in 2008, these findings are still relevant. Each of the Channel Islands is very susceptible to change, and it is possible that foxes will need to be brought back into a captive breeding program. Therefore, relevant findings can be potentially beneficial to future island fox captive breeding programs.