Conclusions

1) Immunocontraception, using a pZP (porcine zona pellucida) vaccine administered to females, has the best potential to control reproduction in individual female bears, while minimally affecting normal social dynamics. Neutersol® is very likely to be effective in sterilizing male bears, although treated males will be relegated to subordinate social status because of the effects of the treatment on hormone levels. (Males could, however, be vasectomized without affecting social structure and dynamics.)

2) Because one male can inseminate many females and because males tend to disperse more widely than do females, fertility control applied to females, is the most effective strategy for managing population size of wildlife species, including black bears.

3) Of the options presently being considered for bear fertility control, only Neutersol® and vasectomy have regulatory approval. Although pZP vaccines, which contracept females with minimal effects on treated animals, are best suited for wildlife population control, none has regulatory approval. Whether the FDA would permit field trials of pZP vaccines on black bears is unknown.

4) If all or most dominant male bears in a population are effectively removed from their social positions by sterilization with Neutersol®, it is likely that the consequential social disruption would allow an influx of young males, which would do much of the breeding.

5) Managing black bear populations using fertility control will be much more technically difficult and costly than in other wildlife species, such as deer and wild horses, where this approach has been successfully applied. This is a consequence of the difficulty of capture, lower density, and the variable and wide-ranging nature of bear movements.

6) Fertility control is very unlikely to be a feasible means of managing black bear populations in New Jersey.

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