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Modified Preferred Alternative

The modified preferred alternative employs an adaptive management approach that allows the agencies to gain experience and knowledge before proceeding to the next management step, particularly with regard to managing bison on winter range outside YellowstoneNational Park (see Modified Preferred Alternative map). The alternative uses many tools to address the risk of transmission, but primarily relies on strict enforcement of spatial and temporal separation of potentially infectious bison or their birth products and susceptible cattle. Until an existing cattle lease on acquired lands north of the park’s Reese Creek boundary expires, step 1 would follow the interim plan with the exception that seronegative pregnant bison would be released onto the western boundary area along with other seronegative bison (up to a designated 100-bison tolerance level). When the lease expires, it is assumed step 2 of the plan would begin, and seronegative bison would be released into the boundary area north of Reese Creek as well, up to a designated 100-bison tolerance level. After a minimum of two years of experience managing bison outside the park in both the northern (or Reese Creek) and western boundary areas, step 3 would begin, which allows untested bison (up to the 100-bison tolerance level) to occupy them. Parkwide vaccination of vaccine-eligible bison would begin when a safe and effective vaccine and remote delivery system become available.

Spatial and temporal separation would be maintained by monitoring both boundary areas 7 days a week. As bison move further from the park, management would become increasingly aggressive. All bison outside the park in these areas would be hazed back into the park in the spring, approximately 45 days before cattle return to these same lands. Research performed since the completion of the Draft Environmental Impact Statement (K. Coffin, pers. comm.; Cook 1999) indicates that as few as 4.7 days would be required to ensure the die-off of any remaining bacteria in weather typical of a Wyoming June. As an additional risk management measure, the agencies would maintain a population target for the whole herd of 3,000 bison. This is the number above which the NAS (1998) report indicates bison are most likely to respond to heavy snow or ice by attempting to migrate to the lower elevation lands outside the park in the western and northern boundary areas. Seronegative bison attempting to leave the park and not amenable to hazing when either the population exceeds 3,000 or tolerance levels outside the park have been met or exceeded, would be removed to quarantine. If the quarantine facility is full or otherwise unavailable, they would be sent to slaughter. If population numbers are low, bison, up to the capacity of the StephensCreek capture facility, would be held until weather moderates or until spring green-up begins and then released back into the park. Additional risk mitigation measures under the modified preferred alternative include the following:

Vaccination of cattle in the impact area would be required if 100% voluntary vaccination is not achieved.

APHIS and Montana would conduct additional monitoring of cattle herds grazed in the impact area, including regular testing of test-eligible cattle and possible adult vaccination of these cattle herds.

Seronegative pregnant females allowed into the boundary areas would be fitted with radio collars and vaginal transmitters (in step 1 in the West Yellowstone area and in step 2 in the Reese Creek area) so that agencies can monitor the birth site for bacteria if bison give birth or abort while outside the park.

To minimize lethal control, agencies would maximize the use of hazing to keep bison off private land, to keep them from exiting the park, and to return them to the park in exiting would mean their removal to slaughter or quarantine.