Restoration of Trumpeter Swans on the Flathead Indian Reservation and Adjacent Aboriginal Lands in Northwestern Montana

Abstract

In an effort to restore extirpated native wildlife to the Flathead Indian Reservation (FIR) and aboriginal lands in western Montana, the Confederated Salish and Kootenai Tribes (CSKT) commenced reintroduction and restoration efforts for Trumpeter Swans in 1996 with a trial reintroduction.  Since then, 264 captive-propagated Trumpeter Swans were released on the FIR from 2002 through 2016.  By 2004, breeding pairs had formed and the first production of wild cygnets in possibly 100 years or more fledged from local wetlands.  During the intervening years, at least 119 nesting pairs have produced at least 343 fledgling cygnets.  Swans from this project have colonized into several wetland habitats throughout northwestern Montana and may soon do the same in southeastern British Columbia.  The primary cause of mortality of released swans has been powerline collisions, and lines are regularly marked with flight diverter installations to minimize potential future collisions.  Since annual surveys seemed to indicate a healthy, growing population of Trumpeter Swans in northwestern Montana, the CSKT contracted for a population viability analysis with the University of Idaho to assess overall success of the project and the prognosis for the population to continue to thrive.  The results of that analysis indicated that, although the population was predicted to have a low likelihood of persistence, the short time span of data in which adults successfully fledged a brood was increasing (since 2012) was likely a factor in that result.   Projecting this analysis into the future, thereby extending the time span of data, indicated that the likelihood of the population persisting was high (approximately 95-96%) over both the short-term (30 years) and the long-term (100 years).  As additional population surveys are conducted over the years, the long-term data will better estimate the likelihood of reaching the objectives of longterm sustainability in the future.