Purple Martins breed throughout North America; however, they are much less common in the west than in the east (Brown 1997). In some of the western states and provinces martins are listed as a species of concern, and conservation programs have been implemented to increase populations. While several subpopulations of the Purple Martin have been recognized, the degree of their divergence is not well understood. Delineation of the taxonomic relationships between the west coast, Rocky Mountain, and eastern populations is needed to develop Purple Martin conservation and management strategies appropriate to benefit all populations of the species.

Purple Martins are listed by the U.S. Forest Service (USFS) as a Sensitive Species in Region 2 and by the Colorado Division of Wildlife as a Species of Greatest Conservation Need in the Wildlife Action Plan. As recently as the 1970’s, very little was known about the species in Colorado (Righter et al. 2004). Even after the Colorado Breeding Bird Atlas was completed (1987-1994), only 24 breeding locations were confirmed in western Colorado (Kingery 1998). Since initiation of Rocky Mountain Bird Observatory’s (RMBO) Monitoring Colorado’s Birds program, the distribution of Purple Martin has been more completely documented. Now, largely due to RMBO’s efforts, 136 colonies are known throughout the western side of the state. In Colorado, Purple Martins nest in old-growth aspen stands near open meadows that also have water nearby (Righter et al. 2004). Unlike most populations of Purple Martin that use nest boxes, Colorado martins use natural cavities that have been excavated by woodpeckers. The Colorado population probably represents the largest population of naturally-nesting martins in the U.S and Canada (Rich Levad, RMBO, pers. comm.). Although not listed as a Sensitive Species by the USFS Region 4, Purple Martins are a rare breeder in the northern and central part of Utah. Purple Martins in Utah also use natural cavities in aspen and coniferous forests.

The Western Purple Martin Working Group has initiated a study to compare DNA samples from eastern Purple Martins (e.g., Alberta, Manitoba, Ontario, and Pennsylvania) to those of western Purple Martins ( British Colombia, California, Oregon, and Washington). DNA analysis indicates almost complete reproductive isolation (for 200,000-400,000 years) between these martin populations (Baker et al. 2007). Further analysis of midcontinental populations is required to determine where geographically the populations diverge.

Thus, the next step is to determine how the mitochondrial DNA (mtDNA) of the disjunct population of Purple Martins of Colorado and Utah compares with the other populations. To this end, RMBO collected 23 DNA samples from Colorado martins in July of 2006 and 20 DNA samples from Utah martins in July of 2008. The samples were recently shipped to Toronto to be processed and analyzed by Dr. Baker and his lab staff.

For more information contact:
Jason Beason
Special Monitoring Projects Coordinator
jason.beason@rmbo.org or (970) 527-4625