Purple Martin (Progne subis) Anna Kornoelje
© Tom Hodgson This species sponsored by John & Lynda Camburn. (Click to view a comparison of Atlas I to II)
Glossy dark purple gems, nesting Purple concentrated in the three southernmost tiers of counties, and populations become patchy north Martins have long been encouraged by humans. of a line stretching from Allegan to Macomb Early accounts describe Native Americans County and very sparse in the UP. Martins are providing dried gourds for nesting (Allen and particularly vulnerable to cold temperatures, and Nice 1952). Throughout the eastern United the contraction of populations from the northern States, the colonial Purple Martin nests almost regions of Michigan may reflect a response to entirely in nest boxes while in the west, where it climate changes (Brown 1997). Although martin is less common, it still nests in woodpecker populations remain strongest in the southern LP, holes or other natural cavities (Brown 1997). distribution still decreased from 319 confirmed The Purple Martin is North America’s largest townships in MBBA I to 162 confirmed swallow. This Neotropical migrant winters in townships in MBBA II. In the northern LP, South America in the Amazon Basin, Brazil, distribution declined from 143 confirmed Bolivia, and Argentina (Brown 1997). townships in MBBA I to 39 confirmed
townships in MBBA II. The UP showed the Purple Martins are found throughout North most dramatic decrease in Purple Martin America and breed from Canada to Mexico distribution, from 86 confirmed townships in although they are absent in most mountain MBBA I to only five confirmed townships, all regions in the West (Brown 1997) and at higher in the southernmost regions of the UP, in altitudes in the Appalachian Mountains (Andrle MBBA II. and Carroll 1988). Historically martins inhabited forest edges and riparian areas in the Breeding Biology East, but they are now mostly found near human Purple Martins are secondary cavity nesters, habitation (Brown 1997). historically nesting in abandoned woodpecker
holes or other natural cavities (Brown 1997). Distribution However, nest boxes provided by humans have In Michigan, breeding populations are constituted the bulk of nest sites for many years. concentrated in the southern LP and decrease Martins nest colonially in constructed martin northwards. Purple Martin distribution has houses that may be quite large. In general, older declined sharply since MBBA I. Data from males return from wintering grounds before MBBA II shows that martins are now
© 2011 Kalamazoo Nature Center Purple Martin (Progne subis) Anna Kornoelje younger males and select nest sites that are their decline has been observed and a large higher, and suffer less predation from climbing amount of popular literature has been created to predators (Morton and Derrickson 1990). A promote the increase of nesting colonies (Brown typical martin house consists of 12 1997). The most commonly prescribed compartments and for this reason the majority conservation action calls for installation of nest of colonies throughout the eastern United States boxes in order to increase the number of nest is less than or equal to 12 pairs (Brown 1997). sites available for martins. Also it is This suggests that Purple Martin populations are recommended that nest boxes be checked for limited by nest sites. House Sparrows and European Starlings and that these species are removed in order to make Abundance and Population Trends space for the martins. (Click to view trends from the BBS) While the overall Purple Martin population Cold, wet weather kills more Purple Martins appears to have been stable and even increasing than all other sources of mortality combined in some parts of the continent, Michigan, and (Brown 1997). Die-offs occur regularly in North Wisconsin have shown declines (Damro 2006, America during periods of cold weather in Tautin 2007). In Michigan, BBS trends indicate which the birds cannot find their insect prey that Purple Martin populations have declined (Brown 1997). Nest predation by owls or snakes since 2001, although this decline is not can also be a significant local threat. statistically significant (Sauer et al. 2008). BBS trends show that in the Midwest the number of martins per route has declined from between approximately three birds to approximately two birds per route. Further, Breeding Bird Surveys conducted in Illinois, Indiana, Ohio, Ontario and Wisconsin also report declines in Purple Martin distributions (Peterjohn and Rice 1991, Castrale et al. 1998, Kleen et al. 2004, Damro 2006, Cadman et al. 2007). Currently, Purple Martin populations are estimated at 30,000 individuals in Michigan (PIF 2007). The total number of block observations declined from 20.5% in MBBA I to 7.8% in MBBA II. A similar trend occurred in total township observations. Possible, probable and confirmed observations of martins amounted to 45.9% of all surveyed townships during MBBA I compared with 19.3% of all surveyed townships during MBBA II.
Conservation Needs Despite the overall stability of the eastern continental population of Purple Martins, declines in the regional populations in the Upper Great Lakes are cause for concern (Tautin et al. 2008). Although Purple Martins are not currently listed as threatened or endangered,
© 2011 Kalamazoo Nature Center Purple Martin (Progne subis) Anna Kornoelje
Literature Cited Mountain Bird Observatory.
© 2011 Kalamazoo Nature Center