Marsh Wren (Cistothorus Palustris) Thomas Getty Status: Special Concern (MNFI)
Marsh Wren (Cistothorus palustris) Thomas Getty Status: Special Concern (MNFI)
Washtenaw Co., MI 6/14/2009 © Andy Johnson (Click to view a comparison of Atlas I to II)
The visually shy but vocally sassy little Marsh southern LP and infrequently scattered across marshes in the northern LP and UP. During Wren stakes his territorial claim in large, open MBBA I, evidence of breeding was detected in marshes using a highly variable, guttural song 8% of the townships in the UP, 9% of the that ends in a mechanical chatter reminiscent of townships in the northern LP, and 26% of the a sewing machine. Marsh Wrens breed across townships in the southern LP. The pattern in the northern U.S. and southern Canada, and MBBA II was 5%, 7% and 24%, respectively. along the Atlantic, Gulf and Pacific coasts. These slight declines are not statistically They are year-round residents in the Pacific and significant, but the long-term trends in BBS southern states; birds breeding in the north and data, described below, suggest that they are east migrate to the southern and western coasts, biologically significant. Mexico, and as far as Central America for the winter months. Marsh Wrens continue to breed Breeding Biology each spring and summer in wetlands across Monfils (2006) provides an excellent overview Michigan, but populations in Michigan have of the breeding biology of this species. Marsh been gradually declining for decades, a trend Wrens typically arrive in the LP in late April, that probably began when European settlers reaching the UP in mid-May. Males build began draining Michigan’s wetlands. multiple domed nest “shells” of coarse
vegetation in the cattails or reeds, typically over Distribution standing water; females select one to line with Marsh Wrens continue to breed across their fine vegetation and feathers. The species is historical range in North America and double brooded, with a typical clutch size of Michigan. BBS data indicates that populations four to six eggs. The social breeding system is are holding steady or increasing in the Pacific at least partially polygynous, with two or three Northwest and northwestern Great Plains, but females settling on some male territories. Some are declining significantly in the east, a trend females engage in polyandrous behavior (i.e., associated with increasing gaps within the copulating with more than one male), resulting eastern range, including Michigan. Publications in extra-pair fertilizations. Both males and from the late 1800s through the mid 1900s females engage in the typically wren-like described Marsh Wrens as abundant in the behavior of puncturing and tossing eggs, and
© 2011 Kalamazoo Nature Center Marsh Wren (Cistothorus palustris) Thomas Getty Status: Special Concern (MNFI) even nestlings, from the nests of neighboring Conservation Needs conspecifics and heterospecifics. This elicits The gentle but relentless declines in BBS counts vigorous aggression from neighboring of Marsh Wrens in Michigan, USFWS Region blackbirds (Bump 1986), and disapprobation 3, and the Mississippi flyway do not suggest any from some birdwatchers. Whether and how obvious dramatic causes. they might benefit from this behavior remains a It seems most likely that the decline in the matter of speculation and debate among eastern U.S. is caused by breeding habitat loss scholars. and degradation. Nationally, marshland (freshwater emergent) habitat area has been Abundance and Population Trends relatively stable over the last decade (Dahl (Click to view trends from the BBS) 2006). The main source of habitat loss in the The Partners in Flight Population Estimates Great Lakes has been due to urbanization and Database uses BBS data to estimate that there rural development. Suitable breeding habitat are approximately 11,000 breeding adult Marsh includes emergent vegetation, and the Wrens in Michigan, about 0.1% of the estimated conversion of sedge and cattail marshes to open global population (PIF 2008). In comparison, water reduces Marsh Wren density (Linz et al. the similar Sedge Wren is four times more 1996). An additional concern is the extent to abundant, and the familiar House Wren is 30 which invasive plants are degrading the times more abundant. breeding habitat quality of the remaining marshlands. One study found that in mosaics of The slight declines in township presence in cattails and invasive purple loosestrife, Marsh Michigan described above, are not statistically Wrens nested only in the cattails (Maddox and significant. However, BBS data show a Wiedenmann 2005). The MNFI web site remarkably steady, gradual decline in USFWS provides an excellent overview of the status of Conservation Region 3, which accumulates to a Marsh Wrens in Michigan (MNFI 2007). The very significant 8.8% annual decline from 1983 USGS Northern Prairie Wildlife Research through 2007 (Sauer et al. 2008). The Center web site provides an excellent overview cumulative 9.8% decline in BBS counts in of what we know about the relationship between Michigan parallels the trend in Region 3 and it habitat management practices and Marsh Wren is probable that the trend is not statistically breeding densities and success (Zimmerman et significant in Michigan only because of the al. 2002). small sample size (10 routes in MI vs. 81 in Region 3). Following MBBA I, the Michigan Natural Features Inventory (MNFI) listed Marsh Wrens as a species of Special Concern in Michigan. The number of confirmed sightings recorded statewide dropped by one-third (from 36 to 24) from MBBA I to MBBA II. Nationally, the BBS estimates a significant 3.75% increase in the breeding population over this 24 year period, with the biggest gains in the northern plains and eastern Rockies (FWS Region 6), where historically Marsh Wrens have not been abundant.
© 2011 Kalamazoo Nature Center Marsh Wren (Cistothorus palustris) Thomas Getty Status: Special Concern (MNFI) Literature Cited
© 2011 Kalamazoo Nature Center