Aix sponsa - PDF document

1 Woo d Duck ( Aix sponsa)
Woo d Duck ( Aix sponsa) Ron Hoffman © 2011 Kalamazoo Nature Center Cleveland, OH 10/12/2008 © Greg Schneider (Click to view a comparison of Atlas I to II ) M ale Wood Ducks in breeding plumage are the most beautiful waterfowl native to North America. Their name is fitting for a duck with unusual habits of pe r ching and nesting in trees and seldom found far from woodlands associated with water. The species range is primarily in the eastern half of North America extending from southern Canada to the Gulf of Mexico, and along the Pacific Coast. They are common sum mer residents in Michigan arriving in the SLP in late March and usually departing by late October. They spend the winter in the southern states along with a non - migratory population found there. Both MBBA I and MBBA II confirmed nesting in every county in Michigan. Among ducks, only the Mallard is better known by the general public. Distribution Wood Ducks were once common prior to European settlement in Michigan, but they rapidly decreased in numbers during the late 1800s until they were considered a rare breeder by the turn of the 20 th century (Barrows 1912). Unregulated hunting, deforestation, and loss of wetlands caused their decline (Hepp and Bellrose 1995). A slow recovery began with enactment of the Federal Migratory Bird Treaty Act of 1918 and habit at protection. Development of artificial nest boxes in the 1930s further helped Wood Ducks reoccupy their former range (Bellrose and Holm 1994). “Woodies” dependence on nesting cavities near water probably best defines their breeding distribution althou gh other factors such as breeding physiology may be a factor limiting their range in northern areas where suitable habitat exists (Bellrose and Holm 1994). Both MBBA I and II found Wood Ducks more broadly distributed in the SLP than in more northern region s. Their distribution coincides with clay and loam soils being more common in SLP while farther north light sandy loams prevail in the NLP and thin, acidic soils are common in the UP (Bellrose and Holm 1994). Although much of the oak forests in the SLP ha ve been replaced by open land (farms, rural residential) oak woodlots are still common, some of them close to water. Floodplain forests still remain along many rivers and streams in the SLP. Typical deciduous trees in these forest types such as silver mapl e, red maple

2 , black, red, and white oaks provide th
, black, red, and white oaks provide the nest cavities favored by Wood Ducks (Bellrose and Holm 1994). The relatively low productivity of soils further north favors coniferous forests with fewer nest cavities and a smaller wetland food base. Woo d Duck ( Aix sponsa) Ron Hoffman © 2011 Kalamazoo Nature Center Breeding Biology One aspect of Wood Duck breeding biology that seems to have changed since MBBA I is the potential impact of raccoon predation on nesting success. Raccoons have been identified throughout North America as having the single greatest impact o n egg clutches and incubating hen mortality (Bellrose and Holm 1994). DNRE furbearer harvest data indicates a trend of increasing raccoon abundance during the past 20 years (Frawley 2007). It is uncertain whether this trend has a significant impact on Wood Duck production. However, it does support the importance of equipping nest boxes with effective predator guards. Abundance and Population Trends Wood Ducks are one of the most difficult species of waterfowl to survey. Secretive habits combined with thei r use of tree - lined streams and woody swamps make them hard to detect when aerial surveys are conducted for other waterfowl so other methods such as banding data are relied on to estimate Wood Duck abundance. Bellrose and Holm (1994) estimated the 1981 - 85 Michigan breeding population at 139,360. Even the North American Breeding Bird Survey (BBS) provides only long - range indices of the species because so few Wood Ducks are encountered along the survey routes (USFWS 2008). BBS trend analysis suggests (not st atistically significant) a 4.6% per year increase in Michigan during 1966 - 2007 but declined to a 3.3% per year increase during1980 - 2007. Of the surrounding states and provinces, only Ontario had a higher rate of increase. It appears that the status of the Wood Duck in Michigan is stable or slightly increasing. Wood Ducks are more abundant in the SLP than in northern regions of the state. On the average 3.6 ducks per block were found during MBBA II in the SLP compared to 2.1 in the NLP and 2.0 in the UP. T his is considerably less than 21.5 ducks per block in the 1981 - 85 estimate by Bellrose and Holm (1994) for Michigan. As suggested above, north - south population density appears influenced by soil fertility. During MBBA II, the h ighest Wood Duck density was at Shiawassee Na

3 tional Wildlife Refuge (190 ducks per b
tional Wildlife Refuge (190 ducks per block) and at Pointe Mouillee State Game Area (180 ducks per block). Both of these wildlife management areas have extensive forested and emergent wetlands that provide abundant nesting cavities and bro od habitat. Conservation Needs Hunting has played a major role in determining population numbers of Wood Ducks (Hepp and Bellrose 1995). In 2007, hunters shot an estimated 48,200 woodies when the bag limit per day was two (Richkus et al 2008). The bag li mit was increased to three per day in 2008 and 2009 because DNRE believed the population could sustain an increased harvest. Next to the Mallard, Wood Ducks are probably the most adaptable duck in North America (Bellrose and Holm 1994). They readily live near humans and accept nesting boxes. Properly constructed and maintained nest boxes can increase their numbers in local areas, but old growth timber stands near water still produce the bulk of their population. The future of woodies appears bright as lon g as their wetland habitat is protected; especially adequate water for brood rearing. Woo d Duck ( Aix sponsa) Ron Hoffman © 2011 Kalamazoo Nature Center Literature Cited Barrows, W.B. 1912. Michigan Bird Life . Special Bulletin. Michigan Agricultural College. Lansing, MI. Bellrose, FC, and DJ Holm. 1994. Ecology an d management of the Wood Duck . Stackpole Books. Mechanicsburg, PA. Frawley, BJ. 2007. 2006 Michigan Furbearer Harvest Survey. MDNR Wildlife Division Report No. 3480. Hepp, GR and FC Bellrose. 1995. Wood Duck ( Aix sponsa ). In The birds of North America, No. 169 (A Poole and F Gill eds.). The Academy of Natural Sciences, Philadelphia and AOU, Washington, D.C. Richkus, KD, KA Wilkins, RV Raftovich, SS Williams and HL Spriggs. 2008 Migratory bird hunting activity and harvest during the 2006 and 2007 hunting sea sons: Preliminary estimates . U.S. Fish and Wildlife Service. Laurel, MD. U.S. Fish and Wildlife Service (USFWS). 2008. Waterfowl population status 2008 . U.S. Dept. of the Interior. Washington, D.C., USA Suggested Citation Hoffman, R. 2011 . Wood Duck (Aix sponsa) . In Chartier, A.T., J.J. Baldy , and J. M. Brenneman (eds.). 2010 - 2011 . The Second Michigan Breeding Bird Atlas. Kalamazoo Nature Center. Kalamazoo, MI. Accessed online at: www.mibirdatlas.org/Portals/ 12/MBA2010/ WODU acc�ount.pdf .