Change in Density of Duck Nest Cavities at Forests in the North Central United States

• Published in: Journal of fish and wildlife management 2012-06, Vol.3 (1), p.76-88
• Main Authors: Denton, John C., Roy, Charlotte L., Soulliere, Gregory J., Potter, Bradly A.
• Format: Article
• Language: English
• ISSN: 1944-687X; 1944-687X
• DOI: 10.3996/112011-JFWM-067

During the past century, clear-cut hardwood forests of the north central United States have regenerated, and trees have matured into size classes increasingly capable of producing cavities suitable for nesting ducks. We determined the density of natural cavities suitable for cavity-nesting ducks, compared suitable cavity-tree distribution by size class and species, and assessed how forest maturation impacted suitable cavity density and distribution over time at four sites in the north central United States. During 2006–2008, cavities suitable for nesting ducks occurred at densities of 1.76, 1.40, 1.84, and 0.92/ha at Mingo National Wildlife Refuge (NWR) in Missouri, Shiawassee NWR in Michigan, Muscatatuck NWR in Indiana, and a study site including Mead State Wildlife Area in Wisconsin, respectively. Suitable nest-cavity densities increased at Mingo NWR (+300%) since 1965 and Shiawassee NWR (+900%) since 1973, but they remained similar at study sites examined during the mid-1980s (Muscatatuck NWR and Mead Wildlife Area) when previous site-specific cavity-suitability criteria were applied to our cavity data. Differences among sites were due to variation in tree species composition, stage of forest maturation, and potentially forest harvest regimes. Comparison of size distributions of all trees and those with suitable nest cavities indicated these forests have yet to mature into the most prolific cavity-producing size classes. Our findings suggest nest sites are not limiting duck populations at these four sites and hardwood forests with similar composition and structure. Rather than using the traditional practice of supplementing duck nest sites, wildlife managers in the North Central region should assess actual limiting factors before developing habitat management prescriptions for local cavity-nesting duck populations.