Influence of wetland age on bird use of restored wetlands in Iowa

Abstract

A goal of wetland restoration is to provide habitat for breeding populations of waterfowl and other bird species. To meet this goal, it is important to determine how birds respond to restored wetlands and which factors influence their use of restored wetlands. We examined the relationship between bird species richness and years since restoration at restored prairie wetlands in Iowa. We detected 42 bird species in restored wetlands, 15 of which were breeding species. The mean number of breeding bird species was significantly greater in older restored wetlands (4.3 species in 1-year-old wetlands, 7.2 species in 4-year-old wetlands, P = 0.005). The mean number of all bird species, waterfowl species, and breeding waterfowl species did not change with wetland age. Total and breeding bird species richness increased with percent cover of emergent vegetation. Waterfowl species richness and breeding waterfowl species richness were influenced more by wetland area than vegetation characteristics, whereas total species richness and breeding bird species richness were influenced more by vegetation characteristics. If the goal of restoration is simply to provide a breeding site for waterfowl, our data suggest that this can be done in a few years. However, we favor longterm restorations. Such restorations are more likely to have a more diverse bird community that more closely resembles those found in natural wetlands.