What Determines Success? Breeding Habitat Characteristics of the Louisiana Waterthrush (Seiurus motacilla)

Abstract

Riparian habitats perform many important ecological functions, but are frequently affected by anthropogenic development. Recently, using bioindicator species, such as the Louisiana Waterthrush, to evaluate riparian health has become increasingly important. Louisiana Waterthrushes nest along stream banks and feed primarily on benthic macroinvertebrates, making them vulnerable to both changes in riparian production and diversity. It is important to determine aspects of the riparian environment that affect productivity. We measured various habitat characteristics of nesting Louisiana Waterthrushes to determine what territorial factors influence breeding success. Based on independent t-tests, we found that increased canopy cover and oak density were positively correlated with nest success. In contrast, increased poplar density and length of streams that are intermittent rather than perennial within territories were negatively correlated nest success. These four factors were placed in a binary logistic regression model. Canopy cover and poplar density were statistically significant, while oak density and intermittent streams were marginally significant. This model correctly predicted 86.1 percent of nest outcomes. Increased canopy cover may offer greater protection from visual predators. Poplar, a tree species characteristic of relatively open forests, is often replaced by oaks as the forest matures—which typically also increases canopy cover. Increased intermittent flow limits the productivity of streams, and therefore, decreases the reproductive success of the Louisiana Waterthrush. More research must be done to increase sample sizes, and consequently, the understanding of how these habitat factors affect the Louisiana Waterthrush.