Breeding Ecology of Songbirds in Bottomland Hardwood Forests of Louisiana.

I examined productivity, survivorship and nest-site habitat characteristics of small terrestrial landbirds breeding in bottomland hardwood forest study sites in Louisiana. Bottomland hardwood forests are the dominate ecosystem of riverine floodplains in the southeastern United States, and these forests support a diverse bird community. Over 80 percent of this forest type has been lost, primarily due to agricultural clearing, and the relative abundance of many bird species that breed in these forests has also declined. The outcomes of 790 nests of 33 species were determined. For most species, productivity was greater in large forest tracts than in small tracts. Predation was the leading factor affecting nest success, and rates ranged from 25 percent in large ($\u3e$20,000 ha) forest tracts to 43 percent in a 4000 ha select-cut tract. Brood parasitism by Brown-headed Cowbirds (Molothrus ater) was greater in small forest tracts than in large tracts. Rates of brood parasitsm ranged from 5 percent in large tracts to 19 percent in smaller tracts. Parasitism rates of migrant species were 5 times greater than that of resident species, but there was no difference in the predation rate of migrant and resident species. Migrant nests initiated early (before 1 June) were parasitised at a significantly higher rate than nests initiated later. Predation rates of migrant nests did not differ between early and late initiation times. Annual return rates of female migrants were less than that of male migrants at all sites. Resident females returned at the same rate as resident males at two sites and less than males at one site. Return rates of hatching year birds were less than that of after hatching year birds at all sites. Return rates of hatching year birds in this study (7 to 9 percent) were greater than that reported in most studies. Differences between nest-site habitat used and that available were found for most species. No difference was found between the nest-site habitat characteristics of successful and unsuccessful nests. For 6 of 8 migrant species, sweet gum was the most commonly used nest plant