Mottled ducks (Anas fulvigula) are endemic to Gulf Coastal United States and Mexico. Birds from Florida, Louisiana, and Texas were released in coastal South Carolina from 1975-1983, and banding data suggest an expanding South Carolina population. We radio-marked 116 females in August 2010-2011 in the Ashepoo, Combahee, and Edisto (ACE) Rivers Basin and used radio telemetry to study habitat selection, searched for nests of non-radiomarked females, and conducted indicated breeding pair surveys of mottled ducks at various wetlands. Overall, radiomarked mottled duck females selected managed wetland impoundments, wetlands containing planted corn, and brackish wetlands. Overall nest success of 42 nests of unmarked females was 19%. Modeling results indicated that the area of an island on which a nest was located was the only variable influencing nest success. Indicated breeding pair surveys revealed that the size of the wetland was the primary influence of breeding mottled duck immigration into a wetland.

In the lower Rio Grande Valley of south Texas, more than half the nesting groups of Harris's hawks (Parabuteo unicinctus) include at least one auxiliary group member in addition to a breeding pair. To provide further insight into cooperatively breeding raptors, I evaluated sociality in Harris's hawks through the dual benefits framework. I explored the formation, structure, and stability of cooperative group formation across a spatially variable study area, which includes high levels of urbanization and development as well as remote, undisturbed native habitats with low anthropogenic impact. I used color banding, regular censuses of active territories, and a microsatellite relatedness analysis to examine patterns of sociality, including delayed dispersal, the effect of auxiliary group members on reproductive output, parentage of broods, and the relatedness of auxiliaries compared to the nestlings in their territories. I confirmed cooperative polygamy with genetic techniques for the first time in Harris's hawks and found 58% of juvenile hawks delayed dispersal for at least 6 mo. Using the dual benefits framework, I found social associations that formed through delayed dispersal followed predictions for resource-defense benefits, but sociality among mature non-related hawks more closely followed predictions associated with collective action benefits, specifically reproductive output was significantly reduced in undeveloped habitats, presumably due to a less predictable prey-base.