Prey selection by the Little Blue Heron (Egretta caerulea) in Great White Heron National Wildlife Refuge, FL, USA

In coastal Florida where the Little Blue Heron (Egretta caerulea) population is declining, it is unknown if prey selection influences nest success. Little Blue Herons (LBHE) are generalists that eat insects, crustaceans, and fish, but little is known about their diet preferences. We investigated prey selection by LBHE in Great White Heron National Wildlife Refuge (GWH) in Florida, USA during the 2016 breeding period. We sampled prey communities (n=74) along mudflats using a 1-m2 throw trap to determine prey availability. We collected stomach regurgitate (bolus) (n=53) from nests (n=26) to assess prey selection. Fish occurred in 100% of nests, contributed to 32% of available prey biomass and comprised 56% of the boluses. Gulf toadfish (Opsanus beta) occurred in 57% of nests, contributed to 38% of the boluses, and 12% of the available prey community. Shrimp contributed to 23% of the available prey community, occurred in 89% of nests and 39% of the boluses. LBHE did not select for crabs as they made up 45% of the available prey biomass, but were only found in 1% of boluses. Terrestrial prey contributed to 4% of the diet. These results indicate that LBHE at GWH prefer fish and shrimp, and select for O. beta as an essential prey species. Consumption of terrestrial prey suggests foraging habitat is not exclusive to tidal flats. Understanding how prey community composition influences LBHE habitat selection will facilitate conservation decisions, allowing managers to predict how wading bird populations are affected by environmental variations.