The White Ibis is one of Florida’s most abundant and spectacular wading birds, and spring is the most thrilling season to see them and the state’s other avian splendors.
By Rex Graham
Birding 1 to 2 weeks in late-April will allow you to cover the southern two thirds of Florida to see a large percentate of the endemic birds, spring migrants and specialty birds.
Florida visitors first see Ibises flying in graceful V’s. Their huge, noisy rookeries are defining visual icons of the Everglades, which is a must on your birding itinerary.
Ibises provide the fertilizer required to create and nurture vegetated islands in otherwise infertile swamps and marshes.
Graceful Ibises, Everglades Icon
What do they eat? Almost anything. In Florida, the most popular menu entrees include crayfish, Sheepshead Minnows and other fish, dragonfly larvae, Apple Snails, Giant Water Bugs and other water bugs, and Mangrove Crabs.
“As their long, decurved bills might suggest, ibises eat many things that they pull out of the mud,” says the Bird Families of the World (http://bit.ly/BirdFamiliesofWorld). The ibises also catch mobile fish and prawns, but less efficiently that the related spoonbills.
With their bill tips slightly agape, White Ibises probe flooded pastures and the soft flocculent organic debris in marsh sediment. Bays, estuaries, lawns and sides of highways attract them.
They dissect farm manure for horsefly larvae. Municipal sewage sludge holding areas are nice for worms and fly larvae.
White Ibis Seasonal Specialist
Ibises rely on the seasonal, natural variation in water levels. Up to 75% of the biomass of fish concentrated in seasonally fluctuating ponds in southern Florida can be consumed in less than a week. Ibises lead the feeding frenzy by wading birds, including herons and storks.
They form strong pair bonds and nest in rookeries of up to 12,000 pairs. As testosterone permeates a rookery like a morning fog, male ibises stray from their mates. Over 50% of the attempted copulations involving 30 females under observation by one researcher involved “extra-pair” males.
However, ultimately the females control fertilization because “cloacal eversion” is probably required for successful copulation in all birds.
As you might expect, where you find an ibis rookery you will find nest predators. In some extreme cases, Fish Crows take up to 44% of all White Ibis eggs in an entire rookery.