"Tito", one of my favorite bird watching tour guides, recently discovered Boat-billed Herons amongst the mangrove in the back of Ambergris. I had only seen Boat-bills in estuary habitat (the wide low course of a river into which the tides flow) and was excited because its daytime sighting could mean a colony on Ambergris.
Bubba said that the single species of Boat-bill Heron is divided into five races and there are questions concerning whether to include it in the family Ardeidae (herons and bitterns) or to give it its own family. Its largest differences are in its specialized feeding niche and corresponding adaptations (its bill). His excitement is the Boat-bill remains a poorly known bird and somewhat mysterious. The label given to this rare bird's existence in the world is retiring.
Boat-billed Heron inhabit all of Belize but are more strictly nocturnal than the Night Heron, unlikely to be seen in daylight away from roosts or colonies.
A non-migratory bird, Boat-bills inhabit both fresh and salt water areas throughout Belize. They are found often in thickly vegetated rivers but are also known to hunt along beaches.
Boat-billed Herons seem to be strongly nocturnal in their hunting behavior. By day they preen and roost quietly in dense mangrove thickets near feeding areas, venturing forth at dusk to forage. Although Boat-bills can hunt in the wade-and-stab manner of other herons, there is reason to believe that they switch to touch-feeding like the spoonbills during the breeding season when they consume shrimp and other mud dwelling prey that cannot be located except by dwelling. Bubba is following up by checking with Kevin at Ambergris's new NOVA shrimp farm in the Basil Jones area to try to locate the colony's roost.
Bubba said, "Birds often communicate with social signals. The Boat-billed Heron have developed most signals different from other heron; only two of the twelve most common displays in the Boat-bills repertoire are like that of the heron. Instead of the visual signals, characteristic of most heron communication, the Boat-billed heron relies more on acoustic signals, both vocal and mechanical, that penetrate the mangrove tangle more efficiently. The large bill also serves as a resonator, producing single and multiple bill-pops that resemble loud human handclaps.
The postures and movements used in the displays are generally simple and slow. Many are enhanced by the erecting of the broad crown plumes which produces a highly conspicuous black array above the white forehead. Between members of a mated pair there is a great deal of ritualized mutual preening behavior (called bill-clappering) that probably serves to strengthen the pair bond.
It is not known whether the Boat-billed herons form new pair bonds each year or retain the previous year's mate. Both sexes share in nest building, incubating, and feeding the chicks. Three or four pale greenish-blue eggs sometimes bearing small red flecks are laid at roughly two-day intervals. Incubation commences with the first egg, producing an asynchronous hatch. Later, if the chick's total energy demands the parents' ability to provide food, only the youngest chick starves. As in other herons, chicks are fed by regurgitation by the parents. Wouldn't it be wonderful to have a colony on Ambergris to watch all this at close quarters? If it's found and we respect it with quiet undisturbing visits it will be a unique attraction for our bird watching tourist visitors.
