Sunday, October 21, 2012

Northern and Wattled Jaçana

Jaçanas are fascinating. They are a pan-tropical bird family (found in most of the world's tropical areas). The c-cedillia in the spelling of jaçana is usually replaced with a c in English. The c-cedillia also appears in the French words garçon and façade. The point here is that jaçana should be pronounced with a soft c. Jaçanas are also called Lily-trotters or Jesus Birds. These names derive from the Jaçanas' ability to seemingly walk on water--their long toes allow them to walk on waterlilies and other floating aquatic vegetation.

Two species of jaçana inhabit the New World. The Northern Jaçana is found from northern Mexico south to Panama. In the 1960s, I took the top photo near Acapulco, Mexico. The bottom photo is of a Wattled Jaçana from Pucallpa, Peru. This species is found from Panama through much of tropical South America. When I took these photos, the two birds were thought to be one species. Hybrids were reported from Panama, where the two populations overlap. Individuals formerly thought to be hybrids, however, prove to be immature Wattled Jaçanas. Thus I added two birds to my lifelist without revisiting the tropics.

Jaçanas once bred in south Texas, but now only occasional juveniles are found there. I am not sure why the breeding birds have retreated to Mexico. Jaçanas have odd breeding behavior. One female may breed simultaneously with up to four males. The males attend to all the "home" duties (nest building, incubating, and raising the young). Females defend territories (that include the males' nests) against other females and intruders. In order for this polyandry to occur, the females must have rich territories. In poorer territories, the males are spaced further apart, and thus their nests are harder for the females to defend; the females then tend to take on fewer mates (Jenni and Mace 1999).

No comments:

Post a Comment