Reserva Ecológica Costanera Sur

Sitio realizado por aficionados a la observación de aves desde 10 de enero 2006

Feeding Technique - Solitary Cacique

Order: Passeriformes - Family: Icteridae.

This family is restricted to America, ranging from Alaska to Cape Horn. Many of its representatives can be observed at the reserve. Besides the cacique, the commonest ones are: Epaulet Oriole, Shiny Cowbird, Greyish Baywing, Unicolored Blackbird, Chestnut-capped Blackbird, Yellow-winged Blackbird, Orange-backed Troupial, Scarlet-headed Blackbird.
Boyero negro/Solitary CaciqueJune 2009 © Jorge García Vicente
The Solitary Cacique´s bill is massive, conical and very eye-catching since it is ivory-coloured and contrasts sharply with the black plumage. A good clue which, together with the size of this bird (24 cm) and its striking and dissonant voice, helps locate and identify it easily.
The Solitary Cacique feeds on insects, which it searches for inside branches. First, the cacique "bites" the branch to crack it. Then it uses the bill to tear it in shreds. The latter action, known as "gaping", is an innovative technique since it adds the application of force. This is not the passive movement of opening and closing the bill. Modifications of the bill and skull and of the composition, insertion and size of the muscles responsible for acting on the mandibles are the morphological adaptations which permitted this different use of the bill as a tool. This technique is not common among passerine birds. It is found in a few species of icterids and sturnids. Since the modifications do no appear uniformly in these species, there are variants in gaping (e.g.: in fruit, in ground, in ground litter, in leaves or flowers or in wood). This has permitted icterids to implement new ways of exploiting food niches. In the case of the Solitary Cacique: to pry in branches for insects.
Boyero negro/Solitary Cacique Boyero negro/Solitary Cacique Boyero negro/Solitary Cacique
Boyero negro/Solitary Cacique Boyero negro/Solitary Cacique Boyero negro/Solitary Cacique
The cacique "bites" the branch, twists it, bends it to loosen the tissues and causes a fissure. Then the cacique introduces its bill and detaches the shred spreading the mandibles powerfully. The last two pictures show how the cacique has torn the branch.

Photos June 2008 © Roberto Ares