Reserva Ecológica Costanera Sur

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

Agonistic Behaviour - Green-barred Woodpecker

Order: Piciformes - Family: Picidae

The Green-barred Woodpecker is a resident bird which breeds in the reserve. It is easy to recognize because of its size and colour, its striking voice, the drumming on the trees and its flight technique: three wingbeats and a glide.
As breeding time comes, the need for food and nesting place intensify the territorial disputes. These cases show only male contendants. Though in the case of the video there was participation of other individuals, their sex remained unknown. It is still to be solved the role they play and whether the female participates somehow.
When woodpeckers confront they exhibit ritualized behaviours, the function of which is to cause the rival to leave without fighting, or behaviours of overt agression. The ritual is ellicited through a very "lively" body language. The agression, through aerial spiraling chases interspersed with pecks and aerial kicks.

The scene of the ritual is the tree. The territory holder takes position in front of the intruder at a prudent distance and begins with the displays. It intimidates the rival moving its bill in a pompous way. With a stretched neck the bill is swung upwards, downwards and sideways as if it were a baton. This threatening posture is known as the Bill-waving Dance. This dance is accompanied by wing movements, body and tail jerks and striking calls, which combined or singly intensify the threat. One common wing movement is to extend both wings over the back and retract them. The tail, instead, is fanned out.
After an initial bout of displays they wait for the reaction and then they begin again. Antagonists do not necessarily follow a sequential dialogue. Sometimes the rival seems unresponsive to the performance, on some other occasions the response is quick and they overlap.

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Beginning of the ritual. The territory holder finds a position in front of the intruder to begin with the ritual.
Threat display: Bill-waving dance, accompanied by wing movements and a spread tail. In the third photo the woodpecker is extending both wings over the back and withdrawing them.
The intruder, instead, is moveless and waiting. His reaction capacity marks the rhythm of the encounter. Both woodpeckers keep the same position unless the action escalates.
8-2007 © Roberto Ares
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A detail of another wing movement accompanying the bill-waving dance. It is performed with one wing at a time, not necessarily alternated. It hardly opens the primaries and closes them quickly and energetically.
Extracted from the video - 12-2009 © Roberto Ares
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Resolution of another ritual with the intruder giving up and fleeing. This was a very short fight and the intruder was not very responsive.
Another threat display: (first photo) the woodpecker arches the neck upwards sticking its chest out.
8-2008 © Roberto Ares
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Examples of other displays:
Threat display and response alike: the two antagonists exhibiting the same display.
Threat display and appeasement display: before the threat the intruder holds still with its head and bill forward. This body silence reduces the tension of the encounter
Raised Head Feathers Display: as the woodpecker raised its head feathers it pecked at the branch. Excited to resume fight? (extracted from the video)

If threats are not effective to solve the conflict, actions will escalate. Pecks, aerial kicks and aerial spiraling chases around trees are added to the beforementioned displays. They leave the static scene of the branch to move around the whole tree and its surroundings. Face to face woodpeckers peck at each other and dodge strikes with agile maneuvers. Face to face they give aerial kicks with the feet while moving the wings forward and backwards to keep afloat. They also chase each other in a spiral around tree trunks and branches.
This encounter lasted four minutes during which there were breaks. Nevertheless, It was clear there was a latent agitation state. The presence of the other two woodpeckers in the surroundings added excitement to the conflict.
The Displacement Pecking was observed on several opportunities during the conflict. Due to the opponent's unresponsiveness the woodpecker pecks at a branch or trunk to resolve the conflict somehow. The Raised Head Feathers display was also observed.

Video December 2009 © Roberto Ares