The simplest interpretation would be that you witness a visual display
apparently used to assert dominance within a group (the lowered head and,
of course, charging indicates overt-offensive aggression).
Social-dominance hierarchies are not uncommon in species that flock.
Body size, age and sex are usually the three most important factors that
determine position in a social-dominace hierarchy: large over small, male
over female, age over youth, etc. In some species, the more dominant
individuals are also the most colourful and brightest. In fact, the size
of a plumage "status badge" are often used to mediate social interactions
within a flock. In Australian Wood Ducks, I have wondered if the darkest
of the male's head signalled status within a foraging flock (just a guess,
perhaps others can refute or confirm this idea).
Did you happen to notice if the ducks were fighting over food? There is
a possibility that you witnessed the beginning of courtship proceedings
between a pair of ducks. Did the "charging" male and female stay together?
Does anyone know if Wood duck mate for life and when they nest, etc. I
hope this helps.
Dr. Wm. James Davis, Editor
Interpretive Birding Bulletin
On Sat, 20 Jun 1998, Andrew Patrick wrote:
> Irene Denton says 'hello guys'. She hopes to get a new, permanent job soon
> receive email again.
> Last weekend at Kenthurst, Sydney I observed a group of 24 Wood Ducks (9
> female, 15 male) grazing on the lawn, as they often do. Some of the birds
> (both male and female) bobbed their heads up and down with bill wide open
> and making a bit of a cry at the same time. Occassionally they lowered their
> heads so their necks were horizontal with the ground and, again with bill
> open, would charge at another bird. Both males and females did this. One
> male charge a female, she jumped in the air and then charged him back.
> Despite this, the group stayed more or less together as they drifted from
> one part of the garden to the next.
> Why were they doing this?
> Andrew Patrick
> Cumberland Bird Observers' Club
> Intense Software
> work (02) 8338 8888