False behavior
and feigned injury
As a
continuation of false behavior and an introduction to feigned injury, we will
be exploring how birds in particular exploit these forms of deception. The
techniques explored below are often called distraction displays as they
function as anti-predator behaviours, utilised in order to attract the
attention of the predator away from an object such as the nest.
Charadrius volciferus (killdeer) is a medium-sized plover
that displays false behavior as a distraction display. When a predator begins
to approach, the killdeer will move to several places, squatting as if
incubating eggs. This is called false brooding and confuses the predator to the
actual location of its nest. This was the most frequent female response of
killdeer during early incubation when a predator approaches (Brunton, 1990).
This is the response of a female, however, the male will display behavior very
different to their partners. This is known as the broken-wing act and is a form
of feigning injury.
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| Figure 1. Charadrius volciferus performing a broken-wing act. Photographer: Anonymous (2010) |
This
distraction display involves the bird walking away from the nesting area, with
its wings held in a position that simulates injury. It then flaps helplessly
emitting a distress signal. Thinking that they are easy prey, the predators
will follow the killdeer away from the nest. This is done until the predator is
well away from the nest and then the killdeer will simply fly away. Should the
predator show no interest initially to the “injured” killdeer, they will move
closer to the predator themselves and call out louder to grab their attention.
Note that both techniques can be employed by both sexes. Brunton (1990)
continues to state that males took greater risks when performing distraction
displays and this may lead to unintentionally getting caught by the predator; a
disadvantage to the evolved trait.
We will
continue to explore feigned injuries next week.
References
1. Anonymous. (2010). Charadrius volciferus performing a broken-wing act. http://www.anthive.com/killdeer/killdeer.html; retrieved 07/04/2015.
1. 2. Brunton,
D. H. (1990). The effects of nesting stage, sex, and type of predator on
parental defense by killdeer (<i>Charadrius vociferous</i>):
testing models of avian parental defense. Behavioral Ecology and
Sociobiology. 26, 181-190.
This type of behaviour is well known across various species of plovers, but do you know if other bird species (or other animal species) demonstrate feigned injury behaviour too, as an anti-predator strategy? How successful is this strategy (i.e. how often is the predator confused by this false behaviour)?
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