Many species can sometimes bluff instead of actually charging

Dec 4, 2013 13:41 GMT  ·  By
Birds may be capable of bluffing when it comes to manifesting their intentions to attack
   Birds may be capable of bluffing when it comes to manifesting their intentions to attack

Scientists with the University of Washington in Seattle (UWS) found in a new study that aggression in birds is somewhat similar to patterns seen in humans, but only to some extent. They learned that some birds are more cowardly than others, and also determined that some may bluff about their intention to attack others. 

The work was carried out on members of the song sparrow species (Melospiza melodia), which were exposed to either a dummy bird that looked menacing, or to speakers playing back the sounds of other birds. Researchers led by behavioral ecologist Michael Beecher then observed how the birds reacted.

The group also established that, like humans, some song sparrows are more likely to give out slightly exaggerated signs of aggression, but then not attack at all. Conversely, others give little fair warning before pouncing on their victims.

As a general rule, birds tend to announce their aggression by songs and gestures or bodily postures, instead of by appearance. Distinctive soft songs or wing-waving are common behaviors that indicate incoming aggression from birds, Nature reports.

One of the most interesting conclusions of the study was that song sparrows' personality traits influenced their behavior towards the speakers or the dummy birds. Individuals that were bolder tended to attack faster, while others preferred to hang back for longer.

In many bird species, these precursory signals are indicative as to the intensity of the behavior to follow. Researchers call this an honest signal. What Beecher and his team found is that some individuals may talk the talk, but not walk the walk.

Details of the new investigation were published in the December 4 issue of the esteemed scientific journal Proceedings of the Royal Society B. The work was carried out on 69 male song sparrows.

This type of “behavior is intriguing, and hasn't really been discussed in theory. There are benefits to signaling – a fight is avoided, potentially beneficial to both parties – so why not do it?” Beecher says.