Lets Band Together: Cooperative Breeding in the African Starling

“You can turn to me when the going gets tough.” This sentiment is echoed by humans all the time to our friends, family etc. who are in need, but what about other animals, do they extend an offering of help to their brethren in need? Sure, it’s well known of the communal aspects of various insects and animals who work toward the better of their group over the individual, but what about physically stepping in to take over in dire circumstances?

Recently, researchers observed an interesting behavioral pattern among the African starlings, an endemic bird to southern Africa, in which during intense circumstances a “cooperative breeding” occurred. This means that an individual capable of breeding would delay her breeding in order to help another starling and her young in times of environmental stress. What’s more interesting is that the receiver was not necessarily a relative! Ornithologists were puzzled as to why females capable of breeding would delay. A previous theory into cooperative breeding suggested that an individual would engage in cooperation only if they were incapable of breeding themselves, but this was certainly not the case. Also, of the forty-five species of starlings, only a small handful engaged in this act.

A group of Ornithologists from Cornell’s Ornithology Lab performed a genetic analysis of the forty-five species in order to show the pattern of evolution and then correlated it with one hundred and forty years of rainfall data from the African starlings habitat. What they came up with was that the cooperative breeding was only expressed in individuals that resided in the arid savannah regions where the rainfall was, at times, unpredictable. The African starlings that resided in the forests with predictable rainfalls generally would have non-cooperative breeding. Basically, what influenced this behavior was the environment, and through the process of evolution a system arose that allowed the starlings the capability of breeding in extreme conditions while getting the support they need to care for their young. Some innate mechanism must override the starlings sense to breed and cause it to go from a breeder to a caregiver when it sensed the need. At times of adequate rainfall, the "cooperative breeding" starlings would generally return to non-cooperative patterns until the next drought came about. Helping out in times of need,I think that’s great :-)



Sources:

http://www.nytimes.com/2007/08/21/science/21obstar.html?_r=1&oref=slogin

http://beheco.oxfordjournals.org/cgi/content/abstract/10/5/465


Posted by Doug Zelisko (4)