Gull - feeding behavior

Jennifer R. Gamblef2 and Daniel A. Cristolf1 Department of Biology,

College of William and Mary

Received 11 August 2000;

revised 16 January 2001;

accepted 11 July 2001. ;

Available online 12 March 2002.

 

Abstract

 

Behaviours with no apparent adaptive function are sometimes described

as play without rigorous testing of alternative explanations. One such

behaviour is the repeated dropping and catching of objects by birds. We

observed drop-catch behaviour by herring gulls over 3 years at a site

where the birds frequently dropped clams to break them on hard

surfaces below. We tested unique suites of predictions from three

hypotheses, that the drop-catch behaviour is play, that it functions to

expose potential kleptoparasites, or that it serves to reposition clams

before foraging drops. We tested data from 72 drop-catch series and

504 typical foraging drop series to determine which suite of predictions

most closely matched our observations. As predicted if the behaviour

were play, drop-catches were performed more by younger birds, not

necessarily over a hard substrate, and sometimes with nonfood objects.

Clams that were subjected to drop-catches were generally not

repositioned or eaten. These results suggest a motivation for drop-

catching that is distinct from foraging. Finally, drop-catches were more

frequent when it was warm and when there were high winds, also

consistent with the play hypothesis. Drop-catch behaviour closely

matched the predictions of the play hypothesis and we were able to

reject the two alternative explanations.

 

Comments???

I find this interesting, as I recently posted an image of a gull portraying such behavior. It immediately struck me that it was play, and he was having a ball. He kept dropping a stick and would snatch it in mid air or pick it up from the ground.