Ask A Scientist© Biology Archive

Author:      cjervis
Text:        We recently found a bird body in a bird bath near our feeder.  
Actually, it is more like a watering hole.  At ground level we have a small 
water source for the birds which visit our feeder.  In the water we found the 
body of a small sparrow.  In the top of its head was a hole, about half a 
centimeter in diameter and perfectly round with very smooth edges.  There were 
no other noticeable marks on the body.  Any idea what might have killed it or 
caused the hole.  The brains were clearly exposed, although there did not seem 
to be much material in the skull.

Response #:  1 of 1
Author:      wizkid
Text:        Your observation baffles me, too!  If you lived near the 
seashore, I would suggest that limpets were responsible.  They drill perfectly 
round holes about the size you described, right into the shell of mollusks 
(clams, snails, oysters, etc.) and suck out the meat right out of the shell!  
But I never heard of them feasting on birds!  Perhaps, though not likely, the 
hole was caused by some predator's bite like a cat's.  But a bite is usually 
messy, causing peripheral damage, not clean, like you are describing.  Another 
possibility:  the sparrow flew at high speeds right into a sharp protruding 
object, like a weather vane or compass, and died of impact.  Or, maybe another 
bird gave it a strong peck in some kind of defensive behavior (or aggressive), 
and it caught the sparrow in the head.