group may make a swoop per second. 
For the predator, this must be like fac- 
ing an aroused beehive. Most predators 
withdraw rather quickly, but if not, 
mobbing may continue for more than 
an hour. An osprey, under attack by six 
avocets, made the most hurried retreat 
I have seen. 
This vicious-looking behavior is al- 
most entirely bluff. As mentioned pre- 
viously, avocets and stilts lack offensive 
weapons and beneath the veneer of 
breeding-season bluster are remarkably 
gentle animals. Their relatively soft, 
flexible bills culminate in a tiny fragile 
hook on the upper mandible, most pro- 
nounced in avocets, that probably 
keeps slippery prey from slipping away. 
Overall, these bills are most unsuitable 
structures for striking a blow. Indeed, 
hundreds of avocets and stilts that I 
Jim Brandenburg 
Tom Bledsoe 
Reacting to perceived danger, an 
American avocet, top, is attempting to 
lure the source of the threat away 
from its nest. The birds commonly 
take to the water as part of their 
repertoire of distraction maneuvers. 
Somewhat more dramatically, another 
avocet, right, appears to feign injury. 
The idea, apparently, is that predators 
will zero-in on abnormally behaving 
prey, as they often represent an easy 
meal. Similarly, the black-necked stilt, 
leaping into the air, above, is engaged 
in distracting a possible predator. 
Early naturalists, observing such odd 
behavior, presumed they were 
witnessing courtship displays. 
