have banded seemed reluctant to have 
their bills touched, and they certainly 
never pecked at me. 
Most predators of stilts and avocets 
are not only larger than their prey but 
also possess specialized weapons. There 
is little chance for a stilt or avocet to in- 
jure a predator without suffering worse 
consequences itself. Physical contact 
with a predator is extremely rare, but as 
avocets and stilts swoop by, they some- 
times attempt to kick predators that are 
on the ground. It must be uncommon 
for these kicks to come in contact with 
a live (and thus mobile) predator, but 
stuffed hawks, crows, and gulls that I 
set out were kicked so hard that they 
fell over. (After kicking more firmly an- 
chored predator models, stilts some- 
times shook their legs, as though they 
were sore.) Even without contact, wa- 
ter and mud flying from kicking legs 
must be annoying to a predator. 
But why should a predator be re- 
pulsed by such sham attacks? Why does 
it not learn that it will not be injured? It 
should be admitted at the outset that 
avocet and stilt mobbing is not as effec- 
tive as that of species capable of inflict- 
ing injuries on the predator; the 
hard-hitting terns, for example, seem to 
inspire more respect in their nest pred- 
ators. But, as anyone who has experi- 
enced mobbing can attest, it is difficult 
not to flinch in the face of a dive bomb; 
it would be even more difficult for a 
predator that had previously been 
struck by a mobbing tern or even by a 
red-winged blackbird. If the predator 
has not yet seen or captured the eggs or 
chicks, it may be very difficult for it to 
concentrate on searching in the midst 
of a storm of harassment by the par- 
ents. Consequently, it may often be to 
the predator’s advantage to move on 
quickly. But there may be something 
more subtle involved. There is always a 
slight chance that the avocet or stilt 
may strike the predator, even if by acci- 
dent. Such a high-speed collision would 
probably cause as much damage to the 
mobber as to the predator. The avocets 
and stilts should theoretically be more 
willing to take this risk, however, be- 
cause they are playing for higher 
stakes — failure for the mobber results 
in the loss of part or all of a season’s 
breeding effort and possibly its own life, 
whereas failure for the predator results 
in the loss of one meal. Thus, in many 
contest situations, it is the avocet or 
stilt that exhibits “valor” and the pred- 
ator that shows “discretion.” 
There are many records of predators 
turning on their mobbers and killing 
them. This ever present danger, along 
with the need to avoid unnecessary ab- 
sences from the nest (responses to false 
alarms), should be a powerful selective 
force for the ability to recognize which 
animals are predators and w hich pred- 
ators are the most dangerous. I found 
that avocets and stilts are indeed so- 
phisticated in their discrimination of 
predators. I have seen them mob at 
least fifteen bird and four mammal spe- 
cies. Mammals and birds are treated 
differently, and each avian predator 
evokes a different response, which 
seems to depend on how dangerous it is 
to chase. Moreover, avocets and stilts 
distinguish a diversity of nonpredators 
and do not chase chick predators dur- 
ing the egg stage or egg predators dur- 
ing the chick stage. 
Seventeen years ago, Dutch etholo- 
gist Hans Kruuk pointed out that there 
are three basic types of predators that 
nesting birds must contend with: those 
(such as the peregrine falcon) that prey 
on the adults but not their eggs; those 
(such as the red fox) that prey on adults 
and their eggs and young; and those 
(such as the California gull) that prey 
only on eggs or chicks. A different anti- 
predator strategy must be employed for 
each. While a gull can be mobbed with 
reckless abandon, a peregrine must be 
harassed cautiously if at all; a fox is dif- 
ficult to deal with but can be distracted 
away from the nest or chicks. Through 
it all, the parent must not sacrifice its 
life for the brood, because then all 
would be lost — there is virtually no 
chance for the chicks to survive without 
protection, and no chance to rear an- 
other brood. The parent must tread the 
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