achieve these results, avocets and stilts 
may be the versatility champions of the 
bird world. I doubt that any other bird 
possesses such a large repertoire of anti- 
predator displays. Distraction displays, 
w'hich attract attention to the adult 
rather than to its nest, range from a se- 
ries of wing displays, in which one or 
both wings are extended or waved, to 
false incubation displays in which the 
bird squats on the ground as though sit- 
ting on a nest. (Such false incubation 
displays are sometimes performed on 
seemingly inappropriate substrates, as 
when birds would apparently have a 
predator believe they are incubating in 
the water.) Displays may be given in 
rapid sequences or simultaneously, so 
that stilts look like whirling dervishes 
(avocets, being much slower, look more 
like drunken dervishes). Through it all 
Standing tall over its nest in the 
Bear River Migratory Bird Refuge 
in Utah, an American avocet, left, 
peers intently at the photographer. 
Humans and other potential trouble- 
makers rarely get close to the nest, 
with its cryptically colored eggs 
and chicks, below. The parent 
bird usually intercepts would-be 
trespassers of its nesting territory 
and attempts either to lead them 
astray with a distraction display 
or to repel them with dive- 
bombing tactics. 
Torn Bledsoe 
the birds are continually vocal — stilts 
yapping raucously, and avocets piping 
insistently or giving pitiful-sounding 
“wounded bird” calls. 
Distraction displays of avocets and 
stilts differ in details, but the basic form 
is essentially the same. Differences are 
mostly attributable to the ecological ex- 
igencies that have produced two differ- 
ent body plans within this shorebird 
family. Although avocets and stilts 
sometimes look similar in size when 
seen in the marsh, avocets are in fact 
nearly twice as heavy; the stilt, how- 
ever, whose delicate appearance belies 
its rowdy disposition, has wings as long 
as, and legs considerably longer than, 
the avocet’s. The net result is a heavy, 
slow, relatively powerful avocet and a 
skinny, hyperactive, agile stilt. 
Avocet and stilt distraction displays 
are unusual in that they only sometimes 
look as much like “injury-feigning” as 
the displays of other bird species. It is 
widely held that, on encountering prey, 
predators evaluate their chances for 
success and that criteria of special im- 
portance to them are abnormal move- 
ment and appearance — attributes that 
often signal injury' or sickness and 
hence easy prey. The implication is that 
this characteristic of predators ac- 
counts for the origin of distraction dis- 
plays. And there is no disputing the 
abnormal appearance of a stilt or an 
avocet performing a distraction dis- 
play. 
Brief observations of avocet and stilt 
behavior can be misleading. Underesti- 
mating the birds’ sharp eyesight, early 
naturalists believed their presence was 
undetected and misinterpreted distrac- 
tion behavior as courtship. (Pair forma- 
tion is actually a subtle and drawn-out 
affair lasting days or weeks, while copu- 
lation is associated with a set of highly 
ritualized behaviors lasting from forty- 
five seconds to a maximum of three 
minutes.) The following account by one 
early observer of black-necked stilt 
“courtship” serves as a colorful de- 
scription of distraction: 
Although my approach was not especially 
careful, the two pairs of stilts . . . seemed un- 
aware of my presence as I sat on a tussock of 
grass at the edge of the pool. . . . The four 
birds were close together ... in the shallow 
water, bowing, fluttering wings and fre- 
quently half leaping-half flying . . . into the 
air. After a few moments . . . one bird . . . 
executed a flying leap . . . and . . . kicked up 
a shower of spray, using the feet . . . quite 
suddenly ... all four birds flew steeply up- 
ward to a considerable height where they re- 
mained for some time flying ... in wide 
circles, giving utterance to their loud, sharp 
call. Gradually . . . the four birds spiralled 
downward to alight in the shallow water 
and begin anew the . . . ritual of bow , flutter, 
leap, spray. This sequence was repeated 
again and again during the hour and a half 
I sat upon the grassy tussock. 
No less an authority than Arthur 
Cleveland Bent was taken in by the 
same behavior. After two brief visits to 
avocet breeding grounds in Saskatch- 
ewan, he wrote in 1907: 
While conducting their courtships, in May, 
the avocets were always amusing and often 
grotesque in their movements, as they 
danced along the shore or waded in the 
shallow water holding their wings fully ex- 
tended, tipping from side to side, as if bal- 
ancing themselves. Sometimes they would 
run rapidly along crouching close to the 
ground, frequently nodding or bowing and 
sometimes they would lie flat on the water 
or ground, with wings outstretched as if in 
agony. At such times they were very tame, 
apparently oblivious of all else, and could be 
easily approached. 
From the birds' point of view it made 
no difference that their behavior was 
misconstrued. It accomplished its pur- 
pose — neither observer could find any 
nests. 
Still looking for a type of counship 
that is nonexistent among these birds. 
Bent later wrote in his Life Histories of 
North American Shorebirds: “frequent- 
ly they fooled us by squatting down on 
the ground, as if sitting on a nest; if we 
went to investigate, they would run 
away and repeat the act elsewhere: per- 
haps this act carried the suggestion of 
mating as a part of the courtship cere- 
mony.” 
The most spectacular stilt and avocet 
antipredator behavior is formally called 
the dive bomb. As is evident from the 
name, the birds mob their predators, 
swooping at them, but narrowly miss- 
ing them. The avocets and stilts present 
quite a spectacle pursuing a great blue 
heron or a black-crowned night heron 
so hotly that it crawks, harrying a Cali- 
fornia gull until it screams wildly, or 
worrying a short-eared ow l into drastic 
evasive maneuvers. Because avocets 
and stilts defend a 300- to 600-foot-ra- 
dius around their nests and because 
nests are usually aggregated into semi- 
colonies with nests no more than about 
150 feet apart, the intruding predator 
often finds a good deal more than one 
pair of parents zeroing in on it. During 
intense mobbing a single bird generally 
makes a swoop every ten seconds, and I 
have recorded stilts swooping as fre- 
quently as every seven seconds. A mob- 
45 
