Biology Reference
In-Depth Information
(a)
Reed warbler chick
12
8
4
0
kHz
Reed warbler brood
12
8
4
0
Cuckoo chick
12
8
4
0
(b)
Fig. 8.14
Vocal and visual trickery by cuckoo chicks. (a) A common cuckoo chick's vocal
trickery in a reed warbler nest. The sonograms, each 2.5 s long, show the begging calls
of six day-old chicks recorded in the laboratory one hour after they had been fed to
satiation. The cuckoo's begging calls are much more rapid than a single reed warbler
chick and at a week of age are more like those of a whole brood of hungry host chicks.
From Davies
et al
. (1998). (b) A Horsfield's hawk-cuckoo exposing a false gape - a yellow
wing patch - next to its own yellow gape. The host is a blue and white flycatcher
Cyanoptila cyanomelana
. Photo courtesy of Keita Tanaka.
cuckoo has to boost the vocal component by producing extraordinarily rapid calls. Thus,
the cuckoo succeeds by tuning into the host's provisioning rule (Kilner
et al
., 1999).
In Japan, Horsfield's hawk-cuckoo
Cuculus fugax
has an equivalent trick, but it
manipulates the visual component of the begging display. When it begs for food it
exposes yellow wing patches which are the same colour as its yellow gape (Fig. 8.14b).
And visual
trickery by
Horsfield's
hawk-cuckoo
chicks
