Study

A parasite in wolf’s clothing: hawk mimicry reduces mobbing of cuckoos by hosts

Welbergen, J. A.; Davies, N. B.

Behavioral Ecology, 2011

Peer-reviewedfield experimentwild

What they did

Mounted models were presented at wild reed warbler nests: a cuckoo, a sparrowhawk, and a harmless control, together with manipulated models in which barring on the underparts was altered. Host mobbing responses were scored, and responses to the barred and unbarred versions compared.

Studied in: Cuculus canorus, Accipiter nisus, Acrocephalus scirpaceus
Sample size: model presentations at wild host nests

What they found

Hosts mobbed the cuckoo less than the control, and manipulating the barred underparts changed the response: models with hawk-like barring elicited less mobbing than the same models without it.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

The cuckoo’s resemblance to a sparrowhawk functions to reduce host attack, with the barred plumage a key element of the effect.

How NatureHQ reads it

A clean demonstration that a resemblance can be tested rather than asserted. The question is never whether a cuckoo looks like a hawk to us; it is whether the specified receiver — a reed warbler deciding whether to attack — behaves differently, and whether removing the feature removes the effect. Both were measured.

Limitations

Mounted models cannot reproduce flight, which is likely part of the resemblance.
Reduced mobbing is a benefit; whether it is the origin of the plumage rather than a later use is not established by this design.