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Mimicry in birds of prey
Published 4 April 2013

Juvenile Grey-headed Kite (Leptodon cayanensis) with a plumage pattern that imitates almost perfectlyan Ornate Hawk-Eagle (Spizaetus ornatus). Belterra (Pará), March 2013. Photo: Eleonora Pinheiro
1Willian Menq
Email: willianmenq@gmail.com
Translated by Johan Ingels.

Mimicry in birds of prey is impressive although uncommon. Some predators use mimicry as ahunting strategy. This is the case with the Zone-tailed Hawk (Buteo albonotatus) which
imitates the inoffensive vultures of the genus Cathartes to approach prey (Peckhamianmimicry). But a mimic that mimics another more dangerous species, seems to be the mostcommon type of mimicry among hawks in Brazil. So, the Rufous-thighed Kite (Harpagusdiodon) which has a predominantly insectivorous diet mimics a Bicoloured Hawk (Accipiterbicolor) which mostly hunts birds.
Other species of raptors only utilise mimicry as a juvenile, which is the case with the Greybellied Hawk (Accipiter poliogaster) and the Grey-headed Kite (Leptodon cayanensis). Thejuvenile plumage of the Grey-bellied Hawk is very similar to the adult plumage of the Ornate
Hawk-Eagle (Spizaetus ornatus), possibly as a defense against other hawks and large primatesthat could prey on its nest. The juvenile Grey-headed Kites are highly polymorphic, presenting
diverse plumage patterns. There are totally white individuals that mimic the Black-and-white
Hawk-Eagle (Spizaetus melanoleucus), others are almost completely black resembling a Black
Hawk-Eagle (Spizaetus tyrannus), and there are some rare intermediate forms that have little1MENQ, W. (2013). Mimicry in birds of prey - Aves de Rapina Brasil. Available in:<http://www.avesderapinabrasil.com/materias/mimetismo_leptodon.htm>.

Menq, 2013
Brazilian Raptors (Online publications)rufous-brown streaks on the neck and belly making them resemble a Grey-headed Kite. The
hawks of the genus Spizaetus are top predators and live in the same environments as Greyheaded Kites (Leptodon cayanensis) and Grey-bellied Hawks (Accipiter poliogaster). They
imitate powerful predators like the Ornate Hawk-Eagle (Spizaetus ornatus) conferring several
advantages such as protection against predation, having an image of a strong predator ofhawks and monkeys.

Rufous-thighed Kite (Harpagus diodon). Photo:Claudio Guimarães.

Bicoloured Hawk (Accipiter bicolor).
Photo: Jacek Kisielewski.

Recently I came across one of the most fantastic discoveries in the world of "Brazilianraptorology", a juvenile Grey-headed Kite (Leptodon cayanensis) with a plumage pattern thatmimicked almost perfectly an Ornate Hawk-Eagle (Spizaetus ornatus), including the crest andthe same pattern of stripes on its belly.
This incredible hawk was found in the Amazonian forest by the birdwatchers Robson Czaban,
Eleonora Pinheiro and Anselmo D'Anffonseca, during a visit to the Tapajos National Forest inBelterra, west of Pará. The mimicry of this individual exceeded the young Grey-bellied Hawk
(Accipiter poliogaster)Menq, 2013
Brazilian Raptors (Online publications)

Known plumage patterns of the Grey-headed Kite (Leptodon cayanensis). 1. Typical adultplumage. 2. Melanistic juvenile. 3. Juvenile, pale phase. 4. Juvenile, rufous phase.

Juvenile Grey-headed Kite(Leptodon cayanensis). Photo:Victor Castro.

which was previously considered the best mimic of the Ornate Hawk-Eagle (Spizaetusornatus). Most striking was that it had a crest, previously unreported in the literature.

Menq, 2013
Brazilian Raptors (Online publications)

Juvenile Grey-headed
Kite (Leptodon
cayanensis). Photo:
Márcio Moraes.

Black-and-white Hawk-Eagle(Spizaetus melanoleucus). Photo:
Grace Montaivan.

The discovery of the bird led to a series of discussions… Could this hawk be a new species ?
A subspecies ? A hybrid individual ? Or just an extreme variation in plumage pattern ? Wouldthe crest remain in the adult form ? Would the crest be a vestigial feature
manifested only in a juvenile ? Unfortunately many of these questions will remainunanswered.
After talking with some colleagues and reading papers from other ornithologists, and also
considering the great diversity of species variants, I concluded that it was indeed

Menq, 2013
Brazilian Raptors (Online publications)an extreme variation in plumage pattern of a juvenile Grey-headed Kite (Leptodon
cayanensis). The dimensions of its bill and legs, dark eyes, slit shaped nostrils, naked tarsi andwing size in relation to the tail, etc. are all characteristics of the Grey-headed Kite (Leptodoncayanensis), except of course for the crest. This is evolution in action!

Juvenile Grey-headed Kite
(Leptodon cayanensis).
Photo: Robson Czaban.

In Campos do Jordão (Sao Paulo) a juvenile Grey-headed Kite (Leptodon cayanensis) was
found with a crest and plumage pattern similar to that of an Ornate Hawk-Eagle (Spizaetusornatus), but not so perfect as the reported record. Probably natural selection will favour thejuvenile individuals that more faithfully mimic Ornate Hawk-Eagles (Spizaetus ornatus) andBlack-and-white Hawk-Eagles (Spizaetus melanoleucus), and consequently resulting ina longterm increase in abundance of these mimics compared to other forms of plumage
pattern. Perhaps, the same process has happened with the Grey-bellied Hawk (Accipiterpoliogaster) in the recent past.
The new discovery is undoubtedly a major contribution to Brazilian ornithology. The fact
also demonstrates the importance for science of an activity such as birdwatchingwww.avesderapinabrasil.com