Tuesday, December 16, 2008

First Ever Gray-bellied Hawk (Accipiter poliogaster) for Costa Rica

This amazing photo, taken by Cristian Gamboa, documents the first ever Gray-bellied Hawk (Accipiter poliogaster) recorded in Costa Rica. It is also a first for Central America. On June 26, 2008 Octavio Ruiz spotted the bird in a tree next to the suspension bridge over the Puerto Viejo River at the Orgnaization for Tropical Studies La Selva Biological Station in Puerto Viejo de Sarapiquí. He was accompanied by Yahaira Rojas, Kenneth Alfaro and Cristian Gamboa. All four of these lucky birders work as guides at La Selva.

Gray-bellied Hawk is a forest raptor native to South America. The closest previously known records were from northern Colombia (although see the comments in the e-mail correspondence quoted below). It is a poorly known species and is apparently rare throughout its range. The La Selva bird is a juvenile, and looks almost exactly like a mini-Ornate Hawk-Eagle. The adult is very similar to Bicolored Hawk, the biggest difference being that it has gray thighs rather than rufous thighs. In some older references authors have speculated that birds from the southern end of the species' range (Paraguay, and southern Brazil, Bolivia, and Argentina) maybe migratory. As this bird turned up in Costa Rica during the austral winter, it may have been a migrant that overshot its normal wintering grounds. However, there has been some recent discussion on this point and many experts from areas in the southern cone where Gray-bellied Hawk is found consider the species to be a year round resident there. So, migrant?, vargrant?, overlooked resident? we can only ponder the true nature of this exceptional bird.

From: sergio seipke <seipke@yahoo.com.ar> (note: Sergio is writing a guide to S.Am. raptors)
To: Bill Clark <raptours@earthlink.net> (note: Bill is a raptor expert who has authored several guides to N.Am. birds of prey)

Hi Bill! Yes, I agree, undboubtedly a Gray-bellied Hawk. Look how the dark mallar stripe touches the black cap behind the eye - you don't seed this in Ornate Hawk-eagle, where the rufous clearly separates the cap and the mallar stripe.Look for comparison at:http://farm1.static.flickr.com/34/72062929_f61e76f379.jpg?v=0Also the 'barring' on the median portion of the belly is more 'spotty' (unlike in OHE).Great news! Thanks for sharing them!!!I saw one older imature (thighs still barred, but rest like adult) in Darien, Panama in 2005, but since I took no photos and the bird was 'out of range' I usually don't mention it.
Thank you again.


Ps: Please make sure you encourage the observers/photographers to publish this record. You can tell them they can quote my diagnosis if the'd like to -- no problem.---

El lun 15-dic-08, Bill Clark <raptours@earthlink.net>
De: Bill Clark <raptours@earthlink.net>
Asunto: [Fwd: Fwd: fotos ave en la selva]
Para: "sergio seipke" <seipke@yahoo.com.ar>
Fecha: lunes, 15 de diciembre de 2008, 3:26 pm

Hi Sergio,I think this is a juvenile A. poliogastor.
If so, it is way out of range in Costa Rica.

Cheers, Bill

From: Jim Zook <ebirdcr@gmail.com>
To: Bill Clark <raptours@earthlink.net>
Hey Bill,
this funky little raptor was photographed here at La Selva not too long ago and its identification has stumped everyone, myself included. I'm leaning towards some transition juvenile-to-adult plumaged accipiter, but....? I've never seen anything like it before. I didn't see the bird, but those who did said it was not very big, they estimated about Double-toothed Kite sized. I've seen the branches where the bird was photographed (it was right next to the big suspension bridge on the way over to the lab clearing) and it surely must have been a fairly small bird. Anyway, hope all is well with you, and I´ll look forward to hearing your impressions.
bye for now, Jim


Pat O'Donnell said...

Increible!!Jamas pensaba que este especie iba a llegar a Costa Rica.

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