Hook-billed Kite (Chondrohierax uncinatus): Gavilán piquiganchudo; Langschnabelweih; Milan bec-en-croc

Back in September 2018 I wrote a post about the Hook-billed Kites that had appeared in the Aquiares coffee-fields both that year and prior to that, in 2015 and 2016. I mentioned at the time that this species, now considered rare in Costa Rica, seemed not to be in typical habitat in the shade-grown coffee environment. But if I had read my Stiles & Skutch (A Guide to the Birds of Costa Rica) more closely, I should have noted that the Hook-billed Kite hunts “land snails under forest canopy”. Here is a very nice pic of a typical Hook-billed Kite:

Big surprise this spring. From April 23 to May 1 this year I observed in the garden, and almost every day, an even rarer black-phase male bird being harassed by our local song birds. I can find no other reported sighting of any Hook-billed Kite from our San Antonio area.

Our village of San Antonio has neither marshes nor much in the way of forest canopy, and yet here comes the Hook-billed Kite again! The deeply hooked bill is conspicuously much thicker and heavier than that of the much more buoyant Snail Kite (Rostrhamus sociabilis), a species now well established at the Angostura Dam.

At first I had some difficulty in identifying the male bird because its predominantly grey-black upperparts and whitish lower breast suggested a Bicolored Hawk (Accipiter bicolor), a species that has occasionally appeared here. The birds’s behaviour each day was predictably the same: rather heavy, short-distance flight from tree to tree inside the garden pursued by mostly Clay-colored Thrushes, sounding the alarm call that usually indicates a nearby cat. As the days passed I was able to confirm lack of barring on the underparts and no sign of the rufous thighs of a Bicolored Hawk.

I am not a photographer and can unfortunately offer no photos of this particular individual bird. Fortunately it often allowed me a close enough approach to distinguish very clearly the key field marks of the pale iris and greenish-yellow cere, with a separated orange lore. My only doubt is with respect to the age of the bird since the lower breast was definitely pale and not all-black. I therefore surmise an immature black-phase male.

Other local birders have since reported to me verbally a black-phase male Hook-billed Kite down at the CATIE campus in Turrialba. This seems more than purely coincidental, given the rarity of both the species and the black-phase in particular, but I can find no eBird report of this sighting.