If there is a resident bird species in Panama that evokes myths and mystery, that certainly is the Grasshopper Sparrow. Formerly a breeder in the Pacific slope, it was thought eradicated due to habitat loss. Not a single resident, nor a vagrant migrant of northern subspecies, have been recorded since the 60's and thus the endemic subspecies of Cocle, beatriceae, was sadly believed extinct by almost all of those who have crossed the country looking for birds in the last decades... until now.
Last saturday's afternoon, I was returning from seeing my first life bird for 2012 (Ring-necked Duck, more on that in another post) and was almost at the entrance of the dirt road (4 miles west of Penonome, central Panama), already seeing the cars at the Panamerican highway, when I decided to stop just to check a pair of Eastern Meadowlarks. As soon as I stopped, I detected a subtle movement in the short grass next to the car. My very first impression was of a gray, tiny mouse, crawling under the grass... but soon realized that it was a bird! The tiny creature eventually stopped no more than 4 meters from my window, raised its head over its shoulders to inspect me and froze... I was shocked! A mythical bird, almost a ghost, the lost Grasshopper Sparrow was standing in front of me, alive... I still shake only of thinking of it. Nervous, I grabbed my camera and started shooting... and the bird did not move. I was able to see it very well, both with my binoculars and through my camera, realizing how beautifully patterned it was. It stayed for complete five minutes, only moving quickly few steps each time just to stand again. It was doing this whenever I was lowering my look to check the photos or to take the binoculars, and sometimes it was difficult to relocate the bird due to its perfect camouflage. It left so unexpectedly as it appeared, flying very quick and low to taller grass taking advantage of the second I took to check the last series of photos... it was very cautious! I started calling my friends to give the good news, but almost immediately I was concerned about the specific identity of the bird I saw: it was a member of one of the resident subspecies or a migrant from the north?
There is little literature regarding the subspecies of Grasshopper Sparrow found in Panama, and none in recent years. There are descriptions in the monumental work of Alexander Wetmore, and in Ridgely & Gwynne's Birds of Panama, both based on previous papers. However, you can get on-line the paper of Storrs Olson aptly named "The subspecies of Grasshopper Sparrow (Ammodramus savannarum) in Panama" (Proc Biol Soc Wash 1980; 93: 757-9), which describes the three subspecies recorded for the country (two resident, one migrant).
The first thing to take into consideration: the migrant subspecies (pratensis) is essentially indistinguishable of the resident subspecies bimaculatus, distributed along the Pacific slope of Panama (specimens from Chiriqui, in western Panama, and Chepo -east of the Canal area-) and extending to Mexico. There are plenty of photos on-line of pratensis, so it is useful in order to compare with my photos (I took many, but they are essentially variations of those I'm posting here). We have to consider pratensis as a VERY rare vagrant to Panama, only recorded so far in the western Caribbean slope twice in the late 60's and with its southernmost -usual- winter range extends only to Belize. In the other hand, beatriceae (named honoring Alexander Wetmore's wife, Annie Beatrice) is described as quite distinctive in being the palest of all the subspecies.
Based on range, beatriceae is the expected subspecies at that locality (and notice that two specimens examined by Olson were collected exactly at 4 miles west of Penonome). The key characteristics are: throat, breast, flanks and undertail coverts pale pinkish buff (not rich ochraceous yellow as in bimaculatus or pratensis); median crown stripe very pale, almost white (no deep buff). As bimaculatus, beatriceae have distinctly reddish streaks in the nape (distinguishing them from southern subspecies). Others -pale- subspecies from North America have never been recorded south of Honduras in the winter, and are not expected in Panama.
I think (or want to think) the bird of Penonome belongs to the endemic subspecies beatriceae by the field marks highlighted above and that can be appreciated in my photos, which I only cropped (no adjustments of color, contrast or sharpness added)... what do you think?
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