According to the recent Ecuador Field Guide, White-chested Swift Cypseloides lemosi has not been confirmed for the country by specimen or photograph, although there have been a number of sightings on the northern East Slope in the past 10+ years. Mitch Lysinger discovered that this species is a rare but regular visitor to Cabanas San Isidro, southwest of Cosanga - most often seen in the early morning and late afternoon as they apparently "commute" from undiscovered roosting sites in the Antisana Reserve down to feed in the lower foothills/lowlands. I had seen two on a visit to San Isidro nine years ago (plus Jonas Nilsson and I saw one in a mixed feeding flock over the road between Limon and Patuca - roughly due east of Cuenca), but my attempts to get useable photos were stymied by the limitations of emulsion film.
Thus on this visit to San Isidro I planned to try again with digital equipment. Luckily it had been unseasonably rainy, and one afternoon of low, drizzly clouds a loose group of Cypseloides-type swifts were hanging over the entrance road for more than thirty minutes, drifting back and forth into the easterly wind. Most were the expected Chestnut-collared Swifts C. rutilus, plus occasionally a small group of White-collared Swifts Streptoprocne zonaris would burst past at lower levels - but among the higher group of Cypseloides were at least four individuals that I identified as C. lemosi - photographs of which appear below. NOTE: where there are two images adjacent on the same level, the rightmost one is a comparative photo of a White-collared Swift (taken on the same trip but two days earlier- thus not to the same scale):-
Note the relative positions of the white on the underparts of these swifts:-
S. zonaris has the white around the lower throat (thus ahead of the leading edge of the wing, at the body) with this narrow white continuing up the neck-sides to the hindneck.
C. lemosi has the white on the upper chest (thus behind the leading edge of the wing, at the body), the white being thicker in the center of the chest (on adult males, at least?) and no white continuing up along the neck-sides and onto the hindneck:
- the two birds from the photo above are enlarged separately below (with comparative S. zonaris at approx. the same angle, to the right of each):
- given the lack of images of C. lemosi in life (I could not find any on the Internet), I would appreciate feedback from those with appropriate experience - thanks.