This post was submitted to Bird Photography Weekly # 123. Check it out!
Literature consulted:
1. Ridgely RS, Gwynne JA. A Guide to the Birds of Panama. 1993
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watched it. Osvaldo and Rafael used their flashes with the camera... my own photo (digiscoped with my DSLR camera) was with natural light (however, the day was cloudy and the lights conditions were not the best). The Common Pauraque (above photo, a male) can be easily ruled out by tail pattern and lack of conspicuous chestnut cheeks (and less patterned shoulders and wing coverts). The really hard task is to rule out the Rufous Nightjar (RNj). The RNj is one of our resident nightjars, closely related to the ChWW. It prefers drier habitats in the Pacific slope of the country (second growths, thickets and forest edges), so a bird found deep inside a mature. wet forest in the Caribbean slope as this one will hardly be a RNj... in the other hand, the ChWW is
a boreal migrant recorded in a wide variety of habitats in Panama, including mature wet forest, but also the same habitats preferred by the RNj and even residential areas with big trees. So, habitat favors ChWW... but birds doesn't read books, and there are some records of RNj in the Caribbean slope of the Canal area (although in cleared areas), so habitat alone is not enough to separate these birds. Another thing is the size. The ChWW is our largest nightjar, but we all know that size appreciation in the field is very subjective, and depends of maaaaany factors, including posture. About field marks, these two species are almost impossible to tell apart in the field, specially because we do not hear the characteristic call of the ChWW in its wintering grounds. In the hand, the ChWW have lateral filaments to the rictal bristles, absent in the RNj. Enlarge my photo of a RNj (above, from Summit Ponds, just across the continental divide in the Pacific slope of central Panama) and you will see the long rictal bristles arising from the base of its mouth. Now, call me crazy, but enlarge Osvaldo's photo (the first of this post)... although the resolution is not the best due to the distance, I can see that the rictal bristles look like a brush! Photo artifact? Lateral filaments? OK, it is hard to tell, so lets forget it. What about plumage marks. Some references list differences in the overall coloration, the color of the crown, the back and the throat to separate these two species in the field, but I have found that these field marks are not reliable after checking LOTS of ChWW's photos in the internet, and many RNj's photos as well (there not so many published photos of this species). This probably is due to many contributing factors, like age, sex and race (ssp) of the bird, the photographic settings, the light conditions, etc... but one
Mottled Owl due to the rain. The road was very damaged, so we only reached the area just beyond the former Limbo hunt camp, from where I started to walk (umbrella in hand) towards my own birding area around the Mendoza river, at the 8.8 km mark, hearing no dawn chorus due to the rain, a very bad sign. After a while, the team formed by Rafael Luck, Osvaldo Quintero and Venicio "Beny" Wilson (destined to explore the depths of Pipeline road) passed me swiftly aboard the tough FJ Cruiser without a problem, but it was a huge fallen tree (and not the muddy, potholed road) that stopped them... so I joined them in their quest after birds. We walked a lot on hilly terrain, passing the Syristes river and reaching the 11.0 km mark (photo courtesy of Beny,
more at his Picasa Web Album)... and we were rewarded with special birds for this count, like Slaty-backed Forest-Falcon, Buff-throated Foliage-Gleaner, Russet Antshrike, Spot-crowned Antvireo, Tawny-faced Gnatwren, Speckled Mourner, Olive Tanager and even a rare (for that area) White-throated Thrush attending an antswarm. Of course, the antswarm attracted more regular ant-follower birds too, like Bicolored, Spotted and Ocellated Antbirds, Plain-brown and Northern Barred Woodcreepers and a Rufous Motmot. It is always nice to see the 