ABA Photo Quiz

ABA Online Bird Photo Quiz 176

Answer

This narrow-winged bird with dark barring below and on the wing linings and a white slash across the primaries can be nothing other than a Chordeilies nighthawk.  As the photo was not taken in south Florida, we can restrict our efforts to two species, Common and Lesser.  With all that buff barring on the inner primaries and with the outer primary (primary 10, or p10) shorter than p9, this must be a Lesser Nighthawk.  Drop the binocular and look around for the next bird to identify.

Ah, but it is always good to study a bird, at least every once in a while, right?  Maybe try to determine its age, its sex?  Hmm, this nighthawk lacks an obvious white subterminal band in the tail, so it must be a female.  But, wait, it also lacks a pale throat patch.  Hmm.  What does that mean?  How do juvenile nighthawks differ from adults?  Do they lack pale throat patches?  If so, do juvenile males also lack white tail bands?  And what about that white primaries slash?  What was the difference between Common and Lesser in the placement of that slash?  Oh, yeah, the slash on Common is closer to the wrist than on Lesser.  Is this slash closer or farther?  With no comparison bird, it is difficult to be sure.  Huh, now the ID is uncertain.

Our hypothetical observer of this month’s quiz bird took a very useful trip through bird-ID techniques.  That is, instead of just coming to a conclusion in its ID on just one or two characters and moving on, she or he actually studied the bird and wondered, trying to dredge from memory of what the text in the field guide said about nighthawk ID.  Maybe, if the bird was within the range of Lesser Nighthawk and was being ogled in the time period in which Common was also present locally, our observer might have decided to pull back on that snap ID and let the bird go as unidentified due to uncertainty of what the various field characters were telling that observer.  Congratulations are then in order to that observer, because this bird is a Common Nighthawk.

The identification of this bird as a Common is supported by the fact that the white primaries slash is immediately adjacent to the primary coverts (those large, unbanded feathers just below the slash).  In fact, those primary coverts actually obscure a bit of the white slash.  The slash of Lesser Nighthawk is not immediately adjacent to the primary coverts.  The area of the wing beyond the slash is, roughly, a triangle in both species, but the difference in placement of that slash creates triangles of different appearance.  On Common Nighthawk, that triangle is obviously taller than wide, whereas Lesser sports a roughly equilateral triangle (see photos in this paper).

Some readers may now be sputtering, “But, what about all that buff barring on the inner primaries, the overall brown coloration, the short p10?”  Ah, now we have come to the focus of this quiz photo.  Virtually all of the field guides either suggest or state explicitly that buff barring on the primaries is a certain feature of Lesser.  Unfortunately for those that prefer their differentiating field marks cut and dried, like many, many things in biology, it just ain’t so.

Common Nighthawk is represented in the ABA Area by seven named subspecies, with most of those with little in the way of definitive differences, at least for field ID.  However, Henry’s Common Nighthawk (Chordeiles minor henryi), is quite different, being very Lesser Nighthawk-like in appearance.  The most annoying aspect of that similarity is that Henry’s is the breeding subspecies of the southwest, ranging from southeast Utah east through southern Colorado into, at least, panhandle Oklahoma (and probably southwestern Kansas, obviously) and south through Arizona, New Mexico, and west Texas into Mexico.  This is “annoying” as much of that part of the ABA Area also hosts Lesser Nighthawk as a breeder, so one cannot safely ID a nighthawk as a Lesser solely on the brown appearance or the buff barring on the inner primaries.

I encourage all to read the previously-linked paper for further details of the differentiation of henryi Common Nighthawk and Lesser Nighthawk, but also for further details on ageing nighthawks and how inadequate the short p10 is as a nighthawk ID character.

I took this picture of a juvenile henryi Common Nighthawk in western Texas County, Oklahoma, on 21 July 2017.

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The following people (listed by submission date beginning with the earliest) submitted correct answers for the November 2017 Bird Photo Quiz —Common Nighthawk:

  1. Clifford Hawley - Sacramento
  2. Malcolm Gold - Overland Park, KS
  3. Hiram Herrera - Chula Vista, CA
  4. Trevin Braun - Carlsbad, CA
  5. Claude Auchu - La Pocatiere, Quebec
  6. Brian Menker - Dayton, Ohio
  7. Paul Randall - Rosemount, MN
  8. Isaac Denzer - Philomath, OR
  9. Cullen Clark - Richmond, Utah
  10. Zacheriah Cota-Weaver - Hyde Park, Vermont
  11. Linda Millington - Upperville, VA
  12. Deb Pritchard - Beaver Dam, WI
  13. Patricia Brown - Munroe Falls
  14. Ezra Hosch - Mahtomedi, Minnesota
  15. Tim Swain - Concord, Massachusetts
  16. Patrick Tilley - La Mesa, CA
  17. B - New Yorik, NY
  18. Pam Weedman - Hot Springs, Arkansas
  19. Geoff Urwin - Warman, Saskatchewan
  20. Caroline Martin - Edmonton, AB
  21. Peter Lane - Québec, Canada
  22. tom graham - seabrook.nh
  23. Eric Kubilus - Bryn Mawr, PA
  24. Ayyappan Nair - Montgomery, PA
  25. Nicole Durtschi - Simi Valley
  26. Kellen Apuna - Pearl City, HI
  27. A. Algazzali - Hercules, CA
  28. Julie Desmeules - Quebec City, QC, Canada
  29. Bob Proctor - Elgin, Scotland
  30. Sharon Farris - Newport, DE
  31. Louis Hoeniger - Phoenix
  32. Richard Kaunroy - Philadelphia, PA
  33. Jill Kaminski - Floral City, FL
  34. Beko Binder - Pleasant Hill, CA
  35. Denise McLaughlin - Shalimar, FL
  36. David Hollie - Pittsburg, KS
  37. Andy Eckerson - Dighton, MA
  38. Erick Shore - Camas, Wa
  39. Aaron Polichar - San Diego, CA
  40. Frank Mantlik - Stratford, CT
  41. Sage Church - Willis, Virginia
  42. Michele Swartout - Red Bluff, CA
  43. Michael Scott - Levy Centereach, New York
  44. Gayle McKay - Columbus, OH
  45. Tabitha Olsen - Baltimore, Maryland
  46. Dean Shoup - Aurora, CO
  47. Jack Rogers - Mount Pleasant, SC
  48. Birding God - Home of Legends
  49. Dennis Troyer - Dundee, OH


How Did You Compare?

As stated in the quiz rules, answers must consist simply of the Common or English name exactly as it appears in the ABA Checklist.

The following list shows the number of submissions for each species guessed.



Lesser Nighthawk
53
Antillean Nighthawk
6
Eastern Whip-poor-will
1
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

 
 
 
 
 
 
 
 
 
 

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The photo and answer for this quiz were supplied by Tony Leukering.