My Summer of Isolation and the Perched Nighthawks in Rovana


Adult male Common Nighthawk, July 20, 2022. Note the throat and the white subterminal bar on the tail. Photo: Jon Dunn

I live, by choice, in the northern portion of the Owens Valley, Inyo County, a long valley of some 100 miles. I am 12 miles north of Bishop on the southwest side of Round Valley, and at the base of an alluvial fan where Pine Creek passes through. It is a tiny mining community known as Rovana. The tungsten mine at the top of the canyon has long since closed, but the housing remains, and it is there on Idaho Street and earlier on nearby Nevada Street where I have resided for 22 years. Some thought I had moved from Nevada to Idaho, but here all of the streets have state names, none of which are called California where the community is located.

I live between two 14,000-foot ranges, which are snow covered in winter and sometimes (formerly, at least) for a good part of the year (October–July). Immediately to the west is the Sierra Nevada, which still has glaciers. It is one of the most significant ranges in North America in terms of the faunal (and presumably floral) differences between one side and the other, and with birds there are still a number of taxonomic puzzles to be unraveled (Bushtits, White-breasted Nuthatches, and Spotted Towhees to name a few). Across the valley are the White Mountains. The northern end of the range is in Nevada. That state’s highest mountain, Boundary Peak, is on the state line.

Adult female Common Nighthawk, August 7, 2020. Note lack of a white subterminal bar on the tail, present in the male. Photo: Jon Dunn

Owens Valley and the Status of Common and Lesser Nighthawks

The Owens Valley is an interesting mix of characteristics for both the Great Basin to the north and east and the Mojave Desert to the south and east. In California at least, it is an area where one can see the two species of widespread nighthawks in North America: the Lesser Nighthawk (Chordeiles acutipennis) and the Common Nighthawk (C. minor).

Common Nighthawk is the widespread, but declining, species across North America, including parts of California, particularly the Great Basin portions and locally (and declining) in some montane regions. In Southern California, a few are still found in the more eastern portions of the San Bernardino Mountains. Two observations of multiple birds in late summer, on July 28–29, 1978, and August 8, 1987, on Table Mountain in the San Gabriel Mountains of Los Angeles County near Wrightwood presumably involved post-breeding local movement. There is an historical specimen record, the only one from Riverside County, in the San Jacinto Mountains at 2600 meters on June 23, 1893. The Lesser Nighthawk is found mainly in desert regions but also along washes in the Central Valley of California and locally on the coastal slope of Central and Southern California. In eastern California it is found north to Bishop, and just barely across the Mono County line at Fish Slough.

In spring Lesser Nighthawks arrive here by late April, but for Common Nighthawks it is at least a month later, usually the last few days of May and the first week of June. I suspect most don’t arrive until early June. Reports in April, even early to mid-May, are likely all erroneous.

Nighthawks of both species are best viewed near dusk over ponds in the Owens Valley. At the southern end of the Owens Valley (based on one viewing near dusk near Cartago), most of the birds, perhaps nearly all, are Lesser Nighthawks, but in the northern Owens Valley, the ratio is closer to 50:50, and on the lower slopes (e.g., Baker Meadow, above Big Pine), all that I’ve seen are Common Nighthawks. Russel Kokx recently told me that around Lone Pine, Common Nighthawk is just a migrant, and in discussing the matter with Chris Howard, we think that a bit south of Big Pine might be the approximate southern limit for breeding Common Nighthawk on the Owens Valley floor. Keep in mind that breeders will travel a good distance for favorable feeding locations late in the day (e.g., over ponds).

At least from my experience, nighthawks seen naturally during the day (e.g., not flushed) are Common Nighthawks, and midmorning sightings of Common Nighthawks are routine, sometimes in small flocks as they hawk insects in the warming air. At Baker Meadow, sometimes there are Black Swifts too as they come over the Sierra from dozens of miles to the west (usually between 0700–0830). The swifts likely nest under remote Sierra waterfalls in Fresno County.

Dark juvenile Common Nighthawk, August 22, 2022. Juveniles of both sexes have a banded tail and lack a white subterminal bar. Photo: Jon Dunn

Nighthawk Identification

Living here and seeing them together in flight have led to an increasing level of confidence in identification. Common Nighthawks often fly higher and have a more punctuated (less fluttery) wing beat. They have a colder, grayer, and perhaps darker look. The white wing patch really stands out, in part because it contrasts with an otherwise blackish underside to the “hand” of the wing. On Lesser Nighthawks, there are buffy spots near the white patch that dilute the pale patch a bit, and on female Lessers, the color of the patch is buffy, unlike any age/plumage of Common Nighthawk, which always has a prominent and pure white patch—largest on adult males, smallest, on average, in young females (Pyle 1997). Juvenile Lesser Nighthawks lack the white patch (Pyle 1997). As widely advertised in field guides, the pale patch is closer to the tip of the wing on Lesser.

Less advertised is the fact that the wing tip of Common appears more pointed, and this is because the 10th and outermost primary is longer than the 9th. On Lesser the length of P9 and P10 is more equal, giving a more rounded wing tip. Overall, to me, the Common has a longer and disproportionately thinner “arm” on the wing and a longer and more pointed hand. Also, in summer Lesser Nighthawks molt on the breeding grounds, while Common Nighthawks don’t molt until they reach the winter grounds in fall in South America. Thus, any late-summer nighthawk in wing molt is a Lesser.

The call of the male Common Nighthawk, a loud peent, is a frequent summer sound in the skies above many portions of the Owens Valley, at least here in the north. From my experience, Lesser Nighthawks are much quieter, although they do have a purring sound that they give mainly (entirely?) on the ground. The Sibley Guide to Birds compares it to the evenly pitched trill of an Eastern Screech-Owl.

Adult male Common Nighthawk, June 28, 2022. Photo: Jon Dunn

Isolation

I have led tours for Wings for some 45 years and am still a leader at 68, hearing aids and all. After two Covid years, we finally had something approaching regular tours. In late May of 2022, I went to Alaska, and when I returned on June 10, I caught Covid, either on the flight or, more likely, at a crowded LAX before my second flight to Reno. I tested positive on the 14th. Symptoms seemed like a minor cold, except for a little foggy-headedness. I was vaccinated and boosted. I felt fine by the following Monday (the 19th) and celebrated my birthday at home with a negative home test. During this time, I walked alone through my neighborhood, my usual beat, and continued to do so on a regular basis throughout the summer, apart from two birding tours when I was away.

Pale juvenile Common Nighthawk, September 2, 2022, the last date I photographed it. I photographed the darker juvenile as well.

Dark juvenile Common Nighthawk, August 31, 2022. Photo: Jon Dunn

Perched Common Nighthawks

Here in Rovana, only Common Nighthawk has been recorded. During the summer of 2022, unlike, say, the past decade, I had perched Common Nighthawks all summer (June 10–September 3) in trees just two doors down on Idaho Street; they were sometimes perched in trees in my yard. Sometimes there was one, but often there were two, and on more than a few occasions there were three, once even four. Nearly all were males and nearly all were in two adjacent trees. I kept track of them and kept notes on their behavior.

I heard my first one on June 10 and a few days later (during the day) heard one call seemingly from a tree, but I didn’t see it. On the 18th I heard one in late morning from my house. I suspected it was perched since I couldn’t see it in flight, yet could still hear it repeatedly close by. I found it on a branch and watched it call with binoculars. On the 22nd I heard it call again at about the same time in the morning. I grabbed my scope and found it on the same branch, where it remained all day. I set up the scope and watched it call in sequences over 30 minutes or so, each time delivering its characteristic and loud peent. Since I was so close, I was able also to detect a soft, low, rattle, or grrrr note just after the characteristic peent. Each time it called, it would lift its tail and slightly vibrate its body and open its mouth wide. The bird would call five to ten times and then would tire and gradually close its eyes. A few minutes later, the eyes would open again, and out would come more calls, and the sequence would be repeated.

On the 28th, a day with three males in one tree (joined by a fourth male later in the afternoon), I got to see one rotate its body on the branch. The movement was initiated by rocking movements, and then it would rotate 90 degrees or even seemingly 180 degrees. I presume this was done to get its head out of the sun. I saw this rotation on several birds, but on other days I noted the body position of a perched bird had changed during the day, even though the bird was sitting in the same exact location.

While I watched a male call on a branch on multiple occasions (latest one calling was on August 7), more typically they were silent when perched. The only females I saw were one (or more?) on July 9 and 10 and August 7. The one I saw on the 10th was flushed from a conifer. It flew by a perched male, which promptly called peent in response, as if to say, “Hey, I’m over here.” I presume the females mostly roosted on the ground, presumably on eggs in the sagebrush that surrounds Rovana. They are easily sexed when perched, as the females lack the distinct white subterminal bar of the adult male on the outer tail feather (see photo). Juvenile males also lack the white bar on the outer tail feather. Adult males also have a distinct white throat patch.

Adult male Common Nighthawk, July 20, 2022. Note the prominent white subterminal bar on the tail on the outer tail feather on each side, exhibited as a white band across the tail. This mark can be seen in flight from below, if the distance is not goo great and the light is good. Photo: Jon Dunn

On August 22, I saw my first juvenile perched in the two trees, and on the 23rd, I saw a second, a much paler juvenile perched at a distance. From then on until September 3 when I left for the WFO Reno conference, I saw one juvenile, or more often both, the dark one and the distinctly paler juvenile. The adult male was also present on August 22 and 24, but no adults were seen afterward. The juveniles were gone when I looked on September 12 and afterward.

Discussion

During my observations, I looked through my Birds of North America species account and found the one written by Poulin et al. (1996). Under “Sounds” (Vocalizations), they state “nasal peent or beernt produced during level flight by both sexes (fig.3), yet the text under fig. 3 says, “Peent call given by male during its booming display.” I can say that from my years of experience here in Rovana and elsewhere, only the male gives this call. Under behavior (ibid) I found nothing about movements on a branch, but Kimball L. Garrett recalled seeing this behavior once on a roosting Common Poorwill on the ground. I haven’t taken the time to research behavior in other nightjar species.

I was curious about the two juveniles (easily aged by distinct pale primary fringes) and wondered why they were different colors. Puolin et al. (1996) cite Goossen (1986), who observed distinct color variation in juvenal plumage in subspecies minor and hesperis in southeast British Columbia, and suggested that these differences reflected “plumage dichromatism.” However, in a detailed later study, Dickerman (1990) showed such differences in color probably represented individual variation. Dickerman (ibid) also indicated that the juvenal plumage differed strongly by subspecies. I remember Robert Dickerman setting out for me the juvenile specimens by subspecies at the United States National Museum (Smithsonian) in Washington, DC, back in 1981 or 1982. I was particularly taken by the pale silvery-gray subspecies (sennetti) from the northern and central Great Plains and as a result added this figure for the first edition (1983) of the National Geographic Field Guide to the Birds of North America. For the sixth edition (2011), that figure was repainted by T. R. Schultz and we added juvenile western hesperis. Within the United States, juveniles of the eastern subspecies are dark, but hesperis is (or can be) rather dark and henryi of the Southwest is quite rufous.

Common Nighthawks almost invariably have an egg clutch size of two (Poulin et al. 1996). It is tempting to think that the two juveniles, usually in the same tree each day, were siblings, but I can’t prove this. Interestingly, on August 30 I saw both juveniles in the morning, noting their locations. When I returned in the afternoon, the dark juvenile was at the exact same spot on the branch where the paler bird had been; the paler juvenile was now on another branch (sibling dominance?). Poulin et al. (1996) state that Common Nighthawks usually perch horizontally, parallel to the branch, rarely perpendicular to the branch. The nighthawks I studied followed the perching protocols for the most part, but at least on August 31 the pale juvenile was perched crossways to the branch.

Pale juvenile Common Nighthawk, August 31, 2022. Photo: Jon Dunn

Another aspect I thought about as I watched these birds is how I could basically walk right up to the trees, even nearly the branch, where the Common Nighthawks roosted. On only perhaps one, or two, occasions did they flush. I thought about my experiences at the south end of the Salton Sea where Lesser Nighthawks routinely roost in trees and then fly before I even get near the tree. I talked about this with Guy McCaskie, who visits the Salton Sea weekly during the summer. He confirmed that being easily flushed is absolutely typical of Lesser Nighthawks. I thought of the recently split Mexican Whip-poor-will (Antrostomus arizonae). From my limited experience, although they sing at dusk from elevated tree branches, they roost on the ground and are easily flushed well before one is near. Every roosting Eastern Whip-poor-will (A. vociferus) I’ve seen (25 plus) during the day was perched on a log or up in a tree, usually at about eye level or slightly above or below, occasionally high up, and simply didn’t move, even with a very close approach. The point is that even with related species, their behavior might differ; it has to be noted and considered, and then researched.

Common Nighthawks in Migration in the Southwest

My final thought about Common Nighthawk concerns its status in migration in the Southwest, where it is essentially only an accidental migrant. The only record in southeast California is a specimen from Bard (October 16, 1924), although there are sight records from Death Valley and in northeastern Kern County, both not far from where they breed. It is unknown from southwest Arizona (Phillips et al. 1964). Commons are also of no more than casual occurrence on the Southern California coastal slope. One much-watched, photographed, and late (latest for California) bird was seen along the Santa Ana River (Anaheim Hills) in Orange County from October 21 to November 10, 2018.

So how do all of the breeders here in the Great Basin, including those in Inyo County, migrate? I wondered if they flew very high and were missed, but on multiple occasions and locations in the East, I have watched birds near dusk migrating at normal heights. In reading Phillips et al. (1964) regarding Arizona, where henryi is the breeding subspecies (the bulk arrive in early June), hesperis is a regular migrant (first half of June, mid to late August) through northern Arizona. Perhaps the California breeders entirely avoid the southwestern deserts, adjusting their migrations accordingly. All subspecies of Common Nighthawks winter in South America, mostly in the central and southern part of the continent, east of the Andes. I add that if one doesn’t have Birds of Arizona (Phillips et al. 1964), try to find a copy. Phillips (as told to Joe Marshall) is at his best in discussing and explaining complex patterns of distribution and the appearance of subspecies within a polytypic species in an understandable manner. I consider him to be the David Quammen of ornithology.

At some point I ran into a neighbor, Gary Milano, who lives on Dakota Street, a fellow naturalist. He proffered that he had been watching the roosting nighthawks in his trees and said that he had seen them well and seen them rotate on the branch. I nodded my head and knew exactly what he meant. Just take the sustained time to look.

—Jon Dunn

Acknowledgments

I thank my colleague Kimball L. Garrett for reviewing a draft of the article. I discussed the distribution of Common Nighthawks in the Owens Valley with both Chris Howard and Russel Kokx. Russell, in particular, gave me a different perspective about the status in the southern part of the valley. Ryan Winkleman provided the dates and exact location for the recent record of the Common Nighthawk from Orange County. Lara Tseng provided technical assistance.

Literature Cited

Dickerman, R.W. 1990. Geographic variation in the juvenal plumage of Common Nighthawk (Chordeiles minor) in North America. Auk 107:610-613.

Goosen, P.J. 1986. Apparent dichromatism in juvenile Common Nighthawks (Chordeiles minor). Murrelet 67:62-64.

Phillips, A.R., J. Marshall, and G. Monson. 1964. Birds of Arizona. University of Arizona Press.

Poulin, R.G., S.D. Grindal, and R.M. Brigham. 1996. Common Nighthawk (Chordeiles minor). In The Birds of North America, No. 213 (A. Poole and F. Gill, eds.). The Academy of Natural Science, Philadelphia, and the American Ornnithologists’ Union, Washington, DC.

Pyle, P. 1997. Identification to North American Birds, Part 1. Slate Creek Press.

 

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  1. That’s a terrific account, Jon. Thanks much for reporting such details. Too bad the species is declining everywhere, but we’ll keep watching them whenever we can.

  2. I’m tempted to write a poem about Common Nighthawk based on your observations. You’ll have the dubious distinction of being one of the first to read/ignore it!

  3. I really enjoyed your article. It was a wonderful discussion. Nice that you could view these birds repeatedly and close to where you live.

    I know very little about nighthawks but have been fascinated by the fact that both species can be found in Florida. When I first met you, in May of 1980, we had CoNi on at least 7 days of our Wings trip. Years later, I learned that LeNi winters in south Florida, especially around the Everglades. I have seen large numbers of them there feeding at dusk ( identified by others) and I photographed one on a branch at Loxahatchee once.