On January 15, my daughter and I were out at Al Asfar Lake in Al Ahsa, conducting the first of a series of shorebird surveys for 2021. Scanning an expanse of marsh to the east of the lake proper, we spied a Golden Jackal moving through the sedge, my second encounter of the winter. Further on, in a gathering of Barn Swallows over 420 meters (1,375 feet) out, there were a few Riparia swallows, one of which looked good for a Pale Sand Martin Riparia diluta, an uncommon to rare winter visitor to the UAE and Oman from Central Asia (see the annotated checklist of UAE birds). On account of the unfavorable distance and the fact we had a survey to finish—a slog of an endeavor given the sheer number of shorebirds around—we carried on our way. I was struck then, however, by the thought that Pale Sand Martin may have wintered at the lake, as I first encountered the species there the end of October and then again every subsequent week after for nearly a month.
On October 30, 2020, I found a pale Riparia speciesbut only managed some low-quality shots of the bird as it perched on some loose reed stems with a few Barn Swallows. I observed it at length through my scope, however, and noted light-brown underwings, which the Birds of the Middle East—the only regional field guide—mentions as one of the key field marks. Owing to less than satisfactory images, I returned the following weekend and relocated a similarly pale Riparia. This time, however, it seemed that there were two in the larger flock of Hirundines. To make sure I had enough frames to support the ID, I shot only video, paying special care to capture the underwings. The flock was even farther away than the previous weekend, but the footage strengthened my initial ID. There were a couple Common Sand Martins Riparia riparia present this time as well, showing dark-brown upper parts, breast-bands, and underwings for comparison.
I subsequently returned to the lake, twice more, found what I was now confident were Pale Sand Martins, and captured even more footage. By and by, I had gathered enough that Dr. Manuel Schweizer, an expert on the species from The Natural History Museum of Bern to whom I reached out, confirmed them as Riparia diluta. The only other record of Pale Sand Martin from Saudi Arabia came from Richard Meinertzhagen in 1948 near Mecca; however, according to Guy M. Kirwan & Andrew Grieve (2013), this record had been “largely ignored in subsequent literature” on the species’ occurrence in Arabia and then ultimately proven by the authors, who examined the specimen among others from Meinertzhagen at The Natural History Museum at Tring in the UK, to be a misidentified Common Sand Martin. That means the birds out at Al Asfar Lake represent the first confirmed record of the species in Saudi Arabia.
Dr. Schweizer and Raffael Aye’s article “Identification of Pale Sand Martin Riparia diluta in Central Asia” was particularly instructive (2007) in helping me build the case for their identification. Initially three field marks, those mentioned in the Birds of the Middle East, led me to think these were Pale Sand Martins out at the lake—light gray-brown upper parts, diffuse and partial breast bands, and light-brown underwings. However, according to Schweizer and Aye, dark eye sockets and lores contrasting with a pale forehead, crown, nape and pale ear-coverts that shade gradually into the white throat are more reliable features on R. diluta. While there are subtler differences between R. diluta and R. riparia, such as wing length and tarsal feathering, this suite of field marks proved critical for clinching the ID of the Riparia swallows at Al Asfar Lake, especially given the challenging conditions.
The biggest challenge I’d faced in IDing them was the ever increasing distance between my position on a utility road on the southern edge of the marsh and the patches of loose reeds where the swallows were gathering. After the first two weekends, subsequent observations were made at no less than 400 meters, which, in the good light of early morning, was just manageable through my 60x spotting scope at full zoom. However, my images and videos, while retaining reasonable color fidelity and ultimately enough detail to clinch the ID, lacked the finer definition they’d need to be considered even remotely “good”. When my daughter and I found the Riparia swallows again this past January, I resolved to address the one thing that had vexed all my previous attempts at better images—the distance—and the only way to do so? Get a pair of waders!
After buying a pair at our local Al Rimaya branch, I met Adam Harris out at the lake the following weekend, but a steady, bone-chilling wind out of the north—what locals call the “shamal”—put off any thought of donning waders and slogging out into the marsh. The swallows weren’t to be seen either way, and most other birds in the area appeared to be laying low as well. I went back out by myself the next Friday, January 29, and found the swallow flock in the same place my daughter and I had seen them two weeks prior, a few Riparia in the mix. I excitedly got my gear on and starting cutting a beeline straight out across the marsh towards the patch of loose reeds where the swallows would return to perch and preen between feeding forays. About half way out I set up the scope and scanned the flock, just to the left of about a dozen and a half Barn Swallows were two good candidates for Pale Sand Martin. While still too distant for the kind of shots I was hoping for, I waited until they took off again and continued closer. I got within 30 meters of where they were perching and then staked out the spot for over two hours, kneeling or sitting at times in the shallow water to rest my joints. Two hours and the whole time and only the Barn Swallows returned to the patch. I couldn’t believe it. The Riparia were nowhere to be seen. I went back the next day, hoping that I might have simply disturbed them and they’d return. This time, despite nice conditions in the morning, all of the swallows, barring two Barns, had appeared to have cleared out. It was frustrating, but so it goes. Saturday’s slog out into the marsh, however, wasn’t a total disappointment. I ventured further than the previous day and had a lot of great encounters, including my first Jack Snipes in Saudi. After flushing one nearly underfoot, a little further on I kicked up another six in short order, most of which cut a few circles around me before dropping back out of sight a short distance away.
Then on February 12, while conducting the second shorebird survey out at the lake, I spotted an even larger flock of Riparia along with about two dozen Barn Swallows in the same spot as before. This was my chance. I pulled my waders on, grabbed my gear, and tromped out once again. This time I was able to approach quite close. Among the Barn Swallows, there were around 10 to 12 Pale Sand Martins along with a few Common Sand Martins. The flock was quite active and flighty, but I was able to capture more video footage and images at a distance that revealed them to be unquestionably R. diluta. The Pale Sand Martinswere molting their flight feathers and preening feverishly, which may have been why they were more obliging this time. I’m hoping the preening means that they’ll remain a few weeks more and with luck I’ll be able to obtain audio recordings as well.
Below I discuss some of the key features to consider when trying to distinguish between Pale Sand Martin and Common Sand Martin so that perhaps, in time, with more records we can better understand the status of this visitor from Central Asia in Saudi Arabia. This is particularly important as the primary regional field guide—The Birds of the Middle East—fails to discuss a couple key field marks that I subsequently discovered, through research and my correspondence with Dr. Schweizer and Oscar Campbell, who’s recorded Pale Sand Martin several times in the UAE, are more reliable than the oft-noted diffuse or absent breast-band. I found Dr. Schweizer’s article “Identification of Pale Sand Martin Riparia diluta in Central Asia” particularly instructive (2007), especially his wonderful side-by-side comparisons of both species, one of which he graciously allowed me to include in this post.
The Jizz and Tail Forking
Even in the rough footage taken on November 13, 2020, the jizz of the Riparia on the left points strongly towards Pale Sand Martin, especially when we have a Common Sand Martin perched to the right of it on the same reed stem for comparison. The head, back, and rump of the bird on the left is gray-brown, contrasting with darker flight feathers; whereas, the Common Sand Martin to the right has uniformly dark-brown upperparts. While not immediately noticeable, there is also a difference in size between the two birds, with the putative Pale Sand Martin appearing marginally smaller than its darker congener. While perhaps harder to judge in the video for certain, there also appears to be a difference in the degree of forking in the tails of the two birds. Common Sand Martin has a more deeply forked tail than Pale Sand Martin, a comparison that can also be made in places in the footage. In the image below, taken on February 12, we can also clearly see the difference in coloring between a Pale Sand Martin (right) and a Common Sand Martin immediately to the left of it. The latter does appear slightly larger than the former as well. Tail forking is harder to judge in this image however.
The size and color difference between the two Common Sand Martins (uppermost) and the four Pale Sand Martins, among other distinguishing features are clearly discernible in the above image.
Breast-bands and Underwings
I should lead with the caveat that a diffuse or ill-defined breast-band on a Riparia should probably only be used to ID Pale Sand Martin if other key features line up. The reason, as indicated in the Birds of the Middle East, is that young Common Sand Martin frequently show a less defined breast-band than adult birds. Given how light, angle, distance, and the relative neatness of the breast feathers can affect how dark, broad, and extensive a breast-band appears, the gathered impression from video footage outweighs that of any single image or still in the absence of other field marks. In Pale Sand Martin, the breast-band could be complete but diffuse, growing fainter towards the center of the breast, or nearly absent with perhaps only light vest-like smudges extending from under the wings. Discussion, in fact, of breast-bands, I would suggest, should also include consideration of the underwing coloration as well, as the dark-brown underwing of Common Sand Martin often appears to coincide with a concolorous, if variably intense, breast-band. The same applies to Pale Sand Martin, which, as can be seen in the screenshot below from one of the videos I shot on February 12, shows a nearly concolorous underwing and breast-band.
A Pale Sand Martin (center) showing a light gray-brown underwing and similarly colored breast-band
A rather worn Common Sand Martin showing a darker brown underwing and breast-band
The Face and Head
Ultimately, it was Dr. Schweizer’s article on IDing Riparia diluta that helped break the stalemate and bring a month’s worth of second guessing into the end game (2007). Two key features on Pale Sand Martin he calls attention to that I’d not yet seen mentioned in the other literature I’d read are dark eye sockets and lores contrasting with a pale forehead, crown, nape and pale ear-coverts that shade gradually into the white throat. The face and head on a Common Sand Martin, on the other hand, are generally a similar dark brown to the rest of the upperparts, including dark, well-demarcated ear-coverts. These features of the Pale Sand Martin show sufficiently well enough in my video from November 6, 2020, and, according to Dr. Schweizer (per comm.), clinched the ID, especially those including Common Sand Martin for comparison, such as in the video from November 20, 2020, at perhaps the greatest distance yet. Both species can be seen fairly close to each other, both facing towards the camera, starting at 1:08. Thankfully, the images and videos from February 12 show these key features much more clearly.
A Pale Sand Martin at Al Asfar showing the distinctive dark eye sockets and lores and pale ear-coverts.
Pale Sand Martins at Al Asfar showing the distinctive dark eye sockets and lores and pale ear-coverts.
A Common Sand Martin (left), clearly darker than the Pale Sand Martin (right), showing a dark brown head and dark, well-demarcated ear-coverts
On February 26, I was able to capture some vocalizations of the Pale Sand Martin. I even manage to shoot some video of a bird vocalizing from its perch; unfortunately, however, the image is out of focus.