San Luis Valley Birding

The San Luis Valley, nestled among towering peaks in southern Colorado, has always had an intangible allure to me. Perhaps it is is the rich history of Spanish conquistadors and early settlers, or that parts of it seem to be vestiges from a bygone era. The allure could also stem from its diverse avifauna and under-birded status. Regardless, I have long wanted to explore the valley thoroughly, and this fall I was afforded such as opportunity.

The sun had sunk below the Sangre de Cristos as we pace the rocky shoreline of Smith Reservoir. Hordes of waterfowl blanket the shallow water, and in the low light it is difficult to identify them. A few birds are close enough to view well through a scope, and among the large rafts of coots and Ruddy Ducks we spy a trio of early Bufflehead. The belt of cottonwoods and willows that line the lake are thrumming with fall migrants, including many White-crowned Sparrows, Yellow-rumped and Wilson's Warblers, and a single Dusky Flycatcher. As the light wanes, we race to get our binoculars on the flitting passerines before darkness engulfs the reservoir.

A fiery sun sets over Smith Reservoir in the San Luis Valley, which held throngs of waterfowl. The lush deciduous habitat on the shore was alive with migrating songbirds, especially sparrows and warblers.

It is mid September, and my family has made the multiple hour trip from the Denver Metro Area to the San Luis Valley. We have less than a day to bird as much of the valley as possible. Earlier that year, we had strategically planned the visit to coincide with the peak of songbird and shorebird migration through the valley. Planning was difficult, as their is a considerable dearth of reports on eBird from the valley. As a result, much of our scouting consisted of finding good-looking riparian corridors or wetlands on Google Earth. This strategy had mixed success; at times it paid dividends, at others it failed miserably.

A defunct train sits among the vast shrublands of the San Luis Valley near the town of Blanca.

The morning after our brief stop at Smith Reservoir, we decided to visit a disc golf course in the vicinity of Alamosa. It looked promising on Google Earth, with extensive cattail marshes and deciduous habitat, but one can never truly tell from the internet alone. Almost immediately after arriving we found our first good bird of the day. My brother, standing at the edge of a marsh, pished out a Northern Waterthrush from the thickets. It foraged obligingly for several minutes before receding into the willows, allowing us to obtain documentation. Waterthrush are rare migrants through the mountains, and this was apparently the first eBird county record.

We proceeded to work the riparian habitat for most of the morning, finding good numbers of warblers and sparrows. On the edge of a marsh, a high count of six Black-crowned Night Herons were perched up in a snag. Also present in the cattails were multiple Sora and an American Bittern. A few minutes before we left, I was tracking a sparrow flock in hopes of an oddity when two spizellas emerged from thick cover. One was a Brewer's Sparrow, drab gray overall with a muted facial pattern. The other was considerably brighter and more contrasty overall. I checked the diagnostic field marks: strong facial markings, unstreaked nape, buffy plumage. This was a Clay-colored Sparrow, a bird seen sparingly west of the Front Range.

Clay-colored Sparrow at the edge of a meadow along the Rio Grande River. The species is a rare migrant through the mountains.

Reluctantly, we left the songbirds to try our luck at waterfowl and shorebirds elsewhere. We soon arrived on the outskirts of Monte Vista, a small town roughly fifteen minutes west of Alamosa. Here we departed from the paved highway and onto a gravel road which had certainly seen better days. There had been good numbers of shorebirds reported here a few weeks ago, but in the absence of rain the seasonal wetland might have dried.

Pulling off the dirt road, we arrived to scan the first of the playas. Several yellowlegs and Least Sandpipers were the only shorebirds present, but we were hopeful that there would be more further on. Sure enough, upon reaching the second playa we were greeted with several dozen shorebirds, most of which were migrating snipes. Also present were several Solitary Sandpipers, a Western Sandpiper, and, best of all, a Stilt Sandpiper. Stilts are rare migrants throughout the mountains, and we were excited to see one from such close range.

A Stilt Sandpiper rests on a mound of earth in a playa along the Rio Grande River. These sandpipers are rare migrants in the San Luis Valley.

Continuing on, we reached an obscure water treatment plant several minutes from the Monte Vista. It had appeared promising on Google Maps, but I was wary that the ponds would be private. When we arrived, it seemed my fears had been realized, but after several minutes of searching we found a small knoll that afforded a panoramic view of the ponds. Along with good numbers of shovelers, Gadwalls, and wigeons, there were several phalaropes and teals foraging in the tepid water. Also present was a large flock of Yellow-rumped Warblers working a belt of cottonwoods vigor, but it seemed to be a homogenous group.

It was nearing midday and we were running behind schedule, so we decided to drive northeast for half an hour and forsake any birding of the riparian along the Rio Grande. After a brief stop at Blanca Wetlands yielded few shorebirds (but an obliging Virginia Rail), we continued on to San Luis Lakes SP. The lakes, set among vast expanses of saltbush and sage, are within several minutes of Great Sand Dunes National Park. Emerging from the car to scan the largest water body, we found a good portion of the lake to be blanketed with waterfowl. A quick scan yielded an impressive diversity of dabbling ducks, including three species of teal, shovelers, wigeon, and gadwall. We decided to settle in with the scope and do a more thorough scrutiny for unusual waterfowl.

Sure enough, several minutes in we were looking at a male Mexican Duck, the first county record on eBird. Although scarcely reported from the Colorado mountains, it seems the species might be more common there than expected. In the past several months, my brother and I have observed seven different Mexican Ducks (plus a brood) at elevations exceeding 7,000 feet. One explanation is that the species is often overlooked due to confusion with Mallards, which is more plausible than a recent influx north of its typical range.

Finishing our scan, we moved to the far northern side of the lake for different views. In addition to many coots and grebes, there was a sizable flock of 11 Red-necked Phalaropes, a Forster's Tern, two Franklin's Gulls, and a late Northern Rough-winged Swallow. The other wetland to the north which we had hoped would hold shorebirds had little of the sort, but an American Bittern was a nice consolation.

The next several hours were occupied by a long drive out of the San Luis Valley. Although rather desolate, the area has a stark beauty that made kept us interested.

As the sun descended, we made a final stop at Antero Reservoir in South Park. Conditions were poor so we stayed only briefly, but several Western Sandpipers and a Ferruginous Hawk were nice to see.

During the fully-day outing, we covered several hundred miles of the Colorado mountains and observed a host of interesting species. Weather was generally favorable, which enabled us to make the most of our opportunities. The diverse host of birds, coupled with grandiose peaks and fall foliage, made for a trip that I will not soon forget.