Ammodramus

 Ammodramus

This October, we had the good fortune to get looks at a Nelson’s Sparrow. It was a rare opportunity to experience one of the most secretive birds in North America. It marked only about the fourth time I have seen one of these stunning, intricately marked, colorful seed foragers. Other birders had found this individual on a farm about an hour south of us. The orange-colored wonder has been there for about a week, a surprisingly long stay this far north for a long-distance migrant, headed for the Gulf of Mexico or the southeast coast of the US. They breed along the shores of Hudson Bay and in the great plains in far northern Canada. Another race of Nelson’s breeds along the coast of Maine.

Nelson's Sparrow, Tullando Farm, Orford, New Hampshire, Oct 2024.

Nelson’s is in a distinctive group of sparrows that are all beautifully patterned and maddeningly hard to see. I like to refer to them as Ammodramus, a genus name that once contained seven similar-looking species. (The name is no longer accurate, since taxonomic gymnastics has resulted essentially in a split between Ammodramus, Ammospiza, and Centronyx. But Ammodramus is a convenient shortcut name, if not entirely accurate. See J.D. Rising and D.D. Beadle, The Sparrows of the United States and Canada, p. 143.) Ammodramus is Greek for "sand runner," which would seem to refer to its habit of walking in marshes in winter.

In my early years of birding, I would flip through the field guide and wonder about the things I still had not seen. The couple of pages of Ammodramus seemed like a complete mystery. Their orange-tinged heads made them look different from all other sparrows. They did not seem to come up in conversation with birders because nobody had a reliable location to go see one. All of them have a habit of staying hidden in thick vegetation in marshy areas or in dense grasslands. It would be many years before I would manage to get looks at them, always by way of information shared among birders.

The most common of the Ammodramus is Grasshopper Sparrow. It also has the largest range, inhabiting most of the North American continent, save for the areas that are grass-free due either to low rainfall or overgrazing or both. In the 1980s-1990s, they were breeding birds at the Las Vegas National Wildlife Refuge, a great place for birding not far from where I lived. This refuge is grazed by cattle, but lightly, and it managed to hang on to some quite fine patches of tall grasses. The decline of Grasshopper Sparrow at this location is mysterious; I am guessing that some complex set of climate factors is to blame, or some subtle shift in the species makeup of the grasses. But the sparrow can still be found in many parts of the country. Sadly, however, surveys demonstrate a national decline in numbers that is the subject of current investigation.

Grasshopper Sparrow. Ohkay Owingeh pueblo, New Mexico, April 2018.

Grasshopper Sparrow showing its characteristic flat head.
Ohkay Owingeh pueblo, New Mexico, April 2018.

Seaside Sparrow, the least colorful member of Ammodramus, is reasonably reliable in Delaware marshes, but restricted to shoreline habitats to a remarkable extent – it never shows up anywhere else.

Seaside Sparrow, Marvel Saltmarsh Preserve, Delaware, May 2021.

So that’s it. The rest of the Ammodramus fall into the category of Ridiculously Hard to See. They don’t move around or sing loud like other sparrows. They breed in far-away lands, and winter at scattered places in the Southeast where birders seldom go. On migration, they generally don’t stay in known locations. They stay under cover – like, all day, every day. They see birders approaching from a long distance, and start to ridicule us. “Hey, it’s about time to sit in this bush and preen for a while,” they think. “That dude with the binoculars doesn’t stand a chance.”

Saltmarsh Sparrow is so restricted in distribution now that I know of only one location for it: the Marvel Saltmarsh Preserve in Slaughter Beach, Delaware. This spot was saved from the bulldozer in the 1980s. Today it is a beautiful expansive stretch of saltmarsh, filled with bitterns rails, herons, and harriers.

Marvel Saltmarsh Preserve. May 2021.

 Stand on the boardwalk here and look out for the tiny shaking of a branch that reveals a bird. I have heard them sing, or “sing,” only at sunrise and well after sunset. The “song” is a strange, mildly insect-like exhalation of breathy sound. (I suspect the song evolved to propagate in the frequent winds that blow.)

Saltmarsh Sparrow, Savage's Ditch, Delaware, November 2020. There are a few records here.

Baird’s Sparrow, Henslow’s Sparrow, and LeConte’s Sparrow are the midwestern members of Ammodramus. Baird’s moves south in the fall and scatters into huge areas of scrub (or former Chihuahuan desert grassland) of the American southwest and (mostly) Mexico. They like to stay on the ground when wintering, and usually walk away from an approaching birder and disappear between plants. This area has been devastated by livestock grazing, making the birds even more scarce than they would otherwise be. My only sighting lasted a fraction of a second, a bird scampering away from me after an five-hour search in early January near Deming, New Mexico. Henslow’s Sparrow is rapidly declining because of grassland loss to agriculture and urbanization. My only sighting was in far western Maryland, where coal mining sites have been converted to artificial grasslands high in the Appalachians that seem to substitute for their preferred prairie habitat.

LeConte’s Sparrow breeds in the Midwest (mostly Canada) and winters in the American southeast, where it is so thinly distributed that it is hard to locate. It may be the most beautiful species in a genus known for its good looks. I have observed it only twice, when a migrant bird stopped for a few days beside a hay field in Maryland, and when a few of them accidentally found themselves beside a reservoir in eastern New Mexico for the winter (thanks, Bill West). The species seems to be holding its own in numbers, but then again, very little is known about it and future research might paint a different picture.

LeConte's Sparrow, Mt. Pleasant Farm, Maryland, Nov 2020.

Nelson’s Sparrow allegedly winters in the marshes in Delaware. But very few are actually detected each winter. I found my first one at a southern Delaware marsh known as Savage’s Ditch, when it raced ahead of me on a wet path and perched for a minute or two about a foot off the ground, on a mostly obscured perch. They occur annually in a marsh near Burlington known as Delta Park, but not when I have visited! So it was good news indeed to hear that we could enjoy the bird a second time at the edge of a large dairy farm in New Hampshire. This bird is using a tiny fragment of habitat, a muddy puddle where runoff accumulates and a few tall grasses grow beside a cornfield (yet another example of opportunism on migration). We stopped there and waited for a half hour, before it was betrayed by tiny movements of branches. Characteristically, it hopped just a few inches from branch to branch, and also walked a bit on the mud while looking for seeds. It never stayed in view for more than a few seconds. (I got photos only by way of a determined effort.) The golden color of the bird’s head seems to scream out “I’m not like the other sparrows.” This pattern is clearly camouflage for when it is wintering among brown stalks in the marsh. But its beauty is obscured by its habit of staying deep in the vegetation, and refusing to produce the kinds of chips that the common Song and Swamp sparrows give so frequently in the same habitat. Nelson’s Sparrows keep it quiet and mysterious.

The loss of marshes, especially salt marshes, is one of the most serious environmental problems of our time. I am still educating myself on the issue, especially on salt marsh restoration. Here is some of the latest information on measuring the loss of global salt marshes. And here is a small sample of information on what is being done to restore former salt marshes.

 For further reading about Ammodramus, be sure to check out the book by James Rising and David Beadle, The Sparrows of the United States and Canada. Shockingly, it seems to be out of print, but there are copies available on the usual used-book websites.

 

Opportunism

 Opportunism and bird migration

Pondicherry National Wildlife Refuge, New Hampshire

Migration for this autumn season brought a few nice surprises to our area. In late August and early September, we enjoyed the usual warbler show in our driveway, where a line of Balsam Firs provide a suitable place to forage. We had Cape-May Warblers, Bay-breasted Warblers (a few with some bay still on the flanks), American Redstarts, many Black-throated Green Warblers, one snazzy Wilson’s Warbler, Black-and-white Warblers, Tennessee Warblers, Nashville Warblers, Common Yellowthroats, Northern Parula, Magnolia Warblers, Blackburnian Warblers, Chestnut-sided Warblers, Yellow-rumped Warblers, Red-eyed Vireo, Blue-headed Vireos, and a few Scarlet Tanagers. Not bad.

Wilson's Warbler, Danville, Vermont. Peeking out from the interior of the vegetation.

Black-throated Green Warbler in its fall plumage. Newport, Vermont

Each migration season brings a reminder that birds have been such a successful life form due in part to a facility for opportunism. Migrating birds need stopover points with abundant food to fuel the long journey. They will be found in the kind of undisturbed habitat patches that you read about in field guides. But in addition, they are found in transient patches that just happen to arise on the route. The birds don’t seem to care whether the food (insects and caterpillars, for warblers and vireos) is provided by mature forests or by gardens and back yards. Shorebirds, herons, and egrets are drawn to healthy wetlands, but man-made wet areas will do, at least for a few hours or days of the journey. To be sure, all forms of wildlife seize on opportunities to feed, but the special mobility conferred upon birds gives them an extraordinary ability to find the smallest bit of far-flung habitat.

The local community of birders in my area has helped me to find a few of these patches. A cornfield beside the Passumpsic River in Saint Johnsbury has drawn in dabbling ducks in spring and fall, when either rain or snowmelt fills it up to a suitable level. Fruit trees around our grocery store parking lot sometimes bring in Bohemian Waxwings in the winter. Shorebirds will make use of flooded farm fields, too. I have spent time tracking down Upland Sandpipers and Buff-breasted Sandpipers in Delaware ag fields (especially sod farms), and I’ve seen Greater and Lesser Yellowlegs and Killdeer in fields close to home.

Birders are no less opportunistic than the birds. If the birds happen to be there, why not stop and look at them? Even when the scenery is – ahem -- not winning any awards, shall we say.  In New Mexico, west Texas, and Arizona, sewage treatment plants become an accidental food source to shorebirds, dabbling ducks, and herons. The Tucson sewage plant is famed among birders: I went there once for a Least Grebe, a rarity from south of the border. (It is comically named "Sweetwater wetlands.") We once ventured to the sewage plant of forlorn Lordsburg, New Mexico to see a Black-bellied Whistling Duck. Similar ponds in New Mexico gave me a chance to see White-rumped Sandpiper, Semipalmated Plover, Short-billed Dowitcher, Wilson’s Phalarope, Red-necked Phalarope, Baird’s Sandpiper, and Solitary Sandpiper. All of these were in places that were arid for tens of kilometers in all directions. (Except for the Rio Grande, which does not form mudflats that attract shorebirds, having been channelized by order of state legislatures.) It demonstrates how shorebirds, while flying thousands of miles south in the fall, mostly over dry land of the interior US, will not pass up an opportunity to exploit a wetland, small though it may be. A sewage pond lacks mud, the key ingredient for shorebird dinner, but it does possess insects in copious numbers.

In Vermont this fall, a birder alerted me to a Solitary Sandpiper in a flooded pasture nearby. Intrigued, I went there and found a pair of Stilt Sandpipers, a rarity away from lakes and oceans (at least in the East). The spot, on Old Silo Road near Barnet, is interesting. In the floodplain of the Passumpsic River, water collects there in spring and fall for a few weeks at most, before disappearing by evaporation and slowly draining to the river. Hoof action from the cows gives rise to mud and shallow puddles that mimics the mudflats around marshes. It becomes a bit of a shorebird magnet. Solitary Sandpipers were there for the whole season. The pair of Stilt Sandpipers stayed only a day (so far as we know). But what a day it was, for the nutritional requirements of a long-traveling sandpiper. Stilt Sandpipers breed in the Canadian arctic, and then fly as far south as Argentina – thirteen thousand kilometers to the wintering grounds. That requires a whole lot of calories.

Stilt Sandpipers in a farm field, Barnet, Vermont

Other birders found a group of gulls at Moore Dam, on the Connecticut River on the state line between New Hampshire and Vermont. I have visited the spot many times in the last few years, with almost no result. The Moore Reservoir just doesn’t seem to do much for avian wildlife. My suspicion is that the water level is yanked up and down to satisfy hydroelectric power demand, and this wreaks havoc with the aquatic food chain. Industrial pollution from past mill operations is also a factor. Ducks and loons just can’t find much to sustain them. Gulls have been few and far between. But in late August, a small group of gulls found their way to the dam, perching on those red buoys guarding the dam structures. The birders found the usual Ring-billed Gulls and Herring Gulls, but also a few Great Black-backed Gulls. The last of these is mostly coastal in distribution, but also makes use of the Great Lakes in winter, and sometimes the Connecticut River farther south. A sharp-eyed observer found that one of the larger gulls didn’t quite fit the pattern, and called out a Lesser Black-backed Gull among them – a coastal bird for sure. That drew another birder, who noticed a small, brown-colored bird in the flock that proved to be a juvenile Laughing Gull. Another coastal species. Yet another birder noticed a tern, which proved to be a juvenile Forster’s Tern. This one uses the interior of the continent routinely, but is rare this far north. These birds were joined by one juvenile Bonaparte’s Gull, an uncommon visitor to the area.

Laughing Gull, out of place at Moore Dam in New Hampshire

What was going on here? A few days prior to the gulls’ appearance, Hurricane Debby pushed through the southeastern US. (It hit South Carolina in the first week of August.) Storms have a way of stirring things up for birds. High winds will push a few of them northward. Some of the birds, especially juveniles with no experience, will drift inland. When the winds dissipate, the birds will find some suitable patch of habitat to land on. In this case, the Moore Reservoir on the Connecticut River was the draw. I observed this flock for several hours spaced across a few weeks of time, and I almost never saw them feeding successfully. They perceived the large body of water to be appropriate, but (being mostly juveniles) they did not recognize that there was very little food there. They eventually shipped out and likely joined their compatriots in better parts to the south. Opportunism drove them to make use of Moore Reservoir, but it was a short-lived impulse.

The ultimate example of opportunistic use of “habitat” must be an example from the northeastern US. Dairy farms generate a lot of manure, which is collected and processed for spreading on hay and corn fields. Manure is initially stored in an open pit, where it becomes a breeding ground for insects. Passing shorebirds take notice. In Vermont, a few of these pits become some of the best places to find shorebirds, since natural mudflats are almost impossible to find. This fall, I found a juvenile Baird’s Sandpiper at a pit near Hardwick. There were large numbers of Least, Semipalmated, Solitary, Spotted Sandpipers, and Killdeer at the same spot. Birding at a manure pit makes birding at a sewage plant seem positively fragrant.

Baird's Sandpiper, at a manure pit near Hardwick, Vermont

Clearly, patches of habitat are needed by migrant birds moving long distances in August, September, and October. What can humans do to help? First of all, we need to care for our wetlands. We have been altering them for human uses and human convenience for centuries. Many wetlands – thousands of square miles worth – have been altogether destroyed. Many have been modified in a quest to reduce mosquito-borne malaria. Many midwestern wetlands have been filled in to grow crops. Although it is hard to quantify, these actions have certainly resulted in population reductions for birds amounting to millions, and perhaps a billion. The modern form of ecological science has begun to quantify the damage, but much of the loss cannot easily be reversed without economic disruption to coastal city populations of people like you and me.

Second, we need to improve the way we manage the wetlands that still remain. Water levels can theoretically be managed carefully to sustain mudflats. This is true for both private and public lands. Reservoirs are mostly managed by the Army Corps of Engineers and the Bureau of Reclamation. Both have dreadful histories of monitoring wildlife populations on and near reservoirs and in the rivers they are situated on. The agencies comply with the Endangered Species Act, but just barely, and often only under pressure from conservation group lawsuits. Many hydroelectric dams in the east, like Moore Dam, are privately owned, and conservation goals are not valued highly.

One might expect better performance from the US Fish and Wildlife Service, which operates National Wildlife Refuges. Indeed, many NWRs today contain some of the best habitat in the country for waterfowl. But there are still problems. NWR managers normally feel that their mandate is restricted to ducks and geese, which generate significant revenue through hunting. Water in NWRs is managed to optimize duck habitat, but this doesn’t always work for shorebirds. Production of mudflats requires attention to the timing and amounts of water in impoundments. The showpiece for shorebird management is the legendary Bombay Hook NWR in Delaware. (The odd name seems to come from a dark chapter in its history, when the wetland was used to train bomber pilots for World War II combat.)

Scanning for shorebirds at Bombay Hook NWR, Delaware

Congress really needs to act to change the USFWS mission to enhance and preserve shorebird habitat on all refuges, even if waterfowl habitat suffers a bit. Congress should also force private dam owners to examine their impacts on wildlife. They operate at the behest of the people on whose land they occupy, so corporate goals should not be allowed to trump the public interest.

A mass of shorebirds at Bombay Hook NWR, Delaware, May 2024. Dunlins, Semipalmated Sandpipers, Short-billed Dowitchers, Semipalmated Plovers, and Black-bellied Plovers.