I stand and watch as waves of songbirds appear in a nearby
mesquite, pause briefly for a snack, and then flit on northward. A Blue Grosbeak perches high in a branch,
brilliant blue in the early morning light, its metallic “chink” call and
delightful mellow warbling song reminding me of dense willows along rivers
coursing through hot deserts. Now there
is a handsome male Black-throated Gray Warbler, heading north to grace montane
oak forests with its cheery buzzing song.
A Townsend’s Warbler appears next, a stunning orange and black gem that
will soon adorn the magnificent Douglas fir trees in the Pacific Northwest. Spritely Wilson’s Warblers, drab greenish Orange-crowned
Warblers, Nashville Warblers, Pacific-slope Flycatchers, Western Tanagers, Black-headed
Grosbeaks; all passing by on their way to various points in western North
America. Above, an endless river of
swallows, swifts, and blackbirds cruise by, and shorebirds forage furiously in
pools of water, fueling up for their journey to the tundra. Four species of rails skulk amongst the marsh
vegetation, their presence revealed only by their strange and evocative calls:
Yuma Clapper Rail, Virginia Rail, Sora, and Black Rail.
This is El Doctór, and this is the most amazing migration spectacle I have ever seen.
El Doctór is a nature reserve that protects 1850 acres of
wetland within the Colorado River Delta in Mexico, providing critical habitat
for marshbirds (including the threatened Yuma Clapper Rail) and stopover habitat
for migrating shorebirds and songbirds.
It is an oasis within the vast Sonoran Desert, and one of the last
remnants of what was once a vast network of wetlands within the Colorado River
Delta. I visited this area as part of a
larger team effort to investigate the effects of a large water release (“pulse
flow”) into the Colorado River channel.
Scientists from both Mexico and the US were out in force, measuring
water flow, seed dispersal, and seedling sprouting - I was there to observe the foraging behavior of birds. While it is
too soon to speculate on how well the birds are responding to the pulse flow, I
can share my experiences with the area's birds.
Birding the Lower Colorado River
Most of the study areas were public lands that could be visited
by anybody, although they were generally not well-signed (except Cienega Santa
Clara) and interested birders should contact a local guide for directions or
assistance getting to the sites (see http://mexicobirdingtrail.org/plan-a-trip/colorado-river-delta/). I had no trouble getting around in my car; then again, I've taken my Saturn on some crazy roads before and know how to drive it
through the myriad sand patches that characterize the dirt roads in this
region. There are hotels in the border
town of San Luis Rio Colorado, and all sites can be reached within an hour and a
half. Gas and delicious
tacos are available in the small town of Luis B. Sanchez. I can’t attest to any of lodging options - I
was hosted by Juan Butrón at his house in a tiny community near Cienega de
Santa Clara.
El Doctór
El Doctór is a wetland is one
of the first places with trees and water that northbound migrants encounter after
crossing the Sea of Cortez or large stretches of surrounding Sonoran Desert-
and as you can see from the map, the desert around here is VERY sparse and dry,
quite unlike the relatively lush saguaro-palo verde-mesquite desert scrub
around Tucson. Hence I saw the largest
concentrations of migrants during my visits to this site. Of course my brief visit provided only a
snapshot of migration - for instance, it was too early for many Empidonax flycatchers other than
Pacific-slope - but this spot had the highest diversity of migrant warblers (10
species) and was the one place at which I heard all four rail species. Year-round residents included Crissal
Thrasher, Verdin, Northern Mockingbird, and Abert’s Towhee. |
Cienega de Santa Clara
This is an even larger area of wetland a bit north of El
Doctór - 14,000 acres of cattail marsh, critically important for the Yuma Clapper Rail. Another
literal oasis in the desert, the last few kilometers of the road to the cienega
pass through bare sand completely devoid of vegetation, bringing to mind the Sahara or another
planet entirely! Juan treated me and a
trio of Canadian journalists to a long boat ride through the cienega on my
first full evening in Mexico. American
Coots bobbed on the water throughout and handsome male Cinnamon Teal caught the
evening sunlight. After an hour of
gliding quietly through the dense cattails, we reached a shallow area on which
hundreds of shorebirds had gathered.
Black-necked Stilts, American Avocets, and Long-billed Dowitchers
dominated the scene, and the sound of a hundred American Coots running on the
water’s surface as they fled our boat sounded like a thunderous ocean
wave. During a second visit to the
cienega another evening, I explored the shoreline, mostly short pickleweed and
a few scraggly tamarisks. Migrant
warblers were using this area, especially Yellow-rumped Warblers (Audubon’s
race), many of which were sallying and tumbling after invisible flying
insects. A large flight of Tree Swallows
came by, a stream of them that lasted a good forty minutes. Song Sparrows sang from the edge of the
pools, and a few shorebirds stopped by now and then, a Least Sandpiper
obligingly foraging in the late evening sunlight mere meters from me. I tried to make a third visit the next week,
but I unwisely chose a windy day, and the blowing dust was so thick as I
approached the cienega that visibility abruptly reduced to ten feet and soft
sand was piling up on the road - I decided to turn around!
Rio Colorado Restoration Sites
I made numerous visits to many places along the Rio Colorado,
but Pronatura Noroeste has some nice restoration areas along the river not far outside Luis B.
Sanchez. Workers have removed large
stands of invasive tamarisk and have replaced them with native mesquite,
cottonwood, and willow. The plots are in
various stages of development - there are bare fields with Horned Larks singing
their tinkling songs from the sky, plots with cottonwoods no taller than me,
and dense thickets with mature willow and mesquite (these were favored by the warblers). The sound of Ring-necked Pheasants from the
surrounding wheat fields brought incongruous memories of a summer working in
Iowa - apparently this species is expected here, but it had not been on my
radar! The larger trees and open spaces
provided habitat for Bullock’s Orioles and many flycatchers - Vermillion
Flycatchers, brilliant red balls of fluff performing their fluttering flight
songs; pugnacious Western Kingbirds; Ash-throated Flycatchers investigating
nest holes. Lesser Nighthawks coursed by
in broad daylight, and Burrowing Owls frequently flushed from the dirt
levees. Remaining areas of tamarisk
housed rasping families of Black-tailed Gnatcatchers, skulking Crissal Thrashers, and Greater
Roadrunners. The river itself held
plenty of slow-moving water and dense marsh vegetation, with rails, Marsh
Wrens, Caspian Terns, and Pied-billed Grebes.
It was a very successful trip, the sheer number of migrants
provided me with a wealth of foraging data, and the sight of cottonwood
seedlings sprouting provided new hope for the region. I was impressed by the dedication to nature
shown by many of the Mexicans I met, and with seven more years of pulse flows
planned, perhaps some of this amazing riparian habitat can expand across the
salt flat currently separating the river from the Sea of Cortez and revitalize
the farthest reaches of the delta.
