A “Grasshopper Hawk” in the Susquehanna Valley

Tropical Storm Ophelia has put the brakes on a bustling southbound exodus of the season’s final waves of Neotropical migrants.  Winds from easterly directions have now beset the Mid-Atlantic States with gloomy skies, chilly temperatures, and periods of rain for an entire week.  These conditions, which are less than favorable for undertaking flights of any significant distance, have compelled many birds to remain in place—grounded to conserve energy.

Migrating Broad-winged Hawks on a Thermal Updraft
In the days prior to the arrival of Tropical Storm Ophelia, thousands of high-flying Broad-winged Hawks were being tallied as they passed hawk-counting stations throughout the region. As the last of this year’s migrants continue through, lack of clear skies, sunshine, and thermal updrafts has slowed the pace of their movements significantly.

Of the birds on layover, perhaps the most interesting find has been a western raptor that occurs only on rare occasions among the groups of Broad-winged Hawks seen at hawk watches each fall—a Swainson’s Hawk.  Discovered as Tropical Storm Ophelia approached on September 21st, this juvenile bird has found refuge in coal country on a small farm in a picturesque valley between converging ridges in southern Northumberland County, Pennsylvania.  Swainson’s Hawks are a gregarious species, often spending time outside of the nesting season in the company of others of their kind.  Like Broad-winged Hawks, they frequently assemble into large groups while migrating.

A juvenile Swainson's Hawk in Northumberland County, Pennsylvania.
A juvenile Swainson’s Hawk in Northumberland County, Pennsylvania.

Swainson's Hawk in Northumberland County, Pennsylvania.

Swainson’s Hawks nest in the grasslands, prairies, and deserts of western North America.  Their autumn migration to wintering grounds in Argentina covers a distance of up to 6,000 miles.  Among raptors, such mileage is outdone only by the Tundra Peregrine Falcon.

Juvenile Swainson's Hawk
The Swainson’s Hawk spends up to four months each year covering a 12,000-mile round-trip migration route.  The long primaries are an adaptation that give the wings additional lift, allowing them to use air currents including thermal updrafts to conserve energy while flying.

Juvenile Swainson's Hawk

Juvenile Swainson's Hawk
Swainson’s Hawks are renowned for spending time on the ground, intermittently running and hopping in pursuit of prey.

During the nesting cycle, Swainson’s Hawks consume primarily small vertebrates, mostly mice and other small rodents.  But during the remainder of the year, they feed almost exclusively on grasshoppers.  To provide enough energy to fuel their migrations, they must find and devour these insects by the hundreds.  Not surprisingly, the Swainson’s Hawk is sometimes known as the Grasshopper Hawk or Locust Hawk, particularly in the areas of South America where they are common.

Juvenile Swainson's Hawk eating a cricket.
The juvenile Swainson’s Hawk visiting Northumberland County has been feeding on grasshoppers, katydids, and is seen here eating a cricket.

So just how far will our wayward Swainson’s Hawk have to travel to get back on track?  Small numbers of Swainson’s Hawks pass the winter in southern Florida each year and still others are found in and near the scrublands of the Lower Rio Grande Valley in Texas and Mexico.  But the vast majority of these birds make the trip all the way to the southern half of South America and the farmlands and savannas of Argentina—where our winter is their summer.  The best bet for this bird would be to get hooked up with some of the season’s last Broad-winged Hawks when they start flying in coming days, then join them as they head toward Houston, Texas, to make the southward turn down the coast of the Gulf of Mexico into Central America and Amazonia.  Then again, it may need to find its own way to warmer climes.  Upon reaching at least the Gulf Coastal Plain, our visitor stands a much better chance of surviving the winter.

Juvenile Swainson's Hawk in Flight
As long as it can still find grasshoppers to eat, our wayward bird in Northumberland County still has time before it needs to make its way south.   As they pass through Texas, Mexico, Costa Rica, and Panama, Swainson’s Hawks are numerous among flocks of southbound Broad-winged Hawks.  But while hawk watches in these areas are presently recording maximum annual counts of the latter, peak numbers of the former won’t occur until the final two or three weeks of October.

Forty Years Ago in the Lower Rio Grande Valley: Day Nine


Back in late May of 1983, four members of the Lancaster County Bird Club—Russ Markert, Harold Morrrin, Steve Santner, and your editor—embarked on an energetic trip to find, observe, and photograph birds in the Lower Rio Grande Valley of Texas.  What follows is a daily account of that two-week-long expedition.  Notes logged by Markert some four decades ago are quoted in italics.  The images are scans of 35 mm color slide photographs taken along the way by your editor.


DAY NINE—May 29, 1983

“Falcon Dam State Park, Texas”

“To the spillway area after breakfast and saw Ringed Kingfisher, Baird’s Sandpiper, and 2 Black-necked Stilts.  Stopped to photograph the Swainson’s Hawk which had flown in a tree.  Also saw a Blue Grosbeak.”

The Ringed Kingfisher (Megaceryle torquata) was notably larger than the Belted Kingfishers with which we were so familiar, so it was easy to identify.  This was yet another tropical species found north only as far as the Rio Grande Valley of Texas.  Baird’s Sandpiper was a pretty good find for this location in late May.

Swainson's Hawk
The Swainson’s Hawk we discovered yesterday in a water-logged flightless condition had recovered.  Shortly after this photograph was taken and we had taken leave of the bird, we looked back and saw it flying away to the north.  Soon, it was out of sight.

“We drove to Santa Margarita Ranch to search for the elusive Brown Jay.”

While en route to Santa Margarita Ranch, we stopped twice to photograph birds we spotted along the way.

Plain Chachalacas
This family of Plain Chachalacas was spotted crossing the road near Falcon Dam.
Harris's Hawks
Harris’s Hawks are known to hunt in groups, hence their alternate common name “Wolf Hawk”.  We spotted these two and several others, presumably a mated pair and their recently fledged young, hunting an area of thornscrub not far from Santa Margarita Ranch near the town of Falcon Heights, Texas.

Beside the road just outside the entrance to the ranch, we observed a Verdin (Auriparus flaviceps), a tiny chickadee-like like bird with a yellow head and throat.  Verdins reside in both thornscrub and desert throughout the southwestern United States and northern Mexico.

“Rancho Santa Margarita is a group of 8 houses.  Cattle roam at will.  We walked a long way along the river — No luck.  Had lunch in the camper and repeated the morning walk.  Cattle dung all over the place.  The dung rollers were as interesting to watch as the leaf-carrying ants.  Met a Mr. McQueary who had seen them 30 min. ago, so he led us to where he had seen them, but — No luck.”

Upon arriving at Santa Margarita Ranch intending to find Brown Jays (Psilorhinus morio), we drove over the in-ground cattle gate at the entrance and back the dirt driveway to the small cluster of houses where we parked.  We checked in with a resident there and slipped them a dollar or two a head for letting us spend the day on their land.  As we walked away from the houses, we noticed some intermittent movement in a pile of construction debris along the dirt road leading to the river.  Initially thinking we may have caught glimpses of some small rodents dashing around, we watched patiently until we saw at least two Blue Spiny Lizards (Sceloporus cyanogenys) among the lumber and tin.  The pair was obviously finding insects or other sources of prey there

To find Brown Jays, one of the five target species of the trip, Father Tom had advised us to follow the advice in James Lane’s A Birder’s Guide to the Rio Grande Valley of Texas.  The recommendations contained therein brought us to Santa Margarita Ranch.  As was the case upriver near Falcon Dam, the Tamaulipan Saline Thornscrub that covers much of the property turns abruptly to subtropical riparian forest near the banks of the Rio Grande where wetter soils predominate.  The habitat was excellent, and we were certain the birds were there, but despite significant effort, we just couldn’t bump into Brown Jays at Santa Margarita Ranch.

We did however get good looks at another Hook-billed Kite sailing above the trees downriver.  During our second walk, Harold, Steve, and I waded down a short section of the Rio Grande in hopes of getting better looks into an area of shoreline forest too thick to enter by land.  Despite recent rains, the water was low, restricted by gates at Falcon Dam to little more than the flow needed to operate the turbines and generate electricity.  We saw orioles, Red-billed Pigeon, and Great Kiskadee—but no Brown Jays.

Bewick's Wren
We heard an Olive Sparrow and this Bewick’s Wren (Thryomanes bewickii) singing in some thornscrub along the edge of the riparian forest at Santa Margarita Ranch.  It took some effort to finally catch a glimpse of the wren.

“On the way out…found a nest of Pyrrhuloxia and saw a 6 ft. snake hanging from a bush with a rabbit in his mouth.  The snake caught the rabbit by the shoulder and it was working hard to get free.  Finally the snake dropped the rabbit, and they both went out of sight.” 

Pyrrhuloxia
A Pyrrhuloxia (Cardinalis sinuatus) in the thornscrub along the dirt entrance/exit road to Santa Magarita Ranch.
Pyrrhuloxia
The pair of Pyrrhuloxia had their nest well-hidden.  We were lucky to have spotted it, but we dared not approach any closer for pictures for fear of frightening the nestlings and prompting premature fledging.

As we eased our way out the dirt road at Santa Magarita Ranch, we began hearing a blood-curdling series of squeals.  Russ stopped the van and as we peered into the thornscrub, we could catch glimpses of an Eastern Cottontail thrashing around.  At first we thought it had somehow become snagged in the quagmire of prickles on the dense vegetation.  Then we spotted the snake draped over the shrubs and attempting in vain to lift the cottontail off the ground.  The struggle, and the squealing, continued for several minutes as we labored to identify the snake.  As the snake attempted to reposition the cottontail so that it could swallow it head first, the rabbit broke free and escaped.  All was silent as the snake quickly fled as well.  As it slithered away we could see just how long it really was—5 to 6 feet or more.  You know, things really are bigger in Texas.  Based upon its large size, overall tan-brown color, and the rapid speed with which it left the scene, we determined it was a Western Coachwhip (Masticophis flagellum testaceus).

“Back to the spillway at Falcon Dam — No luck.  Met Ron Huffman who is leading a trip for 3 women.  We will meet him at the spillway tomorrow AM early.  Back at our camp site for supper — shower and shave.  The Lesser Nighthawks were trilling late in the evening.”

During the evening, we found Black-throated Sparrow (Amphispiza bilineata) and Scaled Quail (Callipepla squamata) in the area of the campsite.  Then, as darkness settled in, the calls of Common Pauraque, Common Nighthawks, and Lesser Nighthawks (Chordeiles acutipennis) commenced.  We walked down the road to a spot where we could overlook a lower-lying area of thornscrub in hopes of catching a glimpse of some of these nightjars, particularly the latter species, as they patrolled for flying insects.  But under cloudy skies and being miles from any man-made sources of light, it was too dark to see anything flying around.

Scaled Quail
Just before sunset, this Scaled Quail appeared among the thornscrub near our campsite.

Forty Years Ago in the Lower Rio Grande Valley: Day Eight


Back in late May of 1983, four members of the Lancaster County Bird Club—Russ Markert, Harold Morrrin, Steve Santner, and your editor—embarked on an energetic trip to find, observe, and photograph birds in the Lower Rio Grande Valley of Texas.  What follows is a daily account of that two-week-long expedition.  Notes logged by Markert some four decades ago are quoted in italics.  The images are scans of 35 mm color slide photographs taken along the way by your editor.


DAY EIGHT—May 28, 1983

“Bentsen State Park, Texas”

“Alarm at 6:00 A.M.  After breakfast we traveled to Falcon State Park and toured the whole camp area, stopping many places to observe birds.  We ran up a good list.”

And so we left what had been our home for the last several days and headed west.  In the forty years since our departure that morning, Bentsen-Rio Grande State Park has experienced a number of operational changes.  Today, it is a World Birding Center site.  For conducting the seasonal hawk census, a tower has been erected to provide counters and observes with an unrestricted view above the treetops.  If you wanted to camp in the park now, you would need reservations and would have to hike your gear in to one of only a few primitive campsites.  Trailer and motor home accommodations no longer exist.  A tram service is now available for touring the park by motor vehicle.

West of Rio Grande City, we exited the river’s outflow delta and entered the Texas scrubland, an area mostly devoid of large trees except in moist soils immediately adjacent to the Rio Grande where the lush vegetation creates a dense subtropical riparian forest in many places.  The reservoir itself is known to attract migrating and vagrant waterfowl, waders, shorebirds, gulls, terns, and seabirds.  (United States Fish and Wildlife Service base image)

Falcon State Park is located along the east shore of Falcon Reservoir.  There are no shade trees beneath which one can escape the scorching rays of the sun on a hot day.  This is the easternmost section of the scrubland’s Tamaulipan Saline Thornscrub, a xeric plant community of head-high brush found only on clay soils with a particularly high salinity.  Many of the plants look similar to other varieties of shrubs and small trees with which one may be familiar, except nearly all of them are covered with nasty thorns and prickles.  And yes, there are cactus.  You can’t make your way bushwhacking cross country without obtaining cuts, gashes, and scars to show for it.  The Falcon State Recreation Area bird checklist published in 1977 has a nice description of the plants found there—mesquite, ebano, guaycan, blackbrush and catclaw acacia, granjeno, coyotillo, huisache, tasajillo, prickly pear, allthorn, cenizo, colima, and yucca.  In the margins between the thornscrub growth, there is an abundance of grasses and wildflowers.  On nearby ridges, Tamaulipan Calcareous Thornscrub, a similar xeric plant community, occupies soils with a higher content of calcium carbonate.  Together, these communities comprise much of the Tamaulipan Mezquital ecoregion of scrublands in Starr County and western Hidalgo County in the Rio Grande valley of Texas.

After being greeted by a Greater Roadrunner at the campsite, we took a walk to the nearby shoreline of the reservoir.  We spotted Olivaceous Cormorants perched on some dead limbs in the water nearby.  Known today as Neotropic Cormorant (Phalacrocorax brasilianus), it is yet another specialty of the Rio Grande Valley.  Elsewhere on or near the water—Cattle Egret, Great Egret, Black-bellied Whistling Duck, Osprey, Common Gallinule, Killdeer, Laughing Gull, Forster’s Tern (Sterna forsteri), Least Tern, and Caspian Tern were seen.

Greater Roadrunner
The Greater Roadrunner is right at home in the Tamaulipan Saline Thornscrub habitat in and around Falcon State Park.  This one came to check us out soon after our arrival at our campsite.  Roadrunners prey on insects, rodents, and lizards including the Texas Spotted Whiptail (Aspidoscelis gularis), a species which we found nearby.

In the thornscrub around the campground, which, like Bentsen-Rio Grande State Park, we had pretty much to ourselves, we saw Scissor-tailed Flycatcher, Curve-billed Thrasher, White-winged Dove, Mourning Dove, Ground Dove, Inca Dove, and White-tipped Dove.  A single Chihuahuan Raven was a fly by.  We saw and smelled several road-killed Nine-banded Armadillos (Dasypus novemcinctus), but never found one alive.

Then, it started to rain.  Not just a shower, but a soaker that persisted through much of the day.  Rainy days can make for great birding, so we kept at it.  Unfortunately, such days aren’t too ideal for photography, so we did only what we could without ruining our equipment.

Cactus Wren
In the campground at Falcon State Park, a Cactus Wren (Campylorhynchus brunneicapillus) takes shelter from the rain beneath a canopy protecting a picnic table.
Cactus Wren
Looks like a good idea, others soon sought shelter there as well.

“Finally we drove to the spillway of the dam and parked.” 

Falcon Dam was another of the numerous flood-control projects built on the Rio Grande during the middle of the twentieth century.  Behind it, Falcon Reservoir stores water for irrigation and operation of a hydroelectric generating station located within the dam complex.  Construction of the dam and power plant was a joint venture shared by Mexico and the United States.  The project was dedicated by Presidents Adolfo Ruiz Cortines and Dwight D. Eisenhower in 1953.

Rainy days aside, the route precipitation takes to reach the Falcon Reservoir and the Lower Rio Grande Valley includes hundreds of miles through arid grasslands and scrublands.  Along the way, much of that water is lost to natural processes including evaporation and aquifer recharge, but an increasing percentage of the volume is being removed by man for civil, industrial, and agricultural uses.  Can the Rio Grande and its tributaries continue to meet demand?

The Rio Grande’s headwaters can be found in south-central Colorado where spring snow melt is vital to establishing adequate flow to allow the river to recharge aquifers in the hundreds of miles of arid lands through which it flows.  Presently, dams in the upper reaches of the river are operated to hold water during the spring thaw, then release it slowly to compensate for base flow lost to withdrawals for irrigation in extensive areas of the middle reaches of the watershed.  With everyone wanting their take, is there enough water to go around?  Diminishing ground water levels suggest the answer is no.  (National Oceanic and Atmospheric Administration base image)
Using the streamflow recharge process, the flowing Rio Grande provides water to the aquifers in the arid regions through which it passes.  Click the image for a slightly larger version.  (United States Geological Survey image)

“On the way in we saw and photographed an apparent sick or injured Swainson’s Hawk.  We approached it very close.” 

Swainson's Hawk
The Swainson’s Hawk (Buteo swainsoni), a bird of prairies and other grasslands, is an abundant migrant through the Lower Rio Grande Valley in both spring and fall.  This one was grounded, rain-soaked, and obviously running late.  Others of its kind were by now on their breeding grounds in the Great Plains and Rocky Mountains.
Swainson's Hawk
The bird allowed us to approach without attempting to flee, which isn’t a good sign.  We looked for any obvious physical injuries and found none.
Swainson's Hawk
The continuous rain had the hawk’s feathers matted down and soaked.
Swainson's Hawk
Was its water-logged plumage the problem, or was it the result of its inability to thrive due to an illness?  We had no way of telling, so we let it be and vowed to stop back later to check on it.
Swainson's Hawk
Steve the hawk whisperer?

“At the spillway we sat in the camper, except when the rain slackened, then we stood out and watched in vain for the Green or Ringed Kingfisher, which we never did see.”

At the spillway House Sparrows, Rough-winged Swallows, and Cliff Swallows were nesting on the dam, the latter two species grabbing flying insects above the waters of the Rio Grande.

Longnose Gar
Despite the rain, anglers were fishing along the spillway walls where this young man caught a Longnose Gar (Lepisosteus osseus).  The reservoir has been stocked with Alligator Gar (Atractosteus spatula), Spotted Gar (Lepisosteus oculatus), and a variety of bass, catfish, and other species to establish a trophy sport fishery.  Many specimens grow to become trophy-size there due to the warm water temperatures.  These guys though were fishing for food, not trophies.

“I made dinner here at this spillway and we continued to watch.  The rain almost stopped, so we walked down the road about 1 1/2 miles, during which time we saw a lifer for Harold — Hook-billed Kite.  We followed Father Tom’s directions to a spot for the Ferruginous Owl — no luck.”

Red-billed Pigeon
A Red-billed Pigeon in a willow tree in the subtropical riparian forest along the banks of the Rio Grande below Falcon Dam.  Prior to this trip, neither Steve nor I had ever seen this tropical species before.

“Back at the spillway we had supper and then repeated the hike — no Ferruginous Owl, but a Barn Owl and Great Horned Owl.  Back to our #201 campsite and wrote up the day’s log.”

Trees along the river provided habitat for orioles and other species.  Since the rain had subsided, we decided to see what might come out and begin feeding.  Soon, we not only saw an Altamira Oriole, but found Hooded Oriole (Icterus cucullatus) and the yellow and black tropical species, Audubon’s Oriole (Icterus graduacauda), formerly known as Black-headed Oriole.  Three species of orioles on a backdrop of lush green subtropical foliage, it was magnificent.

Along the dirt road below the dam, the mix of scrubland and subtropical riparian forest made for excellent birding.  We not only found a soaring Hook-billed Kite, one of the target birds for the trip, but we had good looks at both a Great Horned Owl, then a Barn Owl (Tyto alba) that we flushed from the bare ground in openings among the vegetation as we walked the through.  Both had probably pounced on some sort of small prey species prior to our arrival.  Because there are seldom crows or ravens to bother them, owls here are more active during than day than they are elsewhere.  The subject of this afternoon’s intensive search, the elusive and diminutive Ferruginous Pygmy Owl (Glaucidium brasilianum), is routinely diurnal.  Other sightings on our two walks included Turkey Vulture, Black Vulture, White-tailed Kite, Northern Bobwhite, Yellow-billed Cuckoo, Golden-fronted Woodpecker, Ladder-backed Woodpecker, Couch’s Kingbird, Brown-crested Flycatcher, Green Jay, Black-crested Titmouse, Mockingbird, Long-billed Thrasher, Great-tailed Grackle, Bronzed Cowbird, Northern Cardinal, and Painted Bunting.

The day finished as so many others had earlier during the trip—with insect-hunting Common Nighthawks calling from the skies around our campsite.