Pushing the limits of food supplies on the Laguna Madre
By Matt Young
Wave after wave of redheads boiled off the water ahead of the boat as we raced across the glassy surface of the Laguna Madre just off the south Texas coast. Driven from their feeding grounds, thousands of the birds lifted into the air in great, milling swarms, only to settle once again on the surrounding flats. Watching the spectacle in awe, we were privileged to be witnessing one of the world's greatest concentrations of wintering redheads, especially in an area open to public waterfowling.
Our host, research scientist Bart Ballard of the Caesar Kleberg Wildlife Research Institute, cut the throttle and reversed the engine as we approached a palmetto-brushed blind, staked in the shallows at the edge of a small island dotted with scrub oaks. Formed by rising sea levels roughly 3,000 years ago, the Laguna Madre of Texas has an average depth of less than three feet, and many areas hold barely enough water to float decoys, making shallow-draft boats a necessity to access much of the estuary. Its clear, shallow waters provide ideal growing conditions for shoalgrass, a submersed aquatic plant that is a staple food source for wintering redheads and other waterfowl.
My hunting partners, Dr. Mark Petrie, assistant director of DU's Institute for Wetland and Waterfowl Research, and Dr. Steve Adair, DU's national director of conservation programs, and I hopped from the boat into the knee-deep water and began unloading our hunting gear. When we had safely secured everything in the blind, Ballard departed to hide the boat on the far side of the island.
The first pale light of dawn broke over the flats as we pitched out the decoys amid a classic waterfowling setting that could have come straight from the canvas of Eldridge Hardie or Herb Booth. Ballard came striding down the shoreline just as we finished arranging our mixed spread of diver and puddle duck blocks in separate groups on either side of the blind. An Iowa native, Ballard grew up hunting waterfowl in his home state and moved to south Texas to pursue a career in waterfowl research. His enthusiasm for waterfowling is stronger than ever, despite the countless hours he has spent doing the often tedious work of collecting data for waterfowl research projects.
"If you've ever wanted to hunt redheads, you've come to the right place," says Ballard, who is presently working with DU to study redhead food resources in the estuary. "More than 80 percent of the continental population-as many as 700,000 birds-winters on the Laguna Madre of Texas and Mexico."
In the distance, great rafts of redheads covered the surrounding flats like feathered oil slicks, and the strange, cat-like calls of countless drakes drifted across the water through the humid air. Despite the staggering numbers of redheads nearby, the first ducks to approach our decoys were a trio of pintails that sailed down from high over the estuary. The Laguna Madre also is an important wintering area for these highly prized ducks, particularly during dry winters such as 1999, when water was in short supply on the rice prairies to the north.
The small flock warily circled our spread for several minutes, while we kept our heads down and coaxed them with a chorus of sprig whistles. Exhibiting typical pintail behavior, the birds never fully committed to the decoys, but made a slow gliding pass over the outside of the spread, offering crossing shots to Petrie and Adair, seated on the far side of the blind. Experienced waterfowlers, the biologists smoothly shouldered their 12-bores, and each folded a drake with one shot.
As the sun climbed higher above the estuary, a cool breeze began to blow off the Gulf, putting a light chop on the water. The waves rousted the great rafts of redheads feeding around us, and several flocks began trading across the flats in our direction. It was only a matter of time before a knot of redheads spotted our decoys and came roaring into the rig. As Ballard called the shot, I rose from behind the screen of palmettos and tumbled a fully plumed drake from the leading edge of the flock, while Petrie and Adair sent two more skipping across the water through the decoys.
We waded to retrieve the birds through the gin-clear shallows covered with mats of shoalgrass uprooted by redheads while feeding on the fleshy rhizomes (roots) of the plants. Lifting the heavy drakes by their necks, we could see beads of saltwater glistening on their warm feathers as we admired their rich russet brown heads, broad black chests, and slate gray bellies. Weighing from two and one-half to three pounds, redheads are the second largest members of the pochard family of diving ducks, exceeded in size only by canvasbacks. During the market hunting era, redheads were almost as highly prized among East Coast epicures as their larger cousins.
During the next hour, several more flights of redheads piled into our rig, enabling us to easily collect our two-bird limits with all drakes. The second bird taken by Adair was wearing a U.S. Fish and Wildlife Service leg band, stained a dull bronze color by the hypersaline waters of the estuary. We would later learn that the drake was banded as an adult on a prairie marsh in southern Saskatchewan two years earlier. In 2000, almost 90 percent of all breeding redheads were surveyed in the Prairie Pothole Region of the north central U.S. and Canada. Smaller numbers of redheads nest on valley marshes in the western U.S. and on river deltas in the boreal forest of northern Canada.
Although redheads breed across the vast prairies of the continent, almost the entire continental population winters in only a handful of limited areas. Favoring an almost exclusively vegetarian diet, redheads historically have wintered on coastal bays and estuaries rich in submersed aquatic vegetation, especially shoalgrass. As the abundance of these plants has declined along the Atlantic Coast in recent decades, the majority of the continent's redheads are now confined to wintering areas on the Gulf of Mexico.
The largest remaining strongholds of shoalgrass and, consequently, the most important wintering areas for redheads, are the Laguna Madre estuaries of south Texas and northeastern Mexico. Unfortunately, the vast beds of shoalgrass that once covered these coastal waters are also declining, foreboding serious consequences for redhead populations.
Stretching roughly 130 miles from Corpus Christi to the Rio Grande delta near the Mexico border, the Laguna Madre of Texas historically was protected from the Gulf of Mexico by Padre Island, on its eastern boundary. With limited freshwater inflow from the mainland, and among the highest evaporation rates in the U.S., salinity levels in the lagoon typically ranged from 200 to 300 percent that of seawater. Few species of vegetation can withstand such conditions, except for the highly salt tolerant shoalgrass, which flourishes in the clear, shallow waters. The vast beds of vegetation not only provide an abundance of food for wintering redheads and other waterfowl, they are also excellent habitat for fish and shrimp.
The Laguna Madre ecosystem was changed forever in 1948, when the construction of the Intracoastal Waterway permanently connected the estuary to the Gulf. The resulting decrease in salinity provided favorable growing conditions for less salt tolerant seagrass species, principally manateegrass and turtlegrass. These more robust invaders are now rapidly displacing shoalgrass throughout the estuary, and increased sediment loads from canal dredging have caused further losses of shoalgrass in other areas. Since 1965, the U.S. Geological Survey estimates that shoalgrass has declined by more than 40 percent in the Laguna Madre of Texas, and this trend is expected to continue, especially in the upper portions of the estuary. Coastal navigation projects recently completed on the Laguna Madre of Mexico have had similar impacts on the abundance of shoalgrass in its waters.
While shoalgrass has declined on the Laguna Madre of Texas and Mexico, redhead populations have soared to record highs in recent years, possibly placing greater pressure on remaining shoalgrass beds on their wintering grounds. Studies conducted during the late 1980s suggest that redhead populations were consuming as much as 75 percent of shoalgrass rhizomes produced in a given year in parts of the estuary. Waterfowl managers fear that under current population levels, redheads may in some years exhaust their traditional food supplies prior to the spring migration.
To help answer this important question, DU's Institute for Wetland and Waterfowl Research (IWWR) has joined Texas A & M University-Kingsville and the Coastal Bend Bays and Estuary Program in an ambitious three-year study that will inventory the Laguna Madre's remaining shoalgrass resources and monitor the impacts feeding redheads are having on the vegetation. The research, being conducted by Ballard, also will examine survival of wintering redheads on the estuary to determine if the birds presently have adequate food supplies. This information will be critical to DU and its partners in order to develop long-term conservation strategies for redheads and other waterfowl in south Texas and Mexico.
In addition to the importance of shoalgrass to wintering redheads, the birds also are highly dependent on freshwater wetlands located on the mainland near the coastline. Research conducted by Adair revealed that redheads must fly at least once, and sometimes two or three times, each day to inland ponds, where they drink copious amounts of freshwater to purge their bodies of high salt loads consumed while feeding on shoalgrass.
Among the primary objectives of Ballard's research will be to determine if the use of shoalgrass beds by redheads is dependent on proximity to freshwater, and if redheads are more likely to overgraze shoalgrass beds that are adjacent to freshwater sources. If this link can be established, DU and its partners could possibly relieve redhead feeding pressure on heavily grazed shoalgrass beds by restoring freshwater wetlands adjacent to unexploited feeding areas.
The majority of the freshwater wetlands used by redheads wintering on the Laguna Madre are located on private lands, primarily managed for cattle grazing. The largest privately owned tracts of land in the region are the legendary King and Kenedy ranches, which cover roughly half of the coastline on the western shore of the estuary. Both ranches have done an admirable job of conserving freshwater wetlands and have supported numerous wildlife research projects on their extensive landholdings.
We joined Mickey Hellickson, chief wildlife biologist for the King Ranch, for a morning duck hunt on one of the ranch's hundreds of small freshwater wetlands, which collectively support hundreds of thousands of redheads and other waterfowl each winter. Hellickson manages the ranch's world-renowned trophy whitetail deer program, as well as many other game and nongame species that inhabit this vast 835,000-acre estate.
A dense coastal fog shrouded the landscape as we bounced along in Hellickson's pickup down a worn two-track, winding through miles of unbroken scrub oak, cactus, and sage. After a long, jarring drive, we came upon a network of small wetlands nestled among the sand dunes less than a mile from the coastline. Known locally as hurricane ponds, many of the freshwater ponds in the region are dependent on rainfall from tropical storms. Due to the vagaries of the regional weather, the abundance of these semipermanent wetlands varies dramatically from one year to the next.
Hellickson dropped Petrie and me at one end of the wetland complex, then he drove Ballard and Adair to another pothole just over a sandy ridge. As we towed a layout boat full of decoys behind us, dozens of pintails, wigeon, and mottled ducks thundered into flight ahead of us through the mist. We took up shooting positions on a small island flanked by deep, open water on one side and a shallow, weedy cove on the other-an ideal location for both dabblers and divers.
While we were tossing out the decoys, several flocks of ducks-drawn by the sound of the splashing-wheeled low over our heads, almost close enough to touch. We hustled back to the island and jammed shells into our autoloaders, just as a squadron of pintails loomed out of the fog and hovered above the decoys. Moments later, two long-tailed drakes lay motionless in the decoys as ringlets of water spread around them.
We enjoyed steady shooting as several flights of dabbling ducks vectored through the dense fog into our decoys, enabling us to collect a colorful mixed bag of pintails, wigeon, and mottled ducks. The flurry at dawn, however, proved to be only a warm-up for better things to come. Shortly after the mist burned off at midmorning, we were startled by the low-frequency hum of countless beating wings gradually building in the distance. Looking far over the open waters of the Laguna Madre, we could see endless waves of redheads flying rank upon rank toward the coastline.
Their morning flight to freshwater had been delayed by the fog, and now the thirsty birds were flying inland en masse. Crossing over the beach ridge, the great formations of divers broke into smaller flocks and dispersed among the many watering holes scattered among the dunes. Our pond seemed to be particularly popular that morning. A succession of large flocks came tearing into our decoys, the iridescent red heads of the drakes shining like rubies in the bright sunlight.
With our limits in hand, we quickly retreated to the high dunes overlooking the wetland. Over the next hour, we watched more than 5,000 redheads pour into the pond to drink. When the birds had thoroughly sated themselves with water, they once again took flight and returned to the protective waters of the estuary. As the flocks faded into the distance, I couldn't help wondering what the future will hold for the redheads of the Laguna Madre. During my brief visit, I had witnessed firsthand just how important the estuary's shoalgrass beds and associated freshwater wetlands are to so many of the birds. If these critical habitats disappear, wintering redheads may have nowhere else to go.
Lying just south of the U.S. border, the Laguna Madre of Tamaulipas is among the most important waterfowl wintering areas in Mexico. Recent surveys indicate that the estuary supports nearly 1 million ducks, including 35 percent of the continental population of redheads. Like the Laguna Madre of Texas, however, the estuary has suffered significant losses of shoalgrass to competing seagrass species due to declining salinity levels caused by the construction of permanent shipping channels to the Gulf.
Ducks Unlimited of Mexico (DUMAC) is presently monitoring the health of the estuary's shoalgrass beds, as well as wintering waterfowl and shorebird numbers in the region. DUMAC also is leading efforts to secure government protection of the Laguna Madre, and is working closely with ranchers along the coastline to restore additional freshwater wetlands critical to redheads and other waterfowl wintering on the estuary.
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