The Late Summer Draw-Down

An iconic feature of Malheur Refuge Headquarters is the display pond, also known as Marshall Pond (learn about David Marshall here), fed by an underground spring. The first documented use of this spring by humans occurred around 6,000 years ago, when predecessors of the Burns Paiute Tribe, known as the Wada’tika (meaning “waada eaters”—a native marsh plant), settled there to take advantage of seasonal resources such as fish, ducks, antelope, coyote, muskrat, bison and a variety of plant materials. Based on archaeological evidence found at the site, the spring likely has been flowing continuously for many thousands of years.

Over the past three or four years, however, the spring’s output appears to be waning. Persistent drought, as well as recent groundwater developments in the area, may have drawn down the local aquifer. At any rate, during this hotter-than-average summer, Marshall Pond has fallen unusually low and is shrinking by the day. While this is an unfortunate scenario for the wildlife and visitors that use and enjoy the pond, it provides a unique opportunity to see, on a much smaller scale, what occurs at Malheur Lake through the summer.

The shallow lakes at Malheur Refuge—Malheur, Mud and Harney Lake—are subject to marked seasonal fluctuations in size, depending on winter snowpack and evaporative losses in summer. The process begins early each year and many miles away from the Refuge, at high elevations in the Steens and southern Blue Mountains. As snow accumulates in these mountains during the winter and melts in the spring, it recharges Malheur Lake, providing thousands of acres of water for common carp, an invasive species, to spawn. Large mature females can lay anywhere from 100,000 to one million eggs each year. By midsummer, millions of young carp, 1-3 inches in size, are found throughout the Malheur Lake system and connected bodies of water, including Marshall Pond. (Learn more about how non-native carp impact ecological functions at Malheur Refuge.)

By late July, most of the snow has melted and evaporation rates on the lake exceed water input from the Blitzen and Silvies Rivers. The lake starts to dry up, exposing hundreds of acres of mudflats that provide ideal habitat for migrating shorebirds. As summer advances, the remaining lake water is concentrated in isolated pools a few acres in size.

As these small pools of water evaporate, carp become trapped and provide an easy food source for an incredible variety of birds, from osprey, pelicans, cormorants and mergansers to egrets, herons, terns, gulls and even the odd shorebird! In wetter years, this spectacle can be especially dramatic at The Narrows, where Malheur Lake empties in Mud Lake. But since The Narrows is completely dry this year, Marshall Pond may be the next best place to witness this late-summer phenomenon.

Malheur’s Butcherbirds

While walking through sagebrush-steppe and greasewood flats in the Northern Great Basin, one may occasionally happen upon an odd and macabre scene: bits and pieces of small animals impaled on sharp branches or along strands of barbed wire, baking in the sun. “Some sort of sadist is at work here,” one might reasonably conclude, while slowly backing away from the carnage. But the real culprit isn’t operating out of maleficence. Those skewered animals are the work of a loggerhead shrike, who is simply engaging in a bit of meal preparation.

Loggerhead shrikes, with their masked eyes and subtly hooked beaks, are something of an avian outlier, breaking the typical songbird mold. Being passerines of a flesh-nibbling sort, shrikes lack the gripping talons of raptors but possess in full their killer instinct. They are predatory songbirds—smaller than robins yet substantially more ambitious in their taking of prey. Swooping down from low perches, the shrike tackles creatures sometimes as large as itself—including insects, reptiles, birds and small mammals—delivering a calculated bite to the nape with its hook-tipped beak, maiming the creature or severing the spinal cord to paralyze it. The victim is then transported back to the shrike’s roost where it is effectively “dressed out”.

Skewering prey on thorns and barbed wire serves a number of functions. Most importantly, it anchors the flesh so the shrike can tear bodily at it; without this leverage, the bird can only stand atop the carcass and yank, which usually results in a lot of falling off and flailing about. (Perching feet don’t have the meathook-like grip and sinew of talons.) Secondly, skewered chunks of flesh will desiccate in the sun and slowly break down, making for easier portioning and digestion. This also serves to detoxify certain prey: noxious compounds in monarch butterflies, for example, start degrading after several hours in the sun, becoming more palatable with age. Lastly, there’s the cache factor. Because shrubs and fences are usually rife with thorny excrescences, there’s ample room for storage—why not keep hunting while the getting’s good? Especially if the cuts only improve as they mature.

Shrikes are sometimes accused of being ravening, truculent butchers, killing not out of necessity but with sadistic intent, festooning trees and fence lines with their spoils. But the shrike isn’t acting out of cruelty or profligacy. Shrikes kill in order to eat; they impale and amass their prey in order to better consume it and provision their families. Woodpeckers hoard mast, jays stash pignolis; shrikes dress carcasses to garland their open-air abattoir.

The Superlative Pronghorn

Across the deserts and grasslands of western North America roams a hooved mammal that is neither deer nor goat nor antelope, being instead a relic of a bygone era when giant sloths, dire wolves and mastodons ruled the land. Pronghorn (Antilocapra americana) are one of a scant few remnants of the Pleistocene megafauna, a suite of oversized land animals that went extinct in North America around 11,000 years ago.

The sole surviving member of the ungulate family Antilocapridae—which included twelve other North American species before Pleistocene’s end—pronghorn’s closest extant relatives are the giraffes, and they are distant kin at that. The pronged “horns” of these ungulates comprise a bony core overlaid by keratin sheaths, which are shed every year. Both males and females bear horns.

Pronghorn are capable of sustained sprints topping 50 miles per hour, making them the fastest land mammal in the Western Hemisphere. It’s thought that this impressive speed—which far outpaces any extant North American predator—is a vestigial trait that arose during the Pleistocene, when cheetah-like cats roamed North America’s grasslands and preyed on pronghorn. In an all-out sprint, pronghorn can cover more than twenty feet per stride.

As the North American landscape shifted from grasslands to forests during the end of the last Ice Age, pronghorn stuck to the shrinking open areas, relying on their 320-degree field of vision and unparalleled speed to avoid danger. Today pronghorn predominately occur in the western half of North America, their herds ranging far and wide across sagebrush-steppe and desert scrublands. To follow seasonal food sources, pronghorn in Wyoming lope along the second-longest migration route of any North American mammal, traveling some 150 miles from wintering grounds in Wyoming’s Upper Green River Basin to Grand Teton National Park each spring.

Pronghorn can be seen using the grasslands and shrub-steppe year-round at Malheur Refuge. The most common view of these superlative creatures is from afar, as they bound up hillsides and across plateaus with indifferent, almost facile celerity, until their semaphoric hindquarters disappear over the ridge yonder.

Carp Derby at Malheur Refuge

On Saturday, August 18, FOMR and Refuge staff will host the annual Carp Fishing Derby at Malheur Headquarters. This event, which began in 2010 and has been held nearly every year since, has traditionally served to kick off a week-long carp fishing season at the Refuge. Today, it’s an opportunity for visitors to come to the Refuge and participate in a good-natured fishing competition, as well as learn more about common carp and the management issues they pose to Refuge staff.

Common carp were introduced to Harney Basin waterways sometime in the early 1900s, likely as a source of food for landowners. They began showing up at the Refuge in the 1920s, and by the 1950s their expanded numbers were having detrimental effects on aquatic habitats within the Refuge. Common carp are bottom feeders, and their constant rooting about for food clouds the water and smothers aquatic vegetation, depriving it of the sunlight necessary for photosynthesis. As aquatic and emergent vegetation disappeared from Malheur’s waterways during the height of the carp invasion, waterfowl and shorebirds—dependent on these habitat types for feeding and nesting—abandoned the refuge.

Carp management is therefore a top priority at Malheur Refuge. Past management efforts have involved piscicides, explosives, electroshocking, fish barriers and removal by hand. Each of these methods has upsides and downsides; all have met with lukewarm results thus far. Currently, the Refuge works with commercial fishing fleets to net the carp en masse and convert them to organic fertilizer.

Events like the Carp Fishing Derby at the Refuge put a light-hearted spin on this serious conservation issue. The Carp Derby is designed primarily for kids, but everyone is welcome to participate. There will be games and activities, educational information about the effects of carp on Harney Basin wetlands, plus prizes for the best fishing and some cooking of carp to feed the attendees.

Event Details:
Saturday, August 18, 7 a.m. – 1 p.m. at Refuge Headquarters
Directions: From Burns, Oregon, go south on Hwy 205 to Sodhouse Lane (first left turn after you cross the bridge at the Narrows) and follow the signs to Refuge Headquarters. 

  • Free, open to the public
  • Participants register at Refuge Headquarters
  • Lunch is provided

American White Pelicans at Malheur Refuge

Soaring on wide, black-tipped wings over North America’s inland lakes, rivers and reservoirs in summer, the American white pelican is an impressive bird even from afar. With nearly all-white plumage and a foot-long bill, these ponderous waterbirds are difficult to confuse with any other species in our area.

The American white pelican breeds in interior North America and spends winters along the southern coasts of the U.S. down into Central and South America. It is one of our continent’s largest native birds, measuring 50-70 inches from beak to tail and weighing between 11 and 20 pounds on average. White pelicans have one of the widest wingspans of any North American bird—averaging more than 100 inches from wingtip to wingtip, second only to the California condor’s span.

In the Northern Great Basin, flocks of American white pelicans may be seen far from water, drifting lazily on thermals high above basin floors as they move between feeding and breeding areas. Pelicans are known by a variety of collective nouns, including a “brief”, “pod”, “pouch”, “scoop”, “squadron” and “armada” of pelicans. The latter is particularly apt for the American white pelican, which often congregates in large flocks on shallow waterways to find food.

Unlike the brown pelican of coastal North, Central and South America, white pelicans do not dive from the air for their prey. They instead capture prey while swimming, sometimes working together in groups to scoop up fish, crustaceans and amphibians from the shallows. At Malheur Lake, white pelicans feed predominately on native redband trout, tui chub, various sucker species, and the ubiquitous, invasive common carp. American white pelicans can eat fish up to 14 inches long, making them one of just a few animals at Malheur Refuge capable of preying on nearly adult-sized carp.

Of the eight species of pelican found worldwide, only the American white pelican grows a vertical plate, or “horn”, near the tip of its bill during the breeding season. Both male and female white pelicans bear these plates, which are shed before eggs hatch in mid-summer.

White pelicans are abundant at Malheur Refuge during spring, summer and fall. Malheur Lake historically supported large colonies of breeding white pelicans, but fluctuating hydrologic conditions determine whether pelicans use the lake as a breeding site. During high water years, breeding occurs on islands and other isolated areas in the lake. In low water years, most white pelicans do not breed at Malheur Lake but will often stay throughout the summer as non-breeders, sometimes in flocks numbering in the thousands. Abundant carp populations in Malheur Lake are particularly enticing to non-breeding pelicans in summer, and peak numbers are usually seen by mid-July and early August. By mid-fall, most of the pelicans at Malheur Refuge have departed south for the winter.