Northern Prairie Wildlife Research Center
Sarah E. Dooling
Originally published in:
North Dakota Outdoors
Official publication of the
State Game and Fish Department
100 North Bismarck Expressway
Bismarck, North Dakota 58501-5095
Dooling, Sarah E. 1997. Promise for Plovers. North Dakota Outdoors 60(1)8-11. Robert, Murphy K. 1997. Plover Paradise. North Dakota Outdoors 60(1)11-12.This resource should be cited as:
Dooling, Sarah E and Robert K. Murphy. 1997. Promise for Plovers. North Dakota Outdoors 60(1)8-12. Northern Prairie Wildlife Research Center Online. http://www.npwrc.usgs.gov/resource/birds/plover/index.htm (Version 29AUG97).
Out of the corner of my eye I saw a familiar form of a pale bird dart along near the shore. I scanned the beach with my spotting scope and found an adult plover with three young. Grabbing another water bottle, binoculars and field pack, I left the truck, rolled under the fence, and followed a cattle trail to a prairie hilltop 200 yards from the beach. I sat against a lichen-covered rock and, ignoring the horde of deerflies about my head, began my weekly observations of plovers and their young.
During spring and summer 1996 I was one of three field technicians hired through The Nature Conservancy to monitor breeding success of piping plovers, and evaluate effectiveness of management aimed at reducing predation on plover eggs and chicks. Bob Murphy of the U.S. Fish and Wildlife Service coordinated the work with cooperative help from the North Dakota Game and Fish Department, The Nature Conservancy, Premier Fence Co., Army Corps of Engineers, Lincoln Park Zoo, FWS from Crosby, Kenmare, and Medicine Lake, Montana, and FWS ecological services and wetland habitat offices in Bismarck.
The effort included data from more than 130 plover pairs in northwestern North Dakota and adjacent Montana. With cooperation from private landowners, breeding territories and nests were located in mid-May by walking just above alkali lakeshores and observing plover behavior. We checked each nesting territory weekly, from remote observation points, to avoid disturbing birds. Each plover pair was monitored until its nesting effort failed and territory was abandoned, or chicks hatched and reached fledging age.
Piping plovers are small, bluebird-sized shorebirds, easily identified by pale, sandy-gray plumage, black neck and forehead bands, orange legs, and a short, stout bill with an orange base. In flight they flash a white rump and white wing bars. During non-breeding season, black bands and bill colors fade. Young plovers resemble the winter plumage of their parents until the following spring.
I could no longer ignore the deerfly stings on my hands and incessant buzzing near my covered ears. As I shifted position, an avocet flying overhead became a screaming aerial acrobat, lunging for my head with defiance and belligerence. Alarm notes rose from the shore as plover adults called to their young. Snuggled tight against a rock, one chick became indistinguishable from the peppered pattern of sand, gravel, and rock. Another chick laid motionless in a tuft of grass. I cursed my bug bites and waited for the panic to pass.
Piping plovers have three distinct breeding populations: (1) Atlantic coastal beaches from Newfoundland to North Carolina; (2) Great Lakes beaches; and (3) alkali lake beaches and river sandbars in the northern Great Plains from Alberta and Manitoba south to Nebraska. In winter, plovers migrate south to the Gulf of Mexico and southern Atlantic coastal beaches.
Although plover pairs are still present throughout their historical range, their abundance has dramatically declined. The Great Plains population is declining steadily, mainly because annual production of young is inadequate, due mostly to predation. Also, dams on major rivers in the region disrupt natural water flows, causing loss of plover breeding habitat.
The plover was listed by the FWS in 1985 as "threatened" in the U.S. Great Plains. This means that unless factors causing its population decline are reversed, the species will become endangered, and could eventually become extinct.
|Andi Rogers and Richard Hansen, technicians for USFWS and The Nature Conservancy, carefully secure a wire mesh "nest cage" over a piping plover nest to keep eggs and newly hatched chicks safe from gulls, raccoons and other potential predators.|
Predation threats facing the Great Plains population stem from many sources and are not clearly understood. Typically, plovers lay four eggs, and incubate them for 28 days. Their young fledge (fly) 19-25 days later. Often a ground squirrel may sneak away an egg, or a coyote or fox may destroy all eggs or even small chicks. Large gulls can terrorize breeding pairs, causing them to abandon their territory. Crows are also effective predators of eggs and small chicks. Although plovers may nest again if their eggs are destroyed, young from late nestings typically do not survive to fledging nearly as well as those from first nests initiated in early to mid-May.
Karen Smith, manager at Lostwood National Wildlife Refuge, was one of the first in the Great Plains to try to reduce predation on plover eggs and young. She refined some techniques and tried them locally at Lostwood, but a broader, random application was needed to formally test the methods. Permanent electric fences had been used successfully by Dr. Mark Ryan and co-workers to keep predators away from plover nests at The Nature Conservancy's Williams Preserve in McLean County.
However, a temporary fence that could be easily removed at the end of a nesting season would have greater potential on most privately-owned lands, and where water levels change dramatically from year to year. A fence used at Lostwood since 1993 might have promise...
I located three chicks from the second brood, feeding on a sandy point within 20 feet of an adult plover. Just over a week old, the young resembled cottonballs on toothpicks. Their tininess imparted a sense of vulnerability. With great energy they scurried up the beach with intense concentration. The shadow of a large bird darkened the beach and a squadron of avocets chased the ring-billed gull away. The plover chicks scattered and hunkered down, gone from sight, while the adult patrolled the beach boldly and frantically. Within a minute the adult's warning notes subsided, the avocets returned to their own young, and the plover chicks emerged fearlessly once again.
We decided to use two types of predator barrier fences on randomly selected nesting beaches of alkali lakes in 1996. The first was a "nest cage," a circular enclosure constructed of wire mesh, measuring three feet high and six feet across. Similar cages are widely used on the Atlantic coast, with positive results for nesting piping plovers. Placed over an active nest, the mesh is large enough to allow plovers to move through, but denies access to predators larger than ground squirrels. Wire on top keeps gulls and crows away.
|An electric mesh fence deters predators such as coyotes and red fox from a piping plover nesting beach in northwestern North Dakota. In an initial trial in 1996, plover pairs protected by a combination of electric mesh fences and "nest cage" barriers produced nearly three times as many fledged young as pairs for which no protection was provided.|
A portable, electric mesh fence called "Electrostop," normally used for livestock applications, was the second tool we used. Powered by deep-cell batteries recharged by solar panels, 75- and 150- foot sections of 3.5-foot high electric mesh fence were strung together along upland edges of beaches, with both ends reaching the water's edge. Plenty of current was generated to decisively deter large predators such as coyotes. Three to four nests were enclosed by 200-400 yards of electric mesh fence, erected by two persons in 1-2 hours. At the ends of the electric fence, "water wings" of galvanized mesh fence extended about 12-20 yards into the lake, to keep predators from going around via the water.
Our experimental design included a comparison among nests with no protection (controls), nests protected by cages, and nests protected by a combination of cages and electric mesh fence. Selection of treatment for nests at a given lake was random, decided by coin-toss.
It took me more than an hour, but at last I found that all three plover pairs on Appam's northeast shore continued to reside securely with their young behind the electric mesh fence. A thunderstorm rolled in from the west. I breathed in the promise of rain and exhaled a silent hope that through continued cooperation and stewardship, piping plovers will overcome the odds and, in doing so, represent the strength of our resolve to recover imperiled resources of the Great Plains.
Appam Lake, in northern Williams County, played an important role in evaluating the protection devices. Two electric mesh fences were erected at opposite ends of the lake, enclosing five nests; three nests were protected with cage only; remaining nests were not protected. Predation still occurred at Appam and other lakes despite protection, in addition to losses apparently due to rainy, cold weather.
But once the breeding season was finished, overall results were encouraging. By protecting both beach and nests with electric mesh fence and nest cages, breeding pairs produced nearly three times as many fledged young as unprotected pairs. Production was much higher than the estimated 1.2 fledged young per pair needed to recover the Great Plains population.
|Table 1. Production of fledglings by random selected nesting pairs of piping plovers in northwestern North Dakota and adjacent Montana, 1996.|
|Pairs With Nests Protected By Nest Cage Only|
|Pairs Protected By Mesh Cage and Electric Fence|
Nest cages, when used alone, produced twice as many fledged young as unprotected nests. Evaluation of plover nest protection will be expanded in 1997 with help from Northern Prairie Science Center at Jamestown. Results will be used to try to determine the most cost-effective approaches for conserving plovers in the northern Great Plains.