by Tina Yerkes, Ph.D.
The plight of the pintail continues to be one of waterfowl biology's greatest mysteries and one of even greater concern. Pintail populations remain below the North American Waterfowl Management Plan goals. The pintail is the only prairie-nesting dabbling duck that has failed to respond positively to improved habitat conditions. As other species have returned to favorable numbers, pintails creep along at the bottom of the duck population scale.
What exactly is the problem? Ask five waterfowl biologists and you are likely to get five different opinions. We all agree, however, that the problem is multifaceted and complex. Amazingly, there are many parts of the pintail life cycle that we simply do not understand. Some of these "black holes" of knowledge are being illuminated by a high-tech international research study called PINSAT. The primary focus of this study is to identify spring migration routes and critical spring staging areas of pintails that winter in the Central Valley of California. Sixty percent of the continental pintail population winters in the Pacific Flyway, with the Central Valley of California being the hot spot. However, the number of wintering pintails there has decreased. Native wetlands in this state have been reduced to approximately 6 percent of their original number. Some of these remain under management by public agencies, but the majority are in private hands. Private wetlands have been relatively secure largely due to the strong tradition of duck hunting in California.
Winter is a very important time for pintails, not only because this is when they select mates, but also because this is the time to lay down fat stores for the spring trip north to the breeding grounds. (The majority of the North American pintail population breeds in the Prairie Pothole Region of Alberta, Saskatchewan and the Dakotas.) Research has shown that low nest success is the primary factor limiting pintail population growth.
While improving nest success for pintails in the PPR is generally accepted as the primary mechanism to bolster continental pintail populations, other areas such as Alaska have been critical to maintaining pintails in the interim.) Alaska researchers have found that these fat reserves are critical for pintail success on the tundra breeding grounds. Arriving before the snow even melts, hen pintails choose nest sites immediately and begin laying eggs. By the time the tundra explodes with food, pintail nests are near hatching. The fat carried north from the wetlands and rice fields in California and other spring staging areas allows females to nest immediately upon arrival in the frozen north.
One of the first steps to better understanding pintails is to learn spring migration routes and to identify spring staging areas where hens gain fat prior to arrival at their breeding destination. The PINSAT study is achieving that goal, under the leadership of Mike Miller from the Western Ecological Research Center. Initiated in the winter of 2000 in the Central Valley, this high-tech ground-breaking study was made possible by a grant from the Tuscany Research Institute and is a cooperative effort among the Western Ecological Research Center of the U.S. Geological Survey, California Waterfowl Association, and Ducks Unlimited, with logistic support provided by the U.S. Fish and Wildlife Service and California Department of Fish and Game.
Pintail hens wintering in the Central Valley were trapped in both January 2000 and December 2000/January 2001 and fitted with satellite transmitters. Hens were lured to trap sites with bait corn while biologists watched from afar. Once several females were feeding on the corn, nets were deployed from a remote location. The nets fly over the unsuspecting birds with the aid of explosive rockets; hence the technique is called rocket netting. Pintail hens are removed from the net and transported to a field station where they are fitted with backpack satellite transmitters called platform transmitter terminals (PTTs). The PTTs send a signal to satellites every three days until their batteries die, which is generally no sooner than nine months. This technology enables us to follow the hens' movements through the spring, summer, and sometimes into fall migration.
By tracking hens through spring and summer, we have made valuable discoveries that are helping us focus our conservation efforts and identify habitat programs that will aid pintails. In both years of the study, we have observed hen pintail movements around the Central Valley and their exodus north. Once outside the Central Valley, the first and most notable destination is southern Oregon and northeastern California. Between 80 and 85 percent of the hens visited this area and spent several weeks there before moving farther north. Their favorite areas included Lower Klamath National Wildlife Refuge (NWR) in California; and Warner Valley, Chewaucan Marsh, and Malheur NWR in southern Oregon.
The amount of time hens spend in these spring staging areas seems to be related to their final destination. Hens that have farther to travel to their breeding ground of choice stayed longer to feed and fatten up for the longer flight. Those that traveled directly to Alaska over the ocean stayed up to two months, whereas those traveling directly to the Canadian prairies stayed less than a month. This behavior alerted us to the importance to pintail hens of these staging areas in northeastern California and southern Oregon. These public lands, as well as private farmlands and national wildlife refuges and wildlife areas, are critical to pintails migrating from the Central Valley.
This area is clearly important to waterfowl and was first recognized by President Roosevelt in 1908 when he established the Lower Klamath NWR as the first waterfowl refuge in North America. Because of the scarcity of stopover areas in northern California and southern Oregon, large numbers of waterfowl concentrate in the available wetlands. In some years, as many as a million birds congregate in these basins before traveling north to the breeding grounds. This area has been heavily impacted in the past by drainage activity (less than 25 percent of the wetlands remain) and continues to be threatened. Today, however, the chief concerns are water quality and quantity. The basin has been oversubscribed for water, and there is great competition between agricultural, fisheries, and wildlife needs for water.
Once hens depart northeastern California and southern Oregon, their migration behavior can be divided into three groups based on their final destination. In the study, one batch of females flew directly to the Canadian prairies after staging for about a month. Both years of the study, all of these hens probably found the conditions on the prairies not to their liking, left the prairies, and traveled north to the Northwest Territories, or flew to Alaska. Pintails will not settle in an area where wetland conditions are poor. Unfortunately, the western prairies were relatively dry during the springs of 2000 and 2001, so those females likely flew north in search of greener pastures.
Another group of hens also flew to the Canadian prairies, but indirectly-through various areas such as eastern Oregon and Washington, southern Idaho, and Montana. Of those hens that flew indirectly to Canada, less than half stayed, while the remainder flew on to Alaska and the Northwest Territories.
The final group of hens flew directly to the westernmost part of Alaska: the Yukon-Kuskokwim Delta (Y-K Delta). These were the last hens to depart northeastern California and southern Oregon, but they actually arrived at the same time as those hens that first explored the prairies before traveling to Alaska. It is likely that these females made a single flight over the ocean to reach this isolated area. One female's signal was satellite intercepted while she flew over the Pacific Ocean, west of the Queen Charlotte Islands, while another continued on to Siberia.
Ironically, I was also traveling in the spring of 2000 to Chevak, a small town on the Y-K Delta, to work on a related pintail project. I was keeping track of the marked females in a race to see who would get to the Y-K Delta first: a hen pintail or me. Technology triumphed over avian flight characteristics, and I arrived just a day before seeing the first pintail. When I got there, the area was covered by snow, with only a few patches of tundra vegetation showing through. It was cold, frozen, and isolated, but breathtaking. I had known that pintails are early nesters, but sitting on the patchy, snow-covered tundra in May, while watching hen pintails explore the sparse vegetation, made that knowledge real.
Another issue that potentially clouds our understanding of pintail population patterns is the accuracy of the spring surveys conducted each year to estimate the number of breeding birds. Because pintails respond opportunistically to wet conditions on the prairies, their settling patterns could be different each year and different from other species. This may negatively affect population counts in years when the prairies are dry because birds may be farther north and outside of the surveyed area. Therefore, a secondary objective of the study was to determine the proportion of pintails that are annually unaccounted for by the May population survey conducted by the U.S. Fish and Wildlife Service and Canadian Wildlife Service.
Based on the first year of the study, it is estimated that up to 40 percent of the marked females were missed during the time when the survey was conducted because they were in locations outside the survey area. All the missed females were in Alaska, the Northwest Territories, and Russia, probably displaced there by the dry conditions.
The information obtained during this study not only sheds light on our basic understanding of pintail biology, but also links to our conservation initiatives and helps identify future research needs. Approximately 100 years of banding data are available on pintails from the Central Valley, but until this study we did not understand the different routes birds traveled nor the exact location of the various staging areas important to Central Valley pintails. "Identification of these areas allows us to focus on specific conservation programs that will ensure both the perpetuation of vital habitat and restoration of marginal areas," notes Dr. Fritz Reid, director of conservation planning for Ducks Unlimited's Western Regional Office, located in Sacramento, California. "Specifically," says Reid, "we can focus on easements to protect what is there and work with private landowners and managers to develop large complexes of sheet water and seasonal wetlands in proximity to areas used and identified in this study."
Now that we know what areas are critical for spring staging pintails, we can initiate research programs to determine if those areas are meeting the nutritional requirements of the birds. This spring, we noticed that hens stayed in northern California/southern Oregon longer than the previous year. Coincidentally, this spring was drier than the spring of 2000, and some of the wetlands that hen pintails used in the first year of the study were completely dry. Were the available wetlands providing enough food for spring staging pintails?
Habitat management programs need to fill the gap in dry years, but first we must understand what those needs are from a hen pintail's perspective. Next spring, Ducks Unlimited and its partners will initiate research studies to determine the requirements of spring staging pintails. Through this cooperative high-tech research project, we are one step closer to understanding the elusive pintail.
Pintail Nonconformists During many waterfowl research projects, there are always a few birds that simply do not fit the pattern. Those outliers can make the results difficult to interpret, but they are often the most interesting and unexpected. In both years of the study, we had several hens with Russian connections. In 2000, a hen left the Central Valley and spent significant time in northeastern California and southern Oregon. She then flew to southern Alaska and kept right on going. After spending the summer in Russia, she returned to Alaska to hang around until mid-October, when we did not hear from her again (due to radio life). In 2001, three hens spent the summer on Russian soil. This discovery has sparked interest by Russian biologists, who are planning banding operations for areas never before sampled in eastern Russia.
Another female won the prize for frequent flyer miles. From January 13 to August 31, 2000, she visited the following destinations: Central Valley, Idaho, northeast California, eastern Montana, North Dakota, Manitoba, North Dakota, South Dakota, North Dakota, central Saskatchewan, northeast California, and all that just to return to the Central Valley in August.
The third notable female takes the prize for an unexpected guest. She flew south from the Yukon-Kuskokwim Delta on October 1 and landed on a shrimp boat off the northern Oregon coast to be escorted to land and released into a wetland. Imagine the surprise of the crew to find a radioed pintail hitching a ride.
Technology Makes Duck Research Easier
Without the use of satellite transmitters, researchers would not be able to trace the movements of individual birds over such an expansive geographic area. This technology became available in the early 1990s, but only recently has it been miniaturized for use with small birds such as the pintail. Transmitters used in this study are called PTTs, or platform transmitter terminals and are manufactured by Microwave Telemetry, Inc. Three NOAA (National Oceanic and Atmospheric Administration) polar orbiting weather satellites detect the transmitter signals. These are the same satellites that help forecast the weather, detect forest fires, and monitor volcanic eruptions. For our purposes, however, they pick up signals from pintail radios that are programmed to transmit for six hours every three days. From these signals, locations of hens are estimated based on the information received by the three satellites. Signals are relayed back to a ground station in real time and sent to the USGS' Western Ecological Research Center via the Internet.
For the Love of Pintails
Not surprisingly, this high-tech research is supported by someone with a great fascination for these wonderful birds and who, himself, is an architect by training and deeply involved in high-tech business ventures. Anthony A. (Tony) Marnell II has watched his favorite duck decline in numbers from a time when the California hunting limit was 10 per day to recent lows when only one bird can be taken. During this time he has employed the best-known management practices to support the birds on his own property in the delta of the Sacramento and San Joaquin rivers of California-but has not been rewarded with more birds for those investments.
"Keeping my club at Mandeville Island in prime condition for pintails is a constant challenge-one that I am glad to pursue," said Mr. Marnell. "Nevertheless, I know the pintail problem is the result of factors that are remote from the delta-probably away from the Central Valley altogether. I was intrigued by the possibility that the satellite transmitters might offer a way to discover things that would not be available by any other method. I am delighted that new information is emerging that organizations like Ducks Unlimited can put to work to improve conditions for the birds through habitat conservation efforts wherever they are needed."
Mr. Marnell is the president of the Tuscany Research Institute of Las Vegas, Nevada. Tuscany is supporting this research through two grants, one to Ducks Unlimited and one to the California Waterfowl Association. "This is exciting stuff. The technology and science are great, but we have also been able to share the information with other scientists and the public on the Internet," said Marnell. "Another partner in the project, the U.S. Geological Survey in Dixon, California, has established a Web site, Discovery for Recovery, on which one can trace the movements of all the birds as they make their way north and south each year."