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.