Drought Displaced Movement of North American Pintails into Siberia

Abstract

During the years 1954-70, 230 pintails ( Anas acuta ) banded in North America were reported from eastern Asia, primarily Siberia. Most of the birds were shot on the breeding grounds in May. The movement into eastern Asia of pintails banded in the interior of North America was directly correlated with the overflight of the southern portion of the breeding range in North America (r = +0.73**); this overflight resulted from drought conditions (Smith 1970). Thus, the magnitude of the pintail movement into eastern Asia is believed to be dependent upon water conditions some 3,000 miles away. A higher percentage of the pintails banded in the west was reported from eastern Asia, although the recovery rate index was not significantly correlated with the percentage of pintails found in northern Canada and Alaska (r = +0.46 NS). Apparently, a portion of the pintails which winter in the western United States annually nest in Siberia, regardless of water conditions on the North American breeding grounds. J. WILDL. MANAGE. 37( XJ:23-29 The purpose of this paper is to explore the tansoceanic movement of pintails into eastern Asia, primarily Siberia. Chattin ( 1964 ) noted that pintails banded in various localities in Alaska and other parts of the United States and Canada have been recovered in spring, summer, and early fall in Siberia; and it is generally recognized that pintails are great travellers. Two birds banded in Labrador were recovered in England (Leach 1950, 1952); one banded in Iceland was shot in Quebec ( Lewis 1933); and one banded in Utah was recovered on Palmyra Island, 1,100 miles south of Honolulu, Hawaii (Lincoln 1943). The first record of a banded pintail from America was reported from Siberia in the spring of 1936 ( Cooke 194S) . The bird was banded earlier the same year in Califomia. These recoveries are of interest because it has long been stated that the North American populations differ from those in Europe and Asia, although Hellmayr and Conover ( 1948 ) and Delacour ( 19S6 ) agree that the American subspecies should not be recognized. Several authors have presented evidence that large numbers of ducks continue moving northward into northern Canada and Alaska during years of severe drought in the prairie pothole country of souffiern Canada and the northcentral United States (Hansen 1960, Hansen and McKnight 1964, Crissey 1969, Smith 1970). As the pintail has a circumpolar distribution ( Kortright 1942), perhaps population shifts of great distances may be expected for pintails during years of adverse water conditions on the southern breeding grounds. Smith (1970) showed a significant inverse relationship between numbers of water areas on the prairies of Alberta and Saskatchewan and the portion of the pintail population moving north of the prairies and parldands for the years 1959-68. Furthermore, as the portion of the pintail population moving into northern areas increased, an index of annual production declined. The present paper may be considered an extension of the earlier work by Smith, as pintail band recoveries from the waterfowl breeding grounds in eastem Asia are discussed with respect to water conditions in southern Canada. I wish to thank Dr. R. I. Smith and Dr. V. T. Harris for reviewing an early draft of the manuscript; and W. F. Crissey for informative discussions on pintail movements. J. Wildl. Manage. 37 ( 1 ) :1973 23 This content downloaded from 157.55.39.177 on Sat, 19 Nov 2016 04:38:11 UTC All use subject to http://about.jstor.org/terms 24 PINTAIL DISPLACEMENT INTO SIBERIA * Henny ber of banded birds alive, a 50 percent annual mortality rate was assumed for the birds banded the previous 8 years, i.e., the number alive in the spring of 1970 would be 50 percent of the preseason banded birds in l969, 25 percent of the preseason banded birds in 1968, etc.... together with all of the postseason 1970 banded birds, 50 percent of the postseason 1969 banded birds, etc. Of the birds banded during the hunting season, it was assumed that 75 percent were alive the following spring, and 50 percent died each year thereafter. The annual indexes to the numbers of banded pintails alive in late spring (the primary time of recovery in eastern Asia ) is somewhat crude, but it is believed to be a useful index.