Introduction The greater sandhill crane (Grus canadensis tabida) is listed as endangered by the State of Washington. The Washington subpopulation is designated as part of the Central Valley Population of greater sandhill cranes, which winters in the Central Valley of California. The remaining cranes in the Central Valley Population nest in Oregon, northeastern California and southern British Columbia (Littlefield et al 1979, Cooper 1996). During migration and the winter season, the lesser sandhill crane (Grus canadensis canadensis) and the Canadian sandhill crane (Grus canadensis rowani) also occur in Washington. The identification of these subspecies away from their breeding ranges is difficult due to their similarity in appearance and the separation of some of these populations is still debated. Sandhill cranes were once considered common breeders both east and west sides of the Washington Cascades. However prior to 1975, the last known nesting record was in 1941 on the Yakama Indian Reservation, Yakima County (Jewett et al 1953). Summering cranes were not documented again until 1974 when six were observed in the Glenwood Valley of Klickitat County. During the next decade, ground and aerial surveys documented one to three breeding crane pairs and occasional production in the Glenwood Valley, as well as a summering pair on the Yakama Indian Reservation (H. Cole pers. comm.). In 1994, the crane pair on the Yakama Indian Reservation was confirmed as nesting (Leach 1995). In 1995, the Ridgefield National Wildlife Refuge, which administers Conboy Lake NWR, initiated an intensive monitoring program to further assess the population of greater sandhill cranes nesting in the valley. The program emphasis was to locate all occupied crane territories, document breeding success, and determine the population size. Ground surveys for cranes are enhanced by conducting helicopter flights during the nesting season and mid- summer to locate nests and colts (non-fledged young). These aerial flights are a cooperative effort between the U.S. Fish and Wildlife Service, the Washington Department of Fish and Wildlife and the Yakama Indian Nation. Survey coverage included the public and private lands within the Glenwood Valley and historic and potential sites on the Yakama Indian Reservation. In 1997, this effort was expanded to private timberlands and the Gifford Pinchot National Forest through the cooperation of Champion International and the U.S. Forest Service. Methods Sandhill cranes begin arriving on the breeding areas in late February to early March. Ground surveys and territory monitoring are initiated in mid April and conducted at approximately two week intervals during the nesting season. Monitoring is intensified once hatching commences to determine the number of colts present, their survival until fledging, and their habitat/territory use. Monitoring is reduced after fledging but continues until the cranes depart southward in early to mid October. A helicopter survey is conducted in late May or early June to locate nest sites, verify ground data and survey sites inaccessible from the ground. Nest sites are visited after hatching or nest failure to determine clutch size. A second helicopter flight is conducted in July, approximately six weeks after the peak hatching period. This flight assesses the survival of colts and is used to assist in locating previously undetected colts for banding purposes. Surviving colts are color-banded when possible and monitored until they fledge to determine annual production. Results and Discussion Breeding Pairs The number of observed breeding pairs increased considerably once intensive monitoring was initiated in 1995. It is expected that some pairs remained undetected during pre-1995 surveys, thus the current population increase may not necessarily represent recent recruitment into the breeding population. The Glenwood Valley harbors the majority of the breeding crane pairs, which nest and forage on Conboy Lake NWR and adjacent private lands. This poses some complications to monitoring and banding operations, however the refinement of survey techniques and the accumulation of territory data over the past four years has enhanced the ability to determine nesting status and estimate populations. A total of six breeding pairs of sandhill cranes were confirmed in 1995 within the Glenwood Valley, while one nest was observed on the Yakama Indian Reservation. Three additional pairs were confirmed nesting in 1996. During 1997, twelve breeding pairs were confirmed in the Glenwood Valley, one within the Panakanic Valley and two on the Yakama Indian Reservation. Fourteen pairs nested in the Glenwood Valley in 1998. Nesting elsewhere was not confirmed due to problems conducting the aerial surveys. Based on the 1998 data, five additional non-breeding birds were present including two banded subadults from 1997. The minimum breeding age of cranes varies geographically ranging from three years to seven years and cranes generally mate for life (Tacha and Nesbitt 1994). In 1998, two sibling males banded in 1996 nested with unbanded females. Although these attempts failed, it suggests that factors such as food, habitat, and mate availability are not inhibiting population growth at this time. Except for the Glenwood and Panakanic Valleys, and the Yakama Indian Reservation, there are no known breeding sites elsewhere in Washington. The 1998 post-breeding population of greater sandhill cranes was estimated at 33-39 adult cranes and five fledged young. Table 1 summarizes the estimated population, number of breeding pairs and known fledglings from 1990 to 1998. Production Nesting success and production determination is problematic. Nests and colts fall victim to a variety of natural and man-made factors. Predators such as ravens and coyotes predate nests, and colts are particularly vulnerable to coyote predation. There is considerable information implicating these species as potentially significant crane predators (Littlefield 1995). Nesting success is also impacted by annual water conditions. A sudden influx of water due to snowmelt or rainfall may inundate the over-water nest, while dry conditions may expose the nest to ground predators which are otherwise deterred by water. Water conditions also directly affect the timing of agricultural activities such as grazing and haying. Crane nests and colts on private lands are subject to trampling by cattle. Cranes also extensively utilize private hay fields for foraging which may expose colts to increased mortality during haying operations. This problem has been documented at sites outside Washington. Haying operations on public lands are now restricted until after colts have fledged. Annual crane production is relatively low due to the many factors that plague the nests and colts. This low nest success and colt survival is countered by the relatively long life span of adult cranes, which may approach 20 years. The documented annual production in the Washington population has ranged from zero to five colts. Fledging usually occurs by August 1 in the Glenwood Valley. Annual production is determined by the number of colts known to reach flight stage. Production data is summarized in Table 1. Color-banding A banding program was initiated in 1996 to collect long-term data on individual cranes. The data sought from this endeavor includes winter survival and site fidelity of juveniles, longevity of adults, mate and nest site fidelity, limits of foraging territory and age at first breeding. Banding has focused on colts since they have proved the easiest to capture. Colts are targeted for capture and banding at approximately six weeks of age, just prior to fledging. Cranes are color-marked on one leg with a USFWS metal band and a blue-white-blue color band (site band). The opposite leg is banded with two unique color combinations for individual identification. The color scheme of the site band designates that the crane was banded in Washington. Four colts were color-banded in 1996 on Conboy Lake NWR. Two of these colts (siblings) survived to fledging. These two colts were observed near the town of Glenn, Glenn County, CA on January 14, 1997 (H. Tangermann pers. comm.). This is the first observation verifying that the Washington greater sandhill crane population winters in the Central Valley. These two banded subadult cranes returned to the Glenwood Valley in 1997, and nested in 1998. Two of four fledged colts were color-banded in 1997. These two banded subadult cranes also returned to Conboy Lake NWR in 1998, and were subsequently observed during the fall migration (29 September) at Lower Klamath NWR (J. Beckstrand, C. Herziger, pers. comm.) Three colts were color-banded in 1998; one fledged, one was predated, the status of the other is unknown. Preliminary information from the banding program has provided insights into the fall migration and overwintering sites of the Washington subpopulation of greater sandhill cranes. It also indicates that the subadult cranes have a relatively strong fidelity to their natal grounds and may breed at an early age, if habitat conditions and food availability are adequate. Monitoring of color-banded cranes also indicates that mortality primarily occurs on the breeding grounds prior to fledging. Overall, Washington's nesting population of greater sandhill cranes is increasing. However, there currently appears to be a lack of suitable habitat for expansion outside of the known nesting localities. The long-term survival of this nesting population is tenuous due to increasing development in the Glenwood Valley, and the difficulty in managing refuge habitat due to competing agricultural interests and inholdings within the refuge's proposed boundaries.
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1990-1994 data is based on incidental observations; the numbers presented are unconfirmed estimates. * this data includes only the Glenwood Valley; due to problems conducting the aerial flights, status of the three off-refuge nest sites was unknown Literature Cited Cooper, J.M. 1996. Status of the sandhill crane in British Columbia. Wildlife Bulletin, ISSN 0829-9560; no. B-83. Ministry of Environment, Lands and Parks, Wildlife Branch, Victoria, B.C. 30 pp. Jewett, S.A., W.P. Taylor. W.T. Shaw, and J.W. Aldrich. 1953. Birds of Washington State. University of Washington Press, Seattle. 767 pp. Leach, R.H. 1995. Confirmed sandhill crane nesting in Yakima County, Washington. Northwestern Naturalist. 76:148. Littlefield, C.D. 1995. Sandhill crane nesting habitat, egg predators, and predator history on Malheur National Wildlife Refuge, Oregon. Northwestern Naturalist. 76:137-143. Littlefield, C.D., and S.P. Thompson. 1979. Distribution and status of the Central Valley population of greater sandhill cranes. in J.C. Lewis, ed. Proceedings 1978 Crane Workshop. Colorado State Univ. Press, Fort Collins. Tacha, T.C., S.A. Nesbitt, and P.A. Vohs. 1994. Sandhill Crane. in T.C. Tacha and C.E.Braun, eds. Migratory shore and upland game bird management in North America. International Association of Fish and Wildlife Agencies, Washington, D.C. 223 pp. Submitted by: Joseph Engler, Wildlife Biologist and Eric Anderson, Biological Technician, Ridgefield National Wildlife Refuge Complex