Cranes Home [Update and Maps]  [Colt Capture]  [Adult Capture]

Tracking Lesser Sandhill Cranes
Using Satellite Telemetry

During late-July 2000, the Alaska Department of Fish and Game with supplemental funding from the USFWS (Migratory Bird Management Office - Regions 1 and 7) and a reserch grant from the Webless Migratory Game Bird Program, initiated a pilot project using satellite telemetry to track movements of lesser sandhill cranes from their summer range in upper Cook Inlet, Alaska.  Read why the study was initiated (see below), view maps of crane movements, and learn how they were captured.

INTRODUCTION

Lesser sandhill cranes (Grus canadensis canadensis) are common residents in Alaska during the summer months. Their wide wing span, long legs and neck, and prehistoric call are characteristics that identify this easily recognizable migratory bird.  Soaring high on thermal air currents, the presence of large flocks of migrating cranes signifies the beginning of spring and the coming of fall.  During the nesting season, however, cranes are less gregarious dispersing in low densities to remote areas around the state. 

Two populations of lesser sandhill cranes are currently recognized in Alaska.  The distinction lies in their separate use of summer and winter range, and their separate migration routes. The Mid-Continent Population (MCP) nests across a broad continental range extending from northcentral Canada westward through northern and western Alaska, and across the Bering Sea to Siberia. The major nesting areas in Alaska for the MCP are the Yukon-Kuskokwim Delta, the Tanana Valley and Yukon Flats. The MCP has been gradually increasing, and currently numbers nearly 500,000 cranes. During the fall migration, MCP cranes in Alaska follow an inland route north of the Alaska Range, east of the continental divide and south through the great plains to wintering areas in Texas, New Mexico, Arizona, Oklahoma, and northern Mexico.  A study of marked cranes on the Yukon-Kuskokwim Delta confirmed their migration through the mid-continent region.  Recent satellite telemetry work being conducted by the Northern Prairie Wildlife Research Center is expanding our knowledge about the migration routes of the MCP.
  

The other population of lesser sandhill cranes residing in Alaska is the Pacific Flyway Population (PFP). The PFP is much smaller than the MCP numbering about 20-25,000. However, there has never been a reliable population index for this group.  Considerably less is known about the PFP than the MCP. We currently believe that PFP cranes nest from the Alaska Peninsula and Bristol Bay east to the Kenai Peninsula and Upper Cook Inlet.  The summer range of the MCP and PFP populations are adjacent in western Alaska, however, we don’t know if a precise boundary separates their breeding ranges, or if overlap occurs. 

During the fall, the PFP is believed to follow a coastal route during migration, at least while in Alaska.  Based on historical observations and sightings of a small number of color-marked birds, the PFP travels east then south along the Alaska coast, stopping along the way near the Copper River Delta, Yakutat, Gustavus and the Stikine River Delta. Near the Stikine River Delta in southeast Alaska, the majority of sandhill cranes migrate east through the mountains into interior British Columbia. From there they travel south through eastern Washington and Oregon, eventually arriving in the Central Valley of California where they spend the winter.

It’s speculated that another, smaller group of cranes don’t travel into interior B. C., but continue south along the coast of British Columbia after leaving coastal Alaska.  They enter Washington south of Vancouver, B. C. and continue south to their primary staging areas at Ridgefield NWR, Washington and Sauvie Island, Oregon where they remain from September through November.  They then travel through the Willamette Valley, Oregon to wintering areas in California.  It has been hypothesized that the two separate migration routes through Canada and the northwest states implies that two distinct segments of the PFP exist, an "eastern” (interior route) and "western" (coastal route) segment.  It has been further speculated that the "western segment" is composed only of cranes from the Cook Inlet region; the Bristol Bay cranes taking the interior route south.  

Historical observations have documented fall crane migration along the B. C. coast, into Washington and south to the Willamette Valley. In the 1980’s a group of cranes was observed wintering near Red Bluff, CA apparently separate from PFP cranes further south. However, the identity and origins of these birds has not been determined. The integrity of a “western segment" of the PFP has not been corroborated through banding, marking or observations of individual cranes.  An alternative hypothesis is that these coastal migrants are cranes that breed in Southeast Alaska and may represent a population of intermediate-sized birds—known as "Canadians".  Breeding sandhill cranes are found throughout the muskegs of Southeast Alaska forests, but have not been enumerated, described or banded.

Problems and Needs

Increasingly more information is required to manage populations of migratory birds, especially for species that exhibit disjunct distributions during certain periods of the year. The breeding range separation of PFP cranes in western Alaska from those in the Upper Cook Inlet region warrants investigation of the discreteness of these population units.  Banding and marking of PFP cranes has only occurred a few times and only on the wintering grounds in the Central Valley of California; these markers have not been seen on any breeding areas (closest observations on Copper River Delta staging area). There is little information about distribution, ecology or productivity of this population on the breeding grounds.  For management purposes, it is important to determine whether PFP cranes have a discontinuous breeding range, whether Cook Inlet cranes differ in ecology and behavior from Bristol Bay cranes, and whether the two groups function as separate population segments throughout the year.

The degree to which cranes from different breeding areas mix during migration, and during the winter is unknown.  It is important for managers to determine whether there is an eastern and western "segment" of the population, and if there are traditions for using eastern and western migration routes. Ties to specific migration routes may be traditional and related to breeding origin.  On the other hand, migration route may be a matter of choice influenced by local climatic conditions occurring in southeast Alaska during critical spring and fall staging periods.

Delineating affinities among wintering, staging and nesting areas is necessary to manage the population through reliable inventories and appropriate harvest regimes. The need for this information is particularly important for habitat protection, in that current proposals for development projects in Alaska, Washington, Oregon and California could have important impacts on PFP cranes through habitat degradation and increased disturbance. Potential impact on cranes from local developments has generated public concern and the demand for additional information regarding their breeding origin, population size and harvest rates. Our goal in this pilot project is to use satellite telemetry to identify migration routes, stopover areas, and length of stay at staging areas and winter ranges for PFP sandhill cranes.

For more information about Sandhill Cranes see our Wildlife Notebook Series or visit the International Crane Foundation.