Golden Eagles
- Adult Golden Eagle Satellite Tracking Study
- Determining Gender
- Wing-loading Project
- Eagle Lead Project
Adult Golden Eagle Satellite Tracking Study
Click here to see a map of our two eagle's movements.
Little is known about adult Golden Eagle migratory ecology in North America. Where do they winter and how long do they stay? Do they use the same migration routes and wintering areas annually? What are the major causes of mortality, both human related and naturally occurring? These are just some of the questions that we need to answer in order to determine appropriate conservation and management strategies. To help answer some of these difficult questions, we have partnered with Melanie Smith (Geographic Information Systems analyst) of Missoula, MT.
This year, with major funding from M.J. Murdock Charitable Trust, we secured three satellite transmitters, successfully deploying two of the units on adult males. To our knowledge these are the first two adults ever captured on migration in western North America to be outfitted with satellite transmitters. This allows us to track the
daily movements of these two eagles. We are planning to use our third transmitter this spring. Compared to young eagles on migration, the adults are far less studied. We can learn more about Golden Eagle migratory movements as a whole, as adults are proven survivors and have presumably made their migratory journeys many times over.
Our two adults, male GE53 mapped in red and female GE52 mapped in black, were fitted with transmitters on October 15th and 25th respectively. They migrated along the Rocky Mountain Front, flying nearly identical routes, covering as much as 370 km (230 miles) per day.
From our banding station, they went south, through Yellowstone
National Park, picking up the Wind River Mountain Range in Wyoming. Both birds hung out around the southern end of the Wind River Mountains along the Wind River for several days. Perhaps a good feeding area, or maybe weather conditions necessitated a stop, or both? After which, they flew southeast into Colorado, where they held up in Rocky Mountain National Park, near Lake Granby for about a week. Keeping on the move they continued cruising along the Rocky Mountain Front, riding the updrafts of the Sangre De Cristo Mountains, passing through Great Sand Dunes National Park, south into New Mexico close toRoswell. It is here where GE53 chose to winter. However, GE52 flew through GE53s wintering area and continued along the Davis Mountains to the Rio Grande River and wintering just north of Amistad Reservoir. She covered roughly 2600 km (1600 miles) in 14 days.
Determining Gender in Golden Eagles
Morphological measurements such as, wing-chord, tail length, body weight, etc., have proven to be reliable indicators in determining gender for several raptor species. In many raptors, females are often measurably larger than males. However, this is not always the case with golden eagles. By collecting DNA and comparing it to our morphological measurements, we hope identify the most accurate technique for sexing golden eagles in hand.
Wing-loading Project
In general to determine wing-loading, we utilize wing area and body mass measurements. Wing-loading is known in many species of raptors, but not in golden eagles. This research will add insight into golden eagle aerodynamics and behavioral ecology.
Eagle Lead Project
Lead poisoning in raptors, especially bald eagles has been well documented. A ban on lead shot for waterfowl hunting was initiated in 1991 to remedy this problem. However, colleague Bryan Bedrosian with Beringia South regularly detects elevated blood-lead levels in ravens and bald eagles, from the on-set and shortly after rifle hunting season. Evidence suggests that the contamination may be coming from gut piles.
Like ravens, golden eagles are opportunistic feeders, known to scavenge gut piles. This fall we collected blood from 35 golden eagles. These samples are currently being analyzed for lead by University of Montana chemist Heiko Langner. Preliminary data, using a portable lead test kit reveled elevated lead levels in nine of seventeen birds tested in the field.
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