Working on a wildlife refuge often provides a glimpse of how unforgiving nature is when it comes to predator-prey relationships.
Most species of wildlife all share one thing in common — staying alive from one day to the next. I have observed hooded mergansers eating fish, great blue herons spearing frogs with their sharp bills, coyotes chasing ground squirrels and prairie falcons knocking mallards out of the sky, but by far the most impressive predator-prey encounter I stumbled upon was a golden eagle taking down a white-tailed deer fawn.
While I did not witness the actual take down, I came across two adult golden eagles feeding on a freshly killed fawn. Inspection of the carcass revealed talon marks on the face and ears of the fawn with talon puncture marks on the backside of the neck. Since this was around 9 a.m. in full daylight and the majority of the fawn was still intact, I concluded the kill was quite recent and the eagles were likely responsible.
A coyote or likely a pack would have devoured the small deer quickly and it would be unusual for a mountain lion to make a kill in broad daylight and abandon the kill without attempting to conceal the prize. Watching these magnificent birds defend their prey against magpies and ravens, I was struck by the size of these birds and easily imagined them taking down prey of this size.
Named for the golden appearance of their feathers, especially those around their neck, golden eagles are one of the largest birds in North America. Standing over 30-inches long and boasting a wingspan of over 7 feet, this large raptor has incredible acrobatic flight abilities. While they use those skills largely to capture small mammals like rabbits, ground squirrels and prairie dogs, Golden Eagles have been observed taking down mountain goats, bighorn sheep and domestic livestock. With the abundance of white-tailed deer in the Bitterroot, it certainly makes sense that local goldens have learned to take advantage of the abundance of fawns in the summer and early fall.
Golden eagles are relatively longed lived raptors with the oldest recorded bird living over 30 years. They tended to avoid the complication associated with chemical pesticides by largely avoiding ingesting birds, fish, and insects where pesticides concentrate.
Golden eagles are still threatened with lead poisoning by ingesting lead bullet fragments from big game carcasses. Attempts to replace lead bullets with nontoxic versions are beginning to reduce that threat, but we still have far to go to convince many hunters that nonlead options exist. If you head into the woods this fall, keep that in mind, those lead fragments left behind with carcasses can kill both golden and bald eagles.
Occasionally I will hear someone call out, look there’s a golden eagle when in fact they were pointing at another large soaring bird, the turkey vulture. Other than the golden eagle being a quarter again the size of a vulture, one characteristic to differentiate the two is that vultures soar with more of a “V” shape position to their wings. Eagles soar with more of a straight line, horizontal wing position. The other common point of confusion is misidentifying an immature golden eagle with its cousin the bald eagle.
While the adults are easily distinguishable with bald eagles possessing the classic white head and yellow beak, and white tail, and the golden having its golden chocolate plumage and dark beak, it is the immature of the two species that causes confusion. The immature bald eagle has largely brown plumage and if you look closely you can still see its un-feathered legs with yellow tarsi’s. Golden eagles have feathers extending all the way down to their toes.
Differences in head size is also a distinguishing characteristic, especially in flight. Bald eagles’ heads will look as large or larger than their tail, while a golden’s head will look smaller than their tail. Additionally, if an immature bald eagle has white body plumage it will appear randomly throughout their body while immature goldens will have distinct patches on their wrists and base of their tail.
Golden eagles prefer to build their nests in rocky canyon-cliff country. Peering west from Teller, goldens in the Bitterroot find suitable sites to nest in the many steep rock cliffs present on the east-facing slopes of the Bitterroots. Telemetry data collected by Raptor View Research Institute reveals that some golden eagles spend the entire year moving between the Sapphire Mountain Range and the Bitterroot Mountains and frequently spend time in the Bitterroot Valley between Darby and Florence. Is there a correlation between late August valley visits and the abundance of white-tailed deer fawns?
One can only speculate that there may be some prey driven influence to these valley visits. Perhaps the eagle I observed on Teller that day was an adult female named Rhonda, who spent many months roaming the Bitterroots over the last few years. Unfortunately, her tracking device fell off and current locations are no longer being recorded.
Over 130 golden eagles have been banded by Raptor View Research Institute that will continue to reveal important migration and mortality data guiding the management of the species for years to come. For information on MPG Ranch and Raptor View Institute visit https://www.raptorview.org/mpg-ranch-collaboration.html. Another interesting resource is the Raptor Tracker map that allows you to follow the movements of golden eagles and other raptors captured in the Bitterroot Valley. That link is www.raptortracker.mpgranch.com.
Sam Lawry, Teller Wildlife Refuge Executive Director has 35 plus years in the wildlife conservation profession. His contributions to the Ravalli Republic are intended to share some of that knowledge of wildlife in the Bitterroot with the community. If you would like more information about Teller Wildlife Refuge please visit our website at www.tellerwildlife.org.
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