Monday, October 03, 2011

Golden Eagle Rescue Attempt

Blog post by Sarah Grigg, Flat Ranch Preserve manager

Last weekend, I headed to the field to mend a stretch of fence that had been kicked out and lifted by some wily Corriente cattle. Local USFS wildlife biologist Jennifer Chutz offered to lend a hand for the day, and as we drove the north side of the property, we saw a dark object sitting near the road.

We drew closer in the vehicle and saw that it was a very large raptor, and it didn’t seem bothered by our presence. I observed this same raptor several days earlier, sitting on a post along the same fence line, looking attentive and scanning the field for prey.

I shut off the engine and we hopped out to take a closer look, maintaining a safe distance so as to not stress the bird or place ourselves in too close rage to a raptor equipped with a serious beak and talons. It was dark brown from head to toe, with a yellow, black-tipped beak, and feathers fully covering its legs. We agreed that it was an eagle, and after some debate, determined that it was a golden.

Identifying bald and golden eagles in various stages of immature and adult plumage can be difficult at times, and seeing them in all phases in the wild is the best practice for fine tuning identification. This was the closest either of us had ever observed a golden, as most of the birds we had seen in the past were in flight, or took off from a distant perch before we could get close enough to have a good look.

We were excited to view this incredible raptor at close range, but also aware that something was wrong, as it watched us for a bit, half-heartedly lifted its wings, and then slowly walked to another nearby patch of sagebrush, sitting near the fence line in the shade. Unlike bald eagles, goldens are highly intolerant of people, and the fact that we were able to get within this viewing range indicated that something was amiss.

Golden eagles can lift up to five times their weight—capable of lifting mountain goats and other large prey—but primarily subsist upon marmots, foxes, ground squirrels, and other small to medium mammals. Goldens are found throughout the northern hemisphere around the globe, from North America to Asia, and ranging southward into Mexico and the Arabian Peninsula. They range across the North American continent, throughout most of the “lower 48” at various times of year (with the exception of the Southeast).

Strict regulations pertain to the non-purposeful take of all eagles in the U.S. under the Bald and Golden Eagle Protection Act. Habitat destruction, prey accessibility, and collision with powerlines are the primary threats to the species in the twenty-first century.

Jen contacted wildlife handling experts from the Grizzly and Wolf Discovery Center in West Yellowstone to capture the bird, and secured a permit—as required under the Migratory Bird Treaty Act—through the Idaho Department of Fish and Game to transport this eagle to the Teton Raptor Center in Wilson, Wyoming.

Dan and Leisje Meates, animal care manager and animal keeper at the Grizzly and Wolf Discovery Center, arrived to capture the bird.

Luckily, both Dan and Leisje have extensive experience handling large birds of prey. Dan formerly worked as a master falconer and biologist in the UK, with more than 20 years of experience handling raptors, including Russian golden eagles and harpy eagles. Leisje, also our local bear education technician, formerly worked as a wildlife biologist studying eagles in California and Ohio, accumulating more than 12 years of experience with these raptors.

Upon arrival, they examined the bird from a distance to evaluate the situation. Golden eagles sometimes gorge themselves on carrion, and are unable to take flight for several hours following a large meal (Bald eagles, on the other hand, are able to take flight after “pigging out.”). A gorged golden will exhibit a swollen crop, that is, its upper chest region will be visibly bloated, as if it had a goiter. After taking a look at the animal, they decided that it was definitely not gorged, and that its sluggish behavior indicated severe stress due to injury or sickness.

They also determined that it was a male, about five years old. Goldens are generally 2.5 to 3 feet in length, and weigh anywhere from 7 to 15 pounds, with the females considerably out-sizing the males. Adults of either sex may have wing spans ranging from six to seven feet wide. Immature goldens are distinguished by the large amount of white at the base of the feathers. These white patches are particularly pertinent when the birds are in flight. As they age, this white disappears, shrinking towards the base of the feather, turning to a dark brown. Adult goldens are chocolate-brown overall with marbling on the flight feathers of the wings and tail. The tail feathers on this eagle were primarily brown, with about two inches of white at the base.

Capturing eagles can be very dangerous, as their talons can exert about 1,000 pounds per square inch, and their beaks are equally razor-sharp. Even eagles with injured wings will turn on their backs and fight fiercely with their talons. Because the birds subsist upon meat, the talons are loaded with bacteria that can be harmful to people if it enters the bloodstream. Handlers normally wear special eagle handling gloves, made with thick leather that cover much of the arm.

Dan stood behind the eagle and Leisje distracted it from the side, while two people stood before it and herded it away from the barbed wire fence. It moved from the fence and then stopped in a patch of sage brush, allowing Dan creep behind it. He first pinned the bird by it wings, placed a towel around its back and swiftly grabbed both of its legs. He then lifted the eagle and pinned it to his chest while holding its legs and beak. Once he secured the bird, they inspected it to see if the cause of injury could be determined.

Dan noted that the bird’s stomach felt empty and that it was definitely emaciated. Mites covered its entire body, indicating that it had been on the ground for some time. Leisje pulled two porcupine quills from its leg, and observed that unlike eagles with minor injuries, which normally fight hard with their legs, this bird hardly moved its legs. The eagle was placed in a covered dog kennel, and Idaho Fish and Game Conservation Officer Tony Imthurn transported it to staff at the Teton Raptor Center, where it was promptly taken to a veterinarian. The animal did not survive, and lead poisoning is the suspected cause of death.

Some hunters use lead ammunition to take birds, small game, and other wildlife. These lead-filled carcasses are sometimes left in the field, where raptors, such as golden eagles, will scavenge upon them. Sometimes the birds do not ingest enough lead to cause sickness, but in many cases, significant intake leads to lethal poisoning.

This is quite common in eastern Montana, and several cases have been reported in Idaho over the last few years. The Wildlife Society and other groups are now encouraging hunters and anglers to use non-lead alternatives that perform just as well as lead.

Fish and Game ordered a full necropsy on the animal to determine the exact cause of death. The remains will be sent to the USFWS National Eagle Repository in Denver, CO, which accepts applications from Native Americans requesting feathers to use for religious and cultural purposes.

Thanks to Jennifer Chutz (USFS), Dan and Leisje Meates (GWDC), Rob Cavallaro and Tony Imthurn (IDFG), and the Teton Raptor Center for making the effort to help this eagle.

1 comment:

upsadaisy said...

Please let us know if it was lead poisoning.