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On April 13, 2007 a bald eagle chick hatched naturally on Santa Cruz Island, marking what biologists hope is a comeback for bald eagles on California’s Channel Islands. Since then, tens of thousands of viewers have logged on to the live webcam to watch the eagle chick eat, nap, stretch its wings and grow into adulthood.
Nature.org asked Peter Sharpe, a biologist with the Institute for Wildlife Studies (IWS), to tell us more about the eagle chick. As director of IWS’ eagle restoration work on Santa Cruz Island, Sharpe spends his time parenting, climbing trees, dangling from helicopters and educating the public — all for the love of bald eagles.
nature.org: When will your team go into the nest to check on the chick?
Peter Sharpe: We try not to have contact with the chick until it’s 8 weeks old. Then we go in to band the chick. The banding is scheduled for June 8, but the exact date will depend on weather conditions and our access to the nest.
nature.org: What’s involved in the banding process?
Peter Sharpe: One person climbs into the nest, gently grabs the chick and places it in a bag to be lowered to the ground. We put on blue wing markers, a leg band with a federal ID number and a GPS/radio transmitter. The transmitter weighs about 100 grams, and typically falls off from wear and tear (including the bird chewing at the ties) within a year or two. During the banding process we also draw blood samples and take a few breast feathers for analysis of toxins and contaminants.
nature.org: What do the parents do when you go in to the nest? Is it safe?
Peter Sharpe: If the parents are in the nest at the time, they will fly away. But they can become aggressive, so we have to be careful. We wear helmets and gloves. Ideally the parents won’t be in the nest; when the chick is 4-5 weeks old the parents start leaving it alone at times.
Climbing experience is important — the nest is 40 feet up in the tree. We have an expert who does most of the nest-climbing for us in Alaska and who climbed into this nest for last year’s chicks; if he isn’t available, I usually do the climbing.
nature.org: Will we be able to watch the banding using the live video cam?
Peter Sharpe: Viewers should be able to see us go into the nest to get the chick. The actual banding takes place on the ground, so we’re looking into having a camera ready down below as well.
nature.org: What kinds of changes should we be watching for as the chick grows?
Peter Sharpe: The chick is getting bigger every day! At 4 weeks of age, it’s already reached one-third of its adult size and is beginning to walk and stand, rather than shuffle around. The chick will grow a darker layer of down, then brown feathers will grow on its back and wings. At 6-7 weeks it will start exercising its wings, flapping them, spreading them out and jumping up and down. By 8 weeks of age the bird will be fully grown with a six-foot wingspan.
nature.org: What's the chick's diet right now? How often and how much do the parents feed it?
Peter Sharpe: The parents feed the chick mostly fish and the occasional bird, such as seagulls. The chick eats a lot — probably half a dozen times a day. Right now it weighs about 3 pounds, and by the time we band it will weigh about 9-10 pounds.
nature.org: What are the major threats to the chick's health during this period?
Peter Sharpe: The main risks to the chick’s survival right now are predators and starvation. But those risks are low. Predators — such as red tail hawk and golden eagle — are few. Starvation results when the chick doesn’t get enough to eat because the parents can’t find enough food, but that doesn’t seem to be a problem on the islands.
Another risk is when the adult eagles bring back fish that has a fishing line in it. Humans are really the greatest threat to their survival. About 50 percent of chicks survive into adulthood.
nature.org: How many weeks will the chick spend in the nest before being able to fly off?
Peter Sharpe: The eagle will fledge at about 12 weeks of age. When chicks fledge they usually stay in their parents’ territory for a month, then they begin exploring. Eagles generally come back to within 100-200 miles of where they were hatched.
nature.org: Will the parents continue to warm it with their brood patch until it leaves the nest?
Peter Sharpe: In a couple of weeks the eagle will be too large for the brood patch. Then it will regulate its own heat.
nature.org: Sometimes it seems like the eagles are looking straight at the video camera — do they notice it?
Peter Sharpe: Yes, they can see the camera, but it doesn’t disturb them in any way. If you see them looking right at the camera, it’s just coincidence.
This video camera helps us greatly with our work. Otherwise we have to hike in an hour to where we can observe the nest. The camera was first put up at the end of April 2006. IWS is in charge of the camera and microphone, the Ventura County Department of Education is in charge of the server and transmitter and the National Park Service is responsible for the power supply (solar panels and batteries). And this whole project takes place on land protected and owned by The Nature Conservancy. So the eagle restoration project is truly a team effort.
nature.org: How many IWS staff work on the eagle restoration program?
Peter Sharpe: We have six staff who work on Santa Cruz and Santa Rosa Islands. They work eight days on, then take six days off, so at any given time there are three staff on the islands monitoring the eagles.
After the breeding season is over we focus on trapping, usually in the late summer or early fall. We trap adult birds that don’t have radio transmitters and put them on. We also try to get blood samples every year, to test toxin levels.
Trapping is like fishing for eagles. We put out food where we’ve seen eagles hanging around, then at night we sneak out and put up a trap. We can also use a floating fish noose, which is a method that we will use quite a bit this year.
nature.org: What’s next for the eagle restoration efforts?
Peter Sharpe: IWS was contracted to do bald eagle restoration on Santa Cruz Island in 2002, and on Catalina in 1980. Since then we’ve released 61 eagles on Santa Cruz — the goal has been 12 eagles a year for five years. Last year was the final release on Santa Cruz. Now we move on to the monitoring phase of the program, to see if the eagles can hatch eggs on their own. Our hope is to get 5-10 nests going across all the islands — we think that should be enough to keep the population alive.
nature.org: What is the Institute for Wildlife Studies?
Peter Sharpe: IWS is a non-profit organization based in Arcata, CA. We are a team of biologists who conduct long-term studies of wildlife populations and habitat conservation. You can find out more about our work at www.iws.org.
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Nature picture credits (top to bottom, left to right): Photo © USFWS (Bald Eagle); Photo © IWS (Peter Sharpe); Photo © National Park Service (Bald Eagle Nest Cam)
