Written By: Jim Wright for Duke Farms and Conserve Wildlife Foundation
Veterinarian Erica Miller, who examined the two Duke Farms Bald Eagle chicks as part of the recent banding, has banded more than 375 young eagles in New Jersey.
How difficult is banding?
The actual banding is pretty easy…simply using special pliers or riveters to apply the appropriate sized band.
Getting to the birds is not always so easy! Banding eagles or Osprey may require boating to an island or hiking through a swamp, banding owls requires sitting up all night (sometimes very cold nights!), and songbirds can vary from catching them in their nest boxes to catching them in nets.
A lot of the birds I have banded over the years have been ones we have in the hospital that have recovered from injuries or from being oiled–we band those before returning them to the wild.
And of course, in the case of the eagle banding, someone else (like John!) has the really tough job of climbing to the nest, securing the young birds and sending them down to us.
Have you learned any “tricks” over the years?
Getting everything ready while the climber is going up the tree is really key. That minimizes time that the bird is on the ground, which in turn reduces stress on the bird.
And while it’s not really a “trick,” Kathy and I have done this together often enough that we can anticipate each other’s needs, which also helps things to run smoothly.
Why take blood? What all do you learn?
While it may look like a large amount of blood, it is less than ¼ of the amount of blood that can be safely taken from a bird at any one time. And from this relatively small amount of blood we can get a lot of information.
With a small amount of the blood sample, we can check the health of the bird by looking at the hematocrit (percentage of red blood cells), white blood cells (which tells if they have an infection), and total protein (which roughly corresponds with their nutritional condition).
It takes only a drop or two to fill the tiny hematocrit tubes, (that small amount of the total blood sample), and for virtually no cost other than that of the tubes (which is literally pennies), I can spin down the blood sample and determine the percentage of red and white cells, which tells if the bird is anemic or not, and whether or not it might have an active infection.
I can also use a refractometer (a small instrument I already have, so again, no cost) to look at the serum and get an estimate of protein level in the blood, which reflects the bird’s nutritional status.
We are also getting the genetic work done for free, which is a nice bonus these past two years!
Testing for the contaminants, however, which is something we really want to do, would cost close to $300 per sample…
These contaminants include DDT, DDE, PCBs, heavy metals (like lead, mercury, and cadmium), and other chemicals like organophosphates and rodenticides.
Since eagles are at the top of the food chain (just like us!), many of these substances will accumulate in the tissues of their prey, and eventually end up in the eagles’ tissue and blood.
If these substances are present in the environment, they will show up in the blood of the eagles–even at only six weeks of age!
For the last couple of years, we’ve been saving a small amount of blood for a national eagle genomics project being conducted through Oklahoma State University. Researchers there will be able to confirm the sex of each bird, as well as how closely related they are to one another.
Since NJ was down to only one nest in the 1980s, we hope to determine if the present birds are descendants of the birds introduced from Maryland or Canada, or if they moved in on their own from somewhere else!
Are you encouraged by the eagle’s comeback?
Very much so! When I started volunteering with the NJ Eagle Project in 1994, we had 4 or 5 active eagle nests, and now we have over 150 and the number is rising. The eagle comeback gives me hope that other species might also make a comeback—that maybe it’s not too late to reverse the damage we humans have done to the environment.
Some birders aren’t very keen on banding. They say it can traumatize the bird and if done improperly, can seriously injure it. How do you reply to those who oppose banding?
I agree—if done improperly, banding certainly can harm the bird! That’s why the National Bird Banding Lab requires banders to have extensive training and considerable experience working with another bander before an individual is granted a permit.
Bird banders are banding birds to learn more about them, about their movements and their activities, and then use this information to help them. They don’t want to do anything to harm the birds—that would contradict the purpose of banding!
By banding birds, and collecting the information on the sightings of those bands, we have learned that birds rehabilitated after oil spills do successfully raise young and survive for many years; and we’ve learned that the eagles hatched in NJ often disperse to other states when they fledge, but usually return to NJ to nest.
Anything else you’d like to add?
Only to thank Duke Farms and the other land owners who are fortunate enough to have these birds on their properties.
Thanks for giving them a safe place to nest, and for giving us the opportunity to learn from them, and to share that information with others.
Got a question or suggestion? E-mail Jim at firstname.lastname@example.org.
Jim Wright writes “The Bird Watcher” columnist for The [Bergen] Record. He is the author of four coffee-table books about wild places, and a deputy marsh warden of the Celery Farm Natural Area in Allendale, N.J.