Growing up eagle

Growing up eagle

If Benjamin Franklin had gotten his way, the national emblem of the United States might have been the wild turkey.  Franklin thought the bald eagle “a bird of bad moral character” who “does not get his living honestly.”  He based that opinion on the fact that eagles will often steal fish from ospreys and other birds rather than catch their own.

Last week, we followed the nesting bald eagles from site selection to nest building to hatching and brooding the eggs and chicks.  Regardless of the morality of the method by which the parents acquire meals, the hatchlings grow quickly.  By three months, they are ready to leave the relative safety of the nest.

Most fledglings leave the nest at around 11 weeks of age.  Sometimes initial attempts at flight are unsuccessful, and the youngsters may end up on the ground.  If uninjured, the juveniles can be left on the ground and the parents will continue to provide food to them until they are able to fly.  Attempts to replace the grounded pre-fledgling back into the nest can frighten the sibling, resulting with both youngsters on the ground.  Once fledged, the young will often fly back to the nest for supplemental feeding by the parents for an additional six weeks or more until their foraging skills are more adept.

Although the babies grow quickly, bald eagles are large birds and take a long time to reach maturity.  The characteristic plumage—white head and tail, with dark feathers on the rest of the body—does not show up until the bird is more than five years old.  During the first four years of their lives, the immature eagles participate in an avian Rumspringa, exploring vast territories and traveling up to hundreds of miles a day.  During the fifth year they will select a breeding territory and settle down.  Florida adult resident bald eagles usually do not migrate, but spend their lives within a ten mile radius of their nesting site(s).

Some notable differences in appearance during the first five years of their lives helps to determine a sub-adult eagle’s age:

 

Age (yrs)              Head                     Body/Wings                       Tail                        Bill                         Eyes_________

1                      dark brown           dark brown                        dark brown           dark grey               dark brown

_____________________________________________________________________________________________

2                      brown                  mottled with white              mottled                  little yellow            light brown

_____________________________________________________________________________________________

3                      whitish chin         mottled                               mottled                 grey on                 paler with

and neck                                                                                     tip   only               eye stripe

_____________________________________________________________________________________________

4                      mostly white        mostly dark                        more white          dull yellow            pale yellow

_____________________________________________________________________________________________

5                      white                   dark brown                        white                    bright yellow         pale yellow, almost white

_____________________________________________________________________________________________

Ideally these birds should be left alone, but our fascination with them unwittingly results in human-bird encounters that often end up causing harm to the bird.  Hordes of people flock around a nesting site to watch and photograph each stage of the birds’ progress.  Every attempt should be made to observe from an undetected distance, make no loud noises, and use no flash photography or artificial light.

Florida is second only to Alaska in the number of resident bald eagles within the state.  Eagles are opportunistic foragers and will scavenge carrion whenever available.  One of the best places to see them is around a landfill, especially at dawn or dusk.

Bald eagles live quite a long time.  A bird from New York was 38 at the time of its death in 2015.  PRWC’s resident bald eagles, Arthur and Bilfred, are not quite that old, but they are getting up there in the years.  You can see them every day from 11a.m. to 4p.m., even on holidays like Thanksgiving.

I wonder if Ben Franklin had prevailed if we would be carving the holiday eagle at dinner time today?  Best not to contemplate that.  Enjoy the yams, squash, potatoes, and green bean casserole—I know I will!

by- Robin Jenkins, DVM

Juvenile and adult bald eagles in rehab.

Juvenile and adult bald eagles in rehab.

Bald eagle breeding season

Bald eagle breeding season

The bald eagle has been the national symbol of the United States since 1782.  It is North America’s second largest bird of prey—only the California condor is larger.  With bald eagle breeding season well under way here in Southwest Florida, let’s take a closer look at these regal birds.

Mated pairs may begin selecting sites and nest building or reconstruction as early as late September.  A bald eagle nest can be quite massive.  Often returning to the same nest each year, the birds may add to it annually until the weight of the nest is more than the tree can support and the nest—or sometimes the entire tree—falls.  Typical nests average 5 feet in diameter and 3 feet tall.  The largest nest on record, in St. Petersburg, Florida was 9.5 feet in diameter and over 20 feet tall.

Constructed near, but not at, the top of the tallest tree in the vicinity, the nest affords the birds shade from the sun and a good vantage point to monitor activity in the area.  Nest shape depends on the tree in which it is located and can be flat, conical, or cylindrical.  The eagles often have an alternative nest sight within their territory of approximately one square mile.  They may switch sites if they have an unsuccessful season due to too much noise and commotion or too many predators.

While most bald eagles return to the same nest site and mate each year, if either is no longer available, the survivor will find a new mate and, if necessary, build a new nest or steal one from another large bird (typically, a great horned owl.)  In Florida’s subtropical climate, the eagle’s breeding season can range from October to April, but most clutches are laid during December and January. 

The average clutch size is two eggs and incubation generally takes about 35 days.  Incubation begins as soon as the first egg is laid, so the eggs may hatch one or two days apart.  This is in contrast to other bird species that lay an egg a day over a period of time and do not begin incubation until the last one is laid, ensuring that most of the offspring hatch at approximately the same time.  Due to the rapid growth of the eaglets, the difference in size during the first few weeks can be a determining factor in the welfare of the chicks.

The parents will usually feed the oldest chick at every feeding.  If there is enough food after that baby is full, then they will feed the second.  So not only has the first-born started out larger, but has the advantage of better nutrition.  In this manner, the birds help to ensure they can successfully raise at least one chick even in times when food is scarce.

During the first two weeks, the male provides most of the food, while the female tends to the young.  At three to four weeks, the female brings as much food as the male, with the young pecking at the food, but relying on parents to tear the meat into edible portions.  By six weeks, the eaglets are able to self-feed when supplied fish and rodents by the parents.

As the hatchings grow, the competition for food and attention from the parents can get brutal.  The smaller sibling can be bumped from the nest by a larger more aggressive nestling.  While many people may find this practice unpleasant, it is vital for the natural selection process to ensure the long-term health of the species.  The strong survive.

Next week:  Bald eagles, part deux.

by- Robin Jenkins, DVM

Bald eagle nest, photo courtesty of USFWS

Bald eagle nest, photo courtesy of USFWS

Paranoia will destroy ya

Paranoia will destroy ya

The call comes in at 6 p.m.  Someone had seen an eagle on the ground at 10 that morning.  He had called Florida Fish and Wildlife, but they did not have an officer in the area.  Many calls later, he had finally gotten through to Peace River Wildlife Center, and they called me. Saturday evening.  It will be dark soon. The caller is willing to wait for me.  It’s about a half mile hike back into the scrub off the main trail.  Really?  I don’t think so.   Maybe I’ve read too many James Patterson novels, but that sounds like a recipe for disaster.

 

First thing Sunday morning, I gather my gear and head for the “carefully detailed” location where the injured bird was last reported.  “Back the trail (as if there is only one), where it goes around the corner of where the dried up retention pond used to be…”  I get there and the first thing I see is three trails. I pick the one labeled “A”—seems an obvious choice to me.  Of course it is the wrong choice.  Of course I don’t figure that out until I hike for a good 20 minutes.

 

So, after another 20 minutes I’m back to where I started. Okay, plan B—trail B.   I call the number for the man who found the eagle.  No answer.  I’m not really surprised.  He probably doesn’t have good cell reception in the dungeon where he spends the wee hours of a Sunday morning honing the blades on his machetes and pick axes.  The surgical instruments, I imagine, he leaves dull so that each cut is all the more painful.  (Darn you, Patterson!)

 

Still dragging myself and my rescue equipment down the narrow and overgrown path, I am getting further and further away from civilization.  I am looking for the plastic bag that has supposedly been tied to a tree near where the eagle was discovered.  I see neither an eagle nor a bag.  And we’re walking, and we’re walking…

 

Finally!  A bag tied to a tree.  Maybe there really is an eagle in distress here and not just an elaborate set up to procure an unsuspecting human sacrifice.  I set down my equipment and start looking in earnest for the bird.  Making ever widening circles around the immediate area, I feel like I have scrutinized every square inch of the place for miles around.  Okay, maybe it was just a few feet, but I’m tired by now.  And I’ve gotten myself so caught up in the villain’s scheme to abduct me that every time a branch cracks I jump three feet in the air, so I’m counting that vertical distance in my miles logged.

 

Not surprisingly, I do not find an injured eagle.  I don’t find a feather, a footprint, or any other evidence that any living creature has ever set foot here before me.  Well, there is the plastic bag.  And maybe some raccoon scat, feral pig rootings, and a million different birds.  Actually, all kinds of animals live out here.  It really is quite beautiful.  I suppose if this is the last place I see before the burlap sack gets thrown over my head, I’ll have that lovely image to sustain me through the first few days of torture.

 

I give up and keep walking.  The retention pond is relatively empty at this time of year, just a mucky muddy bottom at the very middle of it.  Its footprint is still quite large and the path encircles it, so I continue my hike, ever watchful for an injured eagle in case he has moved from his original spot.  I make it back to my car with mixed emotions.  I am disappointed to have wasted so much time and yet I am happy to still be alive. Maybe Kreeper McKreppison only comes out at night after all.  But my overriding thought is how much I need a doughnut.

 

As soon as I get to the doughnut shop, my cell phone rings.  It is a lady telling me that the eagle is still there and that she and her husband will be happy to guide me to it.  Hmph.  So my doughnut(s) and I are off again.  This time when I arrive (10 minutes later, and the doughnuts are long gone) a perfectly normal-looking couple are waiting for me in the parking lot.  They even have a perfectly normal-looking dog with them.  Evil villains never have a nice dog with them.

 

We walk to where they had seen the eagle just minutes ago, but now we can’t find the bird.  Did anyone see that coming?!  So they let Boots off her leash and tell her to find the eagle.  Maybe I was premature in thinking these people were perfectly normal.  Do they really think they can hold intelligible conversations with their dog?  Actually what I was wrong about was that the dog, Boots, is anything but normal.

 

Boots crashes through the underbrush for a few minutes, stops, lets out a single bark, and then returns to us.  She then turns and leads us back to where the young eagle is hiding under a palmetto.  A short chase ensues, but we are able to catch the eagle and take him back to PRWC.

 

The bald eagle is a first-year juvenile.  She has probably flown into something while learning how to hunt.  There is a slight swelling near her right shoulder, but x-rays show no broken bones or luxations.  We are hopeful that after a little cage rest, this youngster will be able to go back home and take to the skies with a little more agility.  Had we not found her, she most certainly would have ended up as dinner for some predator.

 

So I guess it turns into more of a Dean Koontz dog-saves-the-day kind of tale than a Patterson man-is-just-plain-evil exploit.  Except that there were no government assassins, time traveling Nazis, or mad scientists.  As far as I know.  Those people did say they were from Vermont.  Who knows what their real origin might have been.  People don’t actually live in Vermont, do they?  But I digress.

by- Robin Jenkins, DVM

The eagle has landed

The eagle has landed

Peace River Wildlife Center received a frantic call from a landscaper recently.  A baby eagle had walked into his open equipment trailer and was just hanging around.  He had tried to shoo it away, but it wouldn’t leave.  I asked him to take a picture with his cell phone and send it to me. 

To his credit, the gentleman was no less concerned about the bird’s health when I explained that it was actually a fancy racing pigeon, not an eagle.  We sent a rescuer to pick up the uninjured bird—it was probably just exhausted after being buffeted by strong winds.  Luckily, we were able to locate the bird’s owner and return it to him.

So, when we got another call about two male eagles fighting in midair at the other end of the county, we took the call with a grain of salt.  But multiple calls from the same area confirmed that there may actually be something to the story.  Then another caller claimed that an eagle was walking around their lawn and seemed injured.

Our favourite snow bird husband-and-wife rescue team, Barb and Tom Taylor, were dispatched to check out the situation.  Quite often in these cases, as soon as the bird is approached, it takes flight.  End of story.  This time, the bird ran into some heavy scrub, evidently not willing or able to fly away.  So Tom, in his infinite wisdom (and short pants), dove into the jagged palmettos after the bird, and a wacky race ensued.  Tom’s shins were shredded, but he caught the bird.

Bald eagle beak fracture after territorial dispute

Bald eagle beak fracture after territorial dispute

It turns out it was an adult female eagle.  Since this is the end of breeding season for these large raptors, she may have been defending her territory or nest from an invading neighbor.  She had suffered deep puncture wounds on her legs and a crack on her beak.  X-rays (with our beautiful new digital x-ray machine; hooray!  Thank you, donors!)  showed the crack at the caudal edge of her beak was superficial.  After a course of antibiotics and anti-inflammatory drugs for her leg lesions, she was healing quite well.

The eagle was taken to our 100-foot flight cage to make sure she was capable of flight.  She was flying fine, although she walked around the cage like a little old lady—actually, like me after a recent reminder that the law of gravity applies to everyone.  She minced and limped with every step.  Obviously, her legs were still sore, but the wounds were healing and there was no evidence of infection.  After a few days of strength training in the flight cage, she was given thumbs-up for release.

Although her wounds were not completely healed, we wanted to get her back out to her home as soon as possible.  Like most wild animals, she will complete the healing process much faster at home than under the additional stress of being in captivity.  She may have had a family waiting for her there, although any offspring should have been old enough by this time of year to be okay without her for a few days.  And presumably, Dad would have been there to babysit in her absence.  And we all know how much Dads appreciate being left alone with the kiddos while Mom goes to the spa for a few days of rest and relaxation.  (Hint, hint.  Mother’s Day is coming.) 

If you can’t send Mom to the spa for a few days, consider a quick trip to Fishermen’s Village this weekend.  This Saturday, May 13 is the Key Lime Festival at Fishville and PRWC will be there with our white owl, Luna, dyed lime green for the event.  Or not.  You will have to stop by the event on your way to or from PRWC and see for yourself.

by- Robin Jenkins, DVM

Fancy racing pigeon with a fierce face

Fancy racing pigeon with a fierce face

Goodbye 2016

Goodbye 2016

2016 is finally over.  As one of the worst years in recent memory, it will not be missed.  We will miss the people we lost and the ideals that have been trampled.  So many bad things happened this past year, with the possibility of causing even more dreadful consequences, that it is difficult to look forward with any hope.  But that is exactly what we must do.

Peace River Wildlife Center is starting the new year off with a bang.  This is normally a slow time for us as far as patient numbers.  Unlike previous years, our intakes have not slowed appreciably and most of our hospital and rehab cages are full to capacity. 

The recent red tide event has been a large part of the issue.  We have had many birds presenting with symptoms of brevitoxicosis—neurological signs due to the toxins ingested from eating fish in water with the red tide organism.  Red tide is the common name given to an algal bloom, an unusually high concentration of aquatic microorganisms in the water, which can cause a reddish or brownish tint especially as seen from afar.  In the Gulf of Mexico that organism is Karenia brevis.  It is a natural phenomenon, but may be exacerbated by nutrient run-off from fertilizers.  The presence of the organisms can cause a depletion of dissolved oxygen in the water, causing fish to suffocate.  The organisms also produce a toxin (brevetoxin) that paralyzes the central nervous system of fish so they cannot breathe.  The asphyxiated fish are in turn eaten by other fish, birds, and mammals and the toxin is passed on to the next victim.  This toxin can also become airborne as waves crash on the beach breaking open the algae cells and releasing the toxin to become an ocular and respiratory irritant to animals and people near the shore.

While we routinely see shore birds during a red tide outbreak, this year we have seen some unusual victims.  We have had some hawks displaying classic red tide symptoms—generalized ascending weakness and no blink response.  Most of them have responded the treatment, which consists primarily of supportive measures until the toxins are flushed from their systems.

Bald eagle unable to hold her head up

Bald eagle unable to hold her head up

An even more unusual patient that presented recently is an adult female bald eagle.  She came in with what looked like head trauma, but we can find no evidence that she had been hit by a car (a common occurrence while feeding on carrion on the side of the road) or interaction with another bird (another common malady during breeding season.)  She was found next to an alligator carcass and she had a very full crop.  Testing for lead poisoning was negative, so red tide cannot be ruled out for this bird either.  Although we do not generally see it in eagles, they do eat species that can be affected.

Upon presentation, the eagle was very weak.  She spent days lying in a padded bed of rolled up sheets and towels, being given fluids by injection.  When she could finally hold her head up, we began tube feeding her a protein slurry—the equivalent of a fish milkshake. 

As she regained a little more strength, she began to accept mice that we fed to her.  Still needing to be assist-fed, she is starting to gain back some of the weight she lost during the early days of her hospitalization.  She spends her days in an outdoor rehab cage to lessen the stress of being around people.  Hopefully she will start to eat on her own soon and we can assess her readiness for release. 

Bald eagle regaining her strength

Bald eagle regaining her strength

Luckily, she is not exhibiting signs of having started a nest already.  She has no brood patch—a featherless patch of skin on the underside of a bird’s belly where the feathers have been plucked to line the nest.  This patch of bare skin has lots of blood vessels near the surface and is used to keep the eggs warm during incubation.  Since it is breeding season for these large raptors, we want to get her out as soon as possible so she can find her nest and mate.

PRWC’s year-end reports are in the works and we will hopefully be ready for assessment by next week.  Preliminary numbers are hinting at a record number of patients passing through our doors.  This is a good news/ bad news scenario.  The bad news is that a lot of Charlotte County’s native wildlife is getting injured.  The good news is that thanks to the generosity of our donors, PRWC is here to help them.  And no matter what the new year throws at us, we will continue to be here to serve the community.

by – Robin Jenkins, DVM