JBS American Bald Eagles

2018-2019

Breeding Season

While American bald eagles have been observed in the wetland since 2008, nesting began in 2012. Since then, our eagles have successfully hatched, raised and fledged 12 eaglets. Thanks to Wetland Steward Tom Fleming for his photos and observations of the eagles’ 2018-2019 breeding season. They provide this retrospective. Previous page: The adult male guards his territory against a 4th-year sub-adult and 3rd-year juvenile.

Oct. 23Oct. 23The eagles are back [the first eagle returned Oct. 3, the second Oct. 6]. This morning, one was on station at the nest tower. We may call this “surveying their realm,” which they do constantly. Or, we could call it energy conservation mode. Like lions, eagles spend a good part of their day resting and digesting the abundant energy obtained from their prey.

Nov. 1 (below, via webcam)

Just caught both eagles hanging out in the

nest.

Nov. 21Surprise Visit: While walking the Pond Trail east of the Center, I noticed some hawks just north of the woods. There were several red-tails, and I heard one call to my left. There I saw a large “hawk” perched in a dead tree. Turned out to be a young bald eagle. It has survived that first difficult year and is well into its second. This eagle left its perch and flew over to inspect me. The young are naturally curious.

Dec. 14The eagles will now be mating with increasing frequency. These matings stimulate hormone production in the female, and eventually the female ovulates. and we get a fertilized embryo. Three days later, the egg is laid. The top of the tower is a favored location for mating. When you visit the wetlands, how can you tell if they will be mating while you are there? There are some preliminary behaviors that can give you some idea. The tower structure affords the opportunity for the male to perch on a strut at a 90° angle to her perch. They can remain like this for 20 minutes or more. They may vocalize. If mating is about to take place, the male will hop over to her strut. Then he sidles closer. They make “greeting” calls, and then he begins to mount her. That part lasts 15-20 seconds, and then it’s all over.

Dec. 12Male and female eagles appear identical to the casual observer. But curiosity drives us to ask, “Who's on the nest?” It's easy to decide when the eagles are side-by-side. The female is considerably larger (about 25%). The other way is to spend a lot of time observing them. Their mannerisms and fine physical details will begin to reveal themselves to you. This image shows the easily discerned size difference.

Dec. 16WE HAVE AN EGG! Mom was exhibiting a lot of attention to

the egg cup this morning. And then she shifted and revealed

an egg at 8:40 a.m. by the screen clock on the webcam. Dad

arrived to take over incubation, and the shift revealed the

egg for us to see [pictured below on Dec. 17 from webcam].

This egg will likely hatch on Jan. 20.

Dec. 20TWO EGGS!! The second egg was laid before 5 p.m., Dec. 19. This picture from the webcam the morning of Dec. 20 shows both eggs while the parents trade places. This egg will likely hatch on Jan. 23.

Dec. 25In the spirit of holiday sweets, I offer this bit of “eye candy.” The same tree that hosted recent images of a young eagle and a red-tailed hawk has delivered one of our bald eagle pair for this photograph. This particular image shows the bird leaving the “raptor tree” and exposes the talons to good advantage. The talons can deliver 400 psi of pressure when clamping onto prey.

Inset photo: Red-tailed hawk on Dec. 3 in the raptor tree. This dead tree is 100 feet to the west of the intersection of the gravel road and Bunker Pond Trail.

Jan. 28CONFIRMATION: I observed Mom upright above the crib rails. For a period of about 10 minutes, her behavior/body language was consistent with an adult feeding young. The adult female spends about 80% of the time on the nest, and the male has the remainder of nest duty. So referring to the adult on the nest as “mom” is convenient when observing from a long distance.

It will probably be 2-3 weeks before the newly hatched become big enough and active enough to be seen.

Feb. 2 (right)

With one eagle on the nest almost constantly, the other is usually nearby. There’s the perch at the top of the tower and another perch in the tree line that faces the wetland ponds. As you make the walk from the Center to the tower, scan to the right. About 800 feet to the right, there is a tall pair of trees that are a favored perch.

Feb. 4 (far right)

BALMY: The weather was warm and pleasant. Mom used this opportunity to give the eaglets some fresh air and sunshine. At this age, the young birds are getting lots of nap time interspersed with meals. They're still not quite big enough to be seen above the crib rails, but they grow fast and that time is coming soon.

Feb. 14NEST MAINTENANCE: Newborn eagles will begin to direct their waste over the side of the nest after reaching the age of a week or so. Old prey lying around the nest is currently the main hygiene issue. Also, the soft bedding is now getting trampled steadily by the young birds. So nest maintenance is one additional duty that falls to the adults. In this image, one of the adults is bringing in some fresh bedding material.

Feb. 18THE SHERIFF: The job of any good sheriff is to patrol the borders of his jurisdiction. While federal law requires a separation of 200m for an active nest (our viewing area is 250m away), our intrepid enforcer will come out to let you know he is watching you - or just to say “hi,” depending on how you look at it.

Feb. 19The eagles mounted an unusual number of aggressive attacks on birds passing near the nest. First, a flight of pelicans drifted too close and had to be steered away. Next, four crows came in yelling, and the eagles responded to this brazenness with a fierce attack. Most of this conflict was low level. Then a hapless vulture cruised by unawares, but now the eagles were in no mood to tolerate any kind of invasion. An aerial dogfight ensued, with the vulture beating a hasty retreat.

The fourth and final attack (shown here) involved two red-tailed hawks. This mated pair are seen frequently near the nest as their territory overlaps the eagles’. But again, no intruder was tolerated on this day. As the attack began, each eagle paired up with a red-tail. The action was frenetic, and the aerobatic maneuvering was awe-inspiring. All four attacks lasted only a minute each, but huge amounts of energy were expended covering an impressive volume of sky.

Feb. 22Female eagles spend about 80% of the time on the nest. It may be an old human stereotype that Mom stays home and Dad brings home the bacon, but the type holds up for the male eagles as well. They bring in most (but not all) of the food for the eaglets. On this day, however, Mom did her gender proud, bringing home an impressively large fish.

March 1FINALLY! Confirmation of both young eagles on the nest. The overcast makes for difficult lighting on the beautiful subjects of this picture. The head of the 2nd eagle (lower) is turned away in this image.

March 3Today’s session started with Dad on duty. Mom returned, and they remained together for about 10 minutes. Then Dad headed north to the tree perch about 800 feet away. About 10 minutes later, a black vulture sailed above the tower. Dad was a bit late but came in hot pursuit. Mom joined in, but the vulture was well past the nest by now, and the chase was more of an escort out of their territory. The aggressive defense theme for this year continues. This shot shows Dad on a return swing by the tower with the head of one of the eaglets showing above the nest.

March 11CATCH-OF-THE-DAY: Our adult eagles bring mainly fish for the young. But birds are on the menu as well along with the occasional small mammal. The birds that are brought in are mostly coots and cattle egrets.

March 14 (below)Today was beautiful but breezy with some blue skies and sun to show off the eagles’ plumage. Our eagle is seen here with gear down and full flaps as he lands into a 20 mph headwind.

March 15TWO HEADS ARE BETTER THAN ONE: Shy, lazy or bad timing. Whatever the reason, these young eagles have been uncooperative in helping me capture an image of the two simultaneously. They are now roughly two months of age and about 90% of their size and weight when they fledge.

March 28FAMILY PORTRAIT: Dad is on the far left just returning from removing another vulture from the area. Mom is attending the nest having just brought in a fish. The attention-getting eaglet is wingercising, and the shy eaglet is hiding behind the tower strut.

There you have it … the family for 2019.

April 12

There was plenty of action at the nest today, but not from the eaglets, who were basically bumps on a nest. Instead, we had visitors of the eagle persuasion. The first of these did a fly-by of the nest. I wasn't sure whether it was one of our pair of adults, but I was struck by the “rough” (veterinary speak for not in top form) appearance. The wing feathers were gapped and some were of different lengths. Shortly after this pass, our adult male came rapidly on the scene.

April 12Dad’s pursuit evolved on a couple of occasions to aerobatic intimidation. But for the most part, it was a game of cat and mouse with Dad herding the visitor away from the tower. The interactions were cautious because both birds are equally capable of harming the other. This first encounter lasted about 15 minutes rather than the fierce, brief attacks seen previously with other bird species. Close inspection indicates the visitor is likely a 4th-year sub-adult. There’s no way to confirm a family relationship, but offspring are known to return to the general area where they were born.

April 12Here’s a good look at the plumage of the visitor. Although the white head and tail feathers have come in (usually connected with being an adult), there still remains a mottled sprinkling of light feathers under the wings. This is indicative of a sub-adult eagle in its 4th year. Sexual maturity normally comes during the 5th year. You can also clearly see irregular features in the flight feathers for this particular bird.

April 15The second outsider to visit the area was a 3rd-year juvenile. Dad was kept busy ushering the two interlopers away from the nest. If you’re wondering where Mom was during this time, so was I. She did come in a little later, but the visitors had already left.

April 15I was young during the DDT crisis in the ’50s that wiped out most of the eagles in the Lower 48. If you had told me that I would someday witness nesting behavior in my lifetime in my native Texas, I would have been incredulous (even though that word wasn’t yet in my vocabulary).

In this image, we have the mature male (Dad) guarding his territory. Also in the shot is the 4th-year sub-adult and the 3rd- year juvenile.

The Trinity River bottomland should provide an abundance of nesting sites for eagles as their population increases in the area.

April 22EMPTY NESTERS: The young eagles successfully fledged April 18 about 85 days after hatching. So now Mom and Dad are thinking vacation time … but not yet. Like college freshmen, these birds will still come home for a good meal and to have their laundry done for awhile yet. Being seen near the nest should continue for about 6 weeks.