Blog: Bald Eagles hatch second brood-- BUT on April 11...

classic Classic list List threaded Threaded
1 message Options
Reply | Threaded
Open this post in threaded view

Blog: Bald Eagles hatch second brood-- BUT on April 11...

This post was updated on .

Sunrise over the entrance to our local wetlands:

Sunrise at gate HDR 20160407

The rainy "dry season" has been followed by more typical Spring weather. Morning clouds
carry a promise of even more rain:

 Looking west before sunrise HDR 20160407

As related in this earlier post, Bald Eagles trying for a family again, our local Bald Eagles
failed to breed last season during the winter of 2014-2015. The new female of the pair
was young and inexperienced and never seemed to exhibit a brooding instinct.
Bald Eagles
usually breed only once in a season, as the rearing and training of an eaglet takes about
4 to 5 months after the egg is laid until it gains independence. Second broods occasionally
occur if a nest or eggs are destroyed early during incubation, and rarely after the loss of
However, this year, because of unusually severe weather during January and
February, 2016, several pairs of Florida's eagles have produced second broods
. Our local
pair hatched out at least one eaglet but it was probably injured and lost by January 20. 

This season, 
Jewel, the female of the pair, laid her first egg on or about December 13, 2015.
This egg was expected to hatch in 5 weeks, around January 17. Unfortunately, several
severe thunderstorms with winds up to 80 MPH roared through in January, depositing
broken branches over the right half of the nest. Since the nest tree is a very limber
Australian Pine, the wind surely whipped it about severely. This photo shows d
to nest on the afternoon after the January 17 storm. Adults kept sitting on the nest and
tried to move the fallen branches:

  Bald Eagle female after storm 20160117
On January 19 there was clear photographic evidence that at least one eaglet had survived
the storm and was being fed by Pride, but this was the last sign of life in the nest:

 Bald Eagle male feeding nestling 7-20160119

Presumably the newly hatched eaglet sustained injuries which proved fatal, and any other
eaglets or eggs were lost. The pair of eagles never abandoned the nest area and the male
spent much time sitting in it after the loss of the brood. Then, on 
January 29 I saw Pride
attempting to mate with Jewel:

BaldEagle Pride flies to Jewel 2-20160129

BaldEagle Pride mounts Jewel 3-20160129

In mid-February the eagle watchers reported that an adult was persistently sitting deep in
the nest, suggesting the possibility that a second clutch of eggs had been deposited. Then,
on February 16, another swarm of severe storms swept through, depositing a second and
much larger branch on the left side of the nest. Look closely at this photo and see that an
adult continued to sit deep despite the new damage:

  Bald Eagle on nest post storm 3-20160216

The eagles stayed on the nest and we feared that the male may have been sitting on one or
more infertile eggs, but then both of the pair appeared to be incubating and our hopes were
On March 16 both eagles were seen peering into the nest. They often do this when
the first eaglet hatches. 
On March 17 we received photographic evidence of at least one
eaglet in the nest. I took this photo of them
feeding a new offspring on March 24th:

 Bald Eagle feeding 02-20160324

Bald Eagle feeding 04-20160324

There were actually TWO eaglets seen in the nest by April 2. One eaglet was more active
and aggressive:

Bald Eagle eaglet HDR 2-20160402

The other was smaller and had more natal down:

Bald Eagle eaglet HDR20160402

The older of the two appeared to be about 2 1/2 weeks old, suggesting it may have hatched
on or about March 16. This meant that incubation of the second clutch of eggs began 5
weeks previously, around February 10, just before the second storm blew the other branch
down over the nest. They have survived so far despite the adversity.
Here they were on
April 7:

Bald Eagle 2 eaglets 2-20160407

Pride was guarding the nest and flew down to check on the eaglets:

 Bald Eagle male Pride in flight 20160410

As we watched the nest, a family of Raccoons decided to cross the busy highway. We held
our breath but they seemed wise enough to wait for a gap in the stream of vehicles:

 Raccoon family crossing Pines 20160402

One youngster (almost fully grown) was reluctant and lingrered behind:

 Raccoon straggler crossing Pines 20160402

After a couple of false starts, it scooted across safely, just ahead of the traffic:

 Raccoon straggler crossing Pines 2-20160402

As I was ready to publish this, I had to add the big "BUT" to the title...  I posted this
photo in my Bald Eagle Nest Watch FORUM on April 10, showing the older of the two
eaglets. I was concerned because its aggressive behavior towards its nest-mate was
quite obvious. I assumed that the younger chick was hiding but asked others to look
for it and keep tabs on its welfare:

  Bald Eagle - one eaglet in nest 3-20160410

My concerns were justified the very next day, when one of the watchers actually saw
and photographed the eaglet being attacked and killed by its sibling. Here is a link to
her report of the horrific event. Scroll down to Kathy's post:

  One eaglet seen in nest -- other has been killed     

In the event that you cannot bear watching this, here was my response:

!t is very sad to learn that the older and more aggressive eaglet killed the younger one. I feared it was
being cowed into laying low or even already injured by the older one when I posted my message.
Siblicide is one of the eagles' keys to success, as it gives the surviving eaglet a much better chance of
becoming an adult. As you may know, the first eaglet is more likely to be a female than a male, and
she is larger than the male at all ages.  The second is more likely a male, so there is a 1:1 sex balance.
The first-hatched, if a female, is more likely to kill a second female, perhaps because it eliminates a
competitor while she is still small and weak. 

A female and male sequence is the most successful combination for survival, maybe because the male
learns his place in the hierarchy and does not challenge the female. This also assures a balance
between the number of males and females as adults. If the first-hatched is a male the entire brood
has less chance of surviving than if the first is a female. Since south Florida eagles developed an
instinct to breed much earlier than those up north, there were inherent advantages-- less heat stress on
the eaglets and better prey availability when they are growing fastest in February and March. Let's
hope that Pride and Jewel can provide for the single eaglet and see her fledge successfully sometime
in late summer.