Tag Archives: Eggs

Peek inside a bald eagle egg: 24 days!

Development of an avian embryo

There are two eagle eggs in Decorah trout hatchery nest N1. DH1 is about 27 days old and DH2 is about 25 days old. What do they look like? Let’s take a peek!  What do embyronic eagles look they look like as they develop and grow inside their eggs? Dr. Peter Sharpe from the Institute for Wildlife Studies developed a table of bald eagle embryonic development based on work done by Hamburger and Hamilton (1951). While this animation uses a chicken

Egg Colors and Shapes

The Chicago Peregrine Program inspired me to write a quick blog on the colors and shapes of eggs. Bald eagles have white eggs, peregrine falcons have eggs that range from light cream through brick red, and red-tailed hawks have pale eggs that are lightly splotched with brown. How and why do the birds we watch lay differently-colored and shaped eggs? Egg Colors Where do egg colors come from? Once a bird’s egg enters its shell gland or uterus, it is

Peek inside a bald eagle egg: 11 days!

Chicken embryos roughly 25% of the way to hatch

What do embryonic eagles look they look like as they develop and grow inside their eggs? Dr. Peter Sharpe from the Institute for Wildlife Studies developed a table of bald eagle embryonic development based on work done by Hamburger and Hamilton (1951). While not all bald eagle eggs hatch in 35 days, the stages of development look something like this… What happens between the third and the 11th day? When we last touched on the topic, our embryonic eagle had

What Makes Bald Eagles Incubate?

February 21, 2022: North Nestoration Follies!

We wrote this blog a year ago. I wanted to revisit it given the events at the North nest this year. Mr. North and DNF have been dealing with intruders for a couple of weeks. Instead of perching near the nest, packing in food, and developing the reserves she needs to lay eggs, DNF is guarding her nest, egg, and mate from potential rivals. After egg number one, her testosterone and progesterone should rapidly decrease, while prolactin, a hormone that

Peek inside a bald eagle egg: 4 days!

An embryonic bird at 33 hours

As of this writing, we’re still waiting for eggs at Fort St. Vrain. The first Decorah North egg is seven days old and the second is four days old. What do embryonic eagles look like as they grow and develop inside their eggs? Dr. Peter Sharpe from the Institute for Wildlife Studies developed a table of bald eagle embryonic development based on work done by Hamburger and Hamilton (1951). While not all bald eagle eggs hatch in 35 days, the

Announcing: Egg Watch at Decorah North!

February 15, 2023: DNF had us pacing the delivery room floor, but she didn't lay an egg!

Egg watch is on at Decorah North after DNF had us pacing the delivery room floor for over three hours last night! We’ve discussed her most likely first egg date, so let’s take a look at her most likely time. Her schedule looks like this: 2022: DNF laid her first egg at 3:17 PM 2021: DNF laid her first egg at 1:44 PM 2020: DNF laid her first egg at 3:36 PM 2019: DNF laid her first egg at 3:23

How long does it take a bald eagle to lay an egg?

An egg in cross section, modified from Romanoff and Romanoff, 1949

How long does it take a bald eagle to lay an egg? We think that female bald eagles begin laying eggs five to ten days after productive mating begins. In 2018 and 2019, Mom laid her first egg about eleven days after copulation went from casual to frequent…and very determined on Mom’s part.  We’ve often seen female eagles take the lead – beak-biting and footing their mates, loudly vocalizing their intentions, and mounting them! You don’t need to be a

Bald eagle mating: Courtship, bonding, copulation, and other things romantic!

February 8, 2023: HD and HM copulate in the nest.

Love is in the nest! This is a traditional Valentines Day post for us, but after HD and HM copulated this morning, we thought we would post it in celebration. Bald eagle courtship Bald eagles are famous for their whirling nuptial flight, but eagle courtship includes any activities that establish a new pair bond or renew an existing one. At our Decorah, Decorah North, and Fort St. Vrain nests, courtship usually begins in early October. Bonded pairs start working on

Tick-tock egg clock! Date guesstimates all around our nests.

January 5, 2023: HM near N1

Tick-tock egg clock! Okay, it’s a little early to start counting the minutes, but here are the days we’ve penciled into our planners for first eggs, first falcons, and ice-out on the Mississippi River Flyway. Get your (RRP) calendars out and feel welcome to make your own best guesstimates. Eggs will be here before we know it! Decorah North I’m saving the afternoon of February 16th for DNF’s first egg! She’s been a remarkably consistent layer date and timewise, although

Finally, an egg at N3!

March 28, 2022: D2 in N3. Photo by Mark Worcester.

What has been going on with Mom and DM2 this year? RRP staff and volunteers have been monitoring Mom and DM2 at N3 and the hatchery, and we have a pretty good record of their whereabouts with boots-on-the-ground observations and appearances on the hatchery cams. We have documented her standing in the nest for long periods of time, but she didn’t begin incubating until sometime between Robin’s observations on Sunday, March 20 and Dave Kester’s observations on the morning of

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