Tag Archives: Eggs

Egg Colors and Shapes

eggs 175x175 - 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? In general, female birds inherit egg colors and patterns from their female parents. Egg-shell is made primarily of calcium carbonate,

Peek inside a bald eagle egg: 11 days!

Chicken embryos roughly 25% of the way to hatch

This blog was first published on March 23, 2017. We reposted it to give everyone a peek inside the eggs! As of this writing, the first Decorah egg is 18 days old, the second egg is 15 days old, and the third egg is 11 days old. 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

Peek inside a bald eagle egg: 4 days!

An embryonic bird at 33 hours

As of this writing, the last Decorah egg is 22 hours old, the last Decorah North egg is 9 days, 23 hours old, and the last Fort St. Vrain egg is 12 days, 22 hours old. 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 not all

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

Why do bald eagles lay eggs in ice and snow?

Egg-laying Map

Why do the Decorah and Decorah North eagles lay eggs in ice and snow? A lot of you – especially those of you who also watch the Florida eagles – are curious about bald eagle egg timing. Wouldn’t it be better to delay egg-laying until mid-March or early April? We’ll unpack the question by starting with a few facts. An Overview of Bald Eagle Nesting Bald eagles don’t all nest at the same time. In the southeastern United States, especially

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