Tag Archives: Eggs

Nothing Goes to Waste

March 16, 2021: Ma and Pa Jr. on the nest, Fort St. Vrain, Platteville CO

Xcel Energy’s Fort St. Vrain eagles rode the big storm out last weekend. Despite an astonishing twelve or so inches of snow, Ma kept the eggs covered through most of it. Male and female eagles both incubate eggs, but females usually cover the nest at night and through bad weather. A female eagle’s larger body size and brood patch helps her stay still for longer periods of time and apply more heat to the eggs and young beneath her. Unfortunately,

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

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 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 inner

Eagles, ‘menopause’, and a new mate at Xcel Energy’s Fort St. Vrain plant

Avian Reproductive System, From Handbook of Bird Biology, Second Edition

Has Ma FSV entered ‘menopause’? This blog was going to be focused on eagles and ova, but Elfruler, our original DE lead mod and a long-time chronicler of bald eagle nests, noticed that the male had a band on his right leg, not his left. A new eagle has replaced Pa FSV. If you’d like to learn more about eagles and ova, please read on (TLDR: Ma FSV has not entered menopause). Thanks to Elfruler for her observations and Donna

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 second Decorah North egg is three days and 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 bald eagle eggs hatch in 35 days, the stages of development

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