3/30/16 – It was another windy day with some cam freezes and some off-nest shift changes, or at least times with no eagle on cam. That makes it even more difficult to determine which eagle is which. Without finding an update to tell you the answer, can you tell which eagle this is?
As Easter approaches I naturally am coloring some eggs, which made me think about what an incredible advancement in evolution the egg really is! Without a shell around the egg, life on earth was essentially confined to the water. Amphibians were able to move about on land, but they needed water to reproduce. The evolutionary advance that created the membranes that surround the egg to create the cleidoic egg (also called amniotic egg) meant the egg would not dry out and thus brought about the invasion of life onto land! This opened up new opportunities for life and created an explosion in species diversity including all the animals in class Reptilia and Mammalia; together these are known as the amniotes (reptiles, birds, mammals).
There are four very important membranes that are required for an embryo to develop inside a shell:
The amnion – this surrounds and protects the embryo
The yolk sac – this holds the nutrients for the embryo in the yolk
The allantois – this holds metabolic waste
The chorion – works with the allantois to exchange gas between the embryo and air sac
The other evolutionary advances that were required to successfully invade land were the evolution of skin that does not dry out, a new mechanism of breathing with the rib cage instead of the mouth, the development of kidneys to conserve water, and internal fertilization (before the egg shell is produced). You can find more information and see a good diagram of an egg with the parts labeled here.
So now you know, which came first, the chicken or the egg? Enter your answer below by leaving a comment!
Reference: Booker, RJ, EP Widmaier, LE Graham, and PD Stiling. 2008. Biology. McGraw Hill, Boston
Cornell Laboratory of Ornithology has put together a really cool, interactive experience exploring the diversification of the Reptilia, with an emphasis on birds, of course! The Wall of Birds is a must-see experience and easy to navigate for anyone interested in exploring.
3/25/16 – Something had the Harmar male’s attention this morning as he called and flapped his wings as he watched another bird circle about. He was off the nest twice before the female arrived to incubate.
3/23/16 – The Harmar female had just completed a nice long stretch when the male arrived for his turn at incubation…you think it was poor timing? The female denied a shift change and the male headed off after a short wait.
3/22/16 – The Harmar eagles amused us today when the female brought a giant ball of fluff on to the nest! We had a fun time describing what it looked like: a tumbleweed, a groundhog, a Dr. Seuss wig that went through a car wash and dry..! Let us know what you think by posting a comment!
Later in the evening the male cruised past the nest, see if you can spot the movement in this series of screen shots…
3/20/16 – Happy Spring Equinox! Wow, spring sure has sprung around here and there was much excitement on the nest today. The next-nest neighbors, the Hays eagles, have their first pip of the season (Other nests)!
Meanwhile, at the Harmar nest the female easily handled the harassment by the red-tailed hawk (scroll down for pictures), and later the male brought her something for dinner! If you have the stomach for it, take a look at these pics and tell us what you think it was! Use the comments, or send an email to firstname.lastname@example.org.
The Harmar female has some excitement while incubating eggs today! A red-tailed hawk took a swipe at her, but she saw it coming and handled it with no problem!