Earlier this week, as I was watering my potted plants on the front porch, I discovered a new resident had moved in. There, smack dab in the middle of my sage plant, I spotted a nest with two small eggs. Later, I saw a Mourning Dove sitting on the nest, her two brown eyes carefully watching my every move.
I wondered how long it would take her eggs to hatch, so I looked it up on the Cornell Lab of Ornithology website: “incubation period 14 days”. As I looked at their photographs of eggs, I started to wonder – why ARE eggs egg-shaped? And then I smiled, because I knew I had found the subject for this week’s SCV Outdoor Report.
Let’s begin by asking a question: what do we mean by “egg-shaped”? To answer that, I invite you to take a closer look at these mallard duck eggs.
These eggs are round-ish but not exactly a sphere, because they are longer than they are wide. These eggs are ovoid but not exactly an oval, because they are tapered at one end. Dr. Karl describes their shape as an ‘asymmetric tapered oval’.
But why are eggs egg-shaped? There are four reasons.
(1) Strength. Eggs need to be strong enough for a bird to sit on them. The Discovery Kids website compares the egg to the shape of a dome, “When an object is placed on top of it, no single point in the dome supports the entire weight; instead, the object’s heaviness is carried down along the curved walls to the dome’s wide base.
(2) Less chance of rolling out of the nest. If you nudge a spherical-shaped object, like a ping pong ball, will roll in a straight line. But an egg will roll in a circle around its tapered end.
(3) They fit closer together. That means the nest can be smaller (and easier to build). It also means less air space between the eggs, so the eggs will stay warmer.
(4) Easier to “push out” of the bird. According to Dr. Karl, “eggs are laid with the blunt end coming out first, followed by the tapered end”.
The egg-laying muscles are shaped like a tube. Pressure around the elongated and tapered end gives these muscles more surface area to work on. To visualize this, think about how you squeeze a tube of toothpaste. Is it easier to push from the end of the tube, or from the middle?
Strength, less chance of rolling out of the nest, closer fit and easier to push – eggs are egg-shaped for very good reasons.
And in the meantime, I’m going to enjoy watching our front-porch visitor and her eggs. Two week’s incubation? Who knows, perhaps this Easter we’ll see more than marshmallow “Peeps” around here.
Free Birding App. For those of you who are looking for a good birding app for your Apple cellphone or iPad, the Cornell Lab of Ornitholgy is offering a free app. Click here for more information.
Upcoming Outdoor Events:
Saturday, April 19, 8-10 am. Spring Birding. With the weather changes and flowers blooming, now is the perfect time to discover which birds live and feed in our local mountains. Beginning birders are welcome. Binoculars optional. Meet at TowsleyCanyon’s front parking lot. 2 hours. Click here for map and directions.
Sunday, April 27, 2 pm. Community Nature Series presents “Butterflies of Placerita Canyon”. Butterflies are all around us! They have been called “flying jewels” or “flying flowers”. Dr. Paul Levine will review the life cycle of butterflies and share photos of the many common butterflies found in our Santa Clarita valley. Click here for more information.
Trail Maintenance Schedule. Come join our volunteers as they help maintain our trails. Contact Steve at email@example.com for time and place.
Wednesday mornings, April 2, 9, 16, 23, & 30.
Saturday mornings, April 19.
New trail maps available. If you’d like to explore a bit on your own, the City of Santa Clarita has a website with trail maps of our local open spaces.
There’s also a new website for bicycle riders.
Ask Dr. Norm: Do you have questions about the flora, fauna, animals, rocks, etc. in our Santa Clarita Valley? Here’s a place for you to ask your questions. Dr. Norman Herr, Ph.D., is a professor of science and computer education at CaliforniaStateUniversity, Northridge.
Tell Us About Your Hike: Here’s a new website where you can post pictures, provide feedback and make suggestions about the City of Santa Clarita’s trails and open spaces.
You can listen to stories like this every Friday morning at 7:10 a.m. on “The SCV Outdoor Report”, brought to you by your hometown radio station KHTS (AM1220) and by the Mountains Recreation and Conservation Authority.
Or check out our Facebook page – L.A. Mountains
Source: Santa Clarita News