We found this robin’s egg on the ground at the base of a cedar tree inland from Sauble beach in June. We looked at the tiny incisor marks seemingly eating the white (calcium?) inner layer of the egg. Could these be squirrel, vole or mouse teeth?
I also looked up how you can tell whether an egg hatched normally or whether it was predated. I found an interesting article called “How to identify egg thieves” from a BBC Wildlife Magazine.
- When hatching, chicks use their egg-tooth (a horny spike on the upper mandible) to make a circular cut across the blunt end of the egg; the edge is jagged where the chick has chipped its way out.
- As the empty shell dries out, the inner membrane contracts and ‘rolls’ the chipped edge inwards.
- Unlike predated eggs, hatched eggs never have yolk or egg-white left inside the shell.
- The two halves of the shell are often found close together. To remove them from the nest, the parent may carry one half of the egg inside the other.
- They make a hole in the side or end of the egg with characteristic chip marks, then lick out the contents.
How to Identify Egg Thieves, July 2010, viewed October 13, 2014. Retrieved from: http://www.discoverwildlife.com/british-wildlife/how-identify-egg-thieves
Hmm…did this egg hatch naturally?
I learned from tracker extraordinaire, Alexis Burnett that robin tracks are overall, very curved. Toes 2 and 4 often point out and back. Robins tracks can also be identified by looking at the pattern of tracks. Robins often run and skip with frequent pauses. In this photo, the tracks are almost side by side, indicating that the robin was skipping or possibly pausing along its trail.