Calcium deficiency can cause egg-binding in laying birds. A calcium deficient bird may produce eggs whose shells are softer or more fragile than normal. It is very difficult for a bird to lay a soft-shelled egg, since the muscles that push the egg out tend to deform the egg rather than moving it. The hen is unable to pass an egg that has formed. The egg may be stuck near the cloaca, or further inside.
An egg-bound bird can die of exhaustion, or from an infection following rupture of the egg inside the bird. Also it is possible an egg could break inside in the oviduct in response to a non-fatal blow (batted by cat, picked up roughly by a person), causing an infection that can be fatal within a week. This is probably a common reason apparently healthy birds are found dead in a box.
Captive birds and reptiles fed a diet consisting primarily of mealworms, especially when growing rapidly, can also develop severe bone disorders caused by an abnormal ratio of calcium to phosphorus in the diet. People who feed a lot of mealworms to their pets routinely dust the mealworms with calcium powder or feed a calcium and vitamin enriched diet to the mealworms (called gut loading) just before feeding to make them more nutritionally complete. Breeding birds are also offered calcium in the form of ground oyster shell or cuttlebone to supplement their diet. Eggshells are mostly composed of calcium. When parakeets are laying, they develop a craving for calcium and will devour a cuttlebone in a few days.
Many areas in the Northeast have also have soil which is severely calcium deficient because the calcium has been leached from the soil by acid rain.
Article, based on research done by the Cornell Laboratory of Ornithology, that explains how calcium deficiency affects reproductive success in woodland birds. http://pages.cthome.net/rwinkler/acidrain.htm
Bluebirding trailwork is exciting. Never are two days exactly alike!
You just never know what is going to happen or what you are going to see
- Fread J. Loane
If you experience problems with the website/find
broken links/have suggestions/corrections, please contact me!
The purpose of this site is to share information with anyone interested
in bluebird conservation.
Feel free to link to it (preferred as I update content regularly), or use text from it for personal or educational
purposes, with a link back to http://www.sialis.org or
a citation for the author. No permission is granted for commercial use. Appearance of automatically generated Google or other ads on this site does not constitute endorsement of any of those services or products!
