A forum search didn't turn up much for me on dummy eggs, but apologies if this has been rehashed a million times. Please feel free to add information of your own or to correct anything I have typed.
What are they?
Dummy eggs are not eggs with a lower than average IQ, rather they are fake eggs or egg substitutes. Different sizes and colors can be purchased for different species of birds. Dummy eggs are often made out of plastic or ceramic, but wood, rubber, glass, and stone are some other materials used. Some people find that painted wooden craft store eggs work, or even just vaguely egg-like objects such as golf balls.
Why use them?
There are many different reasons to use dummy eggs. Some common reasons are:
-A dummy can be placed in a nesting area to encourage laying.
-Dummies can help discourage birds from eating eggs.
-Fake eggs can be used to test a broody hen. If the broody decides to suddenly stop sitting after two or three days on dummy eggs, you haven't lost any valuable eggs. If the broody remains setting, you can replace the dummies with real eggs at that point.
-Dummies can be used to time foster parents. Often this is done with pigeons and ringneck doves. If you do not want a foster bird or pair laying eggs during the time it takes for another pair to lay a clutch, you can set the foster bird/s on dummy eggs.
-You can use dummy eggs to time clutches to hatch out at the same time. This is commonly done with finches. Finches lay a large clutch. If you replace each egg with a dummy as it is laid, then replace all the dummies with the real eggs when the last egg of the clutch has been laid, the chicks will start incubating and hatch at the same time rather than being staggered.
-Laying eggs can be stressful on a bird and her health. If you want to stop egg production for whatever reason, dummy eggs can usually be successfully used for this purpose. Most birds lay a set number of eggs, or clutch, for example, a ringneck dove has a clutch size of two eggs. If you place two dummy eggs in the nest, or place one after the first egg is laid, you can sometimes stop egg production. I have heard of this not working for some birds however.
Where can I get them?
Species specific dummy eggs can be ordered online. You can also make your own dummy eggs. Take freshly laid eggs from your birds. Shake the egg to help break it up, and use a needle to make a hole in one end (most make a hole in the wider/larger end of the egg). You can use a needle to help further break up the contents. Use a syringe (some use a needle to allow for a smaller hole, some use a needle-less syringe) to suck the contents out through the hole. If you are using a needle or completely sealing the hole, a second hole will be needed to balance the pressure. Use the syringe to flush the empty shell with water or an cleaning product that will not damage the shell. Mix up some plaster of paris according to the package directions, and use the syringe to fill the egg with the plaster. Let dry. This method may also be used for craft eggs.
Making your own dummy eggs can more easily fool a wider range of birds and species. Many birds will not accept dummy eggs that they feel or see a difference in. Cranes and corvids are a few examples of birds that may destroy and not be fooled by dummy eggs. It is also cheaper to make your own dummies. The plaster method will give you a natural shell that will not break easily. However, the plaster-filled eggs will not last forever and do break down.