Wrens are common songbirds that live in most areas of the United States. During breeding season, wrens who are injured or killed may leave behind a nest full of eggs. Incubating eggs and caring for hatchlings is challenging, so if you find an abandoned nest, the best option is contacting a trained wildlife rehabilitation expert. If no one is available to take the eggs, however, you will need to incubate them yourself.
Adults may leave their nests behind for brief periods of time, so observe the nest over several hours before removing the eggs. Wrens mate for life, and if one bird is killed, the other will normally provide care for the eggs and babies. Even if you know one parent has been killed, wait a few hours to give the other parent a chance to care for the eggs.
If no adult appears to be providing care for the eggs, remove the eggs from the nest and avoid shaking them. Place them in a chicken egg incubator and incubate at 100 degrees Fahrenheit. Prevent the eggs from drying out by misting them several times a day with a water mister. Though eggs will die if they become too dry, they can also mold if they become too wet. The key is to keep the incubator moist but not wet. Humidity of about 50 percent is usually ideal.
Wren eggs tend to develop hot spots, and if an embryo overheats it can die. Consequently, it's important to turn the eggs several times a day in order to keep the temperature inside of the egg consistent. Most wildlife rehabilitators recommend turning wren eggs a minimum of four times a day. Simply turn the egg 180 degrees without shaking or squeezing it.
The incubation period for wrens ranges from 13 to 15 days. Of course, if you've found the eggs there's no good way to know how long until they will hatch. Check them several times a day for signs of hatching babies. Baby wrens typically take a few hours to fully hatch, so avoid interfering with the hatching process.
Caring for wren babies is exhausting work. They need food dozens of times each day and the quantity and type of food they require changes every few days. Contact an avian veterinarian prior to the time the eggs hatch for advice on specific food items to give the wrens. Most lay people will be poorly equipped to provide care for wren hatchlings, however, so the most responsible strategy is to find a wildlife rehabilitator, veterinarian or avian expert to take the birds prior to hatching.