Bird eggs are laid at different times, so they usually hatch first laid first hatch and so on. This is more common among raptors.   For other birds, embryos develop when th…e egg is incubated, and birds will delay incubation until all eggs are laid so that all the chicks will hatch at the same time. (MORE)
http://www.answers.com/Q/What_time_of_year_do_birds_hatch
How to Create an Egg Incubator for Wild Bird Eggs. Community Q&A. If you want to hatch some wild bird eggs that you may have found and you don't have the money for a pro incubator, you can easily create an efficient incubator from household items.
http://www.wikihow.com/Create-an-Egg-Incubator-for-Wild-Bird-Eggs
Birds’ eggs will take anything from 14 to 28 days to hatch, depending on the bird. A robin’s egg hatches within about 14 days and some larger birds, like swans, have to keep their eggs warm for 6 weeks before they hatch.
http://wildlifegarden.org/when-do-baby-birds-hatch
Tips. 1  Remember that each bird egg has different incubation standards. 2  At night, you can turn off the heat lamp and put the lid on the box.but its best not to with the fish tank) It should be okay for the night because mother birds don't incubate every second of the day.  Don't be sad if the egg doesn't hatch.
http://www.wikihow.com/Create-an-Egg-Incubator-for-Wild-Bird-Eggs
How to Create an Egg Incubator for Wild Bird Eggs. If you want to hatch some wild bird eggs that you may have found and you don't have the money for a pro incubator, you can easily create an efficient incubator from household items.
http://www.wikihow.com/Create-an-Egg-Incubator-for-Wild-Bird-Eggs
Some species will have 2 or 3 hatches a year depending on type of bird, food supply, weather and availability of mates. If they are in parts of the world that have seasons, they hatch in the spring. This gives the chicks time to develop before the next cold season. In places that stay warm year round, it can be anytime. Some species will have 2 or 3 hatches a year depending on type of bird, food supply, weather and availability of mates.
http://www.answers.com/Q/What_time_of_year_do_birds_hatch
Let’s get back to the question: When do baby birds hatch? Winter temperatures are terribly cold in many areas of the world and the birds would have quite a tough time keeping their chicks warm and finding food for them. Most birds lay their eggs and hatch their chicks in spring when the weather warms up. In the warmer climates this will happen a little earlier in spring than in the colder areas. They will not breed until there is food for them and their chicks.
http://wildlifegarden.org/when-do-baby-birds-hatch
They sit on their eggs for 6 weeks. After the eggs hatch the birds will continue to sit on the nest for another few weeks while the chicks grow their feathers. Small birds don’t usually stay on the nest for more than 2 months at the most, including the hatching time and giving the chicks time to grow feathers.
http://wildlifegarden.org/when-do-baby-birds-hatch
Find a wildlife rehabilitator. Wildlife rehabilitators are licensed to care for injured or orphaned wild animals. If you find wild bird eggs and suspect that something’s wrong, contact your local wildlife agency or search online for a licensed rehabilitator. Do not take the egg(s) to a rehabilitator. Instead, be prepared to direct the rehabilitator to the egg(s).
http://www.wikihow.com/Find-and-Take-Care-of-Wild-Bird-Eggs
Replace the egg. If you come across a wild bird egg and see a nest nearby that’s empty or contains similar looking eggs, you could try to return the egg to its nest. If you do not see a nest, do not go looking for one, and never assume that an egg is abandoned. Some birds nest on the ground.
http://www.wikihow.com/Find-and-Take-Care-of-Wild-Bird-Eggs
how do birds hatch
They sit on their eggs for 6 weeks. After the eggs hatch the birds will continue to sit on the nest for another few weeks while the chicks grow their feathers.