An internal-combustion engine needs four things to run. They need fuel, mixed with air, in a ratio of 14.7 to one. An ignition-spark lights the fuel and air mixture, creating combustion. Compression of the fuel and air mixture makes it explosive. The final necessity is proper timing, of the components.
1 The length of time it takes for eggs to hatch after incubation begins depends on the species and temperatures. 2  For bluebirds, it USUALLY takes about 12-14 days from the date the last egg was laid.3  Different species have different incubation periods, which can vary within a species due to temperature inside the nestbox. Depending on when incubation begins (on the last, or next to last egg), eggs in the same nest can hatch a day or several days apart. 2  It also takes a while for the bird to break through the shell. 3  It could be a new egg from a subsequent nesting if you didn't clean the box out immediately after the last fledging.
Rating Newest Oldest. Best Answer: Nesting: Two broods of 3-5 blue-green eggs with a 12-14 day incubation period. Fledging occurs 14-16 days after hatching. The nest is a mud cup lined with soft grass and reinforced with grass and twigs. The nest is usually placed in a tree, on a ledge, or on a windowsill. http://www.bird-friends.com/BirdPage.php... So they will hatch 12-14 days after the mother began incubating the eggs, and the babies will be fledging (leaving the nest) about 14-16 days after that. Remember, though, that when they first leave the nest, they will not yet be flying, so you need to be careful of any pets or children that may be in the area.