Since it's breeding season I thought it timely to take a close look at Matthew Vriends "Hand Feeding and Raising Baby Birds" on the subject of incubation. Once in a while it needs to be attempted when there is no alternative.
temperature: 98 - 100 degrees; not more than 104 degrees; any variance on the low side.
Temperature will cool briefly during turning sessions.
humidity: 55% on a hygrometer; light warm water mist spray on the last four days.
During incubation the egg must lose a certain amount of weight in the form of moisture, so that the air sac expands. At the end of the incubation cycle the egg will have lost between 13% and 15% of its weight. If the evaporation proceeds too quickly, it will become too dry for the embryo will not develop satisfactorily.
egg turning: at least three or more times a day (use a clean cloth for home made incubators since the shell is a semipermeable membrane which must remain clean). Turn the egg a quarter turn only each time.
The embryo floats toward the upper surface of the egg. If it is not turned it may stick there. Also, turning stimulates movement in the embryo which stimulates growth. Do not turn the eggs in the last 3 days before the expected hatch date, so the chick can gain a favorable position for pipping the egg and making a clean exit (not drowning in albumen).
time frame: 17 - 18 days after egg laying.
ventilation: Egg produces carbon dioxide which must be evacuated; fresh air is especially important during hatching; ventilate and cool one minute each day.
Avoid direct sunlight.
The above incubations operation can be attempted with a make shift incubator, but it would seem prudent to try this only in an emergency when no brooders, rehabbers, or incubators are available. The humidity cannot be controlled without a hygrometer and I dont know how critical this will be. Heres what you need:
closed container with a window and a roof light rigged to achieve the required temperature i.e aquarium, etc.
thermometer located at egg level and visible through a widow.
pan around the eggs for water; a towel base.