Many sources list one or the other, or even a different temperature as THE one and only number that is correct.

In practice, the truth is that there is no noticeable difference between the two. Eggs that will hatch will do so when set at either temperature, with maybe only hours difference depending on which temp you chose.

In every incubator, there are areas inside that will read at different temperatures at any given time, even forced air incubators, so eggs are always incubated at different temperatures anyway, in the same incubator. The other problem is getting an accurate thermometer reading. Unless you have a several hundred dollar, scientifically calibrated thermometr, you are probably not getting an accurate reading. Put in any three store bought thermometers, and you'll get three different readings. Some may vary as much as 3 degrees or more! The solution is to choose one thermometer, and by trial and error, determine the best temperature to run that one incubator at with that one thermometer. Start at 100. Even if it's actually off by even several degrees, at least a portion of fertile eggs will hatch. If they're early, lower the temperature. If they're late, raise it. As you get closer to the ideal, you're hatch percentage will increase. When the eggs are hatching on the days that they're supposed to, continue to use that temperature on that thermometer in that incubator at that location, even if the reading says something different than what it's "supposed" to be.

Incubation is as much an art as a science. Most people with an attention to detail can hatch a portion of a clutch or two here and there, but it takes real skill, and good equipment to consistently hatch the optimum percentage of fertile eggs. There are also many variables based on species. Waterfowl are generally the most difficult to hatch. The incubation temperature for ratities are sometimes lower than that for many other species.

Good luck.

We sell the Little Giant Incubators you are talking about and we recomend that the temperature be 100 for chickens, Quail, Pheasant, Chukar, Duck and Guinea. Temperature should be 99 for Turkey and Geese. Also you will want to make sure your moisture rings are full of water. Humidity and Ventilation are very important. Also if your incubator is in a room with temperature fluctuation (day and nightime temp differ) you will have a harder time keeping the temperature at a set degree. If you ever need anymore info on egg incubation please visit our site www.flemingoutdoors.com. Good Luck !!

Here is a link that might be useful: Fleming Outdoors