First few days: 95* 1week: 90* 2 weeks: 85* 3 weeks: 80* and so on... just depends on the outside temps....if it is 80* where you live, they only need the heat lamp for about 3 weeks, ducks are hardy also, if they crowd together , give them heat again.
I've never measured the temp under the heat lamp. I use the behavior method of determining appropriate heat: If the ducklings huddle under the lamp cheeping, then they are too cold and need more heat. If they stretch out away from the lamp panting, they are too warm and the heat needs to be turned down. They are comfortable if: They sleep cuddled and peaceful under the heat lamp, but move out to eat and drink without signs of discomfort. With this method, how long they need the heat lamp will depend entirely on your observations and will also depend on your weather and the particular batch of ducklings (some mature faster and other have more body fat--more mature and/or fatter birds will be warmer faster).
