Hen hatching baby chicks outside

[Alisa DC]

I have a broody hen who hatched 4 baby chicks outside in a secure pen. She abandoned the rest of the eggs in the nest. I removed the eggs and incubated. We had a chick hatch. We put it under mama at night she accepted the chick. It is about a week younger than the others but it is active and looks lively. My question is should I put a heat lamp out there to help mama and it stay warm? Outside Temps are about 70 degrees day and evening about 50. Or should I just leave it alone? I don't want the chick to depend solely on the lamp and mama to ignore it.

 

[nuthatched]

Mamma is more than good enough