Expert: Julia Booth - 6/7/2008

Question
QUESTION: A friend found a robin's nest on top of outdoor lighting. The mother robin
has been sitting on the eggs, only leaving the nest when my friend entered
the area. That night, she turned the outdoor lighting on, intending to turn it
off within a few minutes, but forgot. Consequently, the light remained lit for
several hours. In the morning, the mother was sitting on the nest as before. Is
it possible that the lighting caused the eggs to die? And, if so, would the
mother know that or can she sense if her eggs are alive or not? Thanks for
your help.

ANSWER: If she's in direct contact with the actual light source and it exceeds 102 degrees when lit, then it can damage the eggs. Otherwise, I doubt it will affect them.

---------- FOLLOW-UP ----------

QUESTION: Actually, it's not the robin that's in contact with the light, it's the nest, so please
confirm that the answer is correct under those circumstances. Also, we're
interested in knowing if the robin can sense whether her eggs are still alive or
not.

Answer
If the EGGS are in contact with the light source and it exceeds 102 degrees when lit, then it can damage them.

Birds will sit on unfertilized eggs. No, they don't necessarily realize the eggs are no longer viable.

I'm highly doubting that the eggs are ruined, unless that is one super powerful light you've got. Halogen produces more heat, so that could be a concern.