Nesting Wood Pigeons

Hi everyone, this is my first time posting and looking for advice.

I am awaiting a conifer being felled but I keep delaying the contractor as i think there are Woodies nesting. I see the bird fly in and out but not very regular, so are they just using it for shade/roost etc? Activity seems to be confined to morning and evening but not every day.I know they can nest all year round, which makes me nervous about giving the go ahead to fell.

What behaviour would I see, how often and for how long, if there was an active nest? 

Thank you for reading.