I am no expert and cannot confirm your observation. Though from years of watching have seen more feathers in Nests at laying time,
but purely personal,I feel, Mum does not need so much Down, as Chicks hatch and Grow.
Here is a good identification from Hawk and owl Copyright
Thanks for the link, SunnyKate2. Will read that today.
More information: peregrines arrived back in the neighbourhood in the last 4 to 5 weeks.