Nature red in tooth and claw

Last week I spotted a buzzard's nest some 55ft up a beech tree. I knew it was there because I spotted the tell-tale sprig of pine on the woodland floor.
Does anybody out there know why buzzards decorate their nests with spruce? I think it could be to keep the nest fresh, or a natural insecticide, but if anybody knows different please let me know.
If it hadn't been for the trouble I've been having with my herniated disc, I'd have scaled the tree to have a look inside.Instead I had to contend with reminiscing over how I once watched a buzzard chick devour his sibling. There are times when the cruel reality of nature can really hit home.
Read about my memories of that experience in my monthly Yorkshire Post column, which is published this week.