On final at Iowa City, IA in a Cherokee 140 about 1962 with about ~ 20 hours TT.
Very loud thud and yawed to the left, pushed in some rudder and continued to land. While taxiing back to tie down I noticed a bump near the LE of the left wing.
Closer look showed a ~ 6 inch hole in the LE. By the feathers it was a Mallard duck that was on a reciprocal course. They had to remove part of the outer wing skin pannel to remove the shredded remains.
For those not familiar with Mallards they are big and heavy.