Go around the corner to where your Father can't see what your doing and build a second feeder optimized for pigions. Keep it full of whatever seeds are preferred by pigions. Welfare for pigions. ...or... Enclose the feeder in a screened-in patio with the desired birds inside and all others (including the pigions) out in the cold. Welfare for non-pigions. ...or... Get your Father a new hobby that doesn't involve bird-watching.