Golf Balls

Back in the summer, there were golf balls on my lawn (I thought they were from my neighbour who is a golfer)
but they weren't.     
Recently the roofer has been on my top flat roof, and came down with three golf balls        Now which bird is bringing these gifts.     Sea-gulls, magpies, the ravens, or crows.    I am sure it is not all the other little feathered friends.      Mrs Bouquet

My thoughts are as follows:
The rarely-seen bird called the Mashy Niblick, the Pied Wedgeiron or my favourite one to go for is an albatross.