Johannes Gerardus Keulemans ( 1842 - 1912 ) was a Dutch painter. Johannes Gerardus Keulemans s works have been put up for auction numerous times, with realized prices surpassing estimated prices, varying from 182.53 USD for Swallows mobbing a Cuckoo in 2003 to 20000 USD for Red Billed Gull & Black - Billed Gull in 2013 , based on the size and medium of the artwork.