Why would you need to train a dog to hunt in shadows? At a Hunting Test several years ago, in the Junior Stake, a dead bird waas thrown on level land about eight feet back into the shade of a tree. Piece of cake retrieve. Wrong. Most of the dogs headed off on a good line for the bird only to stop short and hunt in the sunshine, never going the eight feet into the shade where the bird lay.
Many dogs seem to see shadows to be as much of an obstacle as a brick wall. So, at some point in your training, work on shadow retrieves. Look for a grove of trees - either early morning or late afternoon - and have your helper throw birds six feet into the shade. You may need to encourage the dog initially to get him to go all the way to the fall. Once he has the idea, lengthen the distance that he must go into the shadows as much as the trees allow. Now find a row of trees - late afternoon is the best time for long shadows - and throw the mark on the far side of the trees so that the dog is running from sun to shade and then back into the sun again. Mix the retrieves - some in shade, some through shade into sunshine. When he seems to have this down pat, move to water.
Find an area where trees come down to the water bank so that you will have deep shade either in early morning or late afternoon. Set up the retrieves to be pretty straightforward with nothing but the shadows for the dog to deal with. Starting out with white bumpers rather than birds may help. Have your helper throw the bumper in open water deep into the shade. Be prepared to help the dog if he starts hunting short. Continue the same mark, graduating to dead ducks after the dog seems confident about going into the shadows.
Include shadows in your regular training schedule once a month or as circumstances allow. I know that this may seem like a strange thing to train for, but believe me, you'll be glad you did when your dog is faced with deep shadows for the first time in a hunting test or out hunting with you. Happy training!