Our very definition of intelligence is part of the issue. There's no question that animals exceed our knowledge in specific domains, a bird who can fly must be vastly more knowledgeable about variable wind conditions than we are. There's a great scene in Lev Grossman's The Magicians where they speak to a talking bear, but all the bear wants to talk about is caves, and area in which his knowledge is so complete that the humans cannot really even talk to him. But our definition of intelligence is narrowed to domains which we live in. That tends to be a wider than most animals, but it's hardly complete.