My wife and I have three boys under the age of 6 and we pay close attention to what they can watch. Two shows that they enjoy are Berenstain Bears (a classic!) and more recently, The Cat in the Hat. These two episodes really got my attention because they relate to birds and conservation. Killdeer, Canada Goose, Purple Martin and others are mentioned in these two episodes. They are a great tool to teach children about birds!
The Cat in the Hat - Migration Vacation
Berenstain Bears - Showdown at Birder's Wood