One of the most important things about wildlife photography is continually updating your knowledge. It is the rare photographer that "knows all". There are many books and magazines that can be read, but the few that I've found that have really helped me out as an advanced photographer are the following two magazines.
Outdoor Photography Canada is a regional print magazine that deals with wildlife photography in Canada. It has informative articles on both photography in general and wildlife/nature/landscape photography. It is an industry specific magazine, unlike other magazines such as Popular Photography and Shutterbug. Digital Photo Pro seems to be geared towards portraiture and weddings. If you are reading this blog, you probably are more interested in wildlife photography or landscape photography.
The other magazine that deals with wildlife/nature/landscape photography is Outdoor Photographer magazine, which despite its similar name, has no relation to OPC. As of late, I have stopped picking up every month at the newstand, due to the magazine's repetitive fascination with a) Ansel Adams and b) it's constant articles on the joys of HDR. I understand Ansel Adams is the god of landscape photography, shooting many of his beautiful black and white landscapes with his 4x5 view camera.
But wildlife photography is a whole different "animal - no pun intended" than landscape photography and there doesn't seem to be many wildlife articles in Outdoor Photographer Magazine as it also concentrates on "travel photography" which is even more of a different genre than outdoor photography which also delves into protraiture as well as landscape photography.
PHOTOGraphic Magazine is a tutorial magazine put out by Shutterbug and it gives you lessons on how to get the most out of your photography with the tutorials by Jim Zuckerman, George Schaub, Joe Farace and others. Those are names that are familiar to anyone who is familiar with photography and to those who are well attuned with photography, they can recognize just from the style of photo, who took them. These articles in the PHOTOGraphic magazine are tailored to help beginning and advanced photographers advance in their knowledge of photography to take the skills gleaned from the pages of the magazine into their own work. Reading these magazines will form an added supplement to anyone who is thinking of taking a photography course. The more you build on your foundation of photography knowledge, the better your photography will become. These magazines can be found at any reputable newstand. I usually get mine from either Chapters, London Drugs or Black Bond Books.