Which Canon DSLR for bird and wildlife photography?

UPDATE: There is a new version of this article which has been expanded and covers all the currently available Canon cameras.
See here for the new version:
Choosing a Canon DSLR for nature photography

Which Canon DSLR is right for bird and wildlife photography?
After answering the question for Nikon DSLRs, I want to focus on Canon digital SLR cameras today.

Here is an overview of the current Canon DSLR lineup:

Canon EOS 1000D

A nice camera with a very good image quality. But I don’t recommend it for serious wildlife and bird photography. The AF is not the best and it doesn’t provide the frame rate needed for action photography.

Canon EOS 450D

If you don’t want to spend a lot of money, the EOS 450D is not bad. I offers great image quality and the AF is better than with the 1000D. It’s not as robust as the 40D and 50D. If you can afford a more expensive camera, I suggest to get the 40D or 50D.

Canon EOS 40D

The camera I currently use. For the price I think the EOS 40D is one of the best cameras on the market. The autofocus is fast and accurate, at least with a fast lens like the Canon EF 4/500L. The frame rate of 6.5 frames per second is enough for most situations. The camera is lighter and smaller than an EOS 1D body which is great when you travel or hike long distances.
The only thing that many photographers don’t like is the fact that AF only works up to f5.6. That means with a 4/500 or 4/300 lens, you won’t have AF with a 2x extender.
With Canon cameras, AF up to f8 only works with the EOS 1D bodies.
Beside this I think the EOS 40D is a great camera for wildlife and bird photography and many photographers use it.
If you need more megapixel but want an otherwise pretty similar camera, I recommend the EOS 50D.

Canon EOS 50D

Everything I wrote about the EOS 40D is also true about the 50D. Great camera with some small improvements over the EOS 40D (like AF micro adjustments) and a huge increase in resolution from 10 megapixels to 15 megapixels. If you want the extra resolution go for the 50D.

Canon EOS 5D Mark II

The successor to the popular EOS 5D. The 5D Mark II can shoot only 3.9 fps which does not make it very useful for action photography. It also has a lower pixel densitiy than a EOS 50D, which means that you get less pixels per subject than with a 50D.
But the image quality of the 5D Mark II is a little better than the 50D, especially at higher ISO settings. If you don’t need the crop factor of the 50D and 3.9 fps are enough for you, the EOS 5D Mark II might be a good but more expensive alternative to the 50D. If you also shoot a lot of landscapes, the EOS 5D Mark II might be a better choice. If you can afford it, go for two bodies. The 50D of wildlife and the 5D Mark II for landscapes and macro work.

Canon EOS 1D Mark III

The EOS 1D Mark III has gotten a lot of bad press because of problems with it’s autofocus system. See this detailed report to get more information.
Quite a few people moved to Nikon because they were disappointed with the 1D Mark III. That said, there are also many photographers who get great results with the AF of the EOS 1D Mark III.
Beside the AF problems, this camera is great. The 1.3 crop factor is useful for shy animals and the 10 fps are perfect for action scenes. The camera has full weather sealing which is great in harsh landscapes like deserts, rain forests or at sea.
It also can autofocus at f8, which means you can use a 4/500 or 4/600 with a 2x extender and still have AF.

Canon EOS 1Ds Mark III

This is the big sister of the 1D Mark III. It has 21 megapixels of resulotion, but can only shoot a 5 fps. If you want a full frame camera and the 5fps are enough, the 1D has everything you need.
But I would advice to really look at the 5D Mark II if you want a full frame camera. It has the same resolution. The AF is slower and the 5D Mark II isn’t as robust as the EOS 1Ds Mark III, but it is a lot cheaper.
In my opinion, for most photographers it would be better to get the 5D Mark II and invest the money saved in a good lens.

Conclusion:

I don’t recommend getting the EOS 1000D. It’s a good camera for the money but it has too many limitations for serious bird and wildlife photography.
If 10 megapixels are enough I recommed the EOS 40D. I’ve been using this camera myself for about a year now and I really like it. Autofocus is fast, the 6.5 fps are great for action shoots and the image quality is very good, even up to ISO 1.600.
If you want more resolution, go for the EOS 50D.

The EOS 1D Mark III is a more professional version and if it hadn’t all those autofocus problems, I would highly recommend it and probably own it myself.
If you don’t need the features of the 1D Mark III I think the EOS 40D or 50D will be a good choice.
I expect an 1D Mark IV from Canon soon and I hope that model will not have the autofocus problems of the 1D Mark III.
Another alternative would be to get a used EOS 1D Mark IIN which has a better autofocus, but only 8 megapixel.

The full frame cameres EOS 5D and EOS 1Ds Mark III are great for landscape photography and if you need a lot of resulotion.

If you can afford it, it might be good to get two cameras. Sometimes having two cameras ready can be very helpful. And you have a backup on vacation if one model stops working or gets stolen.

A good combination would be to get a EOS 50D (or 40D) and a EOS 5D Mark II.
Professionals sometimes use a EOS 1D Mark III for birds and wildlife and the EOS 1Ds Mark III for landscapes. This is a great combination (if you have a model without the AF problem) but also very expensive.

The lens is more important than the Camera. It’s better to have a EOS 40D with a Canon EF 500mm f/4L IS USM than a EOS 1Ds Mark III with just a Canon EF 300mm f/4L IS USM. The 300mm is just too short for most situations but would make a great addition to the 500mm lens.