Is it really worth to write something about the equipment i'm using for nature photography? I asked myself this a couple of times. Back in the 80's when pros owned a Nikon F3 and i was a teenager that started to get serious with photography, i read articles where amateur photographers made statements like "if i would have the same equipment as professional xyz owns, i could also take such amazing pictures". Well, as someone who could not afford expensive camera gear i tended to agree. While taking pictures with Kodachrome 64 (the elderly might remember this) and a f8.0/600mm telephoto lens in the evening during a photo trip, the moment came where exposure times dropped below 1/60s. This was the time to store this stuff and either go and search for a cool sunset foreground or go and find a neat restaurant. Meanwhile, photographer xyz with his f4.0/600mm could continue to hit the trigger for another hour or so. That's not fair! Ok, good equipment helps, but does not guarantee excellent results. Without the knowledge about animal behavior, or without being outside at the right time and place, you will never get the cool shot.
So does it make a difference? Yes or no? I think there is no black and white and the answer is somewhere in between. Personally, new or good equipment increases my motivation to get the butt off the couch, take the gear and go. It will not change you into an awesome photographer.
Canon or Nikon or ...? It's also a matter of having a good feeling. In 1990 when i finished school, i decided to switch to an AF system. The little engineer inside me was convinced, that a fully electronic coupling between body and lens is the design of the future. Canon decided that way. They had me with the Ultrasonic AF drive - and with the EOS-1. So i chose Canon and never regretted it. All of my current EF lenses can still be used with my analog EOS-1 from 30 years ago.
In any case it is important to know your equipment well and to practice practice practice.
I would say in the past i had like four generations of camera equipment. From today on, going into the past, the list looks like this:
Canon EOS-1D X
Canon EOS 7D
Canon EOS 5D
Canon EOS 30D(given to my niece...)
Canon EF 2.8/14mm L II USM
Canon EF 4.0/17-40mm L USM
Canon EF 4.0/24-105mm L IS USM
Canon EF 2.8/100mm L IS USM Macro
Canon EF 4.5-5.6/100-400mm L IS USM
Canon EF 4.5/500mm L USM
Sigma EX 2.8/120-300mm DG APO HSM
Canon Speedlight 580 EX II
Tripods from Gitzo, Benro and Novoflex
Canon EOS 600 (EOS 630 in the U.S. and Japan)
Canon EF 3.5-4.5/28-105mm USM
Canon EF 3.5-4.5/70-210mm USM
Novoflex "Schnellschussobjektiv" 8.0/600mm (nickname "Bazooka")
Canon Speedlight 540 EZ
Metz Mecablitz 45 CT-4
Metz Teleconverter 45-33 (this thing can make you blind!)
Pentax Program A
Pentax SMC 2.8/28mm
Pentax SMC 1.7/50mm
Don't know where it is
Kodak Instamatic 104
With the EOS-1D X in Iceland.