Wildlife photography is not easy and the more help your camera can give you the better. I rate high ISO performance as the most important element when selecting a camera for this type of work. For over 30 years I used the old Kodachrome slide films of ASA (ISO) 64 and 25. I was lucky to get 1/30th second exposures and learnt to hold a long lens verrrrry steadily and the exposure latitude was pants, about 2.5 stops.. Nowadays I can use ISO 1000 as standard and get excellent results even with cluttered backgrounds. Here's a couple of pics of a Nuthatch to prove the point. The first is taken at ISO 6400!! The second at ISO 800. How things have come on these last few years. Full frame sensors rule for me.
I've been laid up with a damaged foot for ages. Put my foot down a rabbit hole while carrying 50lb of photo gear and trashed ligaments big style so no carrying photo gear for a long while. Never mind, I can always get the sketchbook out!
This bank vole was one of a pair feeding under Rhododendron bushes. He was very friendly and became addicted to sunflower seeds, often taking 4 into his mouth at a time and scuttling off to hide them. Hard to get good photos of them as the light was very poor.