I've got a Nikon 70-300mm VR G that I used to use on my D90 for bird pictures and wildlife. I have since switched camera systems, so I no longer use this lens. Feel free to send me a message if you're interested and we can chat! It's a great entry level wildlife telephoto lens, and will definitely get you some nice shots as you're starting out. Of course, if your budget is much bigger then you can certainly get more reach or a faster lens for more $$.
It's this lens here: (https://www.amazon.com/Nikon-70-300mm-4-5-5-6G-Digital-Cameras/dp/B000HJPK2C?th=1)
https://www.google.com/nikcollection/
Use Dfine2.
Let the program make an automated measurement. The press the "Reduce" button. In here you can add negative control points to remove the noise reduction where needed (adjust the sliders on the control point to set the area you want to target). It's quite simple.
https://www.youtube.com/playlist?list=PLp5lYDsQi4gmZgD2fdHHipF5albBgzJRW
edit: added better tutorials.
> we cant even begin to suggest that price is comparable.
Not sure what you mean there. The Canon is usually a little cheaper on the used market since they've been making the same lens for 20+ years there's a lot of really nice ones available.
Even new the prices are quite similar.
Sigma - $989
Canon - $1149
there's this one. I met, and photographed Rosy Finches with, the author once.
Barnes and Noble has books full of large Audubon prints in their clearance area.
I use this. https://www.amazon.com/dp/B00GR8KEMS/ref=cm_sw_r_other_awd_lkn4wbCWB9BBK
Wear it under my bins straps... Quick access, can drop it quickly if I need to pick up bins etc....
I carry a 150-500mm