For price under $2000, I highly recomended the RF 200-800mm lens. The only problem is it is currently out of stock everywhere.

If you don't mind the budget, get the RF 100-500mm L lens.

One of the best Canon telephoto lenses for wildlife photography is the Canon EF 100-400mm f/4.5-5.6L IS II USM. This lens offers excellent image quality, a versatile focal range, and fast autofocus, making it ideal for capturing fast-moving subjects in wildlife photography.

Wow ok that changes things. Gonna have to rethink my approach now.

Just catching up on this thread. Looks like everyone has covered the big hitters, but let me throw in a few thoughts from my time in the woods. In my experience, you usually have to pick your poison when you stay under that 2k mark.

• Used market value: I think looking at older professional glass with an adapter is a solid move. IIRC, some people say the older glass focuses even faster on the new mirrorless tech than it did on the old bodies.
• Weather sealing: If you're out in the mud and rain for birds, you really want something that can take a splash. Some of the cheaper options skip this, and honestly, it can be a dealbreaker if a storm rolls in.
• Balance and weight: Not sure but I heard that some of the really long lenses feel a bit front-heavy on the smaller mirrorless bodies. You might want to think about a battery grip to balance things out. Not 100% sure on the specific compatibility for every single older lens out there, but it is definitely worth looking into if you want that high end feel without the massive price tag. Tbh, shooting wildlife is 90 percent patience and 10 percent gear anyway. Dont get too hung up on the newest stuff...

Building on the earlier suggestion, I have to respectfully disagree with sticking solely to native RF glass if your budget is firm. I've been doing this for a long time, and while the Canon RF 100-500mm f/4.5-7.1 L IS USM is incredible, it just blows the $2000 budget. And those f/11 primes? They are basically paperweights as soon as the sun dips below the tree line. In my experience, the smartest move for a bird photographer on a budget is getting a used Sigma 150-600mm f/5-6.3 DG OS HSM Contemporary for Canon EF. Pair it with the Canon Mount Adapter EF-EOS R and you still have a ton of cash left over for travel. The AF is plenty fast for birds in flight on the mirrorless bodies. Ngl, the weight is a bit much compared to the newer RF designs, but for the reach you get... its a no-brainer imo. Dont let the adapter scare you off, it works flawlessly.

@Reply #14 - good point! Honestly, I love the energy in this thread, but I have to respectfully disagree with the idea that you need to stay native Canon to get amazing bird shots on a budget! If you are looking for that sweet spot under $2k, you really should look at the Sigma 150-600mm f/5-6.3 DG OS HSM Contemporary for Canon EF used with the Canon Mount Adapter EF-EOS R. I know some folks worry about using third-party brands, but that Sigma is an absolute beast for the price! You get 600mm at f/6.3, which is way better for low light than those f/11 Canon primes everyone is talking about. Plus, the build quality is fantastic. I have used it for years and the autofocus is still snappy even on the R-series bodies. You basically get almost the same reach as that 200-800 for way less money and it is actually in stock! Just something to think about if you want the most glass for your dollar... the results are honestly amazing for birding.

No way, I literally just dealt with this yesterday. Small world.

Prime lens such as RF 600mm f/11 and RF 800mm f/11 are also great and lightweight wildlife lenses.

For wildlife photography, a good telephoto lens is crucial to capture distant subjects with detail and clarity. Canon's RF lens lineup offers several excellent options. Here are three of the best-selling RF telephoto lenses for wildlife photography under $2,000:

1. Canon RF 100-500mm f/4.5-7.1L IS USM

Why to Buy:

• Versatile Zoom Range: With a focal length range of 100-500mm, this lens offers great versatility, allowing you to shoot both near and far subjects with ease. It’s especially useful for wildlife, where subjects may be at varying distances.
• L-Series Build Quality: As an L-series lens, it boasts superior optical quality and build robustness, including weather sealing, making it durable for outdoor use.
• Optical Image Stabilization: The lens features up to 5 stops of image stabilization, which is beneficial when shooting at longer focal lengths, helping to reduce the effects of camera shake.
• Lightweight Design: Compared to other super-telephoto options, this lens is relatively lightweight, making it easier to carry on long hikes or outings.

2. Canon RF 600mm f/11 IS STM

Why to Buy:

• Super-Telephoto Reach: With a fixed focal length of 600mm, this lens provides excellent reach for wildlife photography, allowing you to capture distant animals without disturbing them.
• Affordable Option: The f/11 aperture and design keep it more budget-friendly compared to other super-telephoto lenses. It’s a great entry-level option for wildlife enthusiasts.
• Compact and Lightweight: Although it offers a long focal length, the RF 600mm f/11 is surprisingly compact and lightweight. This makes it easier to transport, particularly for longer wildlife expeditions.
• Image Stabilization: The lens includes image stabilization, which helps maintain clarity in handheld shots, especially useful for wildlife that may not wait for a perfectly steady shot.

3. Canon RF 800mm f/11 IS STM

Why to Buy:

• Extended Focal Length: This lens boasts an impressive 800mm fixed focal length, making it perfect for capturing distant wildlife, particularly birds and other shy animals.
• Portability: Similar to the RF 600mm, the RF 800mm f/11 is built with a lightweight design, making it feasible to carry for extended periods, despite its enormous reach.
• Affordable for Telephoto: It offers considerable reach at a relatively lower price point than many other long telephoto options, reaching out to wildlife without breaking the bank.
• Image Stabilization: Like its counterparts, this lens has image stabilization, helping you maintain sharp images even in challenging shooting conditions. 

> What focal length would you recommend for good reach while maintaining decent image quality? A focal length of at least 400mm is necessary for reliable performance. First, it provides the magnification needed for small subjects. Second, it ensures enough detail remains for cropping. I actually tried testing my reach at a local park last weekend, but the trip was a mess. There was this huge marathon going on that I didnt know about. Every single trail was blocked by runners in neon shirts, so I couldnt even get near the water where the herons usually hang out. I ended up just sitting at a picnic table eating a very overpriced hot dog while watching people trip over tree roots. It was quite a long walk back to the car too. Anyway lol sorry kinda went off topic there.

@Reply #8 - good point! Getting close enough to birds is honestly the hardest part. Looking at what everyone said so far, you basically have to choose between the really expensive pro zooms, those super light f/11 primes, or that 200-800 lens that nobody can actually find in stock. I am still kinda new to the mirrorless world, but you might want to consider the compatibility stuff before you pull the trigger. Not sure but I think I read somewhere that using adapted glass might not always give you the full burst rate on some bodies? IIRC some older lenses can cap your frames per second. Just be careful and make sure to double check that because it would suck to lose out on speed when a bird finally takes flight. Honestly, the native RF glass seems safer but it is definitely pricier. I would suggest checking some compatibility charts just to be sure... I am still learning the ropes myself so take that with a grain of salt! But yeah, let us know what you end up going with.

Late to the party here but I've been reading through everyone's suggestions. Before I give you a final recommendation, I gotta ask... what kind of lighting do you usually deal with? Are you out at sunrise when the birds are active, or more of a midday hiker? It makes a massive difference. In my experience, if you're always in bright sun, the slower glass is fine, but low light changes the game entirely. I've spent a lot of time with both the Canon RF 100-400mm f/5.6-8 IS USM and the Canon RF 800mm f/11 IS STM over the last year. Here is a quick breakdown of my thoughts:

• The 100-400 is surprisingly snappy and way easier to carry for long days, but you'll definitely find yourself cropping a lot for small birds.
• On the flip side, that 800mm gives you incredible reach for the money, but f/11 is really demanding on your ISO when the clouds roll in or you're under a heavy canopy. Both are well under your $2000 limit tho, so thats a plus. Let me know about your lighting situations and I can give you a better steer.

Re: "Just catching up on this thread. Looks like..."

• Rodrick makes a solid point about the adapted glass. Over the years, I've tried many combinations and the technical side of the RF mount is actually pretty forgiving with older EF lenses. If you're looking for specific specs to maximize that $2000 budget, here's what I'd look at:
• The Canon RF 100-400mm f/5.6-8 IS USM is a sleeper hit. Its technical resolution is high enough that it holds up well even when you crop heavily, which is basically mandatory for birding.
• Adding a Canon Extender RF 1.4x gets you more reach, but you gotta be careful with the f-stop. On high-MP sensors, you hit the diffraction limit pretty early.
• If you go the EF route, look for a Tamron 150-600mm f/5-6.3 Di VC USD G2 for Canon EF. Use it with the Canon Mount Adapter EF-EOS R and you get 600mm for way under your budget. Honestly, the AF tracking on the newer bodies is so good that even slow lenses perform better than we ever expected. Just keep an eye on your shutter speeds and you'll be fine.