Jumping in real quick. For the Everglades, reach is usually the priority so the Tamron SP 150-600mm f/5-6.3 Di VC USD G2 Nikon Mount is the safer bet despite the bulk. The Tamron 100-400mm f/4.5-6.3 Di VC USD Nikon Mount is better for hiking but youll likely end up cropping too much.

• 150-600mm: Essential reach, heavy, better weather sealing for humidity.
• 100-400mm: Light, easy to handhold, lacks that extra pull. Id definitely go with the 600mm... birds just dont sit close enough.

I've been very satisfied with the Tamron SP 150-600mm f/5-6.3 Di VC USD G2 Nikon Mount for wildlife. One methodical tip: buy the Tamron TAP-in Console Nikon Mount to calibrate the autofocus for your D500. It really improves consistency. You can find used copies on MPB or KEH to stay under your $1200 budget. Also, the comparison tools on The Digital Picture provide great objective data for your decision.

> Which Tamron lens is actually the best for birding on my Nikon D500? Unfortunately, the Tamron SP 150-600mm f/5-6.3 Di VC USD G2 Nikon Mount is not as good as expected on the D500. I had issues with focus speed and it felt soft at the long end. Since you have $1200, maybe check out a used Nikon AF-S NIKKOR 200-500mm f/5.6E ED VR instead. Its way more reliable for birding. 400mm just wont cut it for reach.

> My Everglades trip is in two weeks and I only have $1200 to spend so I really need to get this right... Reliability is honestly the main factor when youre heading into that kind of humidity. I used to be obsessed with the technical specs but after years of doing this I mostly just worry about the gear actually surviving the environment. Last time I was down in the Everglades near Flamingo, I spent way more time fighting off those massive horseflies than actually tracking birds. They were biting right through my shirt and I ended up dropping my favorite kit bag in a shallow marsh because I was swatting at my neck. Spent the rest of the afternoon cleaning swamp water out of my filter pouches with a dirty t-shirt... total nightmare. Anyway lol, I kinda drifted off there. Just make sure you get something with decent weather sealing because that Florida air is basically soup.