Recently got a Sigma 100-400mm DG DN, swapped my daughter's A7II for an A6400 for better autofocus, flippy screen (great for setting up video for school). While on a photowalk, we saw an American Robin juvenile fly by and land in a disabled ramp. Looked over and saw another juvenile waiting for food and so I went around to take some shots. I really didn't want to get too close since they were scared and barely able to fly without stumbling about.
The shot's grainy since storm clouds were rolling in and the sun was setting and the lens isn't great for low light situations. Also, the A6400 doesn't have uncompressed RAW which allows pulling up or down the exposure to allow for a lower ISO value, but hey, the pose was cute, shooting low to the ground is easy with the flip out screen and I didn't need to get too close (that crop factor makes it 600+ at the long end) and frighten the birds too much.