Wondering why my pictures are coming out blurry?

I’m wondering why my pictures are coming out blurry as I’m new to photography. I wanted the birds to be very cris, but once you zoom in, you lose a lot of detail and they are soft.

I’m using a Sony a6400 w/ a tamron 18-300mm lens

I put the camera on shutter priority to make sure I capture the birds movements.

Shutter was either at 1/1600s or 1/4000s

ISO was on Auto and for pictures above was between 1000-5000

Aperture was also on Auto and got the pictures above seemed to be at a constant f6.3