Two beautiful images.
Oyster catchers - I dont mind the square crop - but would crop it tighter to accentuate the subjects. If you want to show space - then a 6x4 crop would be good with the birds to the side (golden ratio or thirds placement)
second image - I dont like arb crops - I prefer crops that are "standard". (eg square, 4x6, 16x9 etc)
I would crop that one 6x4 and place the bird on a diagonal line for a stronger images - cropping off some of the top and include rather more of the bottom than the top
That would be my personal preference.