Hares are difficult to photograph because they are exceedingly shy and have a tendency to bolt fast.  When, as in the first photo, they lie motionless and can be exceedingly difficult to spot so any slightly darker smudge in the field is worth checking with binoculars.  Nevertheless they are great to see in the downland fields.  

Gear.  I Had to resort to a 500mm lend with a 1.4 teleconverter.  With a crop sensor on the D500 that’s 1150mm effective focal length.  They don’t really tolerate anything less and these fields don’t give any cover to hide in in this downland situation.  Probably the reason why they are comfortable here.