Dead flat
A light is said "dead flat" when it produces no shadow. For
example this Mallard scene where the light source is almost
perfectly behind the camera. That directionality will leave no
surface unlit so the light will hit every part with equal power.
Harsh
A light is said harsh when it produces hard shadows. This
implies a small light source that can be — to make it even
harsher — far from the subject. Here, the light source is the
Sun — though it is known that our star is much bigger than
our planet, it is nonetheless at height light minutes from this
Mallard and no clouds in the sky to diffuse it. The same ap-
plies at 95% to the Swan shot.
The image of the Goosander is also very harsh but lit from
camera left… and still no clouds to diffuse it; the bird looks
more like 3D because of the directionality of the light.
—
Personally, I would have tamed it tonally so to pull out more
details and texture subtracted by the flat light condition.
Here are two suggestions to attenuate the dead flat light …
Note that your picture was very well recorded and sharp, it
should not be difficult to tweak it!