Hi,

They look like distant lod trees, that have not changed to 'normal' trees.
The whole field between Whiterun and dragonbridge is covered with these 'monsters'...
This suddenly appeared, a few days ago...

http://s20.postimg.org/s95axysxp/Screen_Shot32.png

http://s20.postimg.org/5xla9sxz1/Screen_Shot36.png

http://s20.postimg.org/z19i61m2l/Screen_Shot37.png

http://s20.postimg.org/c12utpo8t/Screen_Shot38.png

http://s20.postimg.org/ejt584zct/Screen_Shot39.png (Dragonbridge)

Sorry, the other pics were taken in the night, the character spend the last part of it in Rorikstead's Frostfruit inn.

This is when the sun went down... you can see everything else is normal.
http://s20.postimg.org/ihgexjm65/Screen_Shot34.png