The bird's feet are grasping the window tightly.
The bird is trying to get past the window.
Grasping the window tightly does not necessarily mean trying to get past the window.
exists e1 s1 x1 x2 x3.(n_window(x3) & n_foot(x2) & of(x2,x1) & n_bird(x1) & a_tightly(s1) & Manner(e1,s1) & Theme(e1,x3) & Actor(e1,x2) & v_grasp(e1))
exists e1 p1 x1 x2.(n_window(x2) & n_bird(x1) & Topic(e1,p1) & Actor(e1,x1) & v_try(e1) & exists e2.(past(e2,x2) & Actor(e2,x1) & v_get(e2)))