There are many types of hazards in addition to fishing line that injure wildlife due to carelessness. Kite string left tangled between trees is just as much a hazard for birds as fishing line. The seagull above flew into this kite string causing it to wrap around the string. A tree trimming truck was called out to cut this bird down, it was then taken to Tri-State Bird Rescue and Research in Newark Delaware where it was successfully rehabilitated and later released.
To retrieve string out of reach in the trees overhead, tie a weight onto some string (to find a weight look on the ground around you, I'm sure you can find something, just be sure it isn't something heavy enough to hurt you or damage anything, it doesn't need to be heavy, a twig will do), toss the weight over the kite string so that you are now holding the weight in one hand and the other end of the string it is tied to in your other hand and it is looped over the kite string above, then pull the kite string till it untangles or snaps. Make sure you are looking down as you do this so if it snaps unexpectedly it doesn't hit you in the eye.
