Seagulls seen scavenging during the day in picnic areas, parking lots and dump sites typically retire to a large body of freshwater to roost on or near at night. Seagulls prefer to sleep on a calm body of water, but will sleep in any wide-open spot.
Gulls often choose to sleep in parking lots and playing fields as a defense, as open spaces enable the early detection of a potential threat coming from a distance. Herring gulls drink freshwater but can also consume saltwater because of a special gland located above their eyes. The salt is released as a runny liquid.