In this image, the female Osprey is on guard and holding the fort ('er nest) down. A nearby Osprey competitor flies in and hovers above her nest to challenge her in hopes of stealing her nest. She calls out to let her mate know of trouble at the nest. This is representative of early season behavior when Ospreys are vying for a place to nest. This pair is well established at this nest. Osprey pairs mate for life and return to the same nest each year to continue building it.