redheads begin forming nests. They are built with thick and strong plant material in emergent vegetation, such as hard stem bulrush, cattails and sedges, over or near standing water. Redheads do not defend their territory or home range and are actually very social while in their breeding ground. This is thought to occur because some younger, inexperienced redhead females parasitize other pochards. Some redheads lay their eggs in other pochards’ nests, including the canvasback, ring-necked duck and greater and lesser scaups and this social parasitism by redheads reduces the hatching success of other pochards’ eggs, especially those of the canvasback. In contrast, because of the parasitic relationship between the redhead and other pochards, redhead hybrids with the ring-necked duck, canvasback and the greater and lesser scaups have been found. Canvasback x redhead hybrids can be fertile. Brood sizes range from 5-7 young, with the mother abandoning the chicks at 8 weeks old, before they are capable of flying. They remain flightless for another 2–4 weeks. Vocalizations There is little information on redhead vocalizations outside of breeding calls. Males will emit calls when courting the female. When the neck is fully extended in the neck-stretching display, males will emit a distinct wheee-oww, which sounds catlike. Males may also produce a soft coughing call, although this call is less frequent. Females will emit a soft errrr note when she is inciting a male. Feeding habits All pochards have similar diets that include both plant and animal materials. Redheads undergo a niche switch when breeding and when wintering. During the breeding season, redheads will eat as much animal matter as possible, including gastropods, mollusks and insect larvae. They will eat the occasional grass and other emergent vegetation. However, once they fly south, redheads will change their diet to include mostly plant material, including pondweeds, wild rice, wild celery, wigeon grass, bulrushes, muskgrass and shoal grass. Gastropods known as food of Aythya americana include: Acteocina canaliculata, Acteon punctostriatus, Anachis avara, Anachis obesa, Caecum nitidum, Calliostoma sp., Cerithidea pliculosa, Cerithium lutosum, Crepidula convexa, Diastoma varium, Melanella sp., Mitrella lunata, Nassarius acutus, Nassarius vibex, Natica sp., Neritina virginea, Odostomia trifida, Olivella minuta, Olivella watermani, Polinices sp., Pyramidellidae, Pyrgocythara plicosa, Rissoina catesbyana, Sayella livida, Turbonilla sp., Turbonilla interrupta and Vitrinella sp. References External links Redhead Species Account - Cornell Lab of Ornithology Redhead - Aythya americana - USGS Patuxent Bird Identification InfoCenter Sound, Sound metadata Macaulay Library,