Harrier (bird) Harrier (bird) A harrier is any of the several species of diurnal hawks sometimes placed in the Circinae sub-family of the Accipitridae family of birds of prey. Harriers characteristically hunt by flying low over open ground, feeding on small mammals, reptiles, or birds. The young of the species are sometimes referred to as ring-tail harriers. They are distinctive with long wings, a long narrow tail, the slow and low flight over grasslands and skull peculiarities. The harriers are thought to have diversified with the expansion of grasslands and the emergence of C4 grasses about 6 to 8 million years ago
Psittacine beak and feather disease and beak make tissues vulnerable to secondary infection. Because the virus also affects the thymus and Bursa of Fabricius, slowing lymphocyte production, immunosuppression occurs and the bird becomes more vulnerable to secondary infections. Beak fractures and necrosis of the hard palate can prevent the bird from eating. The ornithologist Edwin Ashby observed a flock of completely featherless red-rumped parrots ("Psephotus haematonotus") in the Adelaide Hills, South Australia, in 1888. The species then disappeared from the area for several years. The condition is more prevalent in widely occurring Australian species such as the sulphur-crested cockatoo, little corella and galah. The first