Juvenile budgerigars (Melopsittacus undulatus) observed thin film transistor video playback of a virtual conspecific demonstrator using its beak to remove a stopper from a food box, either by pulling the object upward or by pushing it downward. Simultaneously (Experiment 1) or subsequently (Experiment 2), the observers were offered a similar stopper box and rewarded with access to food for each...

The hypothesis was tested that selection on the basis of family means for increased survival and hen-housed egg production, when sisters with intact beaks were kept together in multiple-bird cage, would cause adaptive changes in behavior. Specifically, it was posited that beak-inflicted injuries causing cannibalistic mortality and feather loss and damage would be reduced. Body weight effects we...

We examined whooper swans naturally infected with avian influenza virus (H5N1) to evaluate the possible zoonotic risk of swan feathers. Viruses were isolated from feather calami. Immunohistochemical testing revealed that virus antigens were present in the feather epidermis and feather follicle wall epidermis of some feathers. RT-PCR and genetic sequencing using paraffin sections of swan feather...

Marek’s disease is a lymphoproliferative disease principally of the domestic chicken known to be caused by herpesvirus i-e oncogenic (serotype 1) strains of Marek’s disease herpesvirus (MDV) that replicates in the lymphoid and epithelial tissues. Pathogenesis is complex, involving cytolytic and latent infection of lymphoid cells and oncogenic transformation of CD4+ T cells in susceptible chicke...