Well known among ornithologists, the Academy of Natural Sciences' VIREO (Visual Resource for Ornithology) is "the world's most comprehensive collection of bird photographs. It houses over 96,000 35mm slides and 5,000 black-and-white prints of over 6,100 bird species," including every species of bird in North America. The VIREO homepage contains four sections: Slides for Publication & Reference (for fee); Slides for Non-profit Educational Lectures (lowest cost); Contributing Images; and Photo Gallery. Interested viewers may browse sample images or search the 6,153 species of birds to locate images of a species of interest.