Budgerigars, Melopsittacus undulatus, were trained to discriminate monochromatic lights
from mixtures of two comparison lights. The addition of small amounts of UV (365 nm) to …

Bird colour vision is mediated by single cones, while double cones and rods mediate
luminance vision in bright and dim light, respectively. In daylight conditions, birds use colour …

Birds have excellent spatial acuity and colour vision compared to other vertebrates while
spatial contrast sensitivity is relatively poor for unknown reasons. Contrast sensitivity …

Birds are assumed to use half of their cones (double cones) to detect fine spatial detail while
their other half (single cones) is used for color vision. However, the spatial resolution of the …

Today, there is good knowledge of the physiological basis of bird colour vision and how
mathematical models can be used to predict visual thresholds. However, we still know only …

The color vision of a population of black-chinned hummingbirds was studied by behavioral
methods. Birds were attracted to feeders equipped with tungsten lamps and interference …

Birds have impressive physiological adaptations for colour vision, including tetrachromacy
and coloured oil droplets, yet it is not clear exactly how well birds can discriminate the …

Abstract Budgerigars (Melopsittacus undulatus) and Bourke's parrots (Neopsephotus
bourkii) are closely related birds with different activity patterns. Budgerigars are strictly …

A fundamental issue in biology is explaining the diversity of coloration found in nature. Birds
provide some of the best-studied examples of the evolution and causes of color variation …

Many vertebrates use colour vision for vital behaviour but their visual performance in dim
light is largely unknown. The light intensity threshold of colour vision is known only for …