Eye white may indicate emotional state on a frustration-contentedness axis in dairy cows
Research on welfare indicators has focused primarily on indicators of poor welfare, but there is also a need for indicators that can cover the range from good to poor welfare. The aim of this experiment was to compare behaviour elements in dairy cows shown in response to a frustrating situation as well as elements shown […]
The scaling of eye size with body mass in birds
We developed a simple method that uses skulls to estimate the diameter, and hence the mass, of birds’ eyes. Allometric analysis demonstrated that, within five orders (parrots, pigeons, petrels, raptors and owls) and across 104 families of flying birds, eye mass is proportional to (body mass)0.68 over a range of body masses (6 g to […]
Initial findings on visual acuity thresholds in an African elephant (Loxodonta africana)
Abstract 10.1002/zoo.20259.abs There are only a few published examinations of elephant visual acuity. All involved Asian elephants (Elephas maximus) and found visual acuity to be between 8′ and 11′ of arc for a stimulus near the tip of the trunk, equivalent to a 0.50 cm gap, at a distance of about 2 m from the eyes. We […]
Lens-anomalies and other ophthalmic findings in a group of closely-related angola lions (Panthera leo bleyenberghi)
Abstract 10.1002/zoo.20094.abs After the diagnosis of bilateral, immature, nuclear, and posterior cortical cataracts in one Angola lioness, and because of the possible implications of the cataracts for a breeding program, complete ophthalmic examinations on a group of related adult Angola lions and their offspring were carried out. Five adult lions, ranging in age from 1.5–5.5 […]
How birds use their eyes: Opposite left-right specialization for the lateral and frontal visual hemifield in the domestic chick
Recent evidence has demonstrated that, in animals with laterally placed eyes, functional cerebral asymmetry is revealed by preferential use of either the left or right eye in a range of behaviors (birds: [[1, 2, 3]]; fish: [[4, 5]]; reptiles: [[6, 7]]). These findings pose a theoretical problem. It seems that there would be disadvantages in […]