Russian olive habitat along an arid river supports fewer bird species, functional groups and a different species composition relative to mixed vegetation habitats

© 2019 Elsevier Ltd The establishment and naturalization of non-native Russian olive (Elaeagnus angustifolia)in southwestern US riparian habitats is hypothesized to have negative implications for native flora and fauna. Despite the potential for Russian olive establishment in new riparian habitats, much of its ecology remains unclear. Arid river systems are important stopover sites and breeding grounds for birds, including some endangered species, and understanding how birds use Russian olive habitats has important implications for effective non-native species management. We compared native bird use of sites that varied in the amount of Russian olive and mixed native/non-native vegetation along the San Juan River, UT, USA. From presence/absence surveys conducted in 2016 during the breeding season, we found 1)fewer bird species and functional groups used Russian olive habitats and 2)the composition of species within Russian olive habitats was different from the composition of species in mixed native/non-native habitats. Our results suggest Russian olive may support different bird compositions during the breeding season and as Russian olive continues to naturalize, bird communities may change. Finally, we highlight the paucity of research surrounding Russian olive ecology and stress the need for rigorous studies to improve our understanding of Russian olive ecology

The two hemispheres of the avian brain: their differing roles in perceptual processing and the expression of behavior

The hemispheres of the avian brain are specialized to carry out different functions. Since each eye sends its input mainly to the contralateral hemisphere, birds respond differently to stimuli seen with the left eye than they do to stimuli seen with the right eye. The right hemisphere attends to novel stimuli, which easily distract it from ongoing functions. It assumes control in emergency or stressful conditions. The left hemisphere attends to learnt categories and controls behavior in routine, non-stressful situations. This division of function extends to processing of auditory, olfactory and even magnetic stimuli. Evidence for this comes from a number of avian species, and has been shown in both laboratory and field tests. Knowledge of these specializations is relevant to understanding the behavior of birds in the wild since birds respond in different ways to stimuli on their left and right sides (e.g. preferential response to predators and conspecific on the left side and to prey on the right side) and they choose to view different stimuli with the left or right eye. Individual differences in the strength of visual lateralization are determined by exposure of the embryo to light, versus incubation in the dark, and by the levels of steroid hormones in ovo. The importance of these influences on lateralization is discussed in terms of behavior in the natural habitat. The potential importance of hemispheric dominance in the welfare of birds is also considered