Clor vision in the tawny owl (Strix aluco).

Martin, Graham R.

doi:10.1037/h0035977

Cited by 30 publications

(11 citation statements)

References 27 publications

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“…Behavioural (Martin & Gordon 1974a,b), electrophysiological (Martin et al 1975) and anatomical (Bowmaker & Martin 1978) studies all furnish evidence that the Tawny Owl visual system functions adequately at high, day-time, light levels. Evidence from analysis of the visual pigments of cone photoreceptors and their associated oil droplets (Bowmaker & Martin 1978) corroborates behavioural investigations of wavelength discrimination (Martin 1974) which suggest that the owl is not capable of such subtle wavelength discriminations as diurnal bird species such as the Pigeon Colurnba livia (Wright 1979). However, Figure 2 shows that maximum spatial resolution in two owl species-(the Tawny Owl and the Great Horned Owl Bubo virginianus)-and in the pigeon is very similar and is attained in all three species at a similar luminance level.…”

Section: Vision At High Light Levelsmentioning

confidence: 63%

Sensory capacities and the nocturnal habit of owls (Strigiformes)

Martin

1986

Ibis

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Behavioural studies show that in the eye of the Tawny Owl Strix aluco both absolute visual sensitivity and maximum spatial resolution at low light levels are close to the theoretical limit dictated principally by the quantal nature of light and the physiological limitations on the structure of vertebrate eyes. However, when the owl's visual sensitivity in relation to naturally occurring ligh levels is analysed, it is concluded that at night there will often be occasions when vision can only be used to control the owl's behaviour with respect to large objects. Owls are capable of detecting and catching prey by hearing alone. However, absolute auditory sensitivity is not superior to that of mammals (including Man), but does appear to have reached the absolute limit on sensitivity in the aerial environment, which is dictated by the minimum ambient sound level. An explanation of the owl's ability to be active at night based only upon high sensory sensitivity is thus untenable. Many features of the natural behaviour of the Tawny Owl (e.g., the high degree of territoriality, prey catching technique, dietary spectrum) may be interpreted as reflections of an additional requirement for the nocturnal habit beyond high sensory sensitivity: detailed knowledge of local topography.

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Section: Vision At High Light Levelsmentioning

confidence: 63%

Sensory capacities and the nocturnal habit of owls (Strigiformes)

Martin

1986

Ibis

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“…With respect to owls, however, we can draw correlations between the large Wulst and small tectofugal pathway and behavior. Owls do have enhanced scotopic vision [Martin, 1977] and global stereopsis [Pettigrew, 1979[Pettigrew, , 1986van der Willigen et al, 1998], but relatively poor visual acuity [Fite, 1973;Martin and Gordon, 1974] and color discrimination [Martin, 1974;Bowmaker and Martin, 1978]. Thus, a relatively small tectofugal pathway may be a reflection of visual abilities and retinal structure in owls, but this does not appear to extend equally to all avian taxa.…”

Section: Discussionmentioning

confidence: 99%

Allometric Scaling of the Tectofugal Pathway in Birds

et al. 2010

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Recent studies have shown that the relative sizes of visual regions in the avian brain are correlated with behavioral differences among species. Despite the fact that the tectofugal pathway is the primary source of visual input to the avian brain, detailed interspecific comparisons of the relative size of nuclei within the pathway, the optic tectum, nucleus rotundus and entopallium, are wanting. Here, we examine the allometric scaling relationships of each of these brain regions relative to the brain as a whole using conventional and phylogenetically based statistics across 113 species. Our results show that the relative size of tectofugal regions of the avian brain varies significantly among avian orders. More specifically, waterfowl (Anseriformes), parrots (Psittaciformes) and owls (Strigiformes) have significantly smaller tectofugal brain regions than other birds. At the opposite end of the spectrum, we found little evidence for the significant enlargement of any tectofugal region among the orders that we sampled. The lack of such hypertrophy likely reflects the heterogeneous organization of the optic tectum, nucleus rotundus and entopallium. We therefore speculate that if neural adaptations do exist in the avian tectofugal pathway that are correlated with behavior, they occur at a more refined level than simple volumetrics.

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“…Owls have three kinds of cone visual pigment (Bowmaker and Martin, 1978) and color vision (Meyknecht, 1941;Ferens, 1947;Martin, 1974). No visual pigments with maximum absorptions in the violet-UV range have yet been found in owls.…”

Section: Optical Adaptations To Uv-visionmentioning

confidence: 99%

Multifocal optical systems and pupil dynamics in birds

Lind

Kelber

Kröger

2008

Journal of Experimental Biology

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SUMMARYIn animal eyes of the camera type longitudinal chromatic aberration causes defocus that is particularly severe in species with short depth of focus. In a variety of vertebrates, multifocal optical systems compensate for longitudinal chromatic aberration by concentric zones of different refractive powers. Since a constricting circular pupil blocks peripheral zones, eyes with multifocal optical systems often have slit pupils that allow light to pass through all zones, irrespective of the state of pupil constriction. Birds have circular pupils and were therefore assumed to have monofocal optical systems. We examined the eyes of 45 species (12 orders) of bird using videorefractometry, and the results are surprising: 29 species (10 orders) have multifocal systems, and only five species (five orders) have monofocal systems. The results from 11 species (four orders) are inconclusive. We propose that pupils ʻswitchingʼ between being fully opened (multifocal principle) to maximally closed (pinhole principle) can make multifocal optical systems useful for animals with circular pupils. Previous results indicate that mice have both multifocal optical systems and switching pupils. Our results suggest that parrots may use a similar mechanism. By contrast, owl pupils responded weakly to changes in illumination and stayed remarkably wide even in full daylight. Moreover, the parrots opened their pupils at higher light levels than owls, which correlates with the differences in sensitivity between diurnal and nocturnal eyes.

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Clor vision in the tawny owl (Strix aluco).

Cited by 30 publications

References 27 publications

Sensory capacities and the nocturnal habit of owls (Strigiformes)

Sensory capacities and the nocturnal habit of owls (Strigiformes)

Allometric Scaling of the Tectofugal Pathway in Birds

Multifocal optical systems and pupil dynamics in birds

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