![]() ) that are influenced by food availability and micro-habitat structure. These foraging strategies require the use of different behaviors (gleaning, sallying, hovering, etc. Specific foraging strategies allow individuals to improve the chances of prey detection and capture under certain ecological conditions. Upon detection, individuals visually track the prey target by flying over it and changing their head movement patterns so that the visual streak is aligned with the prey item. For instance, the retinas of some sea birds have long visual streaks, which are areas with high retinal ganglion cell density that provide high visual resolution along the horizon, to enhance food detection from the distance. Furthermore, in the case of visually oriented organisms like birds, sensory specializations may help gather visual information necessary to detect prey against the background and track them visually until capture. ![]() The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Ĭompeting interests: The authors have declared that no competing interests exist.įoraging specializations are the result of morphological and metabolic capabilities of foragers, food availability, habitat structure, etc. This is an open-access article distributed under the terms of the Creative Commons Public Domain declaration which stipulates that, once placed in the public domain, this work may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose.įunding: This study was funded by National Science Foundation DBI-0641550 ( CTO received funding from the 2008 California State University, Long Beach, Provost's Graduate Student Summer Research Award. Received: AugAccepted: ApPublished: September 22, 2010 PLoS ONE 5(9):Įditor: Eric Warrant, Lund University, Sweden American Kestrels have intermediate-sized binocular and lateral areas that may be used in prey detection at different distances through stereopsis and motion parallax whereas the low degree eye movement (∼1°) may help stabilize the image when hovering above prey before an attack.Ĭitation: O'Rourke CT, Hall MI, Pitlik T, Fernández-Juricic E (2010) Hawk Eyes I: Diurnal Raptors Differ in Visual Fields and Degree of Eye Movement. ![]() Additionally, we found that Cooper's Hawks can visually inspect the items held in the tip of the bill, which may facilitate food handling. ![]() Cooper's Hawks' have relatively wide binocular fields (∼36°), small blind areas (∼60°), and high degree of eye movement (∼8°), which may increase visual coverage and enhance prey detection in closed habitats. Red-tailed Hawks have relatively small binocular areas (∼33°) and wide blind areas (∼82°), but intermediate degree of eye movement (∼5°), which underscores the importance of lateral vision rather than binocular vision to scan for distant prey in open areas. We found inter-specific variation in visual field configuration and degree of eye movement, but not in orbit orientation. We used an ophthalmoscopic reflex technique and an integrated 3D digitizer system. ![]()
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