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1 February 2009 Effects of Physical and Visual Access to Prey on Patch Selection and Food Search Effort in a Sit-and-Wait Predator, the Black Phoebe
Megan D. Gall, Esteban Fernández-Juricic
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Abstract

For sit-and-wait predators, a key factor influencing foraging decisions is the ability to detect and track prey, which is expected to vary with the physical and light properties of the environment. We assessed how changes in visual and physical prey availability altered perch selection and visual search activity (head-movement rate and bout length) in the Black Phoebe (Sayornis nigricans), a sit-and-wait flycatcher. We used an observational approach by studying individuals in foraging areas that varied in the ecological factors of interest across an urbanized landscape. Black Phoebes selected perches with high levels of tree and grass cover and low light intensity, which could increase access to prey and reduce predation risk. Visual searching for prey decreased as grass cover increased and tree cover decreased, likely because of less physical and visual obstruction. Visual searching increased with light intensity, probably as a result of the effects of glare, but chromatic contrast did not exert a significant influence. We suggest that for Black Phoebes in urbanized areas physical access to prey may be mediated through the availability of an open understory and visual access through illuminance rather than discrimination of prey against the background.

© 2009 by The Cooper Ornithological Society. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press's Rights and Permissions website, http://www.ucpressjournals.com/reprintlnfo.asp.
Megan D. Gall and Esteban Fernández-Juricic "Effects of Physical and Visual Access to Prey on Patch Selection and Food Search Effort in a Sit-and-Wait Predator, the Black Phoebe," The Condor 111(1), 150-158, (1 February 2009). https://doi.org/10.1525/cond.2009.080016
Received: 29 August 2008; Accepted: 1 December 2008; Published: 1 February 2009
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