Journal Mobile Options
Table of Contents
Vol. 53, No. 2, 1999
Issue release date: February 1999
Section title: Original Paper
Brain Behav Evol 1999;53:55–66
(DOI:10.1159/000006582)

Visual Fields in Short-Toed Eagles, Circaetus gallicus (Accipitridae), and the Function of Binocularity in Birds

Martin G.R. · Katzir G.
aSchools of Biological Sciences and of Continuing Studies, The University of Birmingham, Birmingham, UK bDepartment of Biology, University of Haifa, Oranim, Israel

Do you have an account?

Register and profit from personalized services (MyKarger) Login Information

Please create your User ID & Password





Contact Information









I have read the Karger Terms and Conditions and agree.

Register and profit from personalized services (MyKarger) Login Information

Please create your User ID & Password





Contact Information









I have read the Karger Terms and Conditions and agree.

To view the fulltext, please log in

To view the pdf, please log in

Buy

  • FullText & PDF
  • Unlimited re-access via MyKarger (new!)
  • Unrestricted printing, no saving restrictions for personal use
  • Reduced rates with a PPV account
read more

Direct: USD 9.00
Account: USD 8.00

Select

Rent/Cloud

  • Rent for 48h to view
  • Buy Cloud Access for unlimited viewing via different devices
  • Synchronizing in the ReadCube Cloud
  • Printing and saving restrictions apply

Rental: USD 8.50
Cloud: USD 20.00

Select

Subscribe

  • Automatic perpetual access to all articles of the subscribed year(s)
  • Unlimited re-access via Subscriber Login or MyKarger
  • Unrestricted printing, no saving restrictions for personal use
read more

Subcription rates


Select


Article / Publication Details

First-Page Preview
Abstract of Original Paper

Published online: 2/10/1999

Number of Print Pages: 12
Number of Figures: 6
Number of Tables: 1

ISSN: 0006-8977 (Print)
eISSN: 1421-9743 (Online)

For additional information: http://www.karger.com/BBE

Abstract

Visual fields were determined in alert restrained birds using an ophthalmoscopic reflex technique. The region of binocular overlap is relatively small: maximum width of 20° occurs approximately 15° below the horizontal, and the field extends vertically through 80° with the bill tip placed close to the centre. Monocular field width in the horizontal plane is 139°, and the field is asymmetric about the optic axis. The cyclopean field extends through 260°, and the blind area above and behind the head reaches maximum width of 100° close to the horizontal. At the frontal margins of the monocular field the retinal and optical fields do not coincide; the retinal field margin lies approximately 10° inside the optical margin. This gives rise to an apparent binocular field that is twice the width of the functional binocular field. Interspecific comparisons show that the binocular field of Short-toed Eagles is similar in shape and size to those of bird species that differ markedly in phylogeny, ecology, foraging technique, and eye size. This suggests that these relatively narrow binocular fields are a convergent feature of birds whose foraging is guided by visual cues irrespective of whether items are taken directly in the bill or in the feet, as in eagles, and irrespective of the size and shape of the monocular and cyclopean visual fields. It is argued that binocular vision in birds results from the requirement for each monocular field to extend contralaterally to embody a portion of the optical flow field which is radially symmetrical about the direction of travel. This is in contrast to functional explanations of binocularity, such as those concerned with stereopsis, which present it as a means of extracting higher order information through the combination of two monocular images of the same portion of a scene.


  

Author Contacts

Prof. Graham R. Martin
School of Continuing Studies, The University of Birmingham
Edgbaston, Birmingham B 15 2TT (UK)
Tel. +44 121 414 5598, Fax +44 121 414 5619
E-mail G.R.Martin@bham.ac.uk

  

Article Information

Number of Print Pages : 12
Number of Figures : 6, Number of Tables : 1, Number of References : 51

  

Publication Details

Brain, Behavior and Evolution
Founded 1968 and continued 1968–1986 by W. Riss, New York, N.Y.
Official Organ of the J.B. Johnston Club

Vol. 53, No. 2, Year 1999 (Cover Date: February 1999)

Journal Editor: R. Glenn Northcutt, La Jolla, Calif.
ISSN: 0006–8977 (print), 1421–9743 (Online)

For additional information: http://www.karger.com/journals/bbe


Article / Publication Details

First-Page Preview
Abstract of Original Paper

Published online: 2/10/1999

Number of Print Pages: 12
Number of Figures: 6
Number of Tables: 1

ISSN: 0006-8977 (Print)
eISSN: 1421-9743 (Online)

For additional information: http://www.karger.com/BBE


Copyright / Drug Dosage

Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher or, in the case of photocopying, direct payment of a specified fee to the Copyright Clearance Center.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in goverment regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.