The abstract of the scientific paper that the BBC news item cites is shown
below:
Courtship dives of Anna's hummingbird offer insights into flight performance
limits
Christopher James Clark*
+Author Affiliations
Museum of Vertebrate Zoology, 3101 VLSB, UC Berkeley, Berkeley, CA 94720, USA
Behavioural displays are a common feature of animal courtship. Just as female
preferences can generate exaggerated male ornaments, female preferences for
dynamic behaviours may cause males to perform courtship displays near intrinsic
performance limits. I provide an example of an extreme display, the courtship
dive of Anna's hummingbird (Calypte anna). Diving male Anna's hummingbirds were
filmed with a combination of high-speed and conventional video cameras. After
powering the initial stage of the dive by flapping, males folded their wings by
their sides, at which point they reached an average maximum velocity of 385
body lengths s−1 (27.3 m s−1). This is the highest known length-specific
velocity attained by any vertebrate. This velocity suggests their body drag
coefficient is less than 0.3. They then spread their wings to pull up, and
experienced centripetal accelerations nearly nine times greater than
gravitational acceleration. This acceleration is the highest reported for any
vertebrate undergoing a voluntary aerial manoeuvre, except jet fighter pilots.
Stereotyped courtship behaviours offer several advantages for the study of
extreme locomotor performance, and can be assessed in a natural context.
Regards,
Stephen Ambrose
Ryde, NSW
-----Original Message-----
From:
On Behalf Of Alan McBride
Sent: Friday, 19 June 2009 4:13 PM
To: Birding Aus
Subject: Are Peregrines too slow?
Interesting page on Hummingbirds here:-)
http://tinyurl.com/lyhrdj
Alan
***********************************************************************************
Alan McBride, MBO.
Photojournalist | Traveller | Writer | Birding Guide +
Member: International Travel Writers & Photographers Alliance
American Writers & Artists Inc.
Travelwriters.com
http://web.me.com/amcbride1
http://www.worldreviewer.com/member/alanmcbride/
http://www.linkedin.com/in/alanmcbride
http://www.twitter.com/alanmcbride
http://www.mygalleryplace.com/Alan1
Good planets are hard to find; until we do, please, be green and read
from the screen
Tel: + 61 419 414 860
Fax: + 61 2 9973 2306
Skype: mcbird101
P O Box 190 | Newport Beach | NSW 2106 | Australia
This e-mail and any files transmitted with it, are confidential and
intended solely for the use of the individual or entity to which they
are addressed. If you have received this e-mail in error please notify
the sender. This e-mail is also subject to copyright. No part of it
should be reproduced, adapted or transmitted without the prior written
consent of the copyright owner.
***********************************************************************************
===============================
www.birding-aus.org
birding-aus.blogspot.com
To unsubscribe from this mailing list,
send the message:
unsubscribe
(in the body of the message, with no Subject line)
to:
===============================
==============================www.birding-aus.org
birding-aus.blogspot.com
To unsubscribe from this mailing list,
send the message:
unsubscribe
(in the body of the message, with no Subject line)
to:
=============================
|
