Directional hearing and acoustic object recognition in echolocating
Nectar-feeding Bats: competition for the limited transfer capacity of
echoes during flower approach

Application Deadline: to filled as soon as possible
Funding: Three years postgraduate stipend by Deutsche
Forschungsgemeinschaft DFG £16000 p.a.
Supervisor: Dr Marc Holderied

Echolocating bats can catch flying prey in total darkness. While the
sensory basis of catching insects in open air is well understood, to
date we have little knowledge how flower-visiting bats resolve a task
considerably more challenging. First, they have to detect motionless
flowers amongst echoes caused by surrounding vegetation. This task is
somewhat eased because in a fascinating plant-pollinator Co-evolution
such flowers have increased their acoustic conspicuousness to
echolocating bats. Secondly, the bats’ swift approach has to hit the
entrance to the flower’s nectarium with millimetre precision. This
remarkable precision is based on directional information contained in
the interference pattern the bat’s outer ears imprint on the echo. This

interference pattern can however mask object-specific information
encoded in the echo. The ’Where’ and ‘What’ of a flower are thus
competing for information transfer capacity of echoes. Using
behavioural
experiments with nectar-feeding bats and echo measurements you will
investigate how the Co-evolution of glossophagine echolocation and
floral echoes might have resolved this conflict.

You will work with captive nectar-feeding bats using a
computer-controlled setup with 64 loudspeakers that replay phantom
echoes to a trained bat. By choosing one of two reward nectar sources
the bat indicates its perception. You will quantify directional
hearing;
manipulate echoes to study if and how directional and object specific
information compete; and finally study true flower echoes to reveal
potential strategies to transmit both types of information
concurrently.

The successful candidate will normally hold a 1st or high 2.1 degree in

biological sciences or a comparable international degree. He/She will
be
highly motivated, independent in training bats and trustworthy in
looking after the trained animals. He/She will contribute to building
the experimental setup and develop respective software.

Details about the excellent teaching and research at the School of
Biological Sciences and the vibrant City of Bristol can be found here:
http://www.bio.bris.ac.uk/admiss/pgrad/intro.htm

Further Information:
D. v. Helversen, M. W. Holderied, and O. v. Helversen Echoes of
bat-pollinated bell-shaped flowers: conspicuous for nectar-feeding
bats?
J. Exp. Biol., 2003; 206(6): 1025-1034.

M. W. Holderied, and O. v. Helversen `Binaural echo disparity' as a
potential indicator of object orientation and cue for object
recognition
in echolocating nectar-feeding bats J. Exp. Biol., 2006; 209(17):
3457-3468.

R. Simon, M. W. Holderied, and O. von Helversen Size discrimination of
hollow hemispheres by echolocation in a nectar feeding bat J. Exp.
Biol., 2006; 209(18): 3599-3609.

Application: Interested prospective candidates should complete and
forward an application form (available from here
http://www.bristol.ac.uk/prospectus/postgraduate/2006/intro/8) and send

a copy of their CV (including the names of two referees) to Dr Marc
Holderied, School of Biological Sciences, University of Bristol,
Woodland Road, Bristol, BS8 1UG, Phone: 0117 331 8049, E-mail:
marc.holderied@bristol.ac.uk from whom further enquiries may also be
made.