Autismus und Sehen « Le Syndrome de Schorderet- Munier ... - ophta

ORIGINALIA
Evidence for Binocular Alternation in Individually
Flying Homing Pigeons
Phillip Hendrickson, 1,2 Alexander Lage, 1
Robert Marionneau 1,3
1 Division of Behavioral Neuroanatomy
University of Zurich Irchel
2 Private Docent for Experimental
Ophthalmology & Physiological Optics,
Basel University Medical Faculty
3 l’Université Paul Sabatier Toulouse III
Fig. 3
Geographical
features of the area.
«One occupational hazard
of researchers is that they tend
to seek answers in places that
confirm their preconceptions.»
Steven Merritt Miner
Background
How homing pigeons find their way
home has been of interest at least since
Aristotle. Now, thanks to new technology,
we can pursue this question 1,2 by
detailed study of what we term their
«Macrobehavior».
The original purpose of the present study
was to evaluate potential navigational
cues and levels of uncertainty (EEG)
during homing-flight over sea, then over
land – (behavioral findings reported
elsewhere 3 ). Quite unexpectedly, close
inspection of GPS tracks revealed evidence
for a novel ophthalmological feature
of pigeon flight.
Materials & Methods
Flights were tracked by on-board GPSloggers,
4 while EEG-loggers 5 (Figure 1)
recorded simultaneous variations in
brain-wave activity.
Fig. 1 Mounting sites of GPS and EEG loggers
prior to release.
Nineteen homing-pigeon flights from
25 June to 8 July 2006 were studied. Each
pre-trained pigeon was released individually
over the sea (• Figure 2) at 10 minute
intervals. There was no land in sight, being
at least 20 km away (Figure 3). As the
home loft was located 10km inland from
the coast and pigeons showed no individual
landfall preference on different days,
each homing flight-path from landfall to
the loft was unique.
To fully appreciate the challenge managed
by such pigeons, the reader should
consider the fact that homing pigeons can
neither swim nor float. (Reassuringly,
there were no losses in this experimental
series – all pigeons returned safely home.
Such pigeons successfully participate in
the Sardinia-to-Rome Race, a considerably
greater distance over water.)
All pigeon releases were from the same
GPS-maintained release site. Weather
was always calm and clear, with excellent
visibility.
Local geography
The home loft lies amidst some striking
geographical features
(Figure 3): to
the north, an extinct
545m-high volcano, to
the east, Rome, and, to
the south, Aeroporto
Fig. 2 Individual
releases out over
the open sea.
Internationale Leonardo
da Vinci. The A12
Autostrada and several
roads criss-cross the
region, as do rivers and
irrigation canals.
Result (Original Behavioral
Experiment)
All pigeons showed obvious uncertainty
(elevated EEG-activity) at the releasesite,
then settled down into direct flight
towards the coast, each in its own way.
Fig. 4 Confusion in all 19 individual flights
superimposed at release site.
One obvious macrobehavioral result was
that flight over the sea clearly differed
from that over land.
Figure 5: All 19 individual flights superimposed
over sea and land.
ophta • 4|2008 267