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Polarized light vision in zebra finches (Taeniopygia guttata)

Danielsson, Joel (2015) BIOM01 20151
Degree Projects in Biology
Popular Abstract
Do birds have a sixth sense?

Many animals have been shown to possess the ability to sense polarized light, but this ability in birds has been a topic for debate. In this study captive male zebra finches were used in order to determine if they could distinguish different angles of polarized light.

Polarized light is the direction of the angle of the light waves, thus two separate light sources can be polarized in different directions, for example; vertically and horizontally. As unpolarized light passes through the atmosphere it becomes polarized, this is known as skylight polarization. Previous studies have shown that birds are sensitive to polarized light, but we do not yet know how or if they can use this type of information. As... (More)
Do birds have a sixth sense?

Many animals have been shown to possess the ability to sense polarized light, but this ability in birds has been a topic for debate. In this study captive male zebra finches were used in order to determine if they could distinguish different angles of polarized light.

Polarized light is the direction of the angle of the light waves, thus two separate light sources can be polarized in different directions, for example; vertically and horizontally. As unpolarized light passes through the atmosphere it becomes polarized, this is known as skylight polarization. Previous studies have shown that birds are sensitive to polarized light, but we do not yet know how or if they can use this type of information. As many other animals rely on the presence of ultra-violet light to see polarized light, it is thought that the same might be true for birds.
It has been suggested that birds may use the polarized light as a tool to calibrate their magnetic orientation. But as of yet, no studies have been able to show that birds can discriminate between two different angles of polarized light in a laboratory setting. As many other animals rely on the presence of ultra-violet light to see polarized light, it is thought that the same might be true for birds. The aim of this study was to use behavioural training methods to find out if birds can detect polarized light and to see if ultra-violet light is involved in the process.
An LCD screen was used to display black and white contrasts as well as polarized light contrasts. The birds were made to choose a side, and were rewarded when they chose the black side or the horizontally polarized side. The illustration shows what the screen looks like when the birds were trained to a black and white contrasting stimulus.

Training the zebra finches reveals…
The results showed that birds learnt to discriminate black and white contrasting stimuli quickly. However, the birds were shown to be unable to discriminate the contrasts when only the polarized stimuli were shown. The conclusion is that UV light has no effect on the ability of zebra finches to learn to discriminate angles of polarized light. Further research is necessary to fully understand the role polarization sensitivity plays in avian behaviour, and the potential importance of UV light.


Advisors: Rachel Muheim & Olle Lind
Master´s Degree Project 30 credits in Biology 2015
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Danielsson, Joel
supervisor
organization
course
BIOM01 20151
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
7756539
date added to LUP
2015-08-07 13:39:10
date last changed
2015-08-07 13:39:10
@misc{7756539,
  author       = {Danielsson, Joel},
  language     = {eng},
  note         = {Student Paper},
  title        = {Polarized light vision in zebra finches (Taeniopygia guttata)},
  year         = {2015},
}