Affiliation:
1. Lund Vision Group, Department of Biology, Lund University, 223 62 Lund, Sweden
2. School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Wits 2050, South Africa
Abstract
Nocturnal dung beetles (
Scarabaeus satyrus
) are currently the only animals that have been demonstrated to use the Milky Way for reliable orientation. In this study, we tested the capacity of
S. satyrus
to orient under a range of artificial celestial cues, and compared the properties of these cues with images of the Milky Way simulated for a beetle's visual system. We find that the mechanism that permits accurate stellar orientation under the Milky Way is based on an intensity comparison between different regions of the Milky Way. We determined the beetles' contrast sensitivity for this task in behavioural experiments in the laboratory, and found that the resulting threshold of 13% is sufficient to detect the contrast between the southern and northern arms of the Milky Way under natural conditions. This mechanism should be effective under extremely dim conditions and on nights when the Milky Way forms a near symmetrical band that crosses the zenith. These findings are discussed in the context of studies of stellar orientation in migratory birds and itinerant seals.
This article is part of the themed issue ‘Vision in dim light’.
Funder
Carl Trygger's Foundation for Scientific Research
the Wallenberg Foundation
the Lars-Hiertas Minne Foundation
the Royal Physiographic Society of Lund
the South African National Research Foundation
the Swedish Research Council
Subject
General Agricultural and Biological Sciences,General Biochemistry, Genetics and Molecular Biology
Cited by
34 articles.
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