How animals follow the stars

Abstract

Throughout history, the stars have provided humans with ever more information about our world, enabling increasingly accurate systems of navigation in addition to fuelling some of the greatest scientific controversies. What information animals have evolved to extract from a starry sky and how they do so, is a topic of study that combines the practical and theoretical challenges faced by both astronomers and field biologists. While a number of animal species have been demonstrated to use the stars as a source of directional information, the strategies that these animals use to convert this complex and variable pattern of dim-light points into a reliable 'stellar orientation' cue have been more difficult to ascertain. In this review, we assess the stars as a visual stimulus that conveys directional information, and compare the bodies of evidence available for the different stellar orientation strategies proposed to date. In this context, we also introduce new technologies that may aid in the study of stellar orientation, and suggest how field experiments may be used to characterize the mechanisms underlying stellar orientation.

Orienting to Polarized Light at Night—Matching Lunar Skylight to Performance in a Nocturnal Beetle

“…Polarization was measured at the same position using a UV-transmissive calcite linear polarizer (Glan-Thompson; GTH5M-A: Thorlabs GmbH, Germany) coupled to a spectrometer (FLAME-S-UV-VIS) via a light guide (P1000-2-UV-VIS; Ocean Optics). Spectra were recorded for four polarizer orientations in order to estimate Stokes parameters S 1 and S 2 (Foster et al ., 2018) and each measurement repeated ten times and averaged (Supplement S1.2) to minimise the effects of sensor noise (Tibbs et al ., 2018). Prior to Stokes parameter estimation, median spectrometer response for each polarizer orientation was weighted by the absorption spectrum of an insect photopigment with a maximum absorbance at 365 nm, calculated using the Stavenga template (Stavenga, 2010), and integrated across the region of the spectrum from 380–450 nm.…”

The impact of artificial light at night on nocturnal insects: A review and synthesis

“…Sand hoppers use the moon to orient along beaches and are known to orient to artificial fiber optic moons in the laboratory (Ugolini, Boddi, Mercatelli, & Castellini, 2005). Other animals can navigate by stars alone (reviewed by Foster, Smolka, Nilsson, & Dacke, 2018). On moonless nights, Noctua pronuba yellow underwing moths orient with respect to the north star (Sotthibandhu & Baker, 1979), and Scarabaeus satyrus dung beetles use the Milky Way as a cue to guide themselves away from dung piles in a maximally efficient straight line (Dacke, Baird, Byrne, Scholtz, & Warrant, 2013).…”

The Right Light: Tiger Salamander Capture Rates and Spectral Sensitivity

“…Animal behaviors are often dependent on detection of cues, such as visual cues (Ghim and Hodos 2006, Borst and Euler 2011). Visual cues are used in fitness‐related behaviors, including foraging, escape from predators (Davies et al 2012), mating (reviewed in Lythgoe 1979), and navigation (Foster et al 2018, Pritchard and Healy 2018). Animal detection of visual cues involves photoreceptors (rods and cones) in the eye (Osorio and Vorobyev 2005, Kawamura and Tachibanaki 2008, Davies et al 2012).…”

“…Behavioral decisions to move relative to light sources (phototaxis) are common and biologically important in animals. Terrestrial animals can use light from stellar cues to orient during navigation (Poot et al 2008, Foster et al 2018). Some aquatic animals use phototaxis to move toward light in water (e.g., McConnell et al 2010, Wolf et al 2017), a behavior that potentially evolved to utilize moonlight or starlight for orientation (Thums et al 2016, Cruz et al 2018).…”

“…Behavioral decisions to move relative to light sources (phototaxis) are common and biologically important in animals. Terrestrial animals can use light from stellar cues to orient during navigation (Poot et al 2008, Foster et al 2018).…”