Whisker touch guides canopy exploration in a nocturnal, arboreal rodent, the Hazel dormouse ( Muscardinus avellanarius )
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ORIGINAL PAPER
Whisker touch guides canopy exploration in a nocturnal, arboreal rodent, the Hazel dormouse (Muscardinus avellanarius) Kendra Arkley1 · Guuske P. Tiktak2 · Vicki Breakell3 · Tony J. Prescott1 · Robyn A. Grant2
Received: 14 July 2016 / Revised: 4 January 2017 / Accepted: 6 January 2017 © Springer-Verlag Berlin Heidelberg 2017
Abstract Dormouse numbers are declining in the UK due to habitat loss and fragmentation. We know that dormice are nocturnal, arboreal, and avoid crossing open spaces between habitats, yet how they navigate around their canopy is unknown. As other rodents use whisker touch sensing to navigate and explore their environment, this study investigates whether Hazel dormice (Muscardinus avellanarius) employ their whiskers to cross between habitats. We analysed high-speed video footage of dormice exploring freely in flat and climbing arenas in near darkness and using infrared light illumination. We confirm that, like rats and mice, dormice move their whiskers back and forth continuously (~10 Hz) in a motion called whisking and recruit them to explore small gaps (1 m in this study) involve crossing on the floor— with only 6% of approaches to smaller (1–3 m) gaps being completed, and 6-m gaps never being crossed. In a translocation study, Mortelliti et al. (2013) found large individual differences in gap-crossing, with some Hazel dormice being capable of travelling over open fields of up to 106 m in as little as 1 day; however, they often stayed for up to 18 days before crossing to their original (or a new) habitat patch. In this sample, 30% of translocated dormice opted to stay in their habitat patch for the entire study duration. Notwithstanding these differences, it is likely that hedgerow gaps significantly reduce movement between habitat patches, and understanding how dormice cross between habitat gaps and navigate their canopy is an important first step in understanding how to manage their populations. Little is known about the biology, sensory ecology, or behaviour of the Hazel dormouse due to its status as a protected species in the UK, its shy, arboreal, and nocturnal nature (Berg and Berg 1999), and the large period of the year they spend in hibernation (Bright et al. 2006). Nevertheless, it is argued that the most highly developed sense in dormice is that of touch (Grzimek et al. 2003). When crossing between platforms in the dark, three blind dormouse species (species not specified) only jumped when they were close enough to touch with their whiskers (Airapet’yants 1974, as cited in Thomas et al. 2004), suggesting that whiskers are essential for gap-crossing. However, it is probable that (like other rodents) hearing, vision and smell also play a role in guiding orientation around their arboreal environments. Dormouse hearing is sensitive up to 60 kHz—a similar range to rats and harvest mice (Thomas et al. 2004)—and their eyes are relatively large to compensate for low light levels (Grzimek et al. 2003), and so, nontactile cues (e.g. echolocation, vision) may be recruited t
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