Acoustic emissions of Sorex unguiculatus (Mammalia: Soricidae): Assessing the echo‐based orientation hypothesis

Abstract

Shrew species have been proposed to utilize an echo‐based orientation system to obtain additional acoustic information while surveying their environments. This system has been supported by changes in vocal emission rates when shrews encounter different habitats of varying complexity, although detailed acoustic features in this system have not been reported. In this study, behavioral experiments were conducted using the long‐clawed shrew ( Sorex unguiculatus ) to assess this orientation system. Three experimental conditions were set, two of which contained obstacles. Short‐click, noisy, and different types of tonal calls in the audible‐to‐ultrasonic frequency range were recorded under all experimental conditions. The results indicated that shrews emit calls more frequently when they are facing obstacles or exploring the experimental environment. Shrews emitted clicks and several different types of tonal calls while exploring, and modified the use of different types of calls for varying behavior. Furthermore, shrews modified the dominant frequency and duration of squeak calls for different types of obstacles, that is, plants and acrylic barriers. The vocalizations emitted at short inter‐pulse intervals could not be observed when shrews approached these obstacles. These results are consistent with the echo‐based orientation hypothesis according to which shrews use a simple echo‐orientation system to obtain information from their surrounding environments, although further studies are needed to confirm this hypothesis.

Selective Gene Loss of Visual and Olfactory Guanylyl Cyclase Genes Following the Two Rounds of Vertebrate-Specific Whole-Genome Duplications

“…Moreover, shrews have developed an additional possibility to explore the immediate environment, namely echolocation ( Forsman and Malmquist 1988 ; Siemers et al. 2009 ; Sanchez et al. 2019 ), making them less dependent on vision.…”

Echolocation in Bats, Odontocetes, Birds, and Insectivores

“…Under all three conditions, the shrews emitted a variety of calls, including clicks and several tonal pulse types ranging in frequency between 5 and 45 kHz with durations of 3-40 ms. While several studies have shown that shrews and tenrecs do show context-dependent changes in vocalization rate, there is little direct evidence for echolocation by these animals (Buchler 1976;Tomasi 1979;Forsman and Malmquist 1988;Siemers et al 2009;Sanchez et al 2019).…”

“…Streaked tenrecs (Hemicentetes semispinosus) emitted clicks of low intensity; while those of Nesogale dobsoni were audible to humans at 7 m. Gould et al (1964) found that, contrary to the audible pulses of tenrecs, shrews (Sorex vagrans, S. cinereus, S. palustris, and Blarina brevicauda) searching for the platform emitted ultrasonic pulses with most energy between 30 and 60 kHz. The pulses were about 5 ms in duration with inter-pulse intervals of about 20 ms. Sanchez et al (2019) recorded five Sorex unguiculatus in three different experimental setups, including soft and hard barrier obstacles. Under all three conditions, the shrews emitted a variety of calls, including clicks and several tonal pulse types ranging in frequency between 5 and 45 kHz with durations of 3-40 ms.…”

Morphology and adaptation of the auricle in Soricidae (Lipotyphla)

“…The vocalizations of shrews are still insufficiently known. Loud sounds of high frequency are known from a number of genera and species (Konstantinov & Movčan 1985), such as Crocidura (Hutterer & Vogel 1977, Hutterer & López-Jurado 1990, Simeonovska-Nikolova 2004, Diplomesodon (Movčan & Šibkov 1982, Konstantinov & Movčan 1985, Neomys (Hutterer 1978, Köhler & Wallschläger 1987, Shibkov et al 2001, Köhler 2012, Sorex (Hutterer 1976, 1982, Movčan & Šibkov 1982, Köhler 1998, Sanchez et al 2019, and Suncus (Hutterer et al 1979, Schneiderová 2014. Some species even echolocate (Gould et al 1964, Buchler 1976, Forsman & Malmquist 1988 or use echo orientation (Siemers et al 2009).…”