Big brown bats are challenged by acoustically-guided flights through a circular tunnel of hoops.

Mines and caves provide essential roosting places for bats, but often they are obstructed to prevent entry by humans. To allow bats to access their roosts, metal corrugated culvert pipes are sometimes installed. Wildlife surveys indicate, however, that bats may abandon caves having corrugated culvert entrances. Culverts may be confusing to bats due to the complex patterns of echoes returned by the regular, ring-like corrugations. We tested the hypothesis that a circular tunnel composed of successive hoops is difficult for big brown bats (Eptesicus fuscus) to navigate. Experiments challenged bats with flights through a tunnel of round plastic hoops or a corridor flanked left and right by rows of plastic hanging chains. The bats swerved sideways and left the pathway on more flights in the hoop tunnel compared to only rarely in the chain corridor. Even during successful flights through the hoops, bats changed the temporal patterning of their echolocation pulses to compress them into more sonar sound groups. From prior research, this active reaction is an indicator of a perceptually more difficult task. To allow bats access to mines through culverts without affecting their echolocation behavior, smoothing or masking the regular corrugations inside with concrete may be effective.

Introduction to the special issue on neuroethology.

This special issue highlights some recent advances in neuroethology based on research presented at the 13th International Congress of Neuroethology and associated satellite symposia in Brisbane, Australia, on July 15-20, 2018. The discipline of neuroethology combines methods and concepts from ethology with those from neurobiology to develop a comparative analysis of the mechanisms of behavior that takes into account a species' ecology and evolutionary history. In his 1951 book The Study of Instinct, Nobel Prize winner Niko Tinbergen called on ethologists and neurophysiologists to join forces to search for mechanisms of motivated behaviors. He used the term "ethophysiology" to describe this integrative research approach, which he felt was crucial for developing a full understanding of behavior in all its complexities. At that time, "the ethologists were as naive about the neurophysiological significance of their findings as the neurophysiologists were about the behavioral implications of theirs" (Hoyle, 1984, p. 371). To rectify these limitations and to move forward, some of the earliest neuroethological research focused on understanding cellular mechanisms underlying the ethological concepts of releasers (sign stimuli) and fixed action patterns in species such as locusts and toads (Ewert, 1980; Hoyle, 1984). The breadth of neuroethological research soon expanded to include many other species, particularly those with distinct sensory or motor specializations (echolocating bats, electric fish, barn owls; Ewert, Capranica, & Ingle, 1983), as well as to understand neural mechanisms of more "general" behaviors, such as learning, memory, navigation, and communication. Molecular genetic, anatomical, and computational approaches are also part of the neuroethologist's toolbox. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Lateral line-mediated rheotactic behavior in tadpoles of the African clawed frog (Xenopus laevis).

Tadpoles (Xenopus laevis) have a lateral line system whose anatomical structure has been described, but whose functional significance has not been closely examined. These experiments tested the hypothesis that the lateral line system is involved in rheotaxis. Tadpoles in developmental stages 47-56 oriented toward the source of a water current. Orientation was less precise after treatment with cobalt chloride or streptomycin, but was similar to that of untreated animals after exposure to gentamicin. In no current conditions, tadpoles exhibited a characteristic head-down posture by which they held themselves in the water column at an angle around 45 degrees. This body posture became significantly less tilted in the presence of water current. Treatment with cobalt chloride or streptomycin increased the angle of tilt close to that seen in no current conditions, while gentamicin treatment tended to decrease tilt angle. The data are consistent with anatomical and physiological findings that tadpole neuromasts are similar to superficial, but not canal, neuromasts in fishes, and they suggest that the lateral line system is involved in both directional current detection and current-related postural adjustments in Xenopus.