8/3/2023 0 Comments Signalscope pro![]() ![]() Its numbers have been declining in recent years for unknown reasons ( Austin et al., 1998). ![]() The lesser scaup is one of the most abundant and widespread species of diving duck in North America, and prefers freshwater, but will winter on brackish bodies of water. Both males and females vocalize throughout the year to signal to mates and offspring ( Johnsgard, 1965). They are capable of diving to depths of at least 18 m, for up to 25 s at a time, to forage primarily on mollusks, crustaceans, and aquatic insects ( Austin et al., 1998). Previous studies on lesser scaup and other diving ducks have focused mainly on foraging and reproductive ecology (e.g., Afton and Ankney, 1991 Cutting et al., 2011 Brady et al., 2013 Warren et al., 2014). ![]() By comparison, psychoacoustic methods can often take months for training and testing. The major advantages of the ABR are that an entire audiogram can often be constructed after one session of less than 60 min, and no animal training is involved (it can be used on temporarily caught wild animals). These elevated thresholds in the ABR can be attributed to differences in stimulus characteristics and measurement techniques between behavioral and electrophysiological methods, and as a result of the lack of synchrony in the neural discharges at lower frequencies ( Silman and Silverman, 1991 Hall, 1992 Szymanski et al., 1999 Brittan-Powell et al., 2002 Schlundt et al., 2007 Ladich and Fay, 2013 Sisneros et al., 2016). The ABR provides a rapid estimate of the shape of the audiogram and range of hearing sensitivity, but thresholds are often 10−15 dB higher than when using behavioral methods ( Borg, 1982 Borg and Engström, 1983 Gorga et al., 1988 Brittan-Powell et al., 2002 Wolski et al., 2003 Yuen et al., 2005 Houser and Finneran, 2006 Henry and Lucas, 2008). The recorded series of waves represents synchronized neural discharge during the progressive propagation of auditory neural activity through the ascending auditory pathway ( Hall, 1992). In contrast, the ABR is an auditory evoked potential, recorded from the scalp, occurring within the first 10 ms following auditory stimulation ( Hall, 1992). Psychoacoustic methods involve training an animal to respond to test stimuli with a particular behavior, such as pressing a lever or pecking a key (e.g., Dooling and Okanoya, 1995 Kastak and Schusterman, 1999 Szymanski et al., 1999 Wolski et al., 2003). For this purpose, the lesser scaup ( Aythya affinis), a species of diving duck that is not commonly kept in captivity, was used. Therefore, the aim of this study was to carry out comparisons of an electrophysiological technique that might be utilized in the field, such as the auditory brainstem response (ABR), with psychoacoustic methods that have been more established as the “gold-standard” of laboratory research ( Fay, 1988). When the opportunity arises to study a species in captivity, it is useful to compare techniques to validate non-invasive methods against standard laboratory techniques. Furthermore, non-invasive techniques to measure hearing in animals are valuable tools to learn about species that are not typical laboratory animals. The accurate measurement of auditory sensitivity in animals is an important addition to the body of knowledge of species about which little information concerning sensory biology is available. ![]()
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