01937nas a2200121   4500008004100000245014400041210006900185260003200254490000800286520142700294100002001721856007401741       2018                        eng d00aThe Auditory Sensitivity and Active Space of the Northern Grasshopper Mouse (Onychomys leucogaster) in Relation to Woody Plant Encroachment0 aAuditory Sensitivity and Active Space of the Northern Grasshoppe  bNorthern Arizona University0 vMSc3 a<p>Vocal communication is a critical component of mate choice and territoriality in many animals. The efficacy of communication depends on signal transmission through an often- cluttered environment. Anthropogenic-induced changes in vegetation structure may impact sound propagation and thus habitat quality, but few studies have explored this hypothesis. In the American Southwest, fire suppression and cattle grazing have facilitated displacement of grasslands by pinyon-juniper woodlands. Northern grasshopper mice (Onychomys<br />
	leucogaster) produce long-distance vocalizations to advertise their presence to rivals and potential mates and inhabit regions impacted by juniper encroachment. Here, we coupled acoustic recordings and physiological measurements of hearing sensitivity in the laboratory with sound transmission experiments in the field to estimate the active space of grasshopper mouse calls. We found that receivers are sensitive to loud (ca. 85 dB re: 20 &mu;Pa at 1 m) 11.6 kHz calls at 30 dB and that calls travel 30 m (range: 20 &ndash; 60 m). However, we found no effect of shrub encroachment on call propagation as juniper and grass density were inversely associated and&nbsp;both present barriers to a 9 cm mouse advertising at ground level. Our findings suggest that juniper encroachment does not affect sound propagation but may influence habitat quality through alternative mechanisms.</p>
1 aGreen, Dana, M.  uhttps://search.proquest.com/openview/e347237ef0544cf639c2d95e4d50a22b