Rock crevice morphology and forest contexts drive microhabitat preferences in the Green Salamander (Aneides aeneus)

Abstract

Little is known about how vertical rock habitats are selected by organisms in forest ecosystems. Multiple lungless salamanders use rock outcrops in the Appalachian Mountains of eastern North America, with Green Salamanders (Aneides aeneus (Cope and Packard, 1881)) showing the strongest associations as an outcrop specialist. Although previous work has identified environmental correlates of rock face and arboreal habitat use in this species, it remains to be known if and how Green Salamanders select crevice refugia as a function of both outcrop morphology and the context of outcrops within the surrounding forest. We performed an intensive survey of an abundant Green Salamander population on Virginia’s Appalachian Plateau to examine which features of vertical habitats are associated with salamander occupancy. Occupancy was highest in deeper rock crevices closer to surrounding trees, a likely consequence of arboreal behavior and the ability for crevice refugia to modulate the surrounding microclimate. Although uncertainty exists with regards to the generality of these results across the species’ range, our results underscore linkages between embedded rock outcrop habitats and their surrounding forest contexts for amphibians. Our results also provide a model of Green Salamander habitat associations that may be valuable to efforts to elucidate its geographic distribution.

A New Green Salamander in the Southern Appalachians: Evolutionary History of Aneides aeneus and Implications for Management and Conservation with the Description of a Cryptic Microendemic Species

“…The newly described North Carolina endemic, A. caryaensis, is restricted to an extremely narrow geographic range and is in need of immediate protection. However, little is known about the ecology of this species, as most work done on Castaneides has been conducted on more westerly populations and the Blue Ridge Escarpment lineage (e.g., Gordon, 1952;Snyder, 1983Snyder, , 1991Cupp, 1991;Corser, 2001;Waldron and Humphries, 2005;Smith et al, 2017). Perhaps the most important research needs at present are population surveys, habitat management guidelines, landscape genetic analyses, and habitat use studies.…”

“…Aneides aeneus is a habitat and microhabitat specialist, making the species particularly vulnerable to habitat loss and fragmentation. These salamanders are generally associated with crevices and hollows of rock outcrop, woody, and arboreal habitats within cove forests (Gordon, 1952;Cupp, 1991;Waldron and Humphries, 2005;Smith et al, 2017). These scansorial animals are frequently found in shady crevices in rock outcrops in mixed mesophytic forests from 300 to 1200 m elevation.…”

“…These scansorial animals are frequently found in shady crevices in rock outcrops in mixed mesophytic forests from 300 to 1200 m elevation. Although they have been observed to exhibit arboreal tendencies, they typically are restricted to areas harboring rock outcrops (Gordon, 1952;Waldron and Humphries, 2005;Smith et al, 2017). A large number of nesting sites have been detected on rock faces (but see Pope, 1928), which may in turn lead breeding populations to be patchily distributed (Petranka, 1998;Corser, 2001).…”

Detecting Sheer Rock Outcrops Using Digital Elevation Models for Ecological Conservation

“…Several rock outcrop specialists occur in Tishomingo County and have been listed as species of greatest conservation need [8], including state endangered or federally petitioned salamanders and mammals like the Green Salamander (Aneides aeneus), Cave Salamander (Eurycea lucifuga), Spring Salamander (Gyrinophilus porphyriticus), and Eastern Spotted Skunk (Spilogale putorius). It is likely the Green and Cave Salamander would be unable to persist during the hot and dry summer months (July-October) if not for cool, moist refuge in rock outcrops [9], [10], [11]. Although there is currently no legal protection for rock outcrops in Mississippi, 2 JSTARS-2023-02246 efforts to locate them are essential for habitat and species conservation to progress, whether regulatory or voluntary [2], [8].…”

“…Smith and Mullins [14] used a slope threshold ≥80%, or ≥38.7° = tan -1 (80% / 100%), to detect putative sheer rock outcrops in Jefferson National Forest, Virginia. This threshold was based on measurements and expert opinion from earlier studies [11], [14], [15] and yielded a 100% accuracy during field validation. However, there is potential that a ≥38.7° threshold could omit putative sheer rock outcrops and, therefore, opportunities for habitat conservation go unrealized.…”