Use of multiple dispersal pathways facilitates amphibian persistence in stream networks.
Although populations of amphibians are declining worldwide, there is no evidence that salamanders occupying small streams are experiencing enigmatic declines, and populations of these species seem stable. Theory predicts that dispersal through multiple pathways can stabilize populations, preventing extinction in habitat networks. However, empirical data to support this prediction are absent for most species, especially those at risk of decline. Our mark-recapture study of stream salamanders reveals both a strong upstream bias in dispersal and a surprisingly high rate of overland dispersal to adjacent headwater streams. This evidence of route-dependent variation in dispersal rates suggests a spatial mechanism for population stability in headwater-stream salamanders. Our results link the movement behavior of stream salamanders to network topology, and they underscore the importance of identifying and protecting critical dispersal pathways when addressing region-wide population declines.
Campbell Grant
Evan H
EH
Northeast Amphibian Research and Monitoring Initiative, US Geological Survey Patuxent Wildlife Research Center, Laurel, MD 20708-4026, USA. ehgrant@usgs.gov
Nichols
James D
JD
Lowe
Winsor H
WH
Fagan
William F
WF
D000663:Amphibians; D025041:Animal Migration; D000818:Animals; D003247:Conservation of Natural Resources; D017753:Ecosystem; D053476:Extinction, Biological; D005828:Genetics, Population; D011157:Population Dynamics; D013045:Species Specificity; D014562:Caudata / Q000502:physiology*; D014768:Virginia; D014872:Water Movements