Trends in Amphibian Occupancy in the United States

Michael J. Adams, David A. W. Miller, Erin Muths, Paul Stephen Corn, Evan H. Campbell Grant, Larissa L. Bailey, Gary M. Fellers, Robert N. Fisher, Walter J. Sadinski, Hardin Waddle, Susan C. Walls

Public Library of Science ONE

22 May 2012.

What we found

Based on sampling on protected areas from across the United States, including from the mid-Atlantic and from National Parks and Refuges across the northeast , ARMI has produced the first estimate of how fast we are losing amphibians.

Even though the declines seem small and negligible on the surface, they are not; small numbers build up to dramatic declines with time.  For example, a species that disappears from 2.7 % of the places it is found per year will disappear from half of the places it occurs in 26 years if trends continue. More concerning is that even the species we thought were faring well – that is, fairly common and widespread -- are declining, on average. Fowler’s Toad (9 total years of data at 1 area: -0.06% annual trend) and Spring Peepers (26 total years at 5 areas: -0.06%) are examples of IUCN Least Concern Species for which we found a declining trend at the places we monitor. We also found evidence that amphibian declines are even taking place in protected areas like National Parks and National Wildlife Refuges. Check out the full publication here.

What we are doing

The Amphibian Research and Monitoring Initiative (ARMI) brings scientists and resource managers together to make real progress on a difficult problem.  The ARMI program is a model for a productive program that links management and cutting edge science – since its inception in 2000, ARMI has produced over 430 publications  on amphibian ecology, methodological advances for studying wildlife populations, and information useful to our DOI partners and beyond.  We now have the first continental scale amphibian monitoring program at a point where broad-scale analyses can occur.  This gives us new ways to study amphibian declines and look for ways to address the problem.

In the northeast, we are working with our resource management partners in NPS and FWS to identify and implement management strategies we think are optimal for maintaining populations - typically involving habitat manipulation.   In addition, we will continue to monitor populations, and to develop novel research approaches to better understand what is causing declines, which will help to generate support for management options.

Sampling amphibians

Appalachian Salamander Display at the National Zoo

The Appalachian Region is well known for its many unique attributes; not least among them are its ancient mountains, variable forest types, and formidable streams. However, one element of its uniqueness remains surprisingly obscure; salamanders. There are 535 salamander species known in the world and 76 of those species occur in the Appalachian Region, with nearly half of those species endemic to this area. The status of these salamanders remains relatively uncertain due to difficulties associated with sampling for individuals and estimating populations. A collaborative effort by NE ARMI and the Smithsonian Conservation Biology Institute is addressing some of these uncertainties by focusing research on eastern hellbenders (Cryptobranchus alleganiensis), and red-backed (Plethodon cinereus) and Shenandoah salamanders (Plethodon shenandoah). One product of this effort is the establishment of an Appalachian salamander lab and exhibit at the Smithsonian National Zoological Park, which is currently in the process of development. The goal is to spotlight these species as well as the science behind conserving this unique hotspot of salamander diversity.

View of the Appalachian Salamander Exhibit that is currently in development at the National Zoo in Washington D.C.

Innovative New Study Looking at Plethodon Competition under Climate Change

The distribution of the federally endangered Shenandoah salamander (Plethodon shenandoah) is restricted to isolated areas of high elevation talus slopes in Shenandoah National Park, Virginia. Their restricted distribution is thought to be a result of competitive pressure from the red-backed salamander (Plethodon cinereus). Because P. shenandoah occupies talus habitats that are already warmer and drier than more optimal soil and litter habitats, this species has the potential to be severely threatened by climate change. A research effort to explore the complex competitive interactions of these salamanders under different climate scenarios is underway at Patuxent Wildlife Research Center. This study may be the first to look at competition in a 3-dimensional space containing both underground and surface habitats. In addition, these competitive interactions will be explored under realistic climate conditions reflecting current and projected scenarios for these high elevation habitats. For more information about this ongoing study, please go here.

Filming salamanders in the underground space of one of the unique 3-dimensional experimental chambers