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. 2013 May 22;8(5):e64347.
doi: 10.1371/journal.pone.0064347. Print 2013.

Trends in amphibian occupancy in the United States

Michael J Adams  1 , 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
Affiliations

Trends in amphibian occupancy in the United States

Michael J Adams et al. PLoS One. .

Abstract

Though a third of amphibian species worldwide are thought to be imperiled, existing assessments simply categorize extinction risk, providing little information on the rate of population losses. We conducted the first analysis of the rate of change in the probability that amphibians occupy ponds and other comparable habitat features across the United States. We found that overall occupancy by amphibians declined 3.7% annually from 2002 to 2011. Species that are Red-listed by the International Union for Conservation of Nature (IUCN) declined an average of 11.6% annually. All subsets of data examined had a declining trend including species in the IUCN Least Concern category. This analysis suggests that amphibian declines may be more widespread and severe than previously realized.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Characteristics of monitoring data.
(A) Location of monitoring areas. (B) Distribution of species among IUCN categories. (C) Number of years monitored in each time series. (D) Mean annual estimates of probability of site occupancy and number of occupancy estimates (N).
Figure 2
Figure 2. Rate of change in the probability of site occupancy for subsets data.
“Red-listed” includes species that the IUCN categorizes as Near Threatened, Vulnerable, or Endangered. The geographic regions of the United States are overlapping and are North or South of 39° latitude or East or West of −104° longitude. Major land managers include the U.S. Fish and Wildlife Service (USFWS) and the National Park Service (NPS). Plotted values are means and standard errors.
Figure 3
Figure 3. The distribution of trend estimates.
Data are trends in the probability of site occupancy based on (A) log-linear and (B) linear models.
See this image and copyright information in PMC

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