title: Roles of patch characteristics, drought frequency, and restoration in long-term trends of a widespread amphibian.
abstract: Despite the high profile of amphibian declines and the increasing threat of drought and fragmentation to aquatic ecosystems, few studies have examined long-term rates of change for a single species across a large geographic area. We analyzed growth in annual egg-mass counts of the Columbia spotted frog (Rana luteiventris) across the northwestern United States, an area encompassing 3 genetic clades. On the basis of data collected by multiple partners from 98 water bodies between 1991 and 2011, we used state-space and linear-regression models to measure effects of patch characteristics, frequency of summer drought, and wetland restoration on population growth. Abundance increased in the 2 clades with greatest decline history, but declined where populations are considered most secure. Population growth was negatively associated with temporary hydroperiods and landscape modification (measured by the human footprint index), but was similar in modified and natural water bodies. The effect of drought was mediated by the size of the water body: populations in large water bodies maintained positive growth despite drought, whereas drought magnified declines in small water bodies. Rapid growth in restored wetlands in areas of historical population declines provided strong evidence of successful management. Our results highlight the importance of maintaining large areas of habitat and underscore the greater vulnerability of small areas of habitat to environmental stochasticity. Similar long-term growth rates in modified and natural water bodies and rapid, positive responses to restoration suggest pond construction and other forms of management can effectively increase population growth. These tools are likely to become increasingly important to mitigate effects of increased drought expected from global climate change. Papeles de las Características del Fragmento, Frecuencia de Sequía y Restauración en las Tendencias a Largo Plazo de un Anfibio Ampliamente Distribuido.
authors.affiliation: U.S. Geological Survey, Aldo Leopold Wilderness Institute, 790 East Beckwith Avenue, Missoula, MT, 59801, U.S.A.. blake_hossack@usgs.gov.
authors.forename: Blake R
authors.initials: BR
authors.lastname: Hossack
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Adams
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Pearl
authors.forename: Kristine W
authors.initials: KW
authors.lastname: Wilson
authors.forename: Evelyn L
authors.initials: EL
authors.lastname: Bull
authors.forename: Kristin
authors.initials: K
authors.lastname: Lohr
authors.forename: Debra
authors.initials: D
authors.lastname: Patla
authors.forename: David S
authors.initials: DS
authors.lastname: Pilliod
authors.forename: Jason M
authors.initials: JM
authors.lastname: Jones
authors.forename: Kevin K
authors.initials: KK
authors.lastname: Wheeler
authors.forename: Samuel P
authors.initials: SP
authors.lastname: McKay
authors.forename: Paul Stephen
authors.initials: PS
authors.lastname: Corn
mesh_terms: D000818:Animals; D003247:Conservation of Natural Resources; D055864:Droughts; D017753:Ecosystem; D005843:Geography; D011156:Population Density; D011157:Population Dynamics; D011898:Ranidae / Q000502:physiology*
keywords: Cambio climático; amphibian decline; climate change; constructed ponds; declinación de anfibios; estanques construidos; fragmentación; fragmentation; hidroperíodo; human footprint index; hydroperiod; modelo estado-espacio; monitoreo; monitoring; restauración; restoration; state-space model; índice de huella ecológica humana