Draft Washington State Oregon Spotted Frog Recovery Plan
 
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Draft Washington State Oregon Spotted Frog Recovery Plan

Category: Threatened and Endangered Species - Recovery Plans

Date Published: May 2013

Number of Pages: 106

Author(s): Lisa A. Hallock

EXECUTIVE SUMMARY:

The Oregon Spotted Frog is a medium-sized aquatic frog endemic to the Pacific Northwest. Historically, it was distributed from southwestern British Columbia, Canada to northeastern California. Today there are approximately 46 locations in British Columbia, Washington and Oregon. In 1997, the U.S. Fish and Wildlife Service concluded that federal listing of the Oregon Spotted Frog as Endangered or Threatened was warranted but precluded from listing by other higher priority species. It is currently a Federal Candidate Species.

The Oregon Spotted Frog was listed as Endangered in Washington in 1997 by the Washington Fish and Wildlife Commission. Museum specimens and substantiated accounts indicate Oregon Spotted Frogs were found in both the Puget Trough and East Cascades ecoregions. The species is known to persist in only six Washington river drainages: Sumas River (Whatcom County), Black Slough (Whatcom County), Samish River (Whatcom & Skagit Counties), Black River (Thurston County), Trout Lake Creek (Klickitat and Skamania Counties) and Outlet Creek at Conboy Lake and Camas Prairie (Klickitat County).

The decline in the occurrence and population sizes of Oregon Spotted Frogs is attributable to several major human-caused stressors. These include:

  • Wetland loss and alteration.
  • Loss of disturbance processes that set back succession.
  • Introduction of non-native/invasive flora and fauna (e.g., reed canarygrass, bullfrogs, game fish).
  • Alteration of creek and river channels.

Oregon Spotted Frogs have specific life history traits, habitat requirements, and population characteristics that limit their distribution and make them vulnerable to these changes. These include:

  • A completely aquatic life history.
  • Communal reproduction concentrated on the landscape with the same localized breeding areas used annually.
  • High levels of population fluctuation.
  • Dispersal limited to aquatic corridors.
  • Association with relatively large permanent wetlands (typically > 4 ha) that include shallow, warm-water habitats.
  • Breeding habitats that have shallow water (≤ 30 cm), short vegetation and full sun exposure with relatively stable hydrology and aquatic connectivity to permanent waters.
  • Overwintering habitats that provide adequately oxygenated water and shelter from freezing conditions and predators.

Additional threats include the geographic isolation of Oregon Spotted Frog populations and the increase of water-borne pollutants and diseases. This list of threats is neither exhaustive nor independent, as a number of factors are interconnected. Climate change is a looming threat of concern because it involves potential changes likely to have severe effects on Oregon Spotted Frogs across their geographic range.

Given the trajectory of habitat change and interrelated conditions that threaten this species, Oregon Spotted Frogs in Washington are not expected to recover without intervention. Habitat management will be an essential part of the recovery plan for this species. To downlist the species, habitat conditions will need to be improved at occupied sites to enhance population numbers and new populations may need to be established or found. This will require the cooperation of many landowners, partners, and other stakeholders. The expertise and facilities provided by zoos and aquariums will also be valuable in these efforts.

The Recovery Plan identifies two recovery zones in Washington: the Puget Trough Ecoregion and the southern portion of the East Cascades Ecoregion. The recovery strategies focus on monitoring and protection of remaining populations, enhancement of occupied habitat through species-specific adaptive habitat management, research to facilitate and enhance recovery, inventory for undiscovered populations and re-establishment of populations within the historical range. Sources of funding for these efforts will need to be identified and secured. The recovery objectives identified in this Plan may be modified as more is learned about the habitat needs and population dynamics of Oregon Spotted Frogs.

Recovery Objectives

The Oregon Spotted Frog will be considered for downlisting to Threatened when the following conditions are achieved:

  1. Washington has populations in at least six drainages that produce a total of ≥ 7,500 egg masses annually and each drainage supports a minimum of 500 egg masses from frogs close enough in distribution to exchange genes. These population levels must be met in 7 of 10 years sampled. A declining trend in the last three years would result in an extension of the sampling period for three additional years to verify that the populations are stable or increasing.
  2. At the time of downlisting, at least one recovery zone supports a minimum viable population.
  3. Management plans and funding are in place to maintain suitable habitat at each occupied site within the six drainages over the long-term.

The Oregon Spotted Frog will be considered for downlisting to Sensitive when the following conditions are achieved:

  1. Washington has populations in at least six drainages that produce at total of ≥ 10,000 egg masses annually and each drainage supports a minimum of 500 egg masses from frogs close enough in distribution to exchange genes. These population levels must be met in 7 of 10 years sampled. A declining trend in the last three years would result in an extension of the sampling period for three additional years to verify that the populations are stable or increasing.
  2. At the time of downlisting, both recovery zones support a minimum viable population.
  3. Management plans and funding are in place to maintain suitable habitat at each occupied site within the six drainages over the long-term.

The recovery strategies outlined in this plan are based on current conditions and scientific knowledge. The status of Oregon Spotted Frog populations and the recovery strategies will be reviewed every five years to determine if recovery objectives have been met and if new recovery approaches are warranted.

After the species is downlisted to Sensitive, a management plan will be prepared that includes the recovery objectives to delist the species.

Suggested Citation:
Hallock, Lisa. 2013. Draft State of Washington Oregon Spotted Frog Recovery Plan. Washington Department of Fish and Wildlife, Olympia. 93 +v pp.