Columbia Spotted Frog

 

 

(Rana luteiventris)

 

 

 Photo by Janice Engle from Population Status and Natural History Update Report.

 

 

Taxonomy:

Kingdom - Animalia

  Phylum - Chordata

    Subphylum - Vertebrata

      Class - Amphibia

        Order - Anura

           Suborder - Neobatrachia

              Family - Ranidae

                 Genus - Rana

                     Species - luteiventris

 

Four populations:

Northern

Wasatch

West Desert

Great Basin  (Candidate Species for listing)

 

 

Identification:

Spotted frogs are a medium sized herp being about the same size as leopard frogs. Females usually grow larger than the males.  Skin color may vary from dark green and brown to a light tan.  Usually frogs will have dark spots to marbeling on their backs.  A good identifying characteristic is the yellow to white stripe just above the upper jaw on adult individuals.  The underside's of the frogs are white to a creamish yellow color.  Some individuals might even have yellow to orange on the insides of their legs.  Adult males can be easily identified by their "beefy" arms and large nuptual pads on their thumbs which they use during breeding season to hold onto females. 

Distribution:

Spotted frogs are found throughout high elevation areas in the Pacific Northwest. The northern population extends from eastern Canada, south through parts of Washington, Oregon, and Idaho.  The Wasatch and West Desert populations are isolated in parts of Utah and southwest Wyoming.  The Great Basin population is located scattered through southern Idaho, Nevada, and Oregon. 

Idaho Distribution:

Spotted frogs are found throughout Idaho in locations of high elevations.  High mountian lakes, meadows, and streams can all be good locations to find these frogs.

The Great Basin population is located in southwestern Idaho, primarily in Owyhee county.  The climate of this location can range from extreme heat in the summer to extreme cold during the winter.  Majority of frogs are found above 5,000 ft in creek drainages and moist meadows.   The presence of water can be a determining factor of whether frogs will be present or not.  The great basin population is currently a candidate species for listing under the Endangered Species Act. Reasons for their decline can mainly be attributed to habitat loss, possibly from current grazing practies. 

Habitat:

Spotted frogs require several things to maintain a healthy population.  First, the presence of water is most critical.  Ponds, streams, rivers, lakes, meadows, bogs, and sometimes cattle tanks, can all contain spotted frogs.  Willows also provide excellent habitat for frogs.  Connectivity between habitats is another very important requirement.  Since these frogs rely greatly on the presence of water they cannot travel very far over dry ground.  During dry summers they rely on consistent flowing streams to escape meadows and ponds which often dry up.

Behavior:

During the summer months frogs will spend most of their day basking and foraging for insects.  Basking is when a frog sits in the sunlight to absorb the warm sun rays to gain energy.  These frogs primarily use the sit and wait method for capturing food.  During the cold winter months, frogs will bury themselves in thick mud under willows and remain there the entire winter untill the warmth of spring melts the snow and ice above them. 

When alarmed individuals will usually seek cover in thick vegetation or jump into a body of water and bury themselves in the mud.  Sandhill cranes, herons, and garder snakes are among the predators who favor spotted frogs the most. 

Reproduction:

After the winter's snow and ice melt, the frogs will emerge from their hibernation areas.  Late spring is the breeding season for spotted frogs.  Adult females usually will only breed in the same pond in which they were born.  Conditions must be perfect for them to lay eggs.  Females will lay their eggs in a jelly like mass containing anywhere from 200-500 eggs on the waters surface.  Eggs will eventually hatch to tadpoles after 15-30 days depending on conditions.  Males often call with quick "crik crik crik" bursts followed by a short break.  Tadpoles will metamorpasize before the end of summer.  Speculation has been made however about tadpoles overwinering in hibernation areas but no hard data is available to prove it.

Scientific Study:

"Population Fragmentation of Spotted Frogs in the Owyhee Mountains" Engle, Janice C. Munger, James C. Technical Bulletin NO. 03-8 Idaho Bureau of Land Management. April 2003

A three year study was performed in the Owyhee Mountains of South West Idaho (1997-199).  The objective was to look at the fragmentations of the Great Basin Spotted Frog population.  The first year of the project primarily focused on tagging as many frogs as possible.  Using PIT (passive integrated transponder) tags researchers tagged every captured adult individual and used the mark-recapture method to analyze movements during the remainder of the study.

During the first field season over 1100 observations were recorded.  This number included both new individuals and recaptures as well. Drift fences were placed around key ponds to monitor when and where individuals were entering and leaving the pond.  During the summer, "Frogs were observed to move away from the overwintering and breeding sites in late spring." (Engle)  Some results of the drift fences suggested individuals exclusively moving at night. 

Some recomendations were made for land use managers at the end of the study: 

-  terminating late fall grazing in riparian areas

-  termination of extensive grazing to remove all vegetation

-  removal of salt block to at least 0.25 miles from riparian areas

-  reintroduction of willows

-  fence riparian areas known for hibernation breeding and foraging

-  monitoring select occurences for long term

-  repairing abandoned beaver dams

-  transplant of egg masses.

Reference:

Engle, J. CSF Presentation. 13 January 2005

Engle, J. Munger, J. "Population Fragmentation of Spotted Frogs in the Owyhee Mountains" Technical Bulletin NO. 03-8.   Idaho Bureau of Land Management. April 2003

Montana Fish, Wildlife & Parks. Animal Field Guide.  25 September 2007

http://fwp.mt.gov/fieldguide/detail

Created By: Robby Engle