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Amphibians and Reptiles

Frog Thomson 512The Pacific Tree Frog, shown above, is one of the twenty species of amphibians and reptiles found at Humboldt Bay NWR.

Amphibians that occur in the local area include the western toad (Bufo boreas), pacific tree frog (Pseudacris regilla), northern red-legged frog (Rana aurora aurora), rough-skinned newt (Taricha granulose), northwestern salamander (Ambystoma gracile), and Pacific giant salamander (Dicamptodon ensatus). These amphibians are associated with the various freshwater wetland habitats on the Humboldt Bay NWR, and breed in permanent freshwater areas near Salmon Creek and on dune units.
 
Snakes also make use of grassland, riparian forest, marsh, and dune habitats on the Humboldt Bay NWR including several species of garter (Thamnophis spp.) snakes and the gopher snake (Pituophis catenifer). Lizards that make use of these habitats include northern alligator lizard (Elgaria coerulea), western skink (Eumeces skiltonianus), and western fence lizard (Sceloporus occidentalis).
 
Most research focusing on management of amphibians has recently been conducted on northern red-legged frogs, due to their limited range in relation to other amphibian species found on the Humboldt Bay NWR. The northern redlegged frog uses freshwater habitat for breeding, which occurs locally on the refuge from mid-December to the end of March, when males and females congregate at breeding sites to deposit egg masses. Larvae hatch out of egg masses 2 to 4 weeks after oviposition, depending on water temperature, and the larvae are free swimming herbivores that go through metamorphosis starting in June to August. Wetlands where breeding occurs but where hydroperiods last only until May may be insufficient in successfully recruiting new individuals into a population.  To help overcome this, we are maintaining wetlands that have longer hydroperiods, such as permanent wetlands and conveyance canals,that will allow for completion of metamorphosis. Post-metamorphic frogs disperse from wetlands and move to upland habitats in alder forest adjacent to wetlands, although some individuals stay year round near wetlands. Adult movements away from breeding ponds can be up to 4.8 kilometers to appropriate non-breeding habitat.  After two years post-metamorphosis, males become sexually mature and females become sexually mature after three years.
 
Page Photo Credits — © David F. Thomson
Last Updated: Mar 25, 2013
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