Shady Creek is Alive with Native Foothill Yellow-Legged Frogs!

Foothill Yellow-Legged Frog

While some look at Shady Creek and see a stream devastated by historic mining activities, SYRCL has succeeded in documenting that Shady Creek is home to a flourishing population of Foothill Yellow-Legged Frogs, a native species of special concern. This spring, SYRCL volunteers conducted four surveys of frogs on a one-mile reach of Shady Creek, a tributary to the South Yuba River which drains the western portion of the San Juan Ridge mine.  Results totaled 134 adult frogs, 34 egg masses, and at least 1,500 tadpoles.

Foothill Yellow-Legged Frogs (FYLF) depend entirely on habitat in streams and rivers.  The adults feed on insects in the stream, lay egg masses in the stream during the relatively calm and stable flows of late spring, and the tadpoles feed on algae and diatoms. FYLF is a California Species of Special Concern and considered vulnerable to habitat lost from altered stream flows, and pollution.  The frogs are particularly sensitive to large-scale land use disturbances such as mining and logging.

Frog expert and survey leader Tom Van Wagner showing a FYLF he caught.

Past studies by UC Davis researchers identified the one-mile reach of Shady Creek, located upstream from Purdon Road , as favorable for FYLF.  While the abundant frog population comes as a surprise to those aware of the intense mining legacy of the watershed, it is important to note that this area immediately downstream from the San Juan Ridge Mine has had many years of natural stream flow and streambed recovery.

Recent efforts to resume mining operations at the San Juan Ridge Mine that discharges into Shady and Spring Creek could jeopardize this FYLF refuge by altering hydrology, channel morphology, riparian vegetation and water quality.  The egg masses are especially sensitive to changes in stream flow; high flows during the breeding season can scour egg masses and low flows in late summer can dry out habitat.

These frog surveys are the most frequent and extensive ever recorded for Shady Creek as they captured an entire breeding season.  Visits will be made in late summer to track tadpole development and the surveys will continue in future years, expanding also to Spring Creek which drains the eastern portion of the San Juan Ridge Mine area.  The goal is to document the status of the frog population and establish a scientific baseline for evaluating any impacts if the San Juan Ridge Mine reopens in the future. SYRCL has also installed continuously monitoring stream flow gages in both streams, thanks to the support of local landowners.

The underside of the FYLF shows how it got its name.

This work is supported by a grant from the Rose Foundation, SYRCL donors and volunteers. Eight volunteers contributed 42 hours documenting the extent of Foothill Yellow-Legged Frogs on Shady Creek.  Special thanks to Tom Van Wagner for his invaluable leadership, skill and enthusiasm with finding, identifying, and characterizing FYLF.  Tom Van Wagner is a local amphibian expert and current board member of the Yuba Watershed Institute.

FYLF breeding in action.
This 2-4 inch diameter grape-like clusters is attached to gravels at the stream bottom. It contains 1000 distinct eggs that will eventually hatch into tadpoles.
An adult Foothill Yellow Legged Frog (Rana boylii) next to egg masses.
River Monitoring Coordinator, Marianne Pott, in awe of one of the day's sightings.

2 Comments

  1. Andrea Eiermann says:

    this is such great news thank you syrcl folks who put this all together..I would love to help later with the flow monitoring that needs to be done..I know it is a challanging trail to get to the monitors..But I would at least like to give it a try with a partner and see how it is…It is close by where I live..so I really wish to help if I can handle it… You all are the best!

  2. Andrea Eiermann says:

    sweet and enduring picture of Marianne's new froggie friend…maybe its a prince in a frog suit1.

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