Download 2016 Season Summary: Foothill Yellow

2016 Season Summary:
Foothill Yellow-Legged Frog Docent Program
Elizabeth Ruiz, Watershed Stewards Program
The only true frog in western North America to breed exclusively in streams 1, the Foothill
Yellow-Legged Frog (Rana boylii), has seen a large decrease in population numbers and range over
time. Its status as a federal “sensitive species” is currently under review by US Fish and Wildlife 2,
though it is currently “near-threatened” according to the International Union for Conservation of
Nature (IUCN) and a “species of special concern” in the state of California. Historically found in
Oregon, California, and western Mexico, the foothill yellow legged frog (FYLF) has lost
approximately 45% of its range in California alone. Invasive species, stabilization of seasonal
stream flows, recreation, and habitat loss have all contributed to the decline of the species.3
Within the Mt. Tamalpais watershed, there are two small, yet stable, populations of FYFL,
both of which are threatened by visitor usage, particularly at Little Carson Falls. Visitation to the
falls jumped in popularity in the early 2000’s, turning what was a frog sanctuary into a heavily
trafficked hiking destination. The picturesque cascades and rocky pools, where the FYFL lay their
eggs, are alluring to hikers, and occasionally their dogs, who wish to cool off with a swim. Managed
by the Marin Municipal Water District (MMWD), and almost completely within the boundaries of
the Mt. Tamalpais State Game Refuge, the trails leading to the falls are some of many open to
recreationalists from all over the San Francisco Bay region.
In an effort to raise awareness about the breeding site at
Little Carson Falls, and to balance increased traffic, visitor
enjoyment, outreach, and FYLF protection, MMWD established
the Frog Docent Program in 2005. Volunteers are recruited,
trained on FYLF life history and visitor interaction, and spend
weekends during the March-June breeding period at the falls,
educating visitors about frogs and watching out for harmful
behavior.
Spotted! FYFL and egg mass.
Photo: Sari Kwan
The February 27th training was attended by 17 people,
and the volunteer pool for the season was 13, which included
five new docents and eight returners. Following an introduction
to the program, Garcia and Associates (GANDA) herpetologist Joe
Drennan lead a section on frog biology, and ranger John
1
Worley Firley, Stephanie. "Is the Foothill Yellow-Legged Frog in Hot Water – Because of Cold Water?"US Forest Service. USFS Pacific
Southwest Research Station 29 Apr. 2015
2
"Species Profile for Rana Boylii." Environmental Conservation Online System. US Fish and Wildlife Service
3
"Foothill Yellow-legged Frog - Rana Boylii." California Herps. California Herps.
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McConneloug trained the group in safety, radio use protocols, and successful interactions with the
public. The second half of the training included a hike to the falls from the Azalea Hill Trailhead,
where we observed several frogs basking in the upper pools, allowing practice with the spotting
scopes.
Weekends were grey
and rainy until mid-March, and
when the weather began to get a
little nicer the docents began filling
up shifts. The weather stayed
warm and dry for the rest of the
season, through Memorial Day,
which marked the end of the
season on May 30th. Over the
course of the season the 13
docents dedicated a total of 226.5
hours to the protection of the
frogs! An increase from last year,
and 20 hours shy of 2014’s record.
Docents covered 63% of the 56 total weekend shifts, either morning (9am-1pm) or
afternoon (1-5pm), and 86% of the 28 possible volunteer days. The number of shifts covered is
slightly higher than last year’s 58% coverage rate, though the percentage of days covered is very
similar.
This year was a unique one for the docent program. On March 14th a landslide closed a
portion of the Fairfax-Bolinas road and blocked access to Cataract Falls, another popular hiking
destination. Hikers instead appeared to visit Little Carson in droves. Visitor usage was so high the
docents requested additional volunteers for the afternoon shifts, and throughout the covered
shifts docents encountered a total of 1636 individual visitors, almost 600 more than the previous
record in 2010. Due to the fact that there are no docents during the week, we have no visitor usage
numbers for weekdays.
Docents shared FYLF information with 85% of the
visitors, for a whopping total of 1393 individuals. They
observed 19 people in the pools, and while that is more than
three times the previous total, that number accounts for 1%
of the total traffic this season. More than 150 of our fourlegged friends enjoyed a hike to the falls as well, and of
those, only three were observed in the water, though GANDA
biologists recorded disturbance to egg masses by dog
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presence in the pools. Following this observation, MMWD maintenance and resource staff
removed a social trail leading to the pools by covering it with brush and blocking it with heavy
logs.
Almost all of the visitors to the falls leashed their dogs or
removed themselves from the water upon request, and docents
recorded only two negative reactions for the season, which were
expertly handled by the volunteers.
FYFL amplexus
Photo: Fair Family
Swimming away post-survey
Photo: E. Ruiz
In addition to educating watershed visitors, docents also make
observations of the frogs and other wildlife. This season there were
128 frog sightings, including observations of amplexus (mating).
Additionally, volunteers observed a host of other wildlife, from garter
snakes, newts, tadpoles, and dragonflies, to hummingbirds, towhees,
nuthatches, and even a bald eagle. The data collected by docents are
particularly useful for GANDA biologists when deciphering signs of
damage or predation to egg masses.
Surveys conducted by Garcia and Associates yielded
observations of 45 adult males, at least 10 female frogs, and 13 egg
masses at Little Carson Falls. The season total for the number of egg
masses observed on the tributaries and mainstem of Big Carson in
addition to the 13 at Little Carson was 41, the highest number
recorded since surveys began in 2005. The highest number of egg
masses observed prior to this year was 38 in 2012. Breeding season
was longer than usual, with the last egg mass observed on May 26th in
the Big Carson system.
To date, volunteers with the frog program have
dedicated more than 2500 hours to the protection of the
frogs and the education of watershed visitors. They’ve
informed 6156 individuals about the plight and
conservation of the FYLF. The docents are vital in ensuring
that all watershed residents and visitors can enjoy the
natural resource. We are immensely appreciative of our
2016 docents: Maria Melendez-Martinez, Cindi Darling,
Peter Suri, Frederic Leist, Sari Kwan, Janet Bodle, Lorri
Gong, Lindsey Going, Jim Garlock, Rich Crimino, Harold
Hirsch, Rob Ruiz, Bill Bain, James Fair, and our youngest
docent in history, Ethan Fair. Thanks to all of you for your
time and support!
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