Description of monitoring:
We track the distribution, reproduction, and abundance of three frog species
(red-legged, tree and bull frogs) on the Reserve and monitor the quality
of their habitats. We carry out: 1) daytime surveys of our aquatic habitats
to monitor water quality and pond vegetation and to identify egg masses,
tadpoles, metamorphs, and adults; 2) evening listening surveys to identify
areas used by breeding males; and 3) night surveys to assess adult population
size.
Objectives:
Our primary goal is to track populations of threatened California red-legged
frogs on the Reserve. We are interested in identifying areas used as adult
and breeding habitat. In response to this monitoring data, we can carry
out adaptive management of our aquatic habitats.
Current Results:
 From
1997-2001, ESNERR monitoring efforts were lead by researcher Dawn Reis,
with a team of staff and docents providing assistance. Since 2001, frogs
have been monitored by a variety of ESNERR staff, docents, and interns,
with especially dedicated work by volunteers Nina D'Amore and Amy Weiss.
These censuses have revealed a California red-legged frog population with
greater than 300 adults living on the Reserve, in various ponds and wildlife
guzzlers. Reproduction occurs primarily in one of the larger ponds, Cattail
Swale, where chortling male calls can be heard and egg masses can be seen
in winter. Why is the Reserve such a good place for
red-legged frogs? We think it is the juxtaposition of protected, healthy
aquatic habitats, riparian areas, grasslands and woodlands. Red-legged frogs
move around, and the Reserve provides a variety of different aquatic habitat
types (ponds of different characters, and guzzlers in between) with safe
passages through vegetated habitat in between.
We obtained a small
grant from the Monterey Bay Aquarium conservation action fund to improve
the value of the aquatic habitats even further by replacing invasive vegetation
around the fringes with natives, regulating water levels, and removing bullfrogs.
For more information on our frog monitoring
program, contact Kerstin Wasson (
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