Climate Change and Amphibians in California
Ongoing and Proposed Research - 2003
Amy J. Lind
USDA Forest Service – Pacific Southwest Research Station
Sierra Nevada Research Center
Overview - Wildlife and Climate Change
* In order to study the potential response of wildlife to climatic changes, we
need good predictions on bioregional and local scales of likely changes in:
- temperature and precipitation patterns
- hydrologic regimes – groundwater, stream flow, etc.
- vegetation community composition and distribution
* Modeling of potential responses based on ecology and life history information.
* Short-term research to address species responses to short-term change.
* Establishment of long-term research and monitoring sites.
Recent Meta-Analyses of Ecological Responses to Climate Change
Types of Changes Expected
* Range shifts and changes in densities.
* Phenology of ecological events – eg. breeding, migration, tree leaf-out, etc.
* Morphology and behavior.
Timing of Spring Events
* Genetic frequencies.
(from 61 studies)
-6.5
-6
Some Concerns
days / decade
* Earlier breeding may not be in
sync with food availability.
-5.5
-5
-4.5
-4
-3.5
-3
* Species may need to “move” up in
elevation or latitude to maintain
physiological processes but
appropriate habitats may not be
available in these “new” areas.
-2.5 0
-2
1
2
Invertebrates Am phibians
3
Birds
4
5
Non-tree
Plants
6
Trees
After Root et al. 2003
Characteristics of Amphibian That May Make Them Especially Vulnerable
* Relatively small geographic ranges and narrow elevational limits.
* Low mobility, poor dispersal abilities.
* Many are habitat specialists.
* Ectothermic – narrow temperature/moisture thresholds for activity,
reproduction, development, etc.
* Known sensitivities to changes in microclimate and other environmental
stressors.
On-Going Climate Related Studies at Low-Mid Elevations
Focal species – foothill yellow-legged frog (Rana boylii), declining,
stream-dwelling frog, occurs in the foothills (up to 1800m)
of the Sierra Nevada and Coast Ranges of California and Oregon.
Two projects
* Large scale analysis of potential causes of decline.
* Breeding phenology in relation to temperature, water flow, and day length.
Causes of Decline - Analysis
* Modeled after Davidson et al. 2001, 2002
* Accurately map museum records and sightings of the foothill yellow-legged
frog in California and Oregon.
* Identify current status of mapped localities.
* Spatially and statistically relate locality status to landscape features and characteristics:
- elevation
- latitude/longitude
- precipitation and temperature
- upstream dams
- agricultural land use & potential drift of ag chemicals
- urban land use
- bullfrog presence?
372 mapped localities in California
from museum and sighting database
(Jennings and Davidson):
Currently present = 175
Currently absent = 153
Unknown= 44
Causes of Decline – Preliminary Results
* Presence of foothill yellow-legged frogs at a locality explained by:
- latitude of locality (positive)
- amount of agricultural land use (negative)
- precipitation of locality (positive)
- proximity to nearest large upstream dam (negative)
* Latitude and precipitation together may be indicative of a climatic
effect.
* Further investigations of interaction between dam characteristics and
precipitation are forth-coming.
Breeding Phenology – Field Set-Up and Methods
* Seven northern CA creeks/rivers in 1994-1995
* 1m and 1cm air temperatures, water
temperature, water depth, solar radiation,
and calling activity recorded at 15 min intervals.
* Weekly site visits to download data, count egg
masses, and basic maintenance.
Foothill yellow-legged frog Breeding Activity in 7 Streams in Northern California
Data logger results – breeding timing chart
Breeding Phenology – Results
Breeding Phenology – Results
Future Directions
* Modeling potential responses to climate change using the Sierran All-Species
Information db (SASI) and possibly envirograms.
* Establishment of both short and long-term research sites covering a
large elevational gradient:
- FHYL frogs and other species at low-mid elevations
- MYL frogs and other species at higher elevations (with K. Matthews)
- Focus on ecology and life history characteristics that will help us understand
responses to climate change:
+ phenologies of ecological events
+ survival rates
+ food habits/prey base
+ body condition/disease load
- Measured in concert with environmental variables
- Geographic scope – Sierra Nevada with possible collaboration in the
Klamath Mountains region (Hart Welsh)
Thoughts and Discussion Items
* How do we do research at small scales and on short time scales
that will help us learn about longer climatic cycles?
* How do we sort out immediate and local effects from longer term
climate-related effects and the interaction of the two?
* Because of large spatial and temporal scales of climate changes,
we need to engage in collaborative work:
- within PSW and the Forest Service
- with other agencies/academics - eg. USGS Amphibian Research
and Monitoring Initiative