Blogging with Frogs- Acoustic Monitoring of Riparian Frogs

Written By: Paolo Solari

Frogs are both terrestrial and aquatic animals, which means they live both on the land and in the water, making all parts of the riparian corridor and creek potentially critical habitat.

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Pacific Chorus Frog. Photo © W. St. John

Pacific Tree Frogs are noisy critters, especially the males, which make relatively loud breeding calls. Additionally, each frog’s call has a fairly unique tone, making it pretty easy to distinguish between individuals. With this in mind, we decided that a call survey (documenting the total number of frogs heard while walking the length of Copeland Creek) would be a great way to determine the Pacific Tree Frog abundance in the area. Unfortunately, things did not go quite like we had planned.

Amy and I met by the ETC building at around 6:30 pm on a Monday night. With a tally clicker in our hand, and hope in our hearts, we began our walk down Copeland Creek.  By the time we had reached the end, we heard a total of three frogs.  As it turns out, frog activity is highly dependent upon temperature, rainfall, and relative humidity. This cold, dry night provided less than ideal conditions to properly account for frogs in the area. As the Fall season slowly turns into Winter, these conditions only worsen. In other words, we were too late. While Pacific Tree Frog breeding season is technically from November to July, they do prefer warmer nights.

Even though we did not hear as many frogs as we had hoped, we do not consider our attempt a failure. Learning proper sampling techniques is not something that we take for granted, as we realize this is something that we can take with us into our future. We also realize that our experience may help direct future endeavors in the right direction.

Copeland Creek Understory Restoration

By Jana Johnston and Jessi Laughlin

We were tasked with collecting base line data for the under story vegetation of Copeland Creek. To do this, we measured whole plot species richness as well as absolute and relative cover of herbaceous species by using a point intercept method and percent cover of shrub species using a line intercept method . 

Our two objectives were 1) to increase ground cover of native species to 25% or greater by 2020 and 2) to ensure a 1 meter radius around native plants with 0% Himalayan blackberry (Rubus armeniacus) cover.

First, we located and mark all seven transect lines. The transect lines were established by previous classes so we were provided with GPS coordinates to locate these points. Once we found the point we marked each one by hammering a piece of PVC pipe into the ground and spray painting a bright pink arrow pointing to the location. Once we found all seven transects we moved on to data collection.

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Megan Gaitan marking our first transect of the day. Photo © Jessi Laughlin

We used a point intercept method to measure herbaceous species. To do this we extended a measuring tape from the PVC pipe to the top of the creek bank facing north. Next we walked along the transect line with a flag dropping it at every half meter. At each point we recorded every species (or bare ground) the flag touched, as well as within a 5 cm radius of the flag. For any unknown species we encountered, we documented them on our “unknown species master list” and took a small sample to take back to the lab for identification.

We also collected whole plot species richness of herbaceous species. To do this we flipped a coin, student ID, car key or any other flippable item we had, to determine whether we would measure the east or west side of the transect. Once we decided this, we walked along the transect with a meter stick recording all species present within this area.

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Transect line crossing an unknown species. Photo © Jessi Laughlin

To measure percentage of shrub cover we used a line intercept method. Using the same seven transects, we took the measurement (meter) of any shrub foliage overlapping our transect. From these measurements we were able to calculate percent cover of each species for each transect. We also measured the shrub height at every 2m along the transect.

 During this process we encountered several stabbing, stinging and poisonous plant species and acquired a few injuries along the way. We discovered, as we were expecting, that many sections of the creek have been over taken by invasive species particularly Himalayan blackberry. Himalayan blackberry is a huge problem because it can grow extremely fast and large, choking and shading out other plant species. For more information check out the problem species blog post. However we also found that many native plant species are thriving including snowberry, California grape and California rose.

Based off of our data it’s clear that in order to promote a healthier creek habitat the Sonoma State community and future Restoration Ecology classes need to focus on removing Himalayan blackberry especially around the native plants we are hoping to keep alive. Removing the Himalayan blackberry will allow for planting of more native species that will have a better chance of succeeding along the riparian corridor.

One of the most interesting parts of this process was seeing the dramatic shift in vegetation from the overgrown black patches to the bare redwood grove up stream.

Throughout this process we created a step by step lab guide for future students to use to collect the same data we did. As the creek restoration project continues, students will be able to document the progress of the understory vegetation and will hopefully see a shift from an invasive dominated habitat to a more healthy, fully-functioning native understory system.