TURTLE OBSERVER PROGR REPORT 214 INTRODUCTION: Marin Municipal Water District Erin Tracy, AmeriCorps Watershed Stewards Project Member Eric Ettlinger, Aquatic Ecologist June, 214 As California s only native freshwater turtle, the western pond turtle (Actinemys marmorata) is a symbol of species diversity and ecosystem health on the watershed. The turtle observer program began as a way for volunteers to observe these turtles around the watershed and collect valuable data on the status of native and non-native turtle populations. Volunteers complete a three hour training session in which they learn how to identify native western pond turtles and non-native red-eared slider turtles (Trachemys scripta) as well as other non-natives. Turtle observers then use these skills to fill out data sheets about the species and behavior of turtles they observe at the various lakes and trails on the watershed. Thanks to our volunteers, this is the sixth consecutive year we have been able to complete turtle surveys since 23. The goals for the 214 observer program were to train observers in species identification, establish population estimates for native and non-native turtles in each reservoir, and determine the proportion of native to non-native turtles. Turtle trapping was not conducted this year due to a lack of time and personnel. METHODS: AmeriCorps Watershed Stewards Project members and MMWD staff trained 23 new volunteers in turtle biology, species identification, and observation skills on March 8th, 214. Once trained, volunteers could visit any of four sites on their own time until June 7th. The four locations identified for volunteers to make observations are as follows: the dam and shoreline of Lake Lagunitas, the shoreline of Alpine Lake along Bullfrog Trail, Alpine Lake below Bon Tempe Dam, and the shoreline of Phoenix Lake. These locations were chosen for their relatively high turtle activity compared to other locations on the watershed. Maps of turtle observation locations are included at the end of this report. Volunteers spent anywhere from thirty minutes to five hours at a given location. Observations were recorded on a data sheet which included the volunteer name, age, date, time interval, and
weather. For each turtle sighted, volunteers were asked to record a series of qualitative observations. These observations are as follows: the observing location, whether the turtle was basking or swimming, if the head was visible, if the turtle had a red stripe behind the eye, if the turtle had green or yellow facial stripes, if the throat was noticeably lighter than the face, and if there were yellow markings on the shell. Based upon these observations, volunteers could then classify the turtle as a western pond turtle (), red-eared slider (TS), unidentified non-native (), or an unknown species (U). Data sheets for all locations were submitted to and compiled by WSP interns. Classifications that appeared to be inconsistent with the recorded facial and body characteristics were changed accordingly. Any observations recorded at the same location on the same date were reduced to only the high count of each classification for the day. Populations for each location were estimated using the high count of each classification for that location. Turtle on Phoenix Lake Log 1 taken by Lorri Gong Hatchling western pond turtle taken by Caleb Porter and his two daughters. Ruffles the western pond turtle taken by Kathy Tama Western pond turtle on log taken by Kaisa Lee
RESULTS: The annual turtle observer training was attended by 23 new people in 214. Of these new volunteers, 9 submitted at least one data sheet after training, as did 1 volunteers who had been trained in previous years. In 214, the 19 volunteers observed for a total of 11. hours on 42 separate visits. Volunteers made 1,463 individual turtle observations. The 214 season marks the highest ever number of observations made by volunteers. However, the total number of volunteer visits and the total volunteer observation hours fell from the 213 totals of 7 to 47 and 13 to 1., respectively. From the 213 to the 214 season, volunteer participation decreased by 48%, the number of volunteer visits decreased by 32% and the total number of volunteer hours decreased 18% (Figures 1, 2, and 3). Figure 1. Total number of volunteers who participated 4 3 37 3 3 2 2 19 1 11 9 1 21 211 212 213 214 14 12 1 8 6 4 2 Figure 2. Total number of volunteer visits 131 4 37 7 47 21 211 212 213 214 3 2 2 1 1 Figure 3. Total volunteer observation hours 21 63 76 13 11. 21 211 212 213 214 In 214 turtle observers recorded a total of 21 western pond turtles, 948 red-eared sliders, 274 unidentified non-natives, and 134 unknown turtles on the MMWD watershed. Volunteers did not identify other non-native turtles by species, but these likely included river cooters and/or red-bellied turtles (Pseudemys spp). In 212, a very high percentage of turtle observations were classified as unknown, constituting 222 of the 327 (68%) observations (Figure 4). In an effort to reduce unknown classifications, in 213 the importance of binocular use was heavily discussed during training, and in 214 a spotting scope was purchased to further aid volunteers in identification. Out of the 1,66 total observations made in 214, 134 (9%) unknown observations were made, a record low for unknown identification. 1% 8% 6% 4% 2% % Figure 4. Percent of unknown observations. 23% 68% 21% 9% 211 212 213 214 Percent of unknown observations made
BULLFROG TRAIL: In Alpine Lake along Bullfrog Trail (BFT), the season high count constituted 14 western pond turtles () and 73 non-native turtles including 63 red-eared sliders. This is a slight increase over the number of seen last year and a dramatic increase in the total and high count (Figure ). Figure. BFT Turtle High Count by Species Figure 6. BFT Turtle High Count on a Single Day 8 73 9 83 7 8 6 7 4 3 2 1 17 19 18 14 12 14 2 211 212 213 214 6 4 3 2 1 36 3 3 211 212 213 214 The highest total turtle count, including unknowns, for a single day on BFT was 83 on March 16 th (Figure 6). This data was collected over 26 different days in 214 (Figure 7). 1 9 8 7 6 4 3 2 1 7-Mar 8-Mar 11-Mar 14-Mar 1-Mar 16-Mar 18-Mar 2-Mar 23-Mar 2-Apr -Apr 8-Apr 9-Apr 11-Apr 13-Apr 18-Apr 28-Apr 3-Apr 3-May 7-May 12-May 1-May 18-May 3-Jun 4-Jun 6-Jun Number of Turtle Observations Figure 7. Bullfrog Trail Turtle Observations, 214 TS U Total Dates of observations (not temporally scaled)
ALPINE LAKE: On Alpine Lake, below Bon Tempe Dam, turtle observers identified a season high of six and 47 of which were red-eared sliders in 214. In contrast, in 213 observers recorded 4 and 12 (Figure 8). The 214 numbers are a notable increase in observations at Alpine Lake. Figure 8. Alpine Lake Turtle High Count by Species 4 4 3 3 2 2 14 1 12 1 6 4 3 4 211 212 213 214 6 4 3 2 1 Figure 9. Alpine Lake Turtle High Count on a Single Day 6 2 1 7 211 212 213 214 The highest turtle count, including unknowns, for a single day in 214 was 6 on March 16 th (Figure 9). The data was collected over 17 different days in 214 (Figure 1). 6 Figure 1. Alpine Lake Turtle Observations, 214 Number of Turtles Observed 4 3 2 1 TS U Total Dates of Observations (not scaled temporally)
LAKE LAGUNITAS: In Lake Lagunitas, this year s high counts by species were 18, and 3 five of which were red-eared sliders. The 214 data shows an upward trend for observation numbers since 212 (Figure 11). Both the and numbers increased significantly from the previous year. Figure 11. Lake Lagunitas Turtle High Count by Species 3 3 Figure 12. Lake Lagunitas Turtle High Count on a Single Day 3 3 2 3 2 2 1 1 18 1 9 9 4 3 4 211 212 213 214 2 2 1 1 19 11 211 212 213 214 The high count for a single day in 214 was 3 on May 18 th (Figure 12). This data was collected over 19 visits in 214 (Figure 13). 4 Figure 13. Lake Lagunitas Turtle Observations, 214 Number of Turtles Observed 3 3 2 2 1 1 TS U Total Dates of Obsercation (not scaled Temporally)
PHOENIX LAKE: Observers were asked to monitor Phoenix Lake starting in 212, when turtle basking habitat was enhanced around that lake. Phoenix Lake observers found a high count of three and 21 all of which were red-eared sliders in 214 (Figure 14). This shows a drop in the number of since 213. Figure 14. Phoenix Lake Turtle High Count by Species 2 21 2 2 Figure 1. Phoenix Lake Turtle High Count on a Single Day 2 22 22 2 1 1 1 9 1 3 3 212 213 214 212 213 214 The turtle high count on a single day in 214 was 22 on April 26th (Figure 1).This data was collected over five visits in 214 (Figure 16). 2 Figure 16. Phoenix Lake Turtle Observations, 214 Number of Turtles Observed 2 1 1 TS U Total 11-Apr 18-Apr 23-Apr 26-Apr 3-May Dates of Observations (not scaled temporally)
DISCUSSION: The 214 turtle observing season can be broadly characterized by three main trends: 1. Turtle observation numbers have more than doubled since last year 2. Red-eared slider daily high counts are much higher than in any previous season and 3. The percentage of unknown turtle identification has dropped to an all-time low. Figure 17. Total Turtle Species High Count by Year High Count ofturtles 18 16 14 12 1 8 6 4 2 21 211 212 213 214 Species By Year PHX LAG Alpine BFT Figure 17 clearly illustrates that the turtle high count has drastically increased since last year. Western pond turtle numbers have increased from 34 to 41 and non-native turtle numbers have more than doubled since 213 from a high count of 6 to 168 turtles observed in a single day. The increase in turtle observations per site visit can be directly attributed to several hard working volunteers who have consistently spent long hours of observation at multiple different sites each week. This dedication to data collection has produced a much greater volume and quality of data than in previous years. Additionally, the training session this year was held on March 8 th, eight days earlier than the previous session and the observation season ended on June 7 th, three weeks later than the previous year, resulting in more data collection.
7 Figure 18. Daily High Count of Red-Eared Sliders Observation by Site 6 4 3 2 1 BFT Alpine LAG PHX 211 212 213 214 Figure 18 demonstrates the increase in red-eared slider daily high counts. At the Bullfrog Trail and Alpine Lake sites, daily high counts were 63 and 47 respectively, a dramatic increase from any previous year. High counts ranging from 8-63 were recorded on four different Bullfrog Trail site visits in March. A number of factors could have contributed to this increase, such as the rise in volunteer observations, and the purchase of a new spotting scope. On multiple occasions volunteers visited Bullfrog Trail and Alpine Lake for several hours at a time and reported unusually high numbers of redeared sliders. These observations were aided later in the season by the use of a spotting scope purchased to enhance the accuracy of turtle identification. It is likely that the combination of these factors during peak viewing season led to unusually high turtle observations. This data does not necessarily indicate a spike in the overall population, however, but may simply represent a more accurate estimate of the population.
Figure 19. Average Number of observations in onehour time windows 3 3 2 2 1 1 Turtle observation visits were conducted between 9: and 18:. Most turtle observing visits took about one hour, although there were instances of observations spanning over five hours. The weather and season can affect the best time to observe a turtle, but the consistent weather throughout the turtle observing period allowed for exploration of the best time window to observe turtles in this study. The best start time for turtle observing appears to be 12:-13: (Figure 19) during the heat of the day when turtles are basking in the sun. Peak turtle observation dates in 214 varied widely throughout the sites, however the majority of the high counts occurred in mid-march.
SUPPLEMENTAL TURTLE VIEWING LOCATION MAPS: http://marinwater.org/17/directions-maps-to-watershed-sites MMWD WATERSHED LANDS:
ALPINE LAKE BELOW BON TEMPE: LAKE LAGUNITAS: BULLFROG TRAIL: PHOENIX LAKE:
SUGGESTIONS FOR 21 SEASON: Find the resources and time to resume turtle trapping. The data shows a consistent population of non-native turtles living on the watershed. Involve a dedicated volunteer in the turtle trapping. Stress the importance of recording both a start and end time on the observer data sheets so an accurate number of volunteer hours can be recorded. Continue providing and insisting that the observers bring binoculars and/or the new spotting scope during data collection. Enter data as it comes in and make sure that no site is under-visited. If a site is, make sure the volunteers know about it and encourage them to go there. Reconfigure the data sheet so that total the number of volunteer visits and observing hours can be easily totaled. Send out bi-weekly turtle docent updates; include pictures when possible. Offer the training in early March and let volunteers know that the season will end the first weekend of June. This longer observation season leads to more data collection. Talk to the volunteers about the difference between non-native and unknown; some of them were using this interchangeably. Provided a guided tour of Phoenix Lake and of BFT ending at Bon Tempe Dam. One of these could be done at the initial training. Find a way to track nesting turtles, nests, eggs, etc.