Box Turtles

Since 1995, we have marked individual box turtles with a code. We've now marked over 500 turtles found within a 300-acre area of the Sanctuary. Volunteers and staff members record measurements on every box turtle found. From repeated sitings, we are mapping the home ranges of individual turtles. To learn more, read this article in the Bay Weekly.

 

   

 

 

 

 

 

 

 

 

 

 

 

 

 

Box Turtle Study in its 16^th Year

A summary by Mike Quinlan (2010)

 

Background

 

Monitoring of the Sanctuary’s noteworthy Eastern box turtle (Terrapene Carolina Carolina) population began in earnest in the late spring of 1995. During the intervening years we have gathered information through a combination of techniques: radiotelemetry and directed searches (Great Herp Searches and censuses), as well as casual encounters.  To date we have over 5,000 records on 558 individual, marked turtles.

 

Summary

 

2010 was a relatively slow box turtle field season, probably due to the very hot, dry summer we experienced. Turtles do not like to move about when the temperature is high and there is a lack of rain.  They will go into a period of sluggishness called aestivation, analogous to hibernation during cold weather. During this period they will remain under the leaf litter, in the cooler more moist soil. If they do move about, it will probably be into the tidal marshes adjacent to the river or in the wet parts of the Two Run floodplain, neither area where they are frequently encountered. Also, we did not do any radio telemetry in 2010, another reason we encountered relatively small numbers of turtles. Just the same, the ratio of males, females, and juveniles was similar to previous years’ results and therefore was representative of our box turtle population.

 

Total number of box turtle encounters - 55

(3 males and 5 females were seen more than once)

Males – 28

Females – 24

Juveniles – 2

Indeterminate sex - 1

 

Number of different box turtles encountered – 47

Males – 25

Females – 19

Juveniles – 2

Indeterminate sex - 1

 

Previously encountered (marked) turtles – 42

Males – 25

Females – 16

Juveniles – 1

Indeterminate sex - 0

 

 

New (unmarked) turtles – 5

Males – 0

Females – 3

Juveniles – 1

Indeterminate sex – 1

 

Highlights

 

No. 15, a record holder. This female was first captured on 26 May 1998. She served as a telemetry turtle for two seasons and is a denizen of our MAPS study area and a couple of the census plots we surveyed. She has been seen a total of 91 times over the years, the 2010 season record holder. She has been encountered in a total of 10 different years, seven of them consecutive (1998-2004).  The 2010 encounter was 12 years to the day after her first capture.

 

No. 82, a stealth turtle. This big boy, weighing in at 465 grams, was first captured on 3 June 1995, making him one of the earliest turtles ever marked. He has only been seen twice since then; in 2003 and 2010. Although this may seem unusual, his territory encompasses the floodplain of Two Run Branch, above and below the Railroad Bed. This is not an area where many casual encounters occur.

 

No. 128, the champ. This is a female first captured as an adult on 11 July 1995. She has been encountered 82 times since then, including in 15 of the 16 years of the study. In addition to the longevity record, she also holds the record for most consecutive years encountered – 12 (1995-2006)! A former telemetry turtle, she lives near the Otter Point Trail, in the area around the paths to the Observation Deck and the Marsh Boardwalk. No surprise that we see her quite often.

 

No. 265, where has he been? This turtle was first captured and marked on 30 July 1996 as a juvenile. It has only been seen twice since then: in 2006, considered a male then, and again in 2010. All three sightings have probably occurred within a circle of less than 10 meters radius right on the Forest Trail. This record illustrates one of the puzzles we have often considered, but have yet to solve. That is, why haven’t we seen this turtle more often? It lives in an area that is frequently visited and it has been seen repeatedly in the exact same location. This puzzle also illustrates the value of a continuous, long term study such as has been conducted on the Sanctuary. If there was only one sighting from 1996 and the study was terminated even in less than 10 years, we would have no additional records. The turtle might have been considered a “transient”, as some have postulated. However, three temporally separate encounters in the same location is indicative of permanence in the area. In general, males have been shown to have smaller home ranges and to do much less wandering than females, so this may just be a more cryptic individual whose territory is bordered by the Forest Trail.   He may, in fact, spend most of his time off the Sanctuary, as the spot where he has been found is just a few meters from the boundary.

 

No. 362, all grown up.  First captured and marked on 13 July 2001 as a juvenile, this female was encountered eight times since then, including four additional times in 2010, the most of any turtle last year. All sightings were near the Utility Road, not far from the Wetlands Center. By July 2005 she was considered to be a female. On 16 August 2010, she was found on the Wetlands Center lawn, mating with male No. 347 - obviously an adult now! No. 347, first captured on 2 June 2001, had only been seen one other time. He hangs out between the Otter Point Trail and the Utility Road, so it could be expected that these two would cross paths.

 

 

Conclusions

 

The past season was a slow one in terms of observing box turtles, but with juveniles, maturing and long-lived frequent repeaters, and new unmarked turtles being encountered, it shows the population is still dynamic. The identifiable remains of one dead turtle were found outside the study plot; No. 465, a female marked on 12 July 2005 outside our study plot and only encountered that one previous time.

 

The Sanctuary’s box turtle research project clearly illustrates the value of intensive, continuous, long term monitoring.  Comprehensive record keeping has helped us to determine accurately population size and structure, home ranges and territories, hibernation locations, seasonal activity patterns, and has demonstrated impressive site fidelity.   We have also developed and employed effective monitoring techniques and technologies.

 

Acknowledgements

 

Thanks to the following volunteers, students, researchers, and others who contributed to the study in 2010: MAPS banding crew, John Koontz, Frances Koontz, UC Santa Cruz West Nile Virus Team, Lindsay Hollister, Elaine Friebele, Tracy’s Elementary School students, Billy Heinbuch, Kevin Crocetti, Sandy Teliak, Jennifer Muro, Susan Blackstone, Amanda Chavenson, Lisa Chavenson, Granni Annie Campers, Susan Matthews, Andrew Cronin, Bob Williams, Karen Caruso, DNR Summer Campers, Jack Schultz, Mary Burton, Sarah Alley, Stephen Lyddane, Lothian Elementary School students, Robert Frezza, Rosemary Frezza, Pete Uimonen, Kim Elliott, and Chris Swarth.