Population Structure, Growth, Survivorship, and Reproduction of Actinemys marmorata from a High Elevation Site in the Tehachapi Mountains, California

Western Pond Turtles (Actinemys [Emys] marmorata) occur in habitats ranging from large rivers and reservoirs to small streams and ponds, as well as from sea level to about 2000-m elevation. This range of environments can affect population parameters such as body size, growth rates, survivorship, and reproductive output. We marked 321 individuals in 287 trap-days in 2007 and 2010 at a high-elevation pond on the southern flank of the Tehachapi Mountains in Southern California, USA. The population was female-biased (92 F:78 M in 2007, 113 F:60 M in 2010), and estimated to contain 412 individuals. Growth rates were relatively high compared with other populations of A. marmorata. Monthly survivorship was 0.989-1.000 for adults and juveniles and lambda values denoted a stable population. Clutch size averaged 6.3 eggs, and we found 22 instances of intra-annual double-clutching, and possibly a third clutch for one female. Population traits of turtles at this high-elevation pond differed little from turtles at lower elevation sites at the same latitude. Despite conservation threats to this species, this population is indicative that A. marmorata can survive well in small habitats, many of which are human-created, and this has increased the amount of habitat for the species as other natural areas have been eliminated.