Julia Ersan
Biography
Julia Ersan is passionate about contributing to applied research, particularly that which can help mitigate human-caused modification of the environment that has negative consequences for underrepresented wildlife populations. Julia finds behavioral adaption to anthropogenic alteration particularly fascinating. While at the USGS, her focal species has been the giant gartersnake (Thamnophis gigas). After learning about its basic ecology and serving as a field technician for a few years, Julia was able to develop her own project ideas and pursue a Master’s of Science while fostered at the USGS. Julia's graduate research focused on diet, prey preference and prey selection of the giant gartersnake. Currently, Julia manages USGS WERC's giant gartersnake field crew and helps work toward achieving project goals.
EDUCATION
- Master of Science, Biology, 2015, California State University, East Bay (Ecology and Conservation emphasis)
- Bachelor of Science, Wildlife, Fish and Conservation Biology, 2010, University of California, Davis (Behavioral Ecology specialization)
Science and Products
Distribution of giant gartersnakes (Thamnophis gigas) in the Sacramento–San Joaquin Delta, California, 2018–2019
SummaryWe examined the occurrence of giant gartersnakes in the Sacramento–San Joaquin Delta, California, in 2018 and 2019. We made eight captures of seven giant gartersnakes (three females, four males) in 2018, and six captures of six giant gartersnakes (four females, two males) in 2019. Detection probabilities were exceedingly low...
Fouts, Kristen J.; Kim, Richard; Jordan, Anna C.; Fulton, Alexandria M.; Rose, Jonathan P.; Ersan, Julia S. M.; Halstead, Brian J.
Demographic factors affecting population growth in giant gartersnakes
Demographic models provide insight into which vital rates and life stages contribute most to population growth. Integral projection models (IPMs) offer flexibility in matching model structure to a species’ demography. For many rare species, data are lacking for key vital rates, and uncertainty might dissuade researchers from attempting to build a...
Rose, Jonathan P.; Ersan, Julia; Wylie, Glenn D.; Casazza, Michael L.; Halstead, Brian J.
Findings from a preliminary investigation of the effects of aquatic habitat (water) availability on giant gartersnake (Thamnophis gigas) demography in the Sacramento Valley, California, 2014–17
The giant gartersnake (Thamnophis gigas) is a semi-aquatic species of snake precinctive to the Central Valley of California. Because the Central Valley has experienced a substantial loss of wetland habitat, giant gartersnake populations are largely found in aquatic habitats associated with rice agriculture. In dry years, less water may be...
Rose, Jonathan P.; Ersan, Julia S. M.; Reyes, Gabriel A.; Gustafson, K. Benjamin; Fulton, Alexandria M.; Fouts, Kristen J.; Wack, Raymund F.; Wylie, Glenn D.; Casazza, Michael L.; Halstead, Brian J. Reproductive frequency and size-dependence of fecundity in the Giant Gartersnake (Thamnophis gigas)
How reproductive output changes with age or size is a key life-history trait that can affect which demographic rates most influence population growth. Although many studies have investigated the reproductive ecology of gartersnakes, we know little about reproduction in the threatened Giant Gartersnake, Thamnophis gigas. We used X-...
Rose, Jonathan P.; Ersan, Julia; Wylie, Glenn D.; Casazza, Michael L.; Halstead, Brian J.
Construction and analysis of a giant gartersnake (Thamnophis gigas) population projection model
The giant gartersnake (Thamnophis gigas) is a state and federally threatened species precinctive to California. The range of the giant gartersnake has contracted in the last century because its wetland habitat has been drained for agriculture and development. As a result of this habitat alteration, giant gartersnakes now largely persist in and...
Rose, Jonathan P.; Ersan, Julia S. M.; Wylie, Glenn D.; Casazza, Michael L.; Halstead, Brian J.
Behavioral response of giant gartersnakes (Thamnophis gigas) to the relative availability of aquatic habitat on the landscape
Most extant giant gartersnake (Thamnophis gigas) populations persist in an agro-ecosystem dominated by rice, which serves as a surrogate to the expansive marshes lost to flood control projects and development of the Great Central Valley of California. Knowledge of how giant gartersnakes use the rice agricultural landscape, including how they...
Reyes, Gabriel A.; Halstead, Brian J.; Rose, Jonathan P.; Ersan, Julia S. M.; Jordan, Anna C.; Essert, Allison M.; Fouts, Kristen J.; Fulton, Alexandria M.; Gustafson, K. Benjamin; Wack, Raymund F.; Wylie, Glenn D.; Casazza, Michael L.