New paper on habitat restoration impacts on box turtles

Eastern Box Turtle growth is influenced by environmental conditions which in turn can be influenced by vegetative structure. Removal of Autumn Olive and Russian Olive at a site in Illinois occurred during a 16 year mark-recapture study allowing us to analyze impacts of removal on the growth of turtles. The data showed that removing the invasive plants may not negatively impact the growth of the turtles and that growth is variable by individual. This is attributed to reptile growth being influenced by more than just environmental conditions, including genetics.

Read the paper: Edmonds, D., A.R. Kuhns, and M.J. Dreslik. 2020. Eastern Box Turtle (Terrapene carolina carolina) growth and the impacts of invasive vegetation removal. Herpetological Conservation and Biology 15(3):588–596.

Using three decades of data to save turtles

Champaign, IL – Protecting and restoring habitats are the most important steps that can be undertaken to protect turtle populations into the future according to a pair of recent papers analyzing 3 decades of data.

The Spotted Turtle, Clemmys guttata, is a small semi-aquatic turtle that inhabits sedge meadow, cattail marsh, wet-mesic prairie, and dolomite prairie in Illinois. It is protected as an endangered species in Illinois, which is at the western edge of its range. The two known populations in Illinois have been the focus of mark-recapture studies since 1988.

Recent analysis found that Spotted Turtle populations are limited by the amount of available habitat, suggesting that management efforts should focus on increasing suitable habitat. Control of cattails (Typha sp.) and restoration of sedges would increase the amount of available habitat.

Adults have a higher survival rate than younger turtles. Predators including raccoons and muskrats can eradicate eggs and juvenile turtles. While caging nests and headstarting juveniles will help the younger turtles, controlling predator populations could benefit all age classes.

Feng, C.Y.; Ross, J.P.; Mauger, D.; Dreslik, M.J. A Long-Term Demographic Analysis of Spotted Turtles (Clemmys guttata) in Illinois Using Matrix Models. Diversity. 2019, 11, 226. doi:10.3390/d11120226

Feng, C.Y.; Mauger, D.; Ross, J.P.; Dreslik, M.J. Size and Structure of Two Populations of Spotted Turtle (Clemmys guttata) at Its Western Range Limit. Herpetological Conservation and Biology 14(3):648–658

 

Radio telemetry used to improve environmental DNA use

Alligator Snapping Turtle

Environmental DNA (eDNA) is an emerging tool used to detect rare and difficult to detect species. A recent study by INHS PACE Lab herpetologists used radio telemetry to evaluate and improve the efficiency of this technique.

As part of a species reintroduction program, hatchling Alligator Snapping Turtles reared in captivity were tracked using radio telemetry to assess their survival. This work provided an ideal system for evaluating the efficacy and limitations of using eDNA to detect a bottom dwelling riverine turtle. At each radio location, water samples were collected as well as upstream and downstream of the turtle.

The researchers found that eDNA can be used to detect a benthic turtle species but that detection can be diminished by UV exposure from open canopy. This study shows the importance of continuing to use traditional methods such as radio telemetry to better understand the dynamics of eDNA in the environment.

 

Read the complete paper in Environmental DNA

New Publication on Spacial Ecology of Softshell Turtles

Read the complete article at https://www.mdpi.com/1424-2818/11/8/124:

Ross, J.P.; Bluett, R.D.; Dreslik, M.J. Movement and Home Range of the Smooth Softshell Turtle (Apalone mutica): Spatial Ecology of a River Specialist. Diversity 2019, 11, 124.

A new paper by INHS PACE Lab herpetologists examined the movement of the state listed Smooth Softshell Turtle, Apalone mutica, a riverine species. Spatial ecological information is necessary to guide the conservation efforts of river turtles. Turtles were radio tracked and found to move on average 142 m per day, but moved more when water was high or streams were larger. In most situations, females moved greater distances than males. This work will guide future studies of riverine species.

The Enigmatic Asian Clam

Photo by L. Brian Stauffer Illinois News Bureau

UBAP Malacologists Sarah Douglass and Jeremy Tiemann wrote an article for the Fall 2018 issue of Illinois Audubon: “The Enigmatic Asian Clam.” Asian Clams are an invasive species that became established in the Midwest in the 1960s. Douglass and Tiemann identified an unknown species of Asian Clam found in the Illinois River in 2015 and have been studying its distribution. They plan to examine the effect of Asian Clams on the growth of native mussels in Illinois streams.

UBAP Malacologists Sarah Douglass and Jeremy Tiemann wrote an article for the Fall 2018 issue of Illinois Audubon: “The Enigmatic Asian Clam.” Asian Clams are an invasive species that became established in the Midwest in the 1960s. Douglass and Tiemann identified an unknown species of Asian Clam found in the Illinois River in 2015 and have been studying its distribution. They plan to examine the effect of Asian Clams on the growth of native mussels in Illinois streams.

The article is available from Illinois Audubon or by contacting the authors.

Illinois Audubon Magazine

Iowa Darter might not be as rare as believed

netting in ditchUBAP Ichthyologist Andrew Stites wrote a field account for the Illinois News Bureau’s Behind the Scenes to accompany a recent paper by Josh Sherwood, Andrew Stites, Michael Dreslik, and Jeremy Tiemann.

The paper, “Predicting the range of a regionally threatened, benthic fish using species distribution models and field surveys” developed a species distribution model for the state endangered Iowa Darter, after finding it in several new locations. This work was sponsored by the Illinois Tollway.

Read the Behind the Scenes: Finding darters where no one thought to look

Read the paper in The Journal of Fish Biology

Rising temperatures could benefit the Snapping Turtle

Rising temperatures could benefit the Common Snapping Turtle.

CHAMPAIGN, ILL. — A recently published study of snapping turtle nests at Gimlet Lake in Garden County Nebraska from 1990 – 2015 found that warmer fall temperatures positively correlate to larger eggs and larger numbers of eggs, while warmer spring temperatures are negatively correlated with egg size and number.

Nesting females were observed and after depositing eggs, captured, measured, marked, and released. The nests were excavated and eggs were counted and measured before being reburied.

Maximum egg size is limited in many turtle species by the size of the female, specifically the pelvic aperture, thus surplus resources are used to develop a greater number of eggs rather than larger eggs. Although this limitation is present in many species of turtles, it was clear a different pattern existed within Snapping Turtles (Chelydra serpentina). Large adult snapping turtles are not restricted in the size egg they can produce and in warmer years, produced larger eggs but the same number. Small adult snapping turtles, on the other hand, did not increase the size of their eggs, but produced larger clutches in warmer years.

Most temperate zone turtles begin developing their embryos in the fall, suspend development over the winter, and complete development in the spring. Snapping turtles complete the majority of their development in the fall, which may reduce the impact of winter and spring climate conditions.

Forming the eggs in the fall may enable snapping turtles to lay their eggs earlier and provide their young an advantage over other species. Herpetologist Michael Dreslik said,“Generalists like the Snapping Turtle tend to be more adaptable. The added benefit from warmer temperatures could allow Snapping Turtles to gather more resources for larger eggs or larger clutches.”

The mechanisms by which warmer temperatures influence egg and clutch size are unknown. Turtles are ectotherms, thus metabolism and physiology are impacted by environmental conditions.

“Warmer temperatures increase metabolism, but could result in greater food availability and more efficient processing of the food. Warmer temperatures could also affect the physiology of embryo development,” said lead author Ashley Hedrick. “Alternatively, in the spring, increased metabolism before food is readily available may require females to divert energy from egg development.”

While rising temperatures are generally considered problematic for most species, they could play in favor of the Snapping Turtle.

The paper “The Effects of Climate on Annual Variation in Reproductive Output in Snapping Turtles (Chelydra serpentina).” is available online from the Canadian Journal of Zoology.


Corresponding author: J.B. Iverson email:
To reach Ashley Hedrick, email arhedri11@gmail.com
To reach Michael Dreslik, email dreslik@illinois.edu
Photo by Jason P. Ross