An inexpensive box trap with potential to improve welfare ...

Introduction

The cryptic behaviour and patterning of many reptiles and amphibians can make detection during sampling efforts difficult. Trapping is often a preferred method for sampling these taxa and can be more effective than alternatives such as visual encounter surveys (Bartman et al., 2016). Although myriad kinds of traps are available for capturing herpetofauna (McDairmid et al., 2012), unique designs are continually desired for improving cost, construction, and capture efficiency.

In addition to ensuring traps actually capture animals, efforts to improve welfare of trapped individuals is of great importance. Morbidity and mortality can occur in traps due to factors such as stress and dehydration (Enge, 2001), and the traps themselves can cause injury to captured herpetofauna (McDairmid et al., 2012). Traps that show promise for reducing these effects are thus needed (Semeñiuk et al., 2017; Moore et al., 2019). We describe and demonstrate use of a novel box trap design for sampling small terrestrial herpetofauna. Our

goal was to create an inexpensive, easy-to-construct trap made from readily available materials that is potentially safer for and could improve welfare of captured individuals compared to existing designs.

Materials and Methods

This work was conducted at Fort Custer Training Center (FCTC), a United States Army National Guard training facility located near Battle Creek, Michigan, USA (42.1752°N, 85.1943°W; area ca. 3035 ha). Trapping efforts occurred from August–November 2017 and May–July 2018. We placed traps in two open, sandy areas on FCTC primarily in an attempt to capture hatchling Eastern Box Turtles (Terrapene carolina, Linnaeus, 1758) for comparing behaviour and survival to captive-reared and released conspecifics using radio-telemetry (Tetzlaff et al., 2019). However, we expected to trap other herpetofauna given they have been detected in these areas on FCTC during previous survey efforts (Tobin, 2005).

All trap materials were purchased from Menards® (Menards, Inc., Eau Claire, Wisconsin, USA). We constructed traps using 39 cm x 29 cm x 18 cm 13.2 L clear, plastic boxes (F&M Tool and Plastics, Inc./Bella Storage Solution, Leominster, Massachusetts, USA). We drilled several small holes in the lid and bottom of each box to allow air exchange and rainwater to drain, respectively, once placed in the field. After making an appropriately-sized hole with a power drill and hole saw, we installed a 4.45 cm diameter 90o hub x hub

Herpetology Notes, volume 13: 151-155 (2020) (published online on 14 February 2020)

An inexpensive box trap with potential to improve welfare of captured herpetofauna

Sasha J. Tetzlaff1,2,*, David C. Messmann3, Jinelle H. Sperry1,2, and Brett A. DeGregorio1,2

1 Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.

2 Ecological Processes Branch, US Army ERDC-CERL, Champaign, Illinois 61822, USA.

3 Independent researcher, Fort Wayne, Indiana 46805, USA.* Corresponding author. E-mail: [email protected]

Abstract. Trapping is frequently implemented when sampling for herpetofauna, and efforts to improve welfare of trapped individuals are continually needed. We demonstrate use of a novel box trap that is inexpensive to construct (~$5 USD per trap) and may have potential to improve welfare of captured terrestrial herpetofauna, such as by decreasing injuries, buffering effects from climatic extremes, and reducing tampering by predators. Additionally, we suggest our trap offers numerous user-friendly advantages over existing designs. Through further testing and validation, we propose this trap design could prove useful among the numerous current options available to researchers.

Keywords. Amphibian, Inventory, Monitoring, Reptile, Sampling

Sasha J. Tetzlaff et al.152

long-turn PVC elbow on each of the short ends of each box and secured the pipes to boxes using PVC glue (Fig. 1A). Excluding the price of PVC primer and glue (~$7 USD), which can be used for up to 30 traps, each trap cost approximately $5 USD to construct (Table 1).

We employed a total of 24 traps between the two sites. To facilitate animal capture, traps were placed along three straight-line 30 m long x 1 m tall drift fences made from erosion (silt) fencing attached to wooden stakes. Traps were partially buried into the ground so the opening of PVC pipes were flush with the ground, and we often placed vegetation around traps in a manner intended to funnel animals to the PVC openings (Fig. 1B). We put a handful of soil in each trap to aid in moisture retention and provide burrowing substrate. We placed four pairs of traps evenly-spaced apart on each side of each drift fence (Fig. 1C) for a total of eight traps per fence. In an

attempt to reduce damage to traps and depredation of captured animals by mammalian predators, we placed cement bricks on each trap lid (Fig. 1C). Traps were checked at least once (but often twice) per day, and we noted any vertebrate species found in the traps. We covered the openings to the PVC pipes with concrete bricks on days when traps were not open.

Results

We detected two amphibian and four reptile species in traps (Table 2). Juvenile and adult herpetofauna were caught (Fig. 2A–C). All captured reptile species were also incidentally encountered in the same area traps were placed (and no other ones were), but we did not detect either amphibian species visually. Thus, species captured in our traps likely represent the main herpetofauna occupying these areas (Tobin, 2005). Multiple conspecific amphibians were often captured in a single trap, but reptiles were found only in isolation. Notably, a captured hatchling Eastern Box Turtle re-entered a trap on the same trap line where it was originally captured (Fig. 2C). We observed no mortality or apparent morbidity of captured herpetofauna. We also captured a Meadow Jumping Mouse (Zapus hudsonius, Zimmermann, 1780), an unidentified passerine, and numerous unidentified insect and arachnid species.

Discussion

Our box trap design has potential to improve welfare of captured animals compared to other trap types. For instance, unlike simply dropping into a bucket, which frequently occurs with pitfall traps (McDairmid et al., 2012), our design could allow animals to more easily

Table 1. Materials and associated costs ($USD) for constructing a single box trap. Note that one unit of PVC primer and glue costs approximately $7, and the price reflected in the table is per trap.

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Table 1. Materials and associated costs ($USD) for constructing a single box trap. Note that one unit of PVC primer and glue costs approximately $7, and the price reflected in the table is per trap. Item Cost

13 L clear box with lid $ 2.99

90 degree PVC elbow (2 @ $0.71 each) $ 1.42

PVC primer and glue $ 0.23

Cement brick $ 0.99

Total per trap (excluding sales tax) $ 5.63 Table 2. Amphibian and reptile species captured in box traps at Fort Custer Training Center, Michigan, USA, months of capture, and age classes of captured animals. Traps were open from August–November 2017 and May–July 2018.

Class Month(s) captured Age class

Amphibia

Eastern American Toad (Anaxyrus a. americanus, Holbrook, 1836) May, August Adult

Eastern Red-backed Salamander (Plethodon cinereus, Green, 1818) October Adult

Reptilia

Blue Racer (Coluber constrictor foxii, Linnaeus, 1758) May, June, August Adult and juvenile

Eastern Box Turtle (Terrapene carolina, Linnaeus, 1758) October Juvenile

Eastern Gartersnake (Thamnophis sirtalis, Linnaeus, 1758) August Adult

Eastern Hog-nosed Snake (Heterodon platirhinos, Latreille, 1801) June Adult

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Table 1. Materials and associated costs ($USD) for constructing a single box trap. Note that one unit of PVC primer and glue costs approximately $7, and the price reflected in the table is per trap. Item Cost

13 L clear box with lid $ 2.99

90 degree PVC elbow (2 @ $0.71 each) $ 1.42

PVC primer and glue $ 0.23

Cement brick $ 0.99

Total per trap (excluding sales tax) $ 5.63 Table 2. Amphibian and reptile species captured in box traps at Fort Custer Training Center, Michigan, USA, months of capture, and age classes of captured animals. Traps were open from August–November 2017 and May–July 2018.

Class Month(s) captured Age class

Amphibia

Eastern American Toad (Anaxyrus a. americanus, Holbrook, 1836) May, August Adult

Eastern Red-backed Salamander (Plethodon cinereus, Green, 1818) October Adult

Reptilia

Blue Racer (Coluber constrictor foxii, Linnaeus, 1758) May, June, August Adult and juvenile

Eastern Box Turtle (Terrapene carolina, Linnaeus, 1758) October Juvenile

Eastern Gartersnake (Thamnophis sirtalis, Linnaeus, 1758) August Adult

Eastern Hog-nosed Snake (Heterodon platirhinos, Latreille, 1801) June Adult

Table 2. Amphibian and reptile species captured in box traps at Fort Custer Training Center, Michigan, USA, months of capture, and age classes of captured animals. Traps were open from August–November 2017 and May–July 2018.

An inexpensive box trap with potential to improve welfare of captured herpetofauna 153

Figure 1. Box trap viewed from above with lid removed (A), trap placed along a drift fence with vegetation positioned to funnel animals to the trap (B), and cement bricks placed on top of trap lids to deter tampering by predators (C).

transition into traps by minimizing the distance they fall. Wire or box traps often consist of a cube made from wood and/or hardware cloth, and materials such as wire mesh are formed into a cone shape to act as funnels for animals to enter the box (e.g., Murphy et al., 2018). Although such traps can effectively capture herpetofauna, wire mesh funnels can have sharp ends. Thus, using a PVC elbow as a funnel likely results in reduced injuries to captured animals as well as researchers. Traditional box or wire traps are also generally not protected from direct exposure to sunlight unless additional material such as shade cloth is added. Because our traps were mostly buried in substrate, they likely offer protection from the deleterious effects of prolonged exposure to UV light, which can be especially detrimental to amphibians (Licht and Grant, 1997). This could also improve animal welfare if traps are thermally buffered from extreme and fluctuating temperatures compared to traps simply laid on the surface. Further, firmly buried traps could decrease the likelihood of them being excavated by dexterous predators, which might be highly inclined to depredate captured animals.

We suggest our trap offers numerous user-friendly

advantages over existing designs. For example, the trap lids can be removed with ease, facilitating fast monitoring. This also permits easy removal of captured animals, which could be especially useful for venomous or other species requiring skilful handling techniques. When not open in the field, the funnels on the traps could be covered with a plastic cap or the like. These lightweight traps are simple to transport and also easily stacked on one another, facilitating storage.

Another advantage to these traps is they are relatively simple and cheap to construct. The minimum materials required to assemble the traps themselves cost ~$5 USD, and researchers often have many of the tools necessary to construct and install them (e.g., power drill, shovel). The compartment holding captured animals consists of a simple plastic box, which can be purchased at most commercial stores. Thus, aspects of our design such as box and funnel sizes, box material, coloration, and transparency can be modified to meet researchers’ unique needs.

We acknowledge our trap has limited utility for sampling arboreal and aquatic herpetofauna and is likely best suited to capturing small-bodied species.

Sasha J. Tetzlaff et al.154

Figure 2. Sample of species detected in box traps placed in open sandy habitat at Fort Custer Training Center, Michigan USA: adult Red-backed Salamander (Plethodon cinereus) (A), juvenile Blue Racer (Coluber constrictor foxii) (B), and hatchling Eastern Box Turtle (Terrapene carolina) with radio-transmitter attached to the carapace (C).

However, this design could be valuable for trapping terrestrial species or age classes that are typically challenging to capture. For example, juvenile turtles are notoriously difficult to detect during visual encounter surveys. Although we caught only a single individual, it was nevertheless encouraging that we captured a hatchling Eastern Box Turtle given American box turtles (Terrapene spp.) can exhibit strong avoidance of other trap types such as pitfalls (Gibbons and Semlitch, 1982; Christiansen and Vandewalle, 2000). Through further testing and validation, we propose this trap design could prove useful among the numerous current options available to researchers.

Acknowledgements. All research was conducted under an approved protocol by the University of Illinois Institutional Animal Care and Use Committee (#16017) and Scientific Collector’s Permits granted by the states of Michigan and Illinois (#NH17.5980). This work took place during a project supported by the United States Department of Defense’s Environmental Security Technology Certification Program (Project Number: RC-201616). We thank Michael Ravesi and the Herpetology Notes editor and reviewer for valuable feedback on the manuscript. Charlotte Robinson, Brian Huggett, Jim Langerveld, and Bruce Kingsbury facilitated work at Fort Custer Training Center.

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Accepted by Anamarija Zagar

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