{"id":6720,"date":"2026-06-07T22:12:52","date_gmt":"2026-06-08T03:12:52","guid":{"rendered":"https:\/\/vetmed.illinois.edu\/wel\/?p=6720"},"modified":"2026-06-07T22:17:50","modified_gmt":"2026-06-08T03:17:50","slug":"lake-county-week-3-tracking-and-trapping-turtles","status":"publish","type":"post","link":"https:\/\/vetmed.illinois.edu\/wel\/lake-county-week-3-tracking-and-trapping-turtles\/","title":{"rendered":"Lake County Week 3 – Tracking and Trapping Turtles"},"content":{"rendered":"

Both Jenna and Sathvik had a good week in the field, joined by some friends from the Terrestrial Turtle Team! Here are their updates:<\/p>\n

Sathvik:<\/strong><\/p>\n

To start off the week, Gail (part of the NEIU turtle team and helping with the Blanding’s project as well!) and I were left to track down some of our telemetry turtles. As you can imagine, locating a single turtle within even a few square meters of murky wetland can be quite the challenge!<\/p>\n

Radio telemetry is part of the toolkit of any good wildlife ecologist or veterinarian to track movement, relocate, and assess behavior of wild animals. A VHF (very high frequency) transmitter is attached to the animal which emits radio waves that can be detected by a VHF receiver. Transmitters come in many different forms depending on the species from backpack-like transmitters to even subcutaneous ones that are placed under skin. Transmitters require an antenna and power source, hence why it is important that transmitters are replaced regularly in case of damage or a drained battery. In our case, the VHF transmitter is affixed to the turtle’s shell with screws or epoxy. Each turtle is also on a schedule for transmitter replacements or re-touches on epoxy to ensure the longevity of the radiotelemetry data. Since Blanding’s turtles can live so long (70+ years!), it is important that our data is consistent and long-term to truly understand these animals throughout their life history.<\/p>\n

\"\"

Relocating turtles with telemetry requires an eagle-eye, can you find the turtle in this picture?<\/p><\/div>\n

To relocate the animal of interest, we use a VHF receiver to detect the electromagnetic signals from the transmitter. VHF receivers come in many different shapes, but we have some fancy new ones that are just the size of my water bottle. The receiver attaches via wire to a large handheld antenna which captures the radio waves emitted by the transmitter. Each animal’s transmitter emits radio signals at slightly different frequencies. By tuning our receiver to different frequencies, we can selectively “listen” for different individual animals. When it detects the radio waves that it is listening for, the receiver will give off an auditory beep. The beeps\/signals are loudest when the antenna is pointing in the direction of the transmitter.<\/p>\n

An important part of the receiver is the gain knob. According to Radar and ARPA manual (3rd edition, 2014), gain is defined as “a measure of the maximum effectiveness with which the antenna can radiate the power delivered to it by the transmitter towards a target”. Lucky for you, Sathvik didn’t do well in physics class so this means nothing to him as well. The best way for me to understand it in the context of wildlife radiotelemetry is that gain measures the sensitivity\/accuracy\/precision of the receiver to the transmitter. A high gain means that your transmitter is listening for ANYTHING that might be the transmitter. This works great when you are far away from your target and need a general direction to move towards. However, when you are closer to your target, a high gain will show a signal in any direction due to radio waves bouncing off of grasses, trees, buildings, etc. If you are getting close to your target, lowering your gain helps your receiver cut out that extra noise, letting you hone in on a more exact location.<\/p>\n

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Blanding’s turtle with attached radiotransmitter and antenna<\/p><\/div>\n

Actually locating a turtle using telemetry is a little bit harder than it sounds. The first step is determining the closest turtle to you (there is no valor in hiking across the preserve 7 times because you picked which turtle to track at random). First, you keep your gain on high to determine which direction to start moving towards. Once you’ve got your direction, just start walking! That said, there isn’t much sense to just blundering through the wetlands to follow your signal (kind of like in The Office when Michael drives into a lake). I like to stay on trails and dry land as much as possible, especially since the receiver isn’t waterproof! Typically, I’ll keep my antenna pointed toward the wetland that I suspect my animal is in while I walk along the perimeter. When my receiver is at its loudest, I know to get off the path and go into the marsh. Blanding’s turtles rarely like to be found, often burying into the mud or under brush and vegetation. It is important to trust your equipment, but to also know its limitations. For instance, buildings and forested edges can create a false signal by reflecting radio waves from the transmitter. At the same time, the transmitter should always be loudest when pointed at a turtle. This is especially helpful with murky water where you may not even be able to see the animal. At a certain point, you can point your antenna towards the ground, honing in on the animal’s location to within a square meter area. From there, it is up to you to get in and actually find your turtle whether they are furiously swimming away or buried under the mud. It is hard not to feel evolutionarily inferior by the 5th time a turtle has evaded you. You’d be surprised how stealthy these turtles can be and how quickly they disappear into the marsh!<\/p>\n

Once we have the turtle in hand, we can re-examine them and collect additional data. This time of year, we are especially interested in tracking them since it is almost nesting season. Animals have a hierarchy of needs that distributes energy for activities depending on need. This hierarchy typically is as follows: maintenance\/metabolism > immune function > (lactation) > growth > reproduction. An animal that only has enough energy for maintenance will not breed or have strong immune function.<\/p>\n

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Tagged Blanding’s turtle being relocated using VHF radio telemetry<\/p><\/div>\n

For all animals, reproduction is an energetically taxing time. For these turtles, it means producing 4-17 eggs, finding nesting habitat, and digging nests, all while also maintaining their body weight and immune function. Since we have already sampled these animals’ blood this month, we are just checking weights and determining whether our turtles are gravid (carrying any eggs). We can determine whether they are gravid by using our fingers to palpate in the space between their hind leg and the bridge of their carapace\/plastron. If they are gravid, you can feel ping-pong ball sized eggs within their body cavity.<\/p>\n

Studies like these provide long-term intensive understanding of Blanding’s turtle life history and health. When we sample animals via trapping, we are getting an overall understanding of the Blanding’s population throughout the season, but just snapshots of individual turtles and their health. By following individual turtles for longer periods of time, we can more accurately parse through confounding factors and understand how Blanding’s turtles change each year, month, and week of their life. Studies like this would be impossible to achieve without technology like VHF radio telemetry to relocate and recapture individual turtles. Plus, tracking these turtles each week helps you get in the mind of our shelled friends, improving our trapping ability as well.<\/p>\n

Jenna:<\/strong><\/p>\n

I returned from my much-needed vacation on Sunday. I had an incredible time! However, despite the fact that I was able to relax on breathtaking beaches of Kauai, drive an ATV through the rainforest, and enjoy delicious food and beverages, this trip was technically a failure. Everyone knows that the barometer of success of any trip is number of turtles seen per day (1 at minimum to pass). I saw 4 green sea turtles during my 6-day adventure, leading to a disappointing average of only 0.667 turtles seen per day (Sathvik isn\u2019t the only one on this team who can do math!). Clearly, something went wrong in the planning of our itinerary.<\/p>\n

Kidding aside, seeing the turtles was definitely the highlight of my trip! When kayaking up the Hanalei River, a sea turtle surfaced to take a breath about 5 feet away from me, and swam with us for a few minutes. I had no idea that sea turtles would venture so far up river, but the water there must still be brackish enough. I also got to swim with another sea turtle when snorkeling in the ocean and I almost cried.<\/p>\n

However, when I awok`e Monday morning, I was fully focused on our adorable aquatics<\/p>\n

\"Falling

Becca and Grace gracefully adapting to their wetland environment in Lake County.<\/p><\/div>\n

here in Lake County. WEL\u2019s previous studies have consistently identified May as the most likely month to detect viral DNA in our turtles, so we decided that we should conduct a large trapping effort this week, which we dubbed \u201cMini Blandings Bowl.\u201d Even though it is technically the first week of June, we are hoping we still captured this critical sampling period of the early season. With about 100 traps, we ultimately caught 33 Blanding\u2019s turtles this week, which is a solid result. My favorite part of the week was when Becca and Grace Daab of Box Turtle Team joined us for fieldwork on Tuesday. In addition to their great company, of course, it\u2019s always so much fun introducing terrestrial fieldworkers to the world of aquatics and watching them quite literally \u201cfall\u201d in love with the marsh :). I assure you that any claims of abandonment that may be mentioned on their blogs this week are entirely hyperbolic. I was always within 10 yards of them and it\u2019s not my fault that I\u2019m so speedy in the field.<\/span><\/p>\n

 <\/p>\n

To finish off my post this week, I thought I\u2019d take the opportunity to remind everyone (including our terrestrial team friends) of what makes a good turtle trap versus a bad turtle trap. We have the REAL Blanding\u2019s Bowl coming up in just a few short weeks, and everyone needs to be on their A-game by then!<\/strong>\u00a0So, here you go: a brief guide to setting a trap. Despite what last year\u2019s Blanding\u2019s Bowl standings may indicate, I do indeed know what I am doing, I swear.<\/p>\n

STEP 1: <\/strong>We need to understand the anatomy of the hoop net, our trap of choice.<\/p>\n

\"hoop<\/p>\n

The turtle enters via the mouth of the trap, which is centrally placed as shown by the arrow. Once it enters, it will not be able to exit due to the nature of the net which cinches together near midline. There are two strands of green twine connecting the two sides of the mouth. They must be placed parallel to the ground. Choosing an intact trap free of any holes is critical, to ensure your turtles are indeed trapped.<\/p>\n

STEP 2:<\/strong> Choose a location. Use your intuition to gauge the turtleyness of the environment. This skill is not easily explained and relies on experience and magic.\u00a0 Sometimes you will happen upon an area with built in \u201cturtle highways.\u201d This is a great place to put your trap. If you are catching lots of turtles but not the species you are aiming for, try switching up the type of habitat you’re choosing; each one has their own unique place in the marsh that they like to hang out in.<\/p>\n

STEP 3:<\/strong> Depth! This is the most critical element of trap placement because it can have severe consequences if done incorrectly.<\/p>\n

When parallel to the ground, the green twine acts as a perfect reference point for how deep your trap is. Aim for those strands to be submerged, but not by more than a few inches. Placing a shallow trap is useless as turtles will be unable to swim in. Placing a trap too deep means that a turtle that enters may not be able to surface to breathe once inside, which could lead to mortality. Obviously, we avoid this at all costs. We are going for a goldilocks approach, where the trap is deep enough for the turtle to swim in, but not so deep that it cannot breathe.<\/p>\n

\"depth

Trap depth: Too shallow, just right, and too deep.<\/p><\/div>\n

STEP 4: <\/strong>Bait your trap. Though it may seem hard to forget to do this step, it can happen! Always bait! As far as what you should bait with, just imagine that you’re a turtle stumbling upon this bait after 4 hot days submerged in wetland waters. What would be appetizing to you? I’m sure countless ideas are coming to mind.<\/p>\n

STEP 5: <\/strong>Mark your trap. Use brightly covered flagging tape and attach it to both the trap itself and a nearby reference point such as a branch or tall reed so that you can find your trap again the next day when you come to check it. If you\u2019re directionally challenged like me, dropping a pin in a GPS app is also a good idea.<\/p>\n

STEP 6: <\/strong>Put it all together! Here are images of a well-placed trap, with the correct depth, flagging tape attached, nestled in a \u201cturtle highway\u201d amongst the reeds. This trap is situated for success.<\/p>\n

\"Well

Well-placed Blanding’s turtle trap.<\/p><\/div>\n

\"well-placed<\/p>\n","protected":false},"excerpt":{"rendered":"

Both Jenna and Sathvik had a good week in the field, joined by some friends from the Terrestrial Turtle Team! Here are their updates: Sathvik: To start off the week, Gail (part of the NEIU turtle team and helping with the Blanding’s project as well!) and I were left to track down some of our […]<\/p>\n","protected":false},"author":1591,"featured_media":6755,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-6720","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/vetmed.illinois.edu\/wel\/wp-json\/wp\/v2\/posts\/6720","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vetmed.illinois.edu\/wel\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/vetmed.illinois.edu\/wel\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/vetmed.illinois.edu\/wel\/wp-json\/wp\/v2\/users\/1591"}],"replies":[{"embeddable":true,"href":"https:\/\/vetmed.illinois.edu\/wel\/wp-json\/wp\/v2\/comments?post=6720"}],"version-history":[{"count":7,"href":"https:\/\/vetmed.illinois.edu\/wel\/wp-json\/wp\/v2\/posts\/6720\/revisions"}],"predecessor-version":[{"id":6761,"href":"https:\/\/vetmed.illinois.edu\/wel\/wp-json\/wp\/v2\/posts\/6720\/revisions\/6761"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/vetmed.illinois.edu\/wel\/wp-json\/wp\/v2\/media\/6755"}],"wp:attachment":[{"href":"https:\/\/vetmed.illinois.edu\/wel\/wp-json\/wp\/v2\/media?parent=6720"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vetmed.illinois.edu\/wel\/wp-json\/wp\/v2\/categories?post=6720"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vetmed.illinois.edu\/wel\/wp-json\/wp\/v2\/tags?post=6720"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}