Citizen Scientists find my seal!

Back in August, we started the story of Toby and Xena (link), two juvenile elephant seals that are part of my graduate research investigating how marine mammals thermoregulate while diving.

I don’t know if researchers are allowed to have favorites, but Toby definitely had me and my team feeling grateful for such a cooperative seal, which made the translocation part of our fieldwork a breeze.

The only thing I can say that was slightly more of a hassle was when he decided to haul out at Piedras Blancas instead of coming back to Año Nuevo. Since finding our seals at the end of their translocation is essential for recovering the tags and downloading data, this meant a 3.5-hour drive down to Piedras Blancas instead of a short half hour drive north of Long Marine Lab (yellow star on map).

Compared to Año Nuevo, the expansive coastline at Piedras Blancas makes it more challenging to find our seal on one of the many small beaches amongst the bluffs. All we have to go on initially is satellite hits that tell us the seal is somewhere in the area, but the location estimate could have an error greater than 1 mile.

The only way to pinpoint which beach the seal is likely hauled out on is to use a VHF antenna and receiver to scan the area for the signal being transmitted from the VHF tag attached to the seal. This technology is used in all kinds of wildlife research, for example to study an animal’s habitat, home range, movement and migration patterns (from fish to anteaters to bees). While VHF does not work in seawater (due to its electrical conductivity), we use it to locate our seals once they are back on land.

VHF stands for Very High Frequency and is a form of telemetry that uses radio waves (a type of electromagnetic (EM) wave) of a frequency range considered to be “very high” (30-300 MHz) to transmit a signal that can be picked up by the receiver’s antenna. The antenna converts the EM wave into electrical currents which ultimately produces an audible pinging signal (Listen to the clip to hear what it sounds like!).

Sounds like an expensive and pretty complex piece of gear, right? At least I thought so, which is why I was really impressed when I heard through word of mouth about Leo and Peggy’s homemade VHF! Leo, a former ham radio operator, and Peggy, a retired cardiac surgery nurse, started volunteering as docents with the Friends of the Elephant Seal (FES) at the Piedras Blancas elephant seal rookery after nine years of volunteering for The Marine Mammal Center in Morro Bay so they are very familiar with elephants seals, both in the wild and in rehabilitation. When the current FES president, Kathy Curtis, mentioned how neat it would be if FES docents started to keep a look out for tagged elephant seals at the Piedras Blancas rookery, it sparked an idea in Leo. Being informed about current elephant seal research and how VHF telemetry is used to find seals that have been instrumented, Leo got to thinking about all the radio equipment he has at home from his career and realized all he really needed was an antenna to scan for seals with VHF transmitters.

So Leo and Peggy put together an antenna using readily available materials, including PVC piping and metal rods, and tried it out on the bluffs using a general purpose radio receiver that would allow them to tune to different frequencies to search for specific VHF signals. While it did work, Leo realized the broad bandwidth of this receiver was not ideal for the weak signals coming from the radio tags. With his 45 years of experience working with radio technology, he was able to set the radio to a different receiving mode, commonly called morse code reception, which has a narrower bandwidth allowing for greater sensitivity to detect weaker radio signals. So now, while working as docents out on the bluffs they can take an active part in the science with their DIY VHF!

Leo and Peggy, docents with the Friends of the Elephant Seal (left picture), built their own VHF antenna to use at the Piedras Blancas rookery. Leo in the background listening for signals received by his VHF antenna (right picture).

Excited to meet Leo and Peggy and see their VHF, I told them about how my seal, Toby, was likely on one of their beaches and how I was planning to head down to Piedras Blancas the next morning with a lab mate, Rachel, in search of him. I explained how I had a very rough location estimate based on the satellite hit and that we would probably need to scan from a lot of different locations along the bluffs to determine where Toby could be. I recalled how we had done this just the year before to find my other seal, C.J., and that it was pretty tricky to narrow down which beach to look for C.J.

By using a directional Yagi-Uda antenna, we can determine the direction from which the signal is transmitting. To narrow down the location of the signal, scanning from different locations will yield a probable location as the directions of the signal will intersect across a smaller area. We can scan from different locations from on top of the bluffs to determine if our seal is likely on that beach or the next one over.

I was so delighted to learn that Leo, Peggy and other docents were enthusiastic about helping me out—the next morning they were up early on the bluffs with their VHF scanning for Toby. As Rachel and I were driving down, we get a call—it’s Leo saying he’s heard our seal! Rather, he heard the pinging signal on his VHF radio that was picking up on the VHF signal transmitted by Toby’s VHF tag. Based on the directionality of the signal, they were even able to narrow down Toby’s location to a certain beach—Cappuccino Cove.

This made our job so much easier—Rachel and I headed straight to Cappuccino Cove and an hour or so later when we arrived, we still heard the signal with our own VHF receiver. So we went down on the beach to search for him and sure enough, he was there, sleeping on the beach.


After recovering my tags, I was excited to tell Leo and Peggy they were spot on with their predicted location and see their neat VHF antenna and radio. Leo recounted how finding Toby was a team effort:

Trying to find an animal by just visual means is very difficult particularly because animals are flipping sand on their backs which makes spotting the radio tag even more difficult…When I arrived at the bluff to look for your seal, Phil [another well-seasoned FES docent] had been there for more than half an hour with a spotting scope trying to locate the seal. Using the radio and antenna, I pointed him in the right direction. He was looking at the wrong part of the beach. This made a believer out of him to use radio tracking equipment.

I was truly impressed and very grateful for their help—they really went above and beyond as citizen scientists!

Written by: Arina Favilla, Graduate Student at the University of California, Santa Cruz

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