Monday, October 24, 2011

GVI Jag Walks Restart With a Bang

The weekly walk from the GVI Biological Station in Jalova to the town of Tortuguero has commenced once again, after about a month of hiatus. These “Jag Walks,” as they’re referred to around base, are a physically challenging 15-mile hike on the beach, sometimes in the scorching sun, other times in the pounding rain (but never during lightning!), documenting the predation of jaguars on sea turtles and the presence and abundance of jaguar tracks on the beach. Only 2 weeks into my position as staff member with GVI, I was lucky to be given the chance to participate in a Jag Walk. Like many experiences down here, this would turn out to be quite a memorable day.

After gear preparation and a solid breakfast, the 5 of us (Benji, me/Kevin, Zach, Li, and Helen) started our walk at 5 AM. As there had been no jag walks for a while, we started encountering predated turtles immediately and rarely had much time or distance before the next. Sometimes the jaguars leave the turtles on the beach, while other times they drag them into the vegetation as much as 20 meters to have more privacy and secrecy, so finding the turtles often requires a keen eye. Each predated turtle was marked on the GPS, measured if the carapace (shell) was in intact, and photographed. In addition to the turtle work, we also collected information on the jaguar tracks on the beach, with special attention being given to the places where the jaguars enter or exit the beach.

We had expected quite a few jaguar tracks, but as the day went on, we found an even higher level than anticipated, with nearly every section containing tracks. Some sections had tracks of at least 3 different jaguars, including a cub, while other sections very close to people (near Tortuguero and near Jalova) also had tracks, which has not been typical until the last few years. There was definitely a mutual feeling of excitement among our group at finding so many fresh tracks of such an elusive animal. For predated turtles, we had expected to find upwards of 20 or 25 on the whole hike, but by Mile 10, slightly over half way, we had already encountered 38 predated turtles. We took a much needed break to eat lunch and decided that due to the slow pace this many turtles required, we would have to stop counting turtles and fast-track it to Tortuguero. Before packing up, Zach spotted a group of dolphins breaching the water a couple hundred meters out, improving an already good day. This wasn’t our only wildlife on the journey. We also found a Brown Wood Turtle down by the waves – an unusual place to find that species – and jaguar claw marks going up a tree near a predated turtle, but unfortunately no sign of the jaguar itself. The last section of a hike like this is always rather difficult, and this day was no different, but after 9 hours and 40 minutes of hiking we arrived in Tortuguero, looking like we had walked from South America, but in good shape aside from some sore feet and sweaty clothes. We promptly concluded and celebrated our day with some extremely satisfying and deserved pizzas and smoothies before catching our ride on the boat taxi back to base.

In addition to the usual turtle and jaguar work, there was also an unfortunate, yet important, part of the day. Signs of poaching were found on various turtles, and it was clear that poachers had scoured the beach the previous night, harvesting turtle meat and possibly eggs. Nonetheless, the day was undoubtedly a success and the information we collected will be very useful in our studies on jaguars. With the data collected by the group walking this coming week, we will have a full view of the jaguar predation over the last month. Despite the surprise of finding a shockingly high number of turtles, it does help reaffirm and validate the information that’s been coming in over the last few years, from GVI’s studies and from elsewhere, documenting the sharp increase in jaguar predation on sea turtles. This is a phenomenon that is still poorly understood, but is hypothesized to be due in large part to human impacts (habitat fragmentation, hunting of jaguar prey species, etc.). Therefore, these jag walks will continue to be a crucial part of the study and conservation of jaguars and turtles.

-Kevin Wells, Expedition Field Staff