The Lizard Log

The Langkilde Lab in Action

The Ants of Guana Island

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As Chris mentioned in a recently post, we both had the wonderful opportunity to do some research on Guana Island. And it was BEAUTIFUL!

The amazing view from my porch.

The amazing view from my porch.

Such clear water!

Such clear water!

But it was also exhausting! Getting used to temperatures in the 80s and 90s and the incredible humidity was a challenge we were to happy to meet. And it’s hard to complain about doing fieldwork on a beach…

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North beach!

North beach!

We had a number of projects to keep us busy. As Tracy described in a previous post, our lab and our collaborators are interested in how invasive fire ants (Solenopsis invicta) affect one of the world’s most endangered iguanas: the Stout Iguana (Cyclura pinguis).  (remember this guy?) This year, Chris and I wanted to address whether fire ants are capable of preying on iguana eggs while in the nest. Thanks to some of Chris’s previous research, we know that fire ants are potential threats to fence lizard eggs: they are capable of foraging at depths of fence lizard nests, can find artificial nests, and can get through the shell of the egg to obtain a meal.  We wanted to know if fire ants could get to depths approaching those of an Iguana nest, which are deeper than those of fence lizards. To do this, we installed fake “nests” next to clear plastic tubes in the beach and forested area nearby. This involved digging a hole roughly 16 inches into the soil (or sand!) and inserting a tube. We then placed slices of hot dogs (faux “eggs”) along the outside of the tube at a standard depth and filled in the hole with sand. Every afternoon, we checked our mock nests by sliding a small camera down the tube and taking video of the hot dogs through the tube wall. We immediately checked these videos to determine if any fire ants were present (or beetle larvae, as we observed in one case!).

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Chris digging a hole on the beach for our nesting experiment.

Tube in a hole before filling in.

Tube in place before we filled in the hole with sand.

During our stay, we also continued to survey the island for fire ant mounds. Our lab has collected this since we started working on Guana in 2010, and the resulting maps help us monitor the spread of fire ants on the island.

Looking for fire ant mounds...

Looking for fire ant mounds.

Crabs like peanut butter too!

Crabs like peanut butter too!

We also set up baits around the island to see which species of ants are actively foraging in the area. The fire ants love our peanut butter balls, but occasionally a crab would stake claim:

Chris and I had 6 days of hard work and amazing views, but we eventually had to return to the Pennsylvania fall. Next step: data analysis!

Taking in the view!

Taking in the view!

So incredible.

So incredible.

Goodnight Guana!

Goodnight Guana!

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Author: Gail McCormick

Science writer at Penn State University; papercrafter, ecologist, theatre-lover.

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