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How Far is Too Far for an Ant?

Thursday, June 26, 2014, by Ariel da Cruz Reis
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Everybody, at some point of their lives, has had some sort of contact with these little and fascinating beings! Of course, I am talking about ants. Ants are hard workers, some species are capable of carrying 100 times their own body weight; they are spread out all over the planet, except for Antarctica and Greenland; they represent a large portion of the biomass in many habitats, and, therefore, they consume and recycle a huge amount of organic matter, maintaining a proper nutrient cycle. It is amazing how many important roles they have and how much we know about them. However, there are still some gaps with respect to our knowledge about them. For example, have you ever thought about how far an ant would travel to find its food? This is a very simple question that few scientists have sought, and nobody really knows the answer. Moreover, this is very important information that is missing for scientists. When somebody studies the ants from any place, we usually need to collect them. Each collection is considered a sample of the place, and each sample is collected with a specific method. Unfortunately, the most common sampling methods used to collect ants are dependent on this piece of missing information: how far does each species of ant travel from its own nest?

[Two baits, in the background pecan sandies cookie crumbs and in the foreground oiled-tuna, on index cards and a measuring tape.]Motivated by the necessity of finding out an answer for this question, I decided to work on a project to measure the traveling distances of as many ant species as I can during this summer. My mentor, Professor Aaron Ellison, and I worked on an experimental design to better measure the excursions of these incredible insects. As I mentioned before, few researches have done this kind of work, and most published studies on foraging distances are from desert habitats. Since we are working in a forest with plenty of debris on the ground, our first challenge was to figure out if we would be able to follow the ants between their nests and food resources. After some discussions with mentors and teammates, I went to the field to test our ideas.

[Two species of ants at a tuna-fish bait.]Equipped with a meter tape, oiled-tuna, and pecan sandies cookies, I started in a hemlock-dominated section of the Harvard Forest. I defined a 20 m² area to work in, and set up some baiting. After a few minutes, the ants showed up! I was enthralled. From that moment I began behaving in a way that most people would consider indication of the loss of my sanity: I started to follow each step of the ants I found carrying my baits. It was indeed a little bit hard to keep track of them, since the path sometimes would lead the ants underneath leaves and sticks. Nevertheless, I was successful! In my first day I found 4 nests. Three of them were nests of the genus Aphaenogaster. One of them was a Camponotus nest, another genus. This last one traveled a distance of 8 meters from the nest to the bait!

I have had a great time here at the Harvard Forest. I am surrounded by marvelous people and working on an exciting project. I hope the information we are gathering throughout this summer helps other studies of ants to be more accurate. Thus, we will be able to appreciate even more these little splendid creatures.