How Many Ants Are There?

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Over at Your Wildlife, Rob Dunn speculates:

How many ants are there in New York? The math is simple enough. We know from work that Britne Hackett and Benoit Guenard began (and Amy Savage is following up upon) that in a sample of one square meter of leaf litter there are about fifty ants, a village. Slightly more in the parks, slightly fewer in more stressed environments such as medians. But fifty is a good round starting place.

Now, how much green space is there in the city? We found one set of land use tables in which “open space” is a measure of part of the green space in the city; it does not include small patches of green such as medians or privately owned abandoned lots, but it is a starting point. If we multiply the number of ants in a square meter by the number of square meters in each borough and then double our estimate (to very conservatively account for the ants under ground at any moment) we get the following…

Lots_o_Ants

At a glance, those numbers don’t look great for people. But do they mean anything?

Functionally, would biomass be a more relevant comparison than body count? And, in light of the many simplifying assumptions underlying Rob’s calculation, might other methods be more accurate?

6 thoughts on “How Many Ants Are There?”

  1. I’ve got a doozy coming out in PLOS ONE on this topic soon with Robert Warren and Mark Bradford. Just wait. It is in final revision (hopefully) now.

    1. Josh, I was looking for that paper when Rob asked around the lab for estimates of ants in NYC! I even looked up your IUSSI abstract. In any case, I am also interested to see your paper when it comes out.

  2. Clint and Alex,
    Will do. In a nutshell, per meter square abundance and biomass of inverts in eastern temperate forests from CT to FL. Ants and termites are REALLY abundant. The numbers may blow your mind. Plus a handy table comparing much of the known per meter squared abundance from around the globe.

  3. Biomass is a useful comparator.

    How much resources (can be measured in biomass as well) a species consumes per unit biomass is another good comparator, which lets you compare energy flow.

    For instance, “warm-blooded” vs “cold-blooded” species comparisons indicate that a smaller biomass of homeotherms consumes the equivalent biomass to a much larger biomass of poikilotherms because of more energy consumed in cellular respiration, etc. Of course, nothing is ever simple; like when ants move brood to warmer exposures, or crocodilians do some internal temp adjustments.

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