It’s amazing how much more you can see when a dozen pairs of eyes are looking. We drove out to the central Minnesota prairie early yesterday morning to participate in a BioBlitz event organized by the Land Stewardship Project — i.e., walk the prairie and record as many species as you can find.
Although we originally split up into a bird team and a plant team, we ended up recording everything we saw, which included a few more flowering plant species (47) than bird species (31).
We had driven by The Nature Conservancy’s Sheepberry Fen property several times, but never walked it. In addition to the rarer plant and animal species that occur there, the area features a collection of calcareous fens fed by alkaline (high calcium and magnesium) ground water.
The weather looked ominous, with a giant storm front parked over central Minnesota, but it didn’t start raining until we had walked around for three hours and were eating lunch under cover.
The prairie was burned this spring to control invasive Red Cedar and other woody species, but was only partially successful as indicated by the dead lower branches of the larger trees in the foreground. Many of the spring blooming perennials were set back and were still flowering, just as the summer blooming species were starting.
Most of the birds were spotted from afar as they flew over us or perched in remote trees. Even on a dreary, cool morning, the birds were pretty active, if not highly visible nearby. However, the insects were mostly absent: a few Halloween Penant dragonflies and one Widow Skimmer comprised my entire species list for that group. We saw one or two Monarch butterflies (there were at least three species of milkweed blooming in our patch of the prairie), a couple of small unidentified skippers, a few flies (no mosquitoes were even out to “bug” us), and just a couple of bees.
However, we did see a few other unusual species that would not have been obvious without the help of those dozen pair of eyes, studying the ground as we walked.
A mound of Thatching Ants, about 18 inches high and 2-3 feet across stuck up out of the prairie floor. This relatively large-bodied ant can form “supercolonies” that are connected below ground. One such supercolony found in Oregon contained 251 nests and over 56 million ants!
A closer view reveals at least two castes (red-headed and black-headed) working on the top of the mound. I might entitle this photo “organized chaos”, but these ants have a system for adding vegetation they collect from around the mound to build it even higher.
Thatching Ants (Formica obscuripes) build their mounds in the sandy soils of arid scrub, old fields, and prairies, but they forage widely to feed on insects and milk the honeydew of aphids that they tend on plants near the mound. Through solar radiation and the heat provided by decomposing vegetation, the mound remains warm during the cooler months, and ants remain active repairing and adding to it. Some have lasted up to 40 years and reach a meter in height.
A Soldier Fly (Odontomyia cincta) was spotted on a tiny Whorled Milkweed plant. Its distinctive green and black body and huge brown eyes made it easy to determine its identity with the help of BugGuide.net.
The soldier fly appeared to be almost comatose on this cool morning. Normally these flies feed on flower nectar as adults, so they might be good pollinators of prairie plants. They lay their eggs near the shores of slow-moving water (like a fen), where their larvae feed on pond algae and are important food sources for other aquatic invertebrates like dragonfly naiads.
When you’re looking at tiny plants, sometimes you find tiny animals, like this prairie millipede. About an inch long with double sets of legs in each segment, he was scurrying along. According to BugGuide, this might be the species (Pleuroloma flavipes) that herds its young in huge densities through forest litter.
Sharp eyes detected movement in the crack of a rock, and we found a Prairie Skink (Plestiodon septentrionalis) hiding there.
We were lucky to see this guy (gal?), because they are quite secretive and usually not seen in the open. During the breeding season, males sport an orange throat, so perhaps this is a female.
Skinks have very smooth scales and look shiny. They tend to lose their tails rather easily when snatched by a predator, and the tail keeps wiggling after it is detached, so the predator concentrates on that rather than the skink itself.
Their shovel-shaped snout helps them dig a deep burrow where they can take refuge or where they might hibernate from September to April, below the frost line.
BioBlitz is a great way to learn a great deal more about a particular place, and meet a few new friends along the way.