Sometimes, you can see a lot by just sitting down.
I carved out some time in the field last Friday to collect data on poison hemlock in our research plots. After finishing that, I had about half an hour before I needed to head back to the office, so I took my camera for a walk along the creek running through our Platte River Prairies. Not having a particular agenda, I stopped to look at a tree that had been recently felled by beavers.
This tree, cut down by our local beavers, had sap seeping from the stump last week. The Nature Conservancy’s Platte River Prairies, Nebraska.
As I was admiring the patterns of tooth marks on the stump, I noticed an interesting-looking little fly hanging around. As I watched, the fly started to feed on the sap that was oozing out of the tree. Taking advantage of the fact that the fly was distracted by its meal, I managed to get a couple photos of it.
This fly seemed to be enjoying its meal enough that it didn’t mind me sticking my lens in its face.
Since I had time, I decided to sit and watch the fly for a bit. Before long, another – different – fly came along.
A second fly joins the meal.
One of my favorite statistics is that there are more than 37,000 species of flies in North America. That seems an almost unfathomable diversity. Taking that into account, I guess I shouldn’t have been surprised to see a third kind of fly arrive at the stump…
Fly #3. A big one with blue and green stripes on its abdomen.
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A rear view of fly #3, showing the striped abdomen.
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A tiny chalcidoid wasp was on the stump as well, though not feeding on sap (thanks to Mike Arduser for identifying it for me – Mike says they are a group of parasitic and important wasps). The quality of this image isn’t very good – my excuse is that the wasp was BARELY 2mm LONG and I had to crop it quite a bit so you could even see it…
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A tiny red mite came ambling along too… It was about the same size as the little chalcidoid wasp
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Fly #3 apparently didn’t like Fly #1 working over the same puddle of sap. This photo captures Fly #1 rearing back as Fly #3 lunged at it.
I wish I’d had more time to stick around; it would have been fun to catalog all the little critters that visited – or were living in – that beaver stump. I also wish I would have gotten a shot of the little wolf spider hiding in the pile of wood chips at the base of the stump – it darted out and almost caught one of the flies when it landed nearby, but didn’t stick around for a photo. Too fast for me…
I think my short time watching the beaver stump brings up a number of interesting points that I could focus on as the overall theme of this blog post. I could focus on the odd side benefits provided by the work beavers do. I could focus on the crazy diversity of life found on a single tree stump. I could focus on the way creatures of all different kinds are able to take advantage of unexpected resources (like oozing tree sap) when they appear.
But I think the biggest point is this: You can see and learn an awful lot by just sitting down and watching.
The Prairie Ecologist 