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Natural Curiosities

barn swallows . . . porcupine quills . . . swim bladders . . . carrion beetles . . . winged wonders . . . carpenter ants . . . loon predators

I work in a large warehouse-type building that is infested with many barn swallows. The droppings are a problem. What can we do?

Dale Schmiesing

Your best bet is to prevent the birds from building the nests in the first place. One idea is to use bird netting, poultry fence, or monofilament line strung back and forth to block off the areas where they tend to nest. Another idea is to hang strips over doors at entrances to the building to discourage the birds from entering. Remember that barn swallows are valuable allies in keeping mosquito and other insect populations under control. If you exclude them from your warehouse, consider putting up nest shelves outdoors so they have an alternative spot to nest. See Woodworking for Wildlife for more detailed instructions.

We are reading Hatchet by Gary Paulsen. In the book Brian gets poked by porcupine quills. We are wondering, do the quills grow back after they are used? If they do, do they grow back thicker and stronger?

Mrs. Grendahl's Third Graders

Porcupine quills are modified hairs, so they grow back after they come out, says DNR wildlife educator Jan Welsh. However, she is not aware of any evidence that they grow back thicker or stronger.

How does barometric pressure affect the swim bladder in fish (for feeding)?

Julie Nordquist
Park Rapids

A change in barometric pressure changes the pressure on the swim bladder. However, says DNR aquatic education specialist Roland Sigurdson, any change would be infinitesimal compared with the pressure changes caused by moving up and down in the water column -- and would be quickly compensated by gases diffusing to or from the blood. Because temperature, cloud cover, wind direction and speed, and precipitation often change when barometric pressure changes, it is difficult to attribute shifts in feeding behavior to change in barometric pressure alone.

I looked out our deck door one evening and saw a dead bird that must have hit a window. It began moving slightly, and I realized that many bees were going in and out of it, and they seemed to be causing it to move! The next morning I looked out and noticed it was about a yard from where it had been the night before. What was going on?

Lynn Hanske

Hornets, also known as yellowjackets, feed on dead flesh in late summer, says DNR entomologist Robert Dana. There's a good chance that's what you observed. Another possibility is that movement was caused by carrion beetles. These black-and-orange insects will transport carcasses and even bury them.

How do birds maintain their distance from each other in flight? I watch large flocks of small birds in wonder.

David Dvorak

Flocking is an example of what's called emergent behavior -- behavior that is a characteristic of a group rather than of individual animals. Each bird makes repeated split-second decisions about where to fly based on where the birds surrounding it are. So if one veers just slightly in one direction or another, the others tend to do so too. Because this takes place very quickly, the result is the impressive flowing effect you observe.

I have carpenter ants behind a wall in my townhouse. Ant poison reduced their numbers, but they keep appearing. I need help before I have to rip out sheetrock and tear up the floors. Any ideas?

Richard Green
Eden Prairie

Carpenter ants perform a valuable role in nature by helping break down wood in dead trees, releasing the compounds trapped inside it for other life forms to use. But it's hard to appreciate their value when they start breaking down our homes instead. DNR entomologist Robert Dana recommends a University of Minnesota Extension online publication called Carpenter Ants.

Is the proliferation of eagles the reason for the reduced number of loons?

Carol McCarthy

Eagle predation is not a problem, and loons appear to be doing fine, according to Minnesota Loon Monitoring Program coordinator Rich Baker. Although eagles do eat loon chicks, their impact is likely no greater than that of other predators such as fish. On a particular lake, a particular eagle or eagle family could have a noticeable impact on the local loon population. The monitoring program has not seen a loon decline in the six areas around the state being monitored.


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