Wednesday, March 27, 2019

The Drowning Machine

Several of us were in the coffee shop talking about the history of the Hepburn Street Dam in the West Branch of the Susquehanna River at Williamsport, Pennsylvania. The original dam, built in the 1850s to create a large stillwater for the storage of logs, was constructed of timber cribs filled with rock; the new dam, of concrete, was constructed in the 1980s to replace the old deteriorated dam.
Our discussion reminded me of several photographs I’d taken of fishermen in a boat just below the dam –

On the concrete dam is a sign mandating that boaters stay at least 100 feet from the “boil” on the downstream side of the dam. The boil is that foaming mixture of air and water that forms as water flows over a low dam. Because the boil is a mix of water and air (up to 30% of the boil is composed of air bubbles), it provides minimal buoyancy and makes low-head dams a significant hazard.

Apparently these fishermen either couldn’t read or thought the sign didn’t apply to them and obviously didn’t recognize the danger presented by the dam –

With the advent of spring’s high water and the return of water sports it’s well to remember that low-head dams such as the Hepburn Street Dam are called drowning machines for good reason as evidenced by this incident on the North Branch of the Susquehanna at Binghamton, New York  –

Three people died in that incident in the 1970s and two died last year at a similar dam in Harrisburg, Pennsylvania (at least 29 people have reportedly drowned at that one dam). People drown in the boil of low-head dams almost every year – be careful.

Thursday, March 21, 2019

Winter in the Hollow

A bit over 50 years ago, when they were newlyweds, friends of ours bought an old hill farm of about 50 acres. The roof on the house leaked with every rain and the water supply was piped from a spring up the hill. The spring is the origin of a small stream that flows through a narrow valley of the kind that’s called a “hollow” around here.

In an aerial photo from 1938 there are only a few trees in much of the hollow, apparently it was used as pasture when the property was farmed.

The farmer that cleared the hollow hoped his cows would squeeze a bit of nutrition from whatever would grow on the shallow acidic soil. The hollow is the kind of place that should have been left as woodland rather than being cleared of trees: the slopes are steep, the soil shallow and the stream at the bottom would have carried a load of silt with every rain.

It’s been a long time since the hollow was pastured, since then trees have been growing on the slopes and along the stream. Now the entire hollow is wooded although the trees are fairly small and grow slowly on the shallow infertile soils. The hollow is once again habitat for wildlife and wildflowers.

For several years I’ve had a camera trap in the hollow to document the wildlife that spends time there. This past winter the camera was one that took videos. Here’s a selection of those videos in the order in which they were taken –

In addition to white-tailed deer (including four young bucks still bearing antlers in mid-February), these are the species in the video: striped skunk, weasel (probably a long-tailed weasel), gray squirrel, screech owl, eastern coyote, red fox, raccoon, cottontail rabbit, and gray fox.

Saturday, March 9, 2019

February Fauna

A camera trap has been on the hill above the house ever since I began using camera traps a number of years ago. Currently there are six of them on the hill (can you ever have too many?). For years they were home-built camera traps that took still images day and night.

In the last several years some brands of commercially built cameras have markedly improved and I’m now using several to take videos of wildlife, color videos during daylight and black and white videos at night.

February was, unlike Februaries of old, a month of variable weather – several times it was warm enough to melt the snow and then cold again, with snow followed by freezing rain, then warm, and then cold again. But, the month of February was good in the land of camera traps, producing photographs and videos of opossums, fisher, gray and red fox, deer and squirrels –

The videos were some of the clearest I’ve ever gotten from a camera trap. Here are the best of the videos in the order they were taken. Because there were so many videos of white-tailed deer and gray squirrels on the camera’s memory card, only one of each were included.

In the first two clips of the fisher the animal follows the same path in front of the camera, the clips must be watched carefully or the second looks like a repeat of the first – actually they were taken three hours apart. Another thing to watch for is how many times the male gray fox scent marks. 

I’m still waiting to get a video of a bobcat on the hill out back – maybe next time, or the time after that, or …