Anchor systems

North Carolina, as a mid-Atlantic state, gets a fair amount of wacky weather in late winter. March is particularly schizophrenic, with 70 degree temps one day, and ice storms the next. High winds and even tornadoes are not that uncommon during this time, as warm air from the Gulf of Mexico moves north to clash with Arctic air moving south. In just the past two weeks, we've experienced a major rainstorm with sporadic tornadoes, a ten year snowfall event, three days of spring-like weather, followed by a devastating ice storm. The day after the ice storm, as trees lay broken over houses and roadways, the temperatures were back up in the 70's.

During the period of recent severe thunderstorms, three of our nest boxes went over. All three of these boxes were empty, but the mere thought of them falling over was keeping me up at night. Part of the problem was placement. All of the boxes placed in lowland areas and marsh did fine in the high winds, but some of the ones placed in open grassland were vulnerable, especially on hillsides.

Barn Owls don't particularly like hilltop placement of nest boxes anyway, favoring areas near running water and wetland. So each of the most vulnerable boxes needed to be moved to lower ground. We also decided to be safe and anchor 21 of the 24 boxes with a cable system, which would require a significant amount of time and work.

After some experimentation, my friend Ken and I devised some anchor systems that had a very small footprint. Where the ground was clay, we used auger anchors, essentially long metal corkscrews, and 1/8 inch cable to prevent any tipping of the tires. Here's what the system looks like:

In areas that had more rocky, unstable soil, we used three foot metal stakes and the 1/8 inch cable. That system, which we also used in the windiest locations, ended up looking like this (the sign is for education purposes only):

Where boxes were adjacent to silos, we anchored the poles directly to the structure.

With each of our three systems, the threat of leverage forces toppling the box was practically eliminated. In many cases, we couldn't even budge the pole when we tried to move it.

Now why wouldn't we save ourselves the hassle, and mount the nest boxes on wooden poles placed directly in the ground? Well, that's certainly an easier and less expensive option, and in dry areas would be the preferred route. I would recommend 12 foot 4x4 posts for most farms with open grassland. (In fact, we will be using a wooden post for our installation at Fearrington Village this weekend). A telescoping metal pole system, set into the ground, is also an option in areas with stable soil.

This tire system requires a lot more work, but allows us to place boxes in less hospitable places subject to flooding. In the Piedmont, Barn Owls are most associated with wetland areas close to open fields. Tires also allow land managers to move the boxes if necessary, as for a prescribed burn. Most importantly for us, moveability allows us to experiment a bit with placement. Wooden posts will likely be used in places where we get some activity.

Due to some very hard work by three of our volunteers, we were able to move the most vulnerable nest boxes to better onsite locations. We also managed to anchor every single nest box that had a remote chance of toppling, 21 boxes in all! The only thing to fear at this point is an inland hurricane.