Wednesday, September 12, 2012

7 nestboxes in 2 days!

I've blogged a little about our pilot kestrel project [click here for kestrel nestbox plans]. We kicked it off last week when we installed the first six boxes along a rural gravel road in Bluffton, Iowa. The kestrel (Falco sparverius) is a small falcon that is in decline throughout parts of its range. There are a number of theories about the kestrel's decline: HawkWatch International's list of factors includes development and reforestation of preferred habitats, poisoning, and the West Nile virus. We've focused on the loss of grassland in Iowa, where farms have grown larger, woodlots, fencerows, and fallow land have shrunk, and small grains and hayland have been replaced with row-cropped soybeans and corn. The Iowa DNR states:

"Between 1990 and 2010, Iowa lost 2,615 square miles of potential pheasant habitat. This habitat was a mix of small grains, hay land, and Conservation Reserve Program (CRP) acres. To put this loss in perspective, 2,615 square miles is a strip of habitat 9 miles wide that would stretch from Omaha to Davenport!" [2012 Iowa Roadside Survey]

So why use rural ditches? Bob started talking about ditches as a sort of habitat of last resort in heavily developed areas. I don't tend to think of farmland as heavily developed, myself - it's all green, right? - but mile after mile of row-cropped corn and soybeans is not a natural environment. As grassland and pothole prairie are converted into farmland, animals and birds are forced into ditches. Water, rodents, insects, and plant life attract a wide variety of larger animals, including deer, rabbits, woodchucks, gophers, mink, muskrats, badgers, fox, raccoon, skunks, snakes, frogs, red-tailed hawks, harriers, kestrels, sparrows, mourning doves, gold finches, bobolinks, and pheasants.

A little back-of-the-envelope calculation. Iowa contains a total of 36,016,640 acres. Over 90%, or 32,414,976 acres, is under till. So how much of what's left is ditch? That's a hard question. The DOT manages about 175,000 acres along interstate and state highways, but that figure doesn't cover county, city, and town roads. When those are added in, the total jumps up to about 1.6 million acres, or 44% of the remaining 3.6 million acres left. Although broken and fragmented, that is a lot of potential habitat. Winnesheik County gave us permission to install nestboxes along 5 miles of dirt road in rural Bluffton, Iowa, and the fun began!

In the wild, kestrels nest in cavities in trees, cliffs, and buildings. They like to be up high, they want perches, and they need a fairly long box with a hole toward the top, preventing direct sunlight from reaching the box's bottom. We didn't want to use cement in the holes we dug to support the pole, since that would mean hauling water out to each site. The pole needed to be strong but also breakaway, given that it was in the county right-of-way. Bob wanted the nestboxes to have a slightly slanting roof to shed rain, sun and weather resistant siding, and a perch for the kestrels to, well, perch on. Here is what the finished boxes look like, absent a coat of paint. Bob and board member John Dingley built the boxes out of T11 siding, which we also use to construct falcon nestboxes:

Board member John Dingley with the kestrel nest boxes

Now for the posts! We weren't able to get 18’ 4x4 posts, so Bob ordered 15 green-treated 2x4 boards. He decided it would be easier to haul materials than posts, so we constructed the posts on site by gluing and screwing them to create a laminated 4x4x18' pole. Voila! Strong enough to stand against the wind, yet still break away against cars, trucks, tractors, and other vehicular interlopers. 

Bob assembles a kestrel nestbox in his mobile workshop

Last Tuesday dawned hot and humid! Bob and John borrowed a truck from camera operator Charlie and set off. The procedure went something like this: they reached a spot, stopped the truck, put up orange cones, and went to work. While John dug a fout-foot deep hole (among many other things, John is a mason), Bob built the pole, attached the pre-made nestbox, and added about two inches of sand in each box.

John digging a nestbox hole

Once the hole was dug and the box was ready, we levered the box up and into the hole. We added dirt, tamping roughly every two inches. When the hole was about half-way full, we added roughly a five gallon bucket of gravel, tmaped that, and finished with dirt. The gravel compacts extremely well - almost like cement - and provides drainage to help keep the wood from rotting.

John with an installed nestbox
The next day we installed a peregrine nestbox on a cliff just south of Bellevue, Iowa, at Bellevue State Park. We were were very pleased to find Indian mounds at the top of the cliff, just above the spot we intended to hang the nestbox. Although these were conical mounds, the Mississippian people revered the falcon and built falcon mounds. It seemed like an appropriate place to put a falcon nestbox. We were joined by Pat Schlarbaum from the Iowa DNR and Park Manager Shannon Petersen, who helped carry gear and were in general very enthusiastic about the project.

Dave, gear and mound 

Bob went down the wall to find a good spot for the nestbox. It has to be unavailable to raccoons (as usual, we found raccoon poop all over the ledges), fairly flat, high up, and visible - it can't be hidden behind foliage. Once he tagged a spot, he came up, cutting brush out of the way to make it easier to handle the nestbox. The nestbox is roughly two feet by three feet, weighs 30-40 pounds, and is constructed of T11 siding in a steel frame, which will not warp or pull off the anchors. It can be a bear to handle, especially in thick brush. The time we took to cut away branches and vines saved us a lot of work!

Bob lowered the nestbox to me, on a ledge, and I caught it and carried over to the edge, belaying it down to Dave. As usual, hazards included rocks and the box itself. Bob put a long rope on the bottom side of the box, which made it much easier for those of us below him to guide it over cliff edges and keep the box away from rocks. I got the box down to Dave and then joined him on rope, where we levered the box into place and anchored it to the wall with our awesome new hammer drill (donated by Pat Schlarbaum, thank you very much!).  Once it was firmly in place, Bob lowered down 80 pounds of pea gravel and a perch. We filled the box with the pea gravel (roughly 3 inches deep, to add drainage and prevent egg breakage), attached the perch, and got off the wall. 7 nestboxes in 2 days - done!

Dave is above the box and Amy is below it
Note: We forgot to add sand to one of the kestrel nestboxes, so Bob and John went out to fill it late last week. They saw 8 kestrels between the first box and the last box, and one box already appeared to have been claimed by a male. We anticipate banding babies here in the spring!


Resources that helped me write this article:


RuthMItchell said...

The only thing you forgot to tell us is where you put the CAMERA so we can watch the action!!! lol But seriously, you all are doing wonderful work, thanks for allowing us to peek over your shoulders to see it!!! Can't wait for more reports on how well received the new nests boxes are!!!

Blannie1 said...

Great post. I'm so appreciative of the work you are doing and I'm sure the kestrels and peregrines appreciate it too! Thank you!

Nora H said...

You guys are all going gung ho as usual and it sounds great so far! Can't wait for the spring updates!

James Avey said...

Thanks for sharing the information and pictures about making the next boxes. Many readers can use the details to save money by making DIY nestboxes.