Happenings around the farm.

June 2007. If you happen to pass by Gingerich Farms these days, you may notice that there are some new features rising out of the blueberry fields. This spring we installed 18 Barn owl, 10 American kestrel and 14 Western bluebird nest boxes on three of our properties to complement the 6 raptor perches we installed last year. We are very excited for the possibilities these boxes bring to our program.

The bluebird boxes are all 4 to 5 ft. off the ground and look like little houses (Pic 1). When you pass, you’ll see them on a fence or on solitary fence posts. The kestrel boxes have the same shape, but are larger and are atop poles that reach 18 ft. into the air (Pic 2). Below each kestrel box is a perch, doubling the usability of the pole. The barn owl boxes look the most like their name, being a rectangular box on a pole 12 ft. in the air (Pic 3). Each nest box design is specific for its type of inhabitant and each is placed at an appealing height to attract occupants.

An especially careful observer may also note that the barn owl and kestrel boxes all face east. For nocturnal owls, as the moon rises above the horizon, the entrance hole is illuminated and sparks interest. The kestrel box orientation serves the same purpose, though the celestial body is different. In the morning, when many birds are extremely active, the sun is shining against the front of the box and the entrance is more pronounced. Raptors chose nest sites in the winter months and then start nesting before many of the song birds you see around your house. This may all seem rather unnecessary, but when put in the context of late winter’s dreary days and darker skies, sun or moonlight on the front of the box can greatly help facilitate the attraction of an occupant. The orientation also shields the entrance from the wind and rain that traditionally come out of the south or west, occasionally from the north and rarely from the east.

The spacing of boxes is also not accidental. Bluebirds are territorial and so the boxes have to be placed at a minimal of 100 m. increments. Kestrels will hold down half mile territories, but have been seen to nest closer when food is especially abundant. Barn owls aren’t territorial at all and as long as there is enough food, they’ll nest close to each other. However, it’s hard to say what the birds are looking for. Therefore, we have aired on the side of caution and put up more boxes than will probably be filled. Despite the fact that kestrels have half mile territories, our boxes are placed only a quarter mile apart. This allows the birds to have a selection of nest sites to choose from.

Our boxes were not put up until the beginning of April, missing the period of time when raptors choose nesting sites. However, by getting the boxes out in the spring, local populations of barn owls and kestrels have an opportunity to discover the boxes well before breeding season, get accustomed to their presence and possibly even use them for cover during the harsh winter months. Another benefit the boxes have served is the simple physical benefit of being a perch for different birds. Swallows and kestrels are seen perching on the boxes when traditionally there hasn’t been any location to perch within the blueberry fields.

This all sounds good, but begs the question, “Aren’t birds problematic in berry crop production? Wouldn’t you want to minimize their presence?” The answer to this is an enthusiastic “Yes and no.” European starlings are our most problematic bird species here at Gingerich Farms. Flocks of invasive European starlings descend on the blueberry fields around harvest time and eat or damage thousands of pounds of fruit. Native birds, like American robins and cedar waxwings (Pic 4), also eat fruit, but don’t match the numbers that the starling has been able to achieve.

Kestrels, barn owls, bluebirds and swallows (primarily barn, cliff and tree swallows), on the other hand, provide a valuable service to the farm and contribute to the integrated pest management (IPM) system Gingerich Farms is working to build. IPM is a complex system that takes an environmentally friendly approach to pest management by utilizing pest life cycles and interaction with the environment, predator/prey relationships and current, available pest methods to develop an economically beneficial plan while minimizing harm to people, the land, and the environment.

If you have ever watched a swallow, they whirl and weave through the air roving over grass fields and ponds. What they are doing is catching insects “on the wing.” They are the daytime equivalent of bats and their bodies are specially shaped like a torpedo (Pic 5) to shoot through the air and catch insects. Bluebirds also have a diet comprised largely of insects, but they hunt from perches by swooping down, grabbing an insect and then perching again. These species offer a benefit with insect pests in the blueberries.

Surprisingly, tree swallows took an interest in a couple of our bluebird boxes and one pair built a nest and had young in the box. Swallows tend to nest high, so the fact that a Tree swallow nested 4 feet off the ground was unusual. Since it could take a while for bluebirds to get established, we were delighted the box was used by another favorable species.

The American kestrel’s diet is extremely varied and includes insects, small rodents, small birds, and small reptiles. On the way home one afternoon, I saw a kestrel swoop down from a telephone line and knock a starling out of the air and to the ground, much to my surprise. Rodents are also a problem in the blueberries because they burrow in the sawdust to create nests, nibble on the plants, and can spread root disease. The kestrel acts as a predatory presence for both the birds and the rodents, creating a dual benefit.

Kestrels, swallows and bluebirds manage the smaller problematic species, but barn owls take care of larger problems. Barn owls eat gophers, voles, mice, and other nocturnal rodents. Like all birds, as the barn owls have young, they are forced to increase their hunting, which amounts to large numbers of rodents captured to support the young owlets. Luckily, we already have one pair of barn owls nesting on the farm (Pic 6). A barn owl box was installed near their traditional nesting location and we’re hoping to see them move into the box in the future. After getting one pair to take to the boxes, it’s easier to fill the rest. Young tend to seek out nesting sites similar to the one they came from, meaning they’re likely to return to one of the other boxes to have their own young.

Putting up boxes doesn’t always mean that they are occupied by the wanted species though. Starlings are also cavity nesters and since putting up the boxes, starlings are the most common occupant seen using them. This means that the boxes have to be monitored and as starlings build nests in them, someone has to use a ladder to remove the nest and stop the starlings from having young. In fact, one particularly attractive box had 5 starling nests removed from it between April and May. Starlings won’t keep owls and kestrels from using the boxes, but we don’t want them to benefit until the proper species move in. Luckily, the bluebird boxes are too low for the starlings and they ignore them altogether.

In the future, we hope to see owls, kestrels, and bluebirds nesting in the majority of our boxes, but for now we have to be patient. Nature moves at its own pace and it’s hard to say if we’ll have occupants next year or in five years. The potential benefits that these species provide are an exciting prospect and we can’t wait until the day that Gingerich Farms is producing barn owls, kestrels and bluebirds along with the blueberries, hazelnuts and grass seed (Pic 7).

Tristan Gingerich

* All pictures in this article were taken at Gingerich Farms.

Well, that is it from Gingerich Farms Products. Until next time.

~Verne

If you have comments or want to contact Verne, send him an email directly, he would love to hear from you.