Action needed to defend the native bluebird

Henry Miller
Tales from the Wild

Sixty years ago naturalists were alarmed to see that the bluebird populations were drastically declining. Two invasive species, the house sparrows and the starlings were driving the bluebirds away and nesting in the limited numbers of natural cavities found in trees and fence posts where the bluebirds themselves liked to nest. In efforts to help the bluebirds, many different groups built bird houses designed specifically for them and hundreds of “Bluebird trails” were established throughout North America. Over the years the bluebird numbers have gradually increased, and today more and more Bluebird trails continue to be created.

The following is some advice to anyone wishing to help our bluebirds: Choose a birdhouse design that has been specifically created for them. You can find many of these designs online and just need to choose the one you like and wish to build. The ones I construct are made of rough cedar and are very simple to make, something very important to me since I cut out all the necessary pieces for 100 to 150 boxes yearly. I then bring these pieces to various classrooms in our local schools for completion by the students (like Mrs. Bonner-Vickers grade 8 class we spoke about last time)

For Bluebird houses to be utilized, they need to be placed in a habitat suited for them. Bluebirds will nest in town if there’s a large enough yard there but they prefer open fields with a small bush near the actual house site. The bush is used by the nestlings as they leave the nest and learn to fly. The first nestlings to leave the nest then hide in this bush until the female has coaxed the last little one out. Avoid placing the box near barns or any other buildings where house sparrows may reside. The entrance holes, although being too small for starlings to enter, are large enough for house sparrows to do so. Bluebirds are very particular when choosing a box to nest in. They prefer the wood’s natural colour, but if painted, a brown or light blue colour. The nesting boxes should be placed 50 meters apart and the house has to be cleaned out each fall.

Protecting birds from predators can be very difficult. There’s not much that can be done to prevent hawks, merlins, eagles, and other birds of prey from attacking adult nesting birds, but predators on the ground such as skunks, weasels, raccoon, other mammals and snakes can be prevented from eating the eggs and nestlings using a variety of control measures. For example, a well-greased steel post or a wooden post wrapped with heavy plastic such as crazy carpets, are too slippery for the predators to climb thereby making the nests inaccessible and keeping the eggs and nestlings safe. Most birdhouses in our ‘Bluebird Trails’ projects are however placed on fence posts where there is no control. What I do, if there is a predator problem, is move the whole trail to an entirely different but safer location.

House wrens too sometimes pose a problem. They fill their nesting box full of twigs and then proceed to fill adjacent houses with twigs as well, even if they’re already occupied by eggs or nestlings. Blowflies may also be problematic by laying their eggs in the bluebird nests, The larvae then suck blood from the nestlings which alone has little effect on the young birds but is harmful if they have been weakened by cold, wet weather. The larvae pupate beneath the nest, so if the nest is cleaned out in the fall, they can easily be removed and crushed which in turn keeps the overall fly numbers down. A tiny wasp (nasomia) also helps limit the blowfly population by eating their pupae.

Weather is a major determinant in the survival of bluebirds with mortality being high in prolonged wet, and cool conditions. On the other hand, hot, dry, weather like we had last summer is conducive to high survival rates. Pesticides are another problem. When crops require the usage of either an insecticide or herbicide many birds living nearby perish. Sick and dying birds in the wild ordinarily hide in the grass to die, thereby making the general public unaware of their deaths. When pesticides are used in the vicinity of birdhouses, they often hide in them as well.

Many thanks to our local Sportsmen’s club members who have volunteered to maintain the ‘Bluebird Trail’ network for the last 29 years. This project is currently being expanded with the addition of another trail thanks to a couple more volunteers. This winter I needed to construct more birdhouses for the proposed trail expansion, but with the Senior Centre workshop being unavailable due to COVID restrictions, this became quite difficult. Jim Pochailo volunteered to help by using the saws from his own workshop. Together we worked outside last December and cut our parts for 24 new birdhouses. Some of these new nesting boxes were used to replace older broken ones on the already established trails while Bob Saunders, another volunteer then used the rest of the boxes to create the new ‘Bluebird birdhouse trail’ along LaVallee Road North.

Now we just await the return of the Bluebirds, hoping they survived the ice storms in the south.

More information about bluebirds can be found on the RRVFN website at rrvfn.org