Nestboxes - By: Colin Bartlett

Photo: Chestnut-backed Chickadee leaving a nest box (R. Habro)

It is a busy time for the songbirds in the backyards, as nesting season is beginning. Around my backyard the birds are already paired of as I have a pair of Northern Flickers, Downey Woodpeckers, and a pair of European Starlings making regular visits to the suet feeder. Along with that there have been two pairs of chickadees around checking out the nest boxes, one in the backyard and the other in the front, but they better hurry if they want it because the Red-breasted nuthatch and the Bewick’s Wren have been looking them over too. With all this going on, the swallows are just beginning to return and they have also been busy starting to look for nesting sites.

All these birds that I have mentioned are cavity nesters and nest in cavities that were created by woodpeckers or other natural means such as a broken branch. With less natural habitat in urban areas these birds will use other cavities such as nest boxes, attics, shoes and even pockets in a coat. Nest boxes are an easy way to provide a nesting cavity for the birds in your backyard but there are few things to know about them.

There are a few requirements for nest boxes that are beneficial for the birds and need to be considered, whether the nest box is built or purchased. The entrance hole determines who can get in, including predator birds, and the height of the hole above the floor is also important. The size of the floor will determine how much work and energy needs to be used and bigger is not always better. Ventilation is a must whether there are holes drilled on the sides or some other way, ventilation is very important. Cleaning out a nest box is necessary, so there needs to be some way to easily get into the box. Although we have always seen nest boxes with perches on them it is best not to have a perch on the box. This perch again allows predator birds a place to sit and attack the nest and adult birds.

A nest box for chickadees, nuthatches and wrens will require a one and one eighth hole, with a floor size that is four by four inches. It is also best to keep the entrance hole about six inches above the floor to keep predators from reaching the eggs or young.

Swallows prefer a slightly bigger entrance hole at one and one and a quarter to one and on half inches in size and a floor size of five by five inches. Unfortunately in some areas there are House Sparrows that may take over the nesting box of swallows and these birds will do anything to get the box, including killing the swallows. To deter the House Sparrows use a nest box with and oval hole that is seven eighths of an inch high and three to three and a half inches wide. Swallows are able to fold their shoulders back and get in through this hole where the House Sparrows cannot. 

When deciding on where to place a nest box, try and have it so the wind and rain do not blow directly into the box. Place the nest box in the habitat of the bird species you are trying to attract, such as swallows prefer an out in the open, straight in approach and chickadees, wrens, and nuthatches prefer it near trees or forested areas. One habit chickadees and nuthatches do in our backyard when nesting is to use a tree close by to land on before entering the nest box. This way they can check of predators and make sure no one knows about the nest. Nest boxes do not need to be mounted high, mine are on the side of my shed about 6 to 7 feet high and the Bewick’s Wren and Chickadee’s battle for it ever year and I have also seen swallow boxes that are four feet above the ground and are constantly in use. To help keep the box cool mount it out of the afternoon sun if possible and make sure there are ventilation holes. A nest box can be painted on the outside and it is best to use light colours that will reflect the heat. Lastly, try and give the nest boxes a little distance from bird feeders, as it is the time of year that the birds are territorial and battles may occur if a feeder is near, resulting in no one using the nest box.

Don’t forget to supply a few nesting materials as well. This can be done with short pieces of wool, string, cat and dog hair, and moss. Place these materials in an onion sack, suet cage or loose around the yard, but do not place them in the boxes as the birds may assume the box is being used. I do not use dryer lint as the fine dust is thought to be harmful to the birds. Also do not use dryer lint if dryer sheets are used, as the chemical residue from the sheets may also be harmful to the birds.

Nest boxes are a great addition to the backyard habitat and are very entertaining but sometimes it does take time for the birds to find and use them, so a little patience is needed.

Happy birding!!

Cleaning your nestboxes:

Cleaning your nestboxes can be done after nesting season has completed (September is the earliest date we recommend cleaning your nestbox). The purpose for cleaning the nestboxes is to prepare the box for use by birds next nesting season, as well as to limit the spread of mites to juvenile birds.  To clean your nestbox simply remove the old nest and discard any eggs that were left behind. To disinefect a nestbox we recommend using a vinegar or bleach solution mixed with water (10 parts water to 1 part bleach or vinegar). In the case of wooden nestboxes, this solution can be put in a spray bottle and after removing old nesting material you can spray the inside of the box with the solution and then allow it to air dry.