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What is Mountain Bluebird Nest Box Monitoring?

A couple of years ago I found out that a work colleague was also into birding and that he had a mountain bluebird nest box monitoring run. For those not familiar with this program, it started in the 1970’s when mountain bluebird numbers were on the decline due to loss of nesting habitat. They typically nest in tree cavities at the edge of wooded areas and are quite particular about where they nest.

There is also a lot of competition for nest locations amongst other birds such as tree swallows, house sparrows and wrens which led to the identification of a need for support for nesting sites. What started as a small program of installing nest boxes along fence posts near wooded areas has expanded to over 5000 nest boxes in Alberta alone. The program extended across the western provinces and into the United States.

The bird numbers have stabilized and they are not on any threatened or endangered list which is positive, however loss of habitat is still a concern, so the program continues.

Volunteers sign up to look after a nest box run which can include up to several hundred nest boxes - my colleague’s run has a total of 60 boxes. He invited me to come out and photograph the mountain bluebirds along the run which was really fun and interesting. The bluebirds are such beautiful birds with the males being a vibrant indigo blue and the females being more muted, but no less beautiful.

I was thrilled when he asked me if I’d like to help with monitoring once I had retired. I started doing this in March of 2023 and I’m continuing again this year.

The role of nest box monitor includes a spring clean out of boxes and general maintenance or replacement of boxes as required. Boxes are fastened to fence posts on the outside of landowners’ fields (with their permission) and sometimes fence posts get moved or replaced which means the nest box needs to be replaced as well.

This particular nest box run has been going for decades and there are legacy nest boxes that are at the end of their life and needing to be replaced. We look to replace 10 - 15 boxes a year.

Ironically it is not weather or age that tends to cause the nest boxes to need to be replaced most frequently, but rather damage from cows and horses rubbing against or chewing on the boxes.

Once the boxes are ready for the birds, monitoring entails visiting the route looking for evidence that the bluebirds have returned and made nests in the boxes. The next step is to monitor the nests for eggs and then nestlings and finally fledglings. Data is collected with each monitoring visit and annually it is summarized and reported where it is aggregated and an annual report is issued by the Calgary Area Nestbox Monitors Society.

Getting ready for the new Mountain Bluebird season.

A new season is upon us and based upon our assessment of the nest boxes’ condition at the end of last season we determined that we will need to replace between 10 - 15 this year. One of the winter/early spring activities is building new boxes. Each box requires a 1’x6”x6’ non treated wood board, screws and a 9/16” hole saw to make the entry hole. (Link to the MOBL nest box plans)

We did a marathon mountain bluebird nest box building session which required us to cut up all of the boards according to the plans and then we took one set of pieces and built a nest box. Once we were happy with the construction and location of the screw holes we disassembled the box and used it as our template.

From there we used the template pieces to drill holes in the rest of the pieces at the correct locations which took about 30 minutes. The next step was to start assembling nest boxes and was this process ever speedy - about 10 minutes a box. We completed fabrication of 11 nest boxes in just under 3 hours from raw material to finished boxes.

The next step was to paint the boxes in order to help preserve them a bit longer.

We choose light coloured paint so that the boxes don’t overheat in the sunshine as it can get pretty hot in rural Alberta in May and June.

This was a fun part of the project - to be able to see the completed boxes really look finished.

The finished boxes looked great and all ready to be taken out to the field and installed. I couldn’t help wonder about whether they will be preferred locations by returning female mountain bluebirds.

I needed to be quick about getting them painted as we had a couple of days of good weather before more snow was forecast. Luckily we managed to get them all installed before the snow came and the ditches filled with water.

What the season looks like.

The season starts in late March or early April with the males returning from their winter locations first. They scope out potential nesting sites and prepare for the females to return.

The females return a few weeks later to choose a mate which is specifically related to the quality of the nest box. She is quite choosy about her nest location and not so much about the male despite his showy displays and melodious singing. Once she has chosen a nest box/mate, she begins to prepare the nest - solo. The male will bring nesting material, but is rarely invited to contribute to the construction.

Eggs are laid one per day for a maximum of 6 - 8 eggs in a clutch, so the nest boxes are occupied from late March until mid June when the baby birds fledge (leave the nest).

I typically monitor the nest boxes once a week during the active season and then for at least a couple of weeks after to see if a second clutch will be laid. Mountain bluebirds will lay up to two sets of eggs in a season before heading back down south in late August/early September.

Bring on the 2024 bluebirds

I am excited for the birds to make their way back to Alberta from their overwintering locations and for a new season of nesting and monitoring to begin. I really appreciate being able to do this work and how the intersection of my photography, background in data gathering/research, and interest in conservation have come together to allow me to do meaningful work.

I believe that the more we have close ties to the nature around us, the more we are able to appreciate our potential impact and modify our behaviour to minimize that impact. The first step for me is education and I continue to try and learn more about these amazing birds through this work. I have plans to write a book about the monitoring work and my experiences with mountain bluebirds.

Do you have any similar programs or conservation efforts in your area that you participate in or are interested in getting involved with? I would love to hear about this in the comments below or feel free to reach out to me directly.

I hope you’ll come back soon, share a cuppa, relax and enjoy more of my musings.