Bluebird Time of Year Again
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Has it been a full year already?
Male mountain bluebird perched on a fence post with snow covered fields in the background. (EXIF data f7.1, 600mm, 1/1000s, ISO800)
I am always amazed at how quickly the new mountain bluebird monitoring season comes around, but I anticipate it with enthusiasm and curiosity about what I will observe and learn each year. This is the 5th year that I will be monitoring these wonderful birds with CANMS (Calgary Area Nestbox Monitoring Society). I really appreciate being part of this network of bird enthusiasts who support education, networking, information and data collection around the monitoring activities. I must say out of the gate that there is a workshop being held May 23, 2026 at the Leighton Art Centre outside of Calgary. I attended this session last year and it is a great way for people to learn about the bluebird monitoring process and especially for children and young teens to increase their knowledge of birds and conservation. It is also a great place for anyone interested in taking on a Nestbox monitoring run to learn what is involved. Information for registration is supplied on the link on the website.
I have been getting all of my monitoring equipment dusted off and ready for the season, but first I needed to get out and do a final clean out of the nest boxes and do any repairs/replacements of boxes that are required now that winter is almost over. I’ve been trying to get out for a few weeks, but snow or excessive melt mud has discouraged this activity so far. I finally managed to get out today and do the whole run as well as installing 6 new nestboxes. It was a great day and so exciting to already see 15 mountain bluebirds returned to the area I monitor. My monitoring run is north west of the city and tends to see their return a little later than other areas.
New Boxes
The CANMS group is a great resource for learning, but they also work on building new nest boxes to be used on the monitoring runs. This year I was able to obtain 6 new boxes in an improved design (previous nestbox building session blog post). I am hoping to use this new design as a template for future boxes.
One of the new nest box designs installed for the 2026 season. (EXIF data f7.1, 1/500s, 600mm, ISO800)
There are a number of reasons why boxes need to be replaced such as usual wear and tear over time, but there are also times when boxes need to be replaced due to damage from other birds trying to take over the nest box (one of our boxes was taken over by starlings who pecked the entry hole until it was enlarged). Unfortunately last year I experienced a very disturbing situation - someone had removed the tops of about 10 boxes to look at the nestlings inside and they didn’t replace the lids completely. This left the nestlings at risk of predators as well as weather. Luckily I go out weekly during the active nesting period and I was able to replace the lids before any nestlings were harmed. Additionally I found that two of the nest boxes were removed from their posts. I was very disturbed and confused about why someone would do this. These birds are facing all sorts of stresses during the nesting period and I would just like to emphasize that it is important to leave nest boxes undisturbed from April 15 to August 15 so that they have the best opportunity to have a successful nesting season.
What I’ve Learned
This has been a great experience for me to learn more about bird behaviour which also translates to helping me in my bird photography in general. The most important thing I’ve learned is to slow down - birds are on high alert and for good reason as they face all sorts of threats on a daily basis. When I approach a nestbox or any birds in a hurried or noisy manner - the birds fly away from the perceived threat.
Birds have all sorts of signs which indicate what they are about to do and recently I was reading a book (What the Robin Knows by Jon Young) which did a great job of outlining some of these signals. When we pay attention to these signals a lot of their behaviour makes more sense.
The robins twenty feet up a tree can see a whole lot farther than the song sparrow a foot off the ground. If that robin discerns a possible problem twenty-five yards away and sounds an alarm with its chirp and tuts and zee-bits and whinnies, the song sparrows jump off the ground and are now hanging on to the trees, chest-high, flipping their tails and trying to determine from what direction any fleeing birds might be flying, how far they’re flying and how fast. (What the Robin Knows - Jon Young)
Interestingly, today at the second last nestbox I was cleaning out there were two robins perched beside the box. As I looked around the field behind them I saw a flash of bright blue (a male mountain bluebird) flipping up in the air - clearly hunting for insects. I approached the nestbox slowly and calmly, but obviously my approach disturbed the robins - they made several shrill cries and flew off away from me. Within seconds I saw the male mountain bluebird stop hopping around after insects and he took flight making a beeline towards where the robins headed. Clearly he felt comfortable hunting insects with the other birds in the vicinity acting as sentinel (guard) birds.
When I show up at the nest box for a monitoring run, I always sit in my vehicle for a few moments to just observe the scene. I look up on the overhead wire where the male is often sitting in the sentinel perch. As I approach the nest box - I often observe the male or female on the fence wire quickly take flight and dip down and then up a position further along the fence wire but still close to the nest box. This is usually indicative that I am seen as less threatening (usually prior to the egg laying phase) - otherwise they tend to fly up to the overhead wire and then dive down close to me (I find tree swallows much more aggressive in dive bombing me when I approach their nestbox).
Male emerging from the nestbox with a fecal sac in his beak ready to take it away from the nestbox. (EXIF data f6.3, 1/1000s, 600mm, ISO500)
Inexperienced birders can initiate the bird plow - startling all birds in their path and causing them to fly out in front and away from their presence. Usually the birds are long gone by the time the person reaches where the birds were perched.
I have found that the best time to check nest boxes is late morning or early afternoon when the parents are most likely off the nest hunting for food. Going too early in the day usually means that the parent leaves the nest and the young can be exposed to cold temperature conditions.
I’ve also learned that when a parent bird heads into the nest with food for the young nestlings it is good to wait patiently with my camera ready as they will emerge from the nest within a minute carrying a fecal sac to keep the nest clean. This sac is an adaptation from the nestling’s digestive system to store fecal matter and once they fledge they no longer produce these fecal sacs. In comparison tree swallows do not produce fecal sacs and they tend to have very messy nest boxes by the end of the season.
Statistics
One of the main reasons for checking nestboxes is to collect data in order for CANMS to compile statistics on the nesting season. Typically this consists of counting the number of successful nests, number of eggs, number of nestlings and also number of fledged birds. All of this information helps to give a good picture of the nesting season and how successful these birds are which gives an indication of the health of the mountain bluebird population.
Seasonal nestbox repairs and clean out. (EXIF data f8, 1/500s, 600mm, ISO400)
CANMS generate an annual report of these statistics which is also shared with other nest box monitoring societies. Nestbox monitoring started in North America in the 1970’s when it was recognized that the habitat for cavity nesters (which mountain bluebirds are) was disappearing causing an increased competition for nest spots which caused the birds to be stressed and reduced their numbers. Mountain bluebirds have readily adapted to nesting in the nest boxes provided and their numbers have continued to increase, but one thing that I’ve noted is how fragile this success is when they are faced with unusual weather during the nesting season.
For example last year was a very wet year with a lot of rain through June and July (I can attest to that as we replaced the roof on our house and it was not weather tight for most of that time causing us considerable stress looking for any signs of leaking). The cold damp conditions resulted in a lot of lost nests which is difficult for nest box monitors to witness and report. Today as I was cleaning out nest boxes I found several with dead fledglings and more than 10% of the nestboxes with unhatched eggs (one nestbox had 7 unhatched mountain bluebird eggs). I am hoping that this year is drier and more consistent temperatures which will help these birds have a successful season.
Bring on the 2026 Season
I am excited and actively anticipating the return of the bluebirds and the beginning of the 2026 season (I saw 15 mountain bluebirds during the cleanup of nestboxes today which is a great start). As I get ready for the season I will be implementing a few improvements as suggested by CANMS. For example I will be installing CANMS tags on each box which indicates that the nest box is part of a monitoring program. I am hoping that this discourages any nest box tampering or removal this year.
I am also hoping to get some great action photographs of the bluebirds doing their thing and I share these with CANMS to use in newsletters or presentations.
Have you participated in nest box monitoring in your area or are you interested in getting involved? I’d love to hear about your experiences in the comments below or drop me a note directly by clicking on Connect With Me.
A male and female mountain bluebird pairing up for the 2026 nesting season. (EXIF data f5.6, 800mm, 1/1000s, ISO800)
I hope you’ll come back soon, share a cuppa, relax and enjoy more of my musings.
