Calgary Area Nestbox Monitors Society


The Calgary Area Nestbox Monitors Society (CANMS) is a group of about 100 volunteers in the Southern Alberta region. Our mission is to provide nestboxes for native cavity-nesting birds, to monitor the birds’ activities, and to collect data. These activities are important for the conservation of these avian species due to habitat loss. Natural cavity-supplying trees have been cleared through human activities such as logging, agriculture, and development. Our focus is on mountain bluebirds and tree swallows. 

CANMS began with seven members and 743 boxes. Founders Don Stiles, his son Andrew, and Ray and Agnes Woods monitored for over 40 years. Today, members monitor 5,000 boxes, covering 2,000 km in ranges of favourable habitat, from the foothills of the Rockies west of Calgary to east of Didsbury and Olds. Some monitors have 500 boxes! About one-third of members band birds, and all members monitor birds’ activities, from nesting attempts to numbers of eggs, hatchlings, and fledglings. This data is collated in an annual report and shared with our members as well as others near and far, including: Nature Alberta, Ellis Bird Farm, Southern Alberta Nest Monitors Association, the North American Bluebird Society, and Cornell University Lab of Ornithology. 

Monitoring begins in mid-April. We clean and maintain the boxes and prepare for the arrival of birds from the southern U.S. and Mexico. Mountain bluebirds usually begin nesting in early May, and by June, two to seven eggs appear. Banding reveals that most pairs return to within 5 km of their previous banding site, sometimes to the same box.

Tree swallows arrive in mid-June. Fortunately, many bluebird pairs have already established nests and some babies are soon to fledge. The tree swallows often use bluebird nests for their eggs, which hatch in July.

In August the nests are empty and we compile our data. We meet each fall to receive the extensive reports produced by volunteers. Everyone is delighted to recount their season’s experiences. In 2022, our bluebirds showed a remarkable success rate: 5,836 birds. Tree swallows are more numerous than bluebirds, with 12,072 fledglings last year, down a bit from 2021.

Certified CANMS members have banded 45,405 mountain bluebirds and 39,559 tree swallows, from 1981 to 2019. Our data over years also provides insight into stressors on the birds, including cold snaps in the spring, extreme heat events in the summer, and predation. Threats include ravens, raccoons, skunks, coyotes, house wrens, and unfortunately, humans. Sadly, vandalism occurred on 14 trails last year; in one case 17 boxes were destroyed. 

Why monitor? For the joy of seeing the process of development, from egg to chick to fledgling; to enjoy the environments where bluebirds thrive; for exercise; and to contribute to the preservation of natural species. We hope to ensure that these iconic birds always find a home in Alberta. To join us, reach out to

Lise Mayne is the Secretary of the Calgary Area Nestbox Monitors Society.