Evergreen Audubon’s nestboxes at Alderfer/Three Sisters and Elk Meadow, which we have been monitoring since 2007, are on course to produce a record number of bluebirds this breeding season. Already, as of the end of June, 39 bluebirds have fledged and about 72 more are getting ready to take flight. We have fewer Western Bluebirds this year but Mountain Bluebirds, which started nesting about a week earlier than we expected, are present in higher than average numbers.

Historically, the number of fledged bluebirds has been close to 100 per season. However, for the last two breeding seasons that number has dropped. In 2022, our boxes only fledged 50 bluebirds, possibly due to drought conditions resulting in fewer beetles, wasps, bees, ants, grasshoppers, and crickets, food for adults and hatchlings alike. Another factor could have been disturbance created by the increased number of visitors to the parks in the past few years. We also suspect that last year’s late spring storms may have disrupted migration and nesting behavior.

So, why has there been a resurgence in youngsters this season? For starters, last fall some of the nestboxes were relocated away from trails and heavily used areas to reduce potential disturbance. Then, this spring, the late-season snowstorms were few and mild, giving our returning birds a head start over previous years. Finally, instead of those snowstorms, Mother Nature has provided lots of rain, meaning that tasty and nutritious insects have flourished in lush grasses and forbs that have also provided protection from predators. Speaking of predators, each breeding season some of the nestboxes located near the forest edges, along with the eggs and nestlings inside, have been lost to bears. This year, relocating some nestboxes, and spraying all of them with regular applications of ammonia seems to have nipped this folderol in the bud. Bears are deterred by the odor but the birds can’t smell it.  

One of the goals of reorganizing our boxes, in addition to reducing park visitor and bear issues, was to ensure that they could be readily monitored by small groups of volunteers, at their convenience, without the long hikes of previous years. Fourteen volunteers, some veteran nestbox monitors and some new ones, are enjoying the thrill that comes from observing the adult bluebirds, opening a box to discover eggs, and watching from visit to visit as the eggs hatch, the squirmy naked nestlings grow feathers, and finally, they fledge.

It should also be noted that, in addition to our bluebirds, we have other species in 12 of our boxes. Violet-green and Tree Swallow numbers are slightly higher than in previous years. They started nesting about two weeks after the bluebirds, about a week later than expected, and are just now beginning to hatch young.  There are also several House Wrens in residence, in various stages of nesting and raising their broods. Unlike prior breeding seasons, we haven’t seen many Mountain Chickadees or nuthatches moving into our boxes this year.

Summary results will be available in the October eDipper. If you are interested in monitoring nestboxes next year or would like to install and monitor a cluster of boxes on your own property, please send me, Rachel Hutchison, an email at: atlarge@evergreenaudubon.org.