by Joanna and Eric Reuter

Chimney Swifts are fascinating birds that are fun and exciting to watch, especially when they congregate at and enter overnight roost sites. On an active night at the right location, hundreds of swifts can gather around, circle, and enter a roost structure—typically a masonry chimney. This genuine spectacle can generate “oohs” and “aahs” from birders and non-birders alike.

Since writing an article for The Chat on Chimney Swifts in the fall of 2023, we’ve learned a fair bit about roosting patterns and locations in Columbia. Here we summarize highlights of  findings from a combination of volunteer monitoring and a 2024 monitoring project funded by the USFWS. However, copious questions remain, including ones that could be addressed through further observation and monitoring.

Roosting locations: More than just the Armory. A couple of years ago, the received wisdom was that the best place to go to watch swifts was the Armory building (officially Armory Sports and Recreation Center). More eBird lists were associated with this roost site than any other. Since then, we’ve learned that the situation is way more complex. We now know of ten buildings in and near downtown Columbia that host roosts that have been active in the past year. Many thanks to the other CAS observers who tipped us off on a couple of these!

Multiple roosts are used simultaneously. Prior to 2023, there was no documentation for Columbia via eBird that multiple roosts in a small geographic area could be active at the same time. That changed during the final roost-watching CAS field trip of 2023, when observers split up and saw three simultaneously active roosts, two of which were conservatively estimated to have hosted at least 500 swifts each.

Use of specific buildings/chimneys is quite variable over time. Continued monitoring from August through October of 2024 showed that the use of individual buildings can change considerably over time. Buildings with chimneys that are used heavily at one time may be completely dormant at other times within the same season. The reasons for these shifts in building use are largely speculative at this point.

Predation happens. One hypothesis that could explain at least some of the shifts in building use relates to predation. Cooper’s Hawks are known predators of Chimney Swifts, and the temporary abandonment of the Armory as a roost site in late September of 2023 may well relate to raptor activity. We saw a Cooper’s Hawk  land on and also look into this particular chimney. In summer 2025, Joanna watched an American Kestrel fly by with a Chimney Swift in its talons, while monitoring an active roost.

Season for interesting swift watching is longer than previously realized. Based on local and state eBird data, we used to be under the impression that swift roost watching was only really worth doing during fall migration. However, we’ve since documented that spring roosts in Columbia can also host hundreds of birds, and that communal roosting can even continue through the summer, presumably based on the congregation of swifts that are not actively engaged in breeding. Rewarding roost-watching can certainly occur from August through end-of-migration departure in mid-October, but it is hard to predict when—and where—the peak will occur.

First-ever simultaneous observation of all known roosts in Columbia. On August 22, 2025, the morning of the MoBCI meeting, thirteen volunteers woke up extra early in the interest of making the first effort to observe all known Columbia roost sites at once. Morning swift exits are actually often easier to count than evening entries, and we had some interesting results. Swifts were observed to emerge from chimneys on 7 of 10 buildings. Exit counts for buildings with swifts were (in descending order): 146, 48, 27, 13, 8, 5, and 3. The building with the second-highest count had a Cooper’s Hawk land on the chimney during the observation. Our prior personal record for earliest morning exit got broken, this time with an exit 27 minutes before sunrise.

Viewing opportunities this fall. If you’d like to get involved in swift watching, these events are a great place to start:
September Logboat Social, followed by Swift Watching Wednesday September 17, 2025
Swift Night Out Thursday September 18, 2025
October Logboat Social, followed by Swift Watching Wednesday October 8, 2025

Possible citizen science opportunities. In Wisconsin, volunteers in La Crosse and Viroqua have been monitoring roost sites on a bi-weekly basis from spring through fall. Similar to Columbia, they have multiple known roost sites, with interesting dynamics and shifts of activity among roosts. What might we learn by implementing a similar effort here in Columbia? Would we have enough volunteers to make this happen?

Building a better understanding of swift behavior is not only interesting, but also important from a conservation perspective. These birds have become reliant on chimney architecture that is limited in availability and not being replenished as new buildings are built. Observing which buildings swifts choose to use, and pondering the reasons why, are worthy citizen science endeavors. A better understanding of roost use also would benefit public outreach efforts. Chimney Swift roost watching is a great way to generate public interest in birds, but organizing such events currently involves some educated guesses about the best location to watch. Can additional data contribute to an ability to better predict patterns of use?

We doubt any amount of data can demystify all aspects of Chimney Swifts, which is perhaps just as well. We find Chimney Swift watching to be genuinely exciting, because we never know just how an evening or morning roost watch will unfold. Various aspects of Chimney Swifts behavior routinely catch us by surprise, and this is one reason we continue to be drawn to urban chimneys at dusk and dawn. Pondering the abundance of questions is part of the appeal.

If you have questions, comments, or would like to get involved, contact Joanna and Eric: birds@ozarkoutsider.com