Vaux's Swifts and Your Chimney in the Rogue Valley: When to Wait Before Sweeping or Capping

Vaux's swifts are federally protected birds that roost in Rogue Valley chimneys each fall, with the Hedrick Middle School chimney in Medford the best known. When sweeping or capping is safe.

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Last updated October 7, 2026

Short Answer

Vaux's swift is on the federal list of birds protected by the Migratory Bird Treaty Act. The US Fish and Wildlife Service says destroying a nest that holds viable eggs or young needs federal authorization, and that the person doing the work is responsible for making sure no birds, eggs or nestlings are harmed. In Oregon the birds use chimneys in two ways: some pairs nest in them in spring and summer, and thousands gather to roost on fall migration, which in the Rogue Valley runs from late August to early October. If you can wait until the birds have gone, sweeping or capping a chimney is safe for them. Bird Alliance of Oregon's advice is to delay a fire or a sweep "until the parents and the young have left the nest, usually by September or October."

What the Law Says

The species is listed in 50 CFR 10.13 as "Vaux's Swift, Chaetura vauxi." The federal definition of a migratory bird includes "any part, nest, or egg of any such bird." The Fish and Wildlife Service's 2025 nest memorandum (MBPM-2-02) then separates nests by whether anything is in them.

What the US Fish and Wildlife Service nest policy (MBPM-2-02, January 15, 2025) says, in its own definitions.
Situation	What the policy says
In-use nest: it holds viable eggs or nestlings, from the first egg until the young have fledged and no longer depend on it	"Destruction of an in-use nest requires MBTA authorization."
Inactive nest: no viable eggs or nestlings, including a nest still being built before the first egg, or one the young have left	May be destroyed without a permit provided no one keeps it. The person destroying it must make sure no birds, nestlings or viable eggs are taken, and unpermitted take is "illegal and fully prosecutable."
Timing	"We recommend conducting activities outside of nesting season because doing so reduces the risk of take."
Other laws	"Even when inactive, migratory bird nests may be protected by additional Federal, State, Tribal, and local laws."

Oregon adds its own layer. Oregon Administrative Rule 635-044-0430 makes it unlawful, except as state law or a letter of authorization allows, to "take, capture, hold, release or have in possession" any non-game bird other than the European starling, house sparrow and Eurasian collared-dove.

When the Birds Are in the Chimney

Vaux's swifts nest mostly in hollow trees. Cornell's life history page says nests are built in hollows of large live or dead trees and "much less often in chimneys or under rooflines." Birds of the World, though, calls hollow trees and unlined chimneys "its favored nesting and roosting sites." In the fall the chimney use is far heavier: Cornell notes that before migration the swifts "gather in large flocks and use both trees and chimneys" as communal roosts.

Vaux's swift calendar in Oregon, from the sources named in the third column. Dates move from year to year.
Period	What the birds are doing	Source
Late April	Arrive in Oregon	Bird Alliance of Oregon
May and June	Court their mates	Bird Alliance of Oregon
By July	Four to six eggs laid and hatched	Bird Alliance of Oregon
Through the summer	Young fledge 28 to 32 days after hatching, and may return to roost at the nest for several nights	Audubon Field Guide
Late August to early October	Migrating flocks gather to roost in tall chimneys, staying about two to three weeks at any one chimney	Rogue Valley Audubon counts (2019); Bird Alliance of Oregon

One caution on the nesting row: Bird Alliance of Oregon's page says the young are cared for "just over two weeks," which disagrees with Audubon's 28 to 32 days, so we have used Audubon's figure.

The Hedrick Middle School Roost in Medford

Rogue Valley Audubon calls the tall brick chimney at Hedrick Middle School in Medford "the most important roosting site for Vaux's Swifts in southern Oregon," and the Southern Oregon Land Conservancy calls it "one of the most important fall migratory stops for the Vaux's Swift." The count sheet for fall 2019 shows the first birds on August 21, a peak of 3,242 on September 12, and the last two birds on October 7, with none on October 9. The count sheet's total of 36,299 adds up 42 nightly counts. It is not a headcount, since the same birds can be counted on several nights.

The Land Conservancy explains why chimneys matter: swifts once roosted in large hollow trees, which are now hard to find, and newer chimneys do not have the right texture for gripping. A news report from the Associated Press, carried by the Seattle Times, said the school district had at one time ordered the chimney capped, then kept it as a place where students count birds. Rogue Valley Audubon says the gym boiler that vented through the chimney was replaced in summer 2019, that the chimney needs a seismic retrofit to be saved, and that it was planning a capital campaign to pay for it.

The sources below do not say what has happened to the chimney since. Rogue Valley Audubon's October 2019 newsletter also records smaller roosts at the Voorhies Mansion at EdenVale Orchards, at Nunan Estates in Jacksonville and at a church across from McLoughlin Middle School in Medford.

If Swifts Are in Your Chimney

Wait. Bird Alliance of Oregon says swifts are unlikely to stay in a chimney more than two to three weeks, and that removing nesting swifts "is almost certain to lead to the death of the nestlings."
Put off the first fire and the sweep until the birds have left. A nest left behind is not a fire hazard: the same page says swift nests "disintegrate soon after they are abandoned."
If a young swift ends up in the fireplace, Bird Alliance of Oregon says to put it back up on the chimney wall and close the flue straight away.
Once they have gone, a cap keeps them from returning to nest or roost. Humane World for Animals, writing about the eastern chimney swift, advises capping metal-lined chimneys because birds that enter them can easily become trapped.

Booking a Sweep or a Cap

If a sweep, repair or cap is booked between late April and early October, ask the contractor how they will check the flue for birds before starting. Sweeping a flue with an active nest in it can kill the nestlings, and under the Fish and Wildlife Service policy the responsibility rests with whoever does the work. Outside those months there is little reason to delay.

What We Could Not Confirm

Whether capping or sweeping a chimney that holds only roosting birds, with no nest, counts as a prohibited take. The federal sources we read address nests, and we found nothing definitive on roosts. Ask the Fish and Wildlife Service or a wildlife attorney if the question is a live one.
Any Medford or Jackson County rule about chimneys used by swifts. Those codes block this machine, so we did not search them, and we found no state guidance on the subject from the Oregon Department of Fish and Wildlife.
The present state of the Hedrick Middle School chimney, and any counts after 2019.

Sources

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