Manitoba Bird Bird Atlas: Species At Risk

Chimney Swift

Early Breeding and Last Migration Dates

South: Regions 1 to 8 Central: Regions 9 to 12 North: Regions 13 and 14
Early Breeding Last Migration Late Breeding Early Breeding Last Migration Late Breeding Early Breeding Last Migration Late Breeding
May-11 May-21 Aug-06

Breeding Evidence

The nests are usually out of sight on the vertical surfaces of large chimneys and other urban structures. They are built of small twigs glued together with a saliva-like secration.

Chimney Swifts now primarily nest inside older brick chimneys. The ideal chimney is brick inside and out; it has a horizontal course of at least 2 1/2 bricks for a minimum inner diameter of 25 to 30 cm (1 foot) that will accomodate the swift’s wingspan (image a). No one has confirmed yet how far down the chimney the birds actually go to roost or nest (some chimneys are really high).

Good candidate chimneys tend to be found on schools, churches, apartment buildings, hospitals, and commercial buildings that were built prior the 1960s. After the 1960s, chimney design and building codes changed resulting in chimneys that were no longer swift-friendly: they tended to be lined with metal, which does not provide sufficient surface irregularities for the birds to get a toe hold or to “spit” attach twigs to make a nest.

When looking for a possible chimney to watch, count the number of bricks per side and then determine if it has any sort of metal insert, metal cap, screen cap, etc which would prevent the swift from flying down the chimney. Sometimes having a TV antennae or dish on the roof near or on the chimney might be a deterrent, as might some form of lightning rod.

Monitoring the chimney

After identifying an appropriate candidate chimney, the next step in verifying chimney swift use is to find a good vantage point on the ground, such that the chimney is silhouetted against the sky. Beginning about 30 minutes before sunset and continuing until about 30 minutes after sunset (sunset times are available at, watch carefully to see if any swifts drop into the chimney. Monitoring at this time of day will reveal most, and possibly all, swifts using the chimney, whether a resident nesting pair with or without a helper bird or two, other non-breeding adults using the site as a night-time roost, or both. Unless the site is determined to be a communal roost with more than four birds entering for the night, such an observation, made after May 21st within the 1-hour period bracketing sunset, would constitute a V: Bird visiting a probable nest site in suitable nesting habitat during the species’ breeding season.

At earlier stages of the nesting cycle, swifts can be very secretive around their home chimneys. There will be little or no circling overhead, and approaches and entries may be silent, rapid and direct (sometimes even horizontal). It is very easy to miss such an entry. Nesting swifts, though resident for much longer, are probably most readily detected in chimneys from mid-July to early August, when many feeding visits are being made throughout the day and evening (though a check then will miss swifts that abandoned early due to nest failure). If there is an active nest in a chimney, swifts may enter and depart a number of times during the day and evening as they build the nest, exchange incubation duties, and feed young. The observation of multiple entries and exits from one chimney, after May 21st, at any time of the day or evening, would constitute an AE: Adult entering, occupying, or leaving a nest site (visible or not) or whose behavior suggests the presence of an occupied nest.

The majority of nesting should be underway by mid-June at the latest. Swifts that are neither migrating nor nesting do not normally enter chimneys during the daytime, except to escape from bad weather. The observation of an entry or exit from a chimney after June 15th during daytime hours (between half an hour after sunrise to half an hour before sunset) and reasonably good weather (not excessively windy or raining) would constitute an AE: Adult entering, occupying, or leaving a nest site (visible or not) or whose behavior suggests the presence of an occupied nest.

If in doubt about the breeding status of the swifts using a particular chimney, it is always recommended to monitor the site more than once.

In the off-season, one can sometimes determine that swifts have previously used a chimney. This is done by checking the chimney clean out in the basement and looking for eggshells, feathers, droppings, fallen nests, and nesting material (nests are made exclusively of small sticks - no grass, straw, or mud). However, these remains can last for years, so it may be impossible to know when the chimney was last used.

For more information, please visit the Manitoba Chimney Swift Initiative (MCSI) website ( or contact the coordinator. Please also report any chimney swift sightings, and especially observations of swifts entering a potential nesting or roosting site to:
Frank Machovec
MCSI Coordinator

Some Chimney Swift behaviours that you could report as breeding evidence are summarized in the following table:

Behaviour Description Dates Atlas
Breeding Code
Flying or feeding Single swift or several birds seen in flight in a given area (not direct line flight over an area) with no apparent association between birds After May 30th
(earlier = possible migrants so care required)
Chasing Loose associatiation of 4 to 7 birds in flight, with pairs sometimes breaking off, some chipping calls After May 16th,
possibly earlier
Trio-flying 3 swifts flying in tight formation (sudden turns in unison); appears to be 2 birds following a leader; often with loud chipping calls After May 16th,
possibly earlier
V-ing 2 swifts gliding with chipping calls, then rear bird snaps wings into “V”, lead bird may also “V” After May 16th,
possibly earlier
Site inspection Feints made toward chimney by 1 or 2 swifts. After May 30th
(earlier = possible migrants so care required)
Entering or exiting chimney Less than 2 entries and exits After May 21st V
Multiple entries and exits by 1-2 (occasionally up to four) swifts during one observation period After May 21st AE
1 entry/exit during daytime hours (from half an hour after sunrise to half an hour before sunset) and good weather.
Note: Non-breeders form communal roosts during the summer. The entry/exit of more than 4 birds should not be considered evidence of breeding unless consisting of parents with fledged young.
After June 15th AE
Fledged young flying Recently fledged young return to nest chimney for up to 2 weeks post fledging and can sometimes be identified.
Note: adults moult in July and are often missing some flight feathers, especially close to the body.
After approx. July 25th until August 4th. Note: immature birds seen after these dates may be too far from nest site to Atlas with confidence. FY
Fall roosting Bird(s) entering chimney in August After July 31st try to distinguish migrants from local birds. After August 11th treat as migrants Do not record


Breeding Evidence Map

Chimney Swifts spend the major part of the day in flight feeding on insects. Flocks can often be seen near bodies of water due to the abundance of insects. They are mainly associated with urban and rural areas where the birds can find chimneys to use as nesting and resting sites. However, it is likely that a small portion of the population continues to use hollow trees. Apparently, there is a “natural” colony in large poplars near the Agassiz ski-hill in Riding Mountain National Park.

-from COSEWIC and The Birds of Manitoba (p. 240)