CSMP Observations May 7

Nature London Chimney Swift Monitoring Program – Report #1 May 7, 2024


On May 7th, the evening was overcast, but a relatively warm 20C at the outset. There was light rain in most locations, starting at 7:55 p.m. or a little later, that lasted about 10 or 15 minutes.

Chimney Observations

 All but two of the 18 chimneys were monitored for this count. Of the 16 chimneys monitored, 13 were monitored on May 7th. The chimney at Smith Fruit was monitored on May 5th and the two at Kingsway were monitored on May 8th. The chimneys at Dundas and Colborne usually house a very small number of swifts and will be monitored soon and going forward.

Chimney Swifts occupied 14 of the 16 chimneys monitored. There were large roosts at Smith (79), Huron (64), Hunt’s (53), and King’s College (43) and a smaller one at Phoenix (20). All other chimneys held between 1 and 3 swifts, except for South Collegiate with 7. Only Elborn College and ICORR were empty, although swifts were heard and seen at ICORR.

The total number of swifts for this count was 284 (May 7, 2024). This is lower than the total one year ago on May 9, 2023, at 385, but is in the range of the totals for early May in previous years. Based on the trend in other years, we expect the number of migrating swifts sheltering in roost chimneys in London to increase through May. Changes in the location of larger roosts are also possible.

Observations of Swift Behaviour

Given the dark skies and light rain, some swifts made entries as early as 7:53 p.m., more than half an hour before sunset at 8:33 p.m. This is a good reminder to us to start monitoring earlier than 30 minutes before sunset when it is very overcast and threatening rain. At First-St. Andrew’s (FSA), five of the eight swifts in the four chimneys were in by 8:01 p.m. We were relieved that we had arrived early that night!

For the remainder of the chimneys, swifts generally started entering by 8:20 p.m. The latest entry on May 7th was at 8:42 p.m. with the last entry at many chimneys well before that. In comparison, the swifts at Smith Fruit only started entering at 8:30 p.m. on the clear night of May 5th. The last entry that night wasn’t until 8:56 p.m. Light levels make a big difference!

We welcome your observations of swift behaviour throughout the evening. At Phoenix, some swifts were observed dipping at the chimney. This suggests the birds may have been unfamiliar with the chimney and/or having a look at the accommodations before entering. At FSA, a trio of swifts were seen flying in a tight formation. Later, three swifts entered the FSA South chimney in close succession. Two other swifts entered FSA SE together.

According to birdsoftheworld.org, aerial courtship displays begin within two weeks of swifts’ return to their breeding area. This consists of much chasing in loose groups of four to seven individuals and frequent separation of pairs of birds flying together, one following the other, and then rejoining other swifts. This is followed by trio-flying: three swifts that follow each other while making constant, louder-than-normal chipper calls. Trio flights often involve one female followed by two males. The reason for this behaviour is unclear but is considered to be related to breeding behaviour. V flying is recognized as a sign of pair formation. You can read more about it and see an illustration under the heading Pair Bond in the birdsoftheworld.org article:


To inspire you to look more closely at what the swifts are up to, we end with “Winnie’s Words of Wisdom”* from May 10, 2022 – “In the early weeks of migration, swifts may remain at a communal roost instead of immediately moving to the chimney in which they plan to nest. Some swifts quickly settle into a nest chimney to spend nights but don’t start nest-building right away. During monitoring sessions, early ins and outs may suggest an interest in nesting, but late ins and outs may indicate swifts trying to decide where to spend the night. It can be very challenging to try to figure out what swifts are really up to! Several monitors reported swifts flying around in twos or threes, typical courtship behaviour in this species.”

Glenn and Susan Berry,

May 11, 2024

*Most of you know about Winnie’s invovlement with swifts. The Spring issue of The Cardinal has an article “NL’s Chimney Swift Program: From Beginning to Now”.

Observations Submitted by the Monitors

This table summarizes the data submitted online for three nights, May 5, 7, and 8. The raw data will be shared with Birds Canada at the end of the season.

Observations for 05/07
Observations for 05/07
Total count 284
Sunset 08:33
Temp 20
Wind 1
Precip trace/occasional
Cloud Cover 10
Elborn CollegeBarb Yeo & Rick Hayman0noneMax in air: 0 Had 4 starlings, 1 cardinal, 2 robins on the ground and 1 robin on a nest in a long doorway entrance (maybe the same one as last year), 1 red-wing blackbird and 3 Canada geese.
FSA NorthGlenn Berry and Mackenzie Amlin17:56 = 1Max in air: 10 Skunk crossed the parking lot.
FSA SouthGlenn Berry and Mackenzie Amlin38:14 = 3Max in air: 10 The three entered together in a line. These may be the trio seen flying close together a few times.
FSA NERon Martin and Susan Berry27:57 = 1 in 7:59 = 1 inMax in air: 8 Susan Berry monitored FSA NE until the arrival of Ron Martin at 7:50 pm. Swifts entered just after very light rain started at 7:55 pm. See further observations in FSA SE report.
FSA SERon Martin and Susan Berry28:01 = 2 inMax in air: 10 At 7:30 pm about 6 swifts, chittering and circling low. Small groups of swifts come and go over the next half hour. One group of 3 flying in close formation seen together often. At 7:55 pm a few drops of rain for a short time, then stopped. Two swifts entered very closely together, no delay. Around 8:30 pm only 2 swifts very high in the sky, seen but not heard, heading east. Other bird species: 2 crows perched on church roof briefly, one perched on NE chimney briefly. Robins, House Finch. Mourning Dove perched (or nesting?) in spruce tree at front of church.
HuntLeslie Rockwell, Glen Winegarden538:12, 1 in 8:31, 1 in 8:33, 4 in 8:34, 22 in 8:35, 13 in 8:36, 11 in 8:41, 1 in, 1 out 8:42, 1 inMax in air: 25 2 starlings were on the roof ledge near the chimney. A raccoon was seen nearby and a skunk was close by (so our noses told us) but not sure where.
Huron CollegeSandy Symmes, Ric Symmes, Lois Ward648:00 1 8:06 1 8:10 4 8:14 4 8:16 18 8:17 15 8:18 5 8:24 10 8:26 1 8:28 2 8:29 1 8:37 2Max in air: 15 1 Kildeer calling, Hawk (possible Redtailed Hawk), all quiet. Swifts came in early in a rush once the shower began around 8:16
ICORRAnn MacPhail, Jack Blocker00 in 0 outMax in air: 2 7:42 heard swifts chittering, saw 2 swifts flying over parking lot near ICORR chimney
King’s CollegeRoslyn Moorhead, Elizabeth Pattison438:19 30 in 8:20 4 in 8:21 6 in 8:22 2 in 8:23 1 inMax in air: 30 Swifts observed in flight overhead in small groups (up to 12) starting at 8:00. 2 bats observed.
Kingsway NorthMarguerite Annen, Shelley Garner38:46=4 in 8:50=1 outMax in air: 15 Observed on 05/08. Swifts were present at the beginning of the watch. Maximum of 15 flying noisily above the building and in the general area. As the evening progressed the numbers dwindled. We saw and heard numerous birds – red tailed hawk, bat, grackles, cardinals, robins, flicker, geese, oriole.
Kingsway SouthShelley and Marguerite28:41 2 inMax in air: 14 Observed on 05/08. Same as Marguerite-also, a hawk, possibly red tail, landed on turrets of seminary half mile away. No mosquitoes. Gate was up, parking in lot.
LabattJOHN BERRY, LESLIE BAKER37:53 3 8:12 1 8:17 -1Max in air: 7 Light shower 7.55 to 8.05. Thunderstorms came later in the night. Cardinal resident around the Labatt site 3 Geese flew overhead 8.45 7.49 3 swifts flew overhead to NE 8.34 7 swifts flew overhead to NE
Old NorthJudy Shaw, Pat Tripp28:05 1 in 8:14 1 inMax in air: 1 …..
PhoenixWinifred Wake, David Wake208:19=3 in; 8:29=1 in; 8:33 =1 in; 8:36=1+3+6 in; 8:38=2+1 in; 8:39=1 in; 8:41=1 in Max in air: 8 From arrival till last entry, swifts were regularly in area, circling in small groups (3 to 8); some dipping at chimney. Lots of excited chatter. When swifts entered individually or by small groups, often at least one swift remained outside. Most of the swifts seemed to be coming and going from the S or SW. No swifts seen or heard after last entry. Rain stopped at 8:10. Other species: Rock Pigeon, House Sparrow, European Starling, American Robin, Canada Goose.
Smith FruitSusan and Glenn Berry798:30 1 8:31 1 8:34 2 8:38 -1 8:39 -1 8:41 1 8:42 3 8:44 30 8:45 14 8:46 23 8:47 1 8:48 2 8:49 1 8:50 5 -1 8:51 -1 8:52 2 8:54 1 8:56 1 Max in air: 40 Observed on 05/05. Other birds: House Sparrow, American Robin, European Starling, Common Grackle with a nest, Baltimore Oriole, Song Sparrow, Northern Cardinal. The first swifts seen: 2 at 7:57. Will update this report after reviewing video.
South CollegiateShelagh Grant72 in 8:19 1 in 8:32 2 in 8:34 1 in 8:36 1 in 8:38Max in air: 4 2 teenage girls filming themselves dancing on the roof