WhenToBird

Tachycineta bicolor · Hirundinidae

When Do Tree Swallows Arrive in Utah?

Adult Tree Swallow
Photo: Carter Dorscht, CC0 1.0 via iNaturalist

Tree Swallows reach Utah in the second week of March, are common by late March, peak in early May (10% of checklists), and most are gone by the second week of September.

When to look

First arrivalsMar 8-14the second week of March
Common byMar 22-31late March
PeakMay 1-7early May
Most gone bySep 8-14the second week of September

Best: early May. First arrivals the second week of March; most are gone by the second week of September. Peak: on about 10% of Utah checklists.

  1. Jannot usually seen
  2. Febrare
  3. Maruncommon
  4. Aprpeak season
  5. Maypeak season
  6. Juncommon
  7. Julcommon
  8. Augcommon
  9. Sepcommon
  10. Octrare
  11. Novnot usually seen
  12. Decnot usually seen

Darker months: more checklists report it. Outlined: peak month.

0%5%10%15%Jan 1-7: 0% of 10857 checklistsJan 8-14: 0% of 8333 checklistsJan 15-21: 0% of 8360 checklistsJan 22-31: 0.1% of 10516 checklistsFeb 1-7: 0% of 7416 checklistsFeb 8-14: 0.1% of 8082 checklistsFeb 15-21: 0.1% of 9643 checklistsFeb 22-28: 0.3% of 7960 checklistsMar 1-7: 1.0% of 7998 checklistsMar 8-14: 1.1% of 8581 checklistsMar 15-21: 1.6% of 8637 checklistsMar 22-31: 2.9% of 13006 checklistsApr 1-7: 5.3% of 10562 checklistsApr 8-14: 7.7% of 11694 checklistsApr 15-21: 9.2% of 11382 checklistsApr 22-30: 11% of 16626 checklistsMay 1-7: 11% of 13523 checklistsMay 8-14: 9.5% of 14714 checklistsMay 15-21: 9.5% of 13711 checklistsMay 22-31: 7.1% of 16546 checklistsJun 1-7: 6.6% of 10284 checklistsJun 8-14: 5.3% of 9530 checklistsJun 15-21: 6.3% of 8854 checklistsJun 22-30: 6.0% of 10566 checklistsJul 1-7: 6.2% of 7987 checklistsJul 8-14: 7.1% of 7471 checklistsJul 15-21: 7.5% of 7240 checklistsJul 22-31: 6.8% of 9329 checklistsAug 1-7: 6.7% of 6521 checklistsAug 8-14: 6.9% of 6423 checklistsAug 15-21: 5.5% of 6208 checklistsAug 22-31: 5.6% of 9089 checklistsSep 1-7: 5.1% of 7081 checklistsSep 8-14: 4.0% of 7306 checklistsSep 15-21: 2.1% of 7208 checklistsSep 22-30: 1.3% of 8876 checklistsOct 1-7: 0.9% of 7265 checklistsOct 8-14: 0.4% of 7226 checklistsOct 15-21: 0.2% of 7007 checklistsOct 22-31: 0.1% of 8443 checklistsNov 1-7: 0.1% of 6711 checklistsNov 8-14: 0.1% of 6290 checklistsNov 15-21: 0% of 6169 checklistsNov 22-30: 0.1% of 8228 checklistsDec 1-7: 0.1% of 6011 checklistsDec 8-14: 0.1% of 6044 checklistsDec 15-21: 0% of 6721 checklistsDec 22-31: 0% of 9982 checklistsJanFebMarAprMayJunJulAugSepOctNovDec
Share of complete checklists reporting it, by week (4 per month). Grey bars: fewer than 10 checklists, not counted.

Frequency is the share of complete checklists in Utah that listed the bird, 2016–2025. It is not a head count, and it follows where and when people go birding. How to read it.

JanFebMarAprMayJunJulAugSepOctNovDec
today
Second week of November

Each county is shaded by the share of complete checklists there that listed the bird, blended with the weeks either side. Darker is more often. It follows where people watch birds, not how many birds there are. How to read it.

Embed this map on your site

Where in Utah

Best counties

Share of checklists at the peak
  1. Wasatch CountyBest the second week of May · 277 checklists that week, 7,780 in all28%
  2. Box Elder CountyBest late April · 451 checklists that week, 9,867 in all28%
  3. Summit CountyBest the second week of May · 403 checklists that week, 13,829 in all28%
  4. Morgan CountyBest the second week of May · 118 checklists that week, 3,178 in all26%
  5. Rich CountyBest late June · 111 checklists that week, 1,563 in all22%
  6. Duchesne CountyBest early May · 51 checklists that week, 2,692 in all20%

Best spots

Share of checklists at the peak
  1. Trapper ParkCache County, best late May · 38 checklists that week, 491 in all80%
  2. Utah Lake WetlandsUtah County, best the second week of July · 21 checklists that week, 1,189 in all73%
  3. Bear River Migratory Bird Refuge (Rock Island)Box Elder County, best late April · 26 checklists that week, 436 in all69%
  4. Bear River Migratory Bird Refuge (Whistlers Bend)Box Elder County, best late April · 21 checklists that week, 248 in all69%
  5. Rendezvous ParkCache County, best late May · 21 checklists that week, 319 in all68%

Busy spots report more of everything; compare the checklist counts before you drive anywhere.

Best time of day

In Utah, the Tree Swallow is most often listed on checklists started between 6 and 8 am (6.1% of those checklists).

0%2%4%6%8%12 am: too few checklists (242) to judge1 am: too few checklists (178) to judge2 am: too few checklists (169) to judge3 am: too few checklists (162) to judge4 am: too few checklists (284) to judge5 am: too few checklists (1984) to judge6 am: 7.6% of 11714 checklists7 am: 5.5% of 33209 checklists8 am: 4.4% of 46944 checklists9 am: 4.2% of 46290 checklists10 am: 4.0% of 43144 checklists11 am: 3.6% of 36893 checklists12 pm: 3.4% of 32758 checklists1 pm: 3.5% of 30142 checklists2 pm: 3.2% of 29414 checklists3 pm: 3.2% of 29491 checklists4 pm: 3.2% of 29154 checklists5 pm: 4.3% of 22256 checklists6 pm: 5.1% of 17383 checklists7 pm: 5.0% of 13099 checklists8 pm: too few checklists (6647) to judge9 pm: too few checklists (1753) to judge10 pm: too few checklists (599) to judge11 pm: too few checklists (307) to judge12a3a6a9a12p3p6p9p
Share of checklists started in each local hour that reported it. It reflects when people go birding as well as when birds are active. Grey hours have too few checklists (under 2% of the state’s, or under 200) to judge.
Week-by-week table
MonthDays 1-78-1415-2122-end
January0%0%0%0.1%
February0%0.1%0.1%0.3%
March1.0%1.1%1.6%2.9%
April5.3%7.7%9.2%11%
May11%9.5%9.5%7.1%
June6.6%5.3%6.3%6.0%
July6.2%7.1%7.5%6.8%
August6.7%6.9%5.5%5.6%
September5.1%4.0%2.1%1.3%
October0.9%0.4%0.2%0.1%
November0.1%0.1%0%0.1%
December0.1%0.1%0%0%

Neighboring states

  • Wyoming: arrives early April, 3 weeks later than Utah
  • Nevada: arrives mid January, 7 weeks earlier than Utah
  • Colorado: arrives late March, 2 weeks later than Utah
  • Idaho: arrives mid March, 1 week later than Utah

Common questions

When do Tree Swallows arrive in Utah?
Tree Swallows reach Utah in the second week of March, are common by late March, peak in early May (10% of checklists), and most are gone by the second week of September.
When do Tree Swallows leave Utah?
Most Tree Swallows have left Utah by the second week of September, when reports fall below half their usual rate. Stragglers are still reported until late September.
When is the best time to see a Tree Swallow in Utah?
The Tree Swallow is reported most often in early May, on about 10% of Utah checklists.
Where in Utah are Tree Swallows seen most often?
By county, Wasatch County, Box Elder County, and Summit County have the highest peak reporting rates for the Tree Swallow (counties with at least 200 checklists).