WhenToBird

Tachycineta thalassina · Hirundinidae

When Do Violet-green Swallows Arrive in Montana?

Adult Violet-green Swallow
Photo: MarvalPhotography19, CC BY 4.0 via iNaturalist

Violet-green Swallows reach Montana in late March, are common by mid April, peak in early July (12% of checklists), and most are gone by early August.

When to look

First arrivalsMar 22-31late March
Common byApr 15-21mid April
PeakJul 1-7early July
Most gone byAug 1-7early August

Best: early July. First arrivals late March; most are gone by early August. Peak: on about 12% of Montana checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marrare
  4. Aprcommon
  5. Maypeak season
  6. Junpeak season
  7. Julpeak season
  8. Augcommon
  9. Seprare
  10. Octnot usually seen
  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 7987 checklistsJan 8-14: 0% of 5561 checklistsJan 15-21: 0% of 5613 checklistsJan 22-31: 0% of 7881 checklistsFeb 1-7: 0% of 5018 checklistsFeb 8-14: 0% of 5598 checklistsFeb 15-21: 0% of 7247 checklistsFeb 22-28: 0% of 5531 checklistsMar 1-7: 0.1% of 6110 checklistsMar 8-14: 0.1% of 6623 checklistsMar 15-21: 0.4% of 7687 checklistsMar 22-31: 1.3% of 11095 checklistsApr 1-7: 2.4% of 7774 checklistsApr 8-14: 4.0% of 8785 checklistsApr 15-21: 5.1% of 9684 checklistsApr 22-30: 7.1% of 13805 checklistsMay 1-7: 8.0% of 11847 checklistsMay 8-14: 9.7% of 13547 checklistsMay 15-21: 9.9% of 13019 checklistsMay 22-31: 10% of 20456 checklistsJun 1-7: 10% of 12993 checklistsJun 8-14: 11% of 11594 checklistsJun 15-21: 11% of 11159 checklistsJun 22-30: 12% of 13786 checklistsJul 1-7: 12% of 9584 checklistsJul 8-14: 12% of 9078 checklistsJul 15-21: 11% of 7905 checklistsJul 22-31: 8.6% of 10906 checklistsAug 1-7: 6.3% of 7335 checklistsAug 8-14: 4.5% of 6868 checklistsAug 15-21: 2.7% of 6866 checklistsAug 22-31: 1.8% of 10076 checklistsSep 1-7: 0.7% of 7670 checklistsSep 8-14: 0.6% of 7490 checklistsSep 15-21: 0.4% of 6804 checklistsSep 22-30: 0.1% of 8016 checklistsOct 1-7: 0% of 5996 checklistsOct 8-14: 0% of 6156 checklistsOct 15-21: 0% of 5742 checklistsOct 22-31: 0% of 7790 checklistsNov 1-7: 0.1% of 5353 checklistsNov 8-14: 0% of 5475 checklistsNov 15-21: 0% of 4603 checklistsNov 22-30: 0% of 6067 checklistsDec 1-7: 0% of 4362 checklistsDec 8-14: 0% of 4467 checklistsDec 15-21: 0% of 5328 checklistsDec 22-31: 0% of 6672 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 Montana 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.

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Where in Montana

Best counties

Share of checklists at the peak
  1. Mineral CountyBest mid April · 69 checklists that week, 2,163 in all42%
  2. Sanders CountyBest late April · 114 checklists that week, 3,767 in all36%
  3. Musselshell CountyBest late July · 24 checklists that week, 961 in all34%
  4. Dawson CountyBest late June · 46 checklists that week, 743 in all25%
  5. Park CountyBest mid June · 245 checklists that week, 7,672 in all25%
  6. Chouteau CountyBest mid May · 40 checklists that week, 954 in all23%

Best spots

Share of checklists at the peak
  1. Thompson Falls ReservoirSanders County, best late May · 23 checklists that week, 414 in all95%
  2. Missouri Headwaters State ParkGallatin County, best the second week of July · 21 checklists that week, 682 in all90%
  3. Pattee CreekMissoula County, best the second week of July · 20 checklists that week, 1,423 in all79%
  4. West Yellowstone Town ParkGallatin County, best late June · 23 checklists that week, 235 in all75%
  5. Bear CreekCarbon County, best late June · 22 checklists that week, 207 in all74%

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

Best time of day

In Montana, the Violet-green Swallow is most often listed on checklists started between 6 and 8 am (6.5% of those checklists).

0%2%4%6%8%12 am: too few checklists (183) to judge1 am: too few checklists (169) to judge2 am: too few checklists (163) to judge3 am: too few checklists (212) to judge4 am: too few checklists (503) to judge5 am: too few checklists (4022) to judge6 am: 7.3% of 12719 checklists7 am: 6.2% of 31202 checklists8 am: 4.5% of 47646 checklists9 am: 4.5% of 44624 checklists10 am: 4.7% of 40704 checklists11 am: 4.2% of 33825 checklists12 pm: 4.1% of 29407 checklists1 pm: 4.0% of 27959 checklists2 pm: 3.6% of 26928 checklists3 pm: 3.5% of 25313 checklists4 pm: 3.8% of 22151 checklists5 pm: 4.9% of 16884 checklists6 pm: 5.5% of 13780 checklists7 pm: 6.8% of 9926 checklists8 pm: too few checklists (5765) to judge9 pm: too few checklists (2099) to judge10 pm: too few checklists (595) to judge11 pm: too few checklists (230) 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%
February0%0%0%0%
March0.1%0.1%0.4%1.3%
April2.4%4.0%5.1%7.1%
May8.0%9.7%9.9%10%
June10%11%11%12%
July12%12%11%8.6%
August6.3%4.5%2.7%1.8%
September0.7%0.6%0.4%0.1%
October0%0%0%0%
November0.1%0%0%0%
December0%0%0%0%

Neighboring states

  • Idaho: arrives mid March, 1 week earlier than Montana
  • Wyoming: arrives late April, 4 weeks later than Montana
  • Utah: arrives early April, 1 week later than Montana
  • Washington: arrives early March, 3 weeks earlier than Montana

Common questions

When do Violet-green Swallows arrive in Montana?
Violet-green Swallows reach Montana in late March, are common by mid April, peak in early July (12% of checklists), and most are gone by early August.
When do Violet-green Swallows leave Montana?
Most Violet-green Swallows have left Montana by early August, when reports fall below half their usual rate. Stragglers are still reported until early September.
When is the best time to see a Violet-green Swallow in Montana?
The Violet-green Swallow is reported most often in early July, on about 12% of Montana checklists.
Where in Montana are Violet-green Swallows seen most often?
By county, Mineral County, Sanders County, and Musselshell County have the highest peak reporting rates for the Violet-green Swallow (counties with at least 200 checklists).