WhenToBird

Vireo swainsoni · Vireonidae

When Do Western Warbling Vireos Arrive in Montana?

Western Warbling Vireos reach Montana in the second week of May, are common by mid May, peak in mid June (24% of checklists), and most are gone by early September.

When to look

First arrivalsMay 8-14the second week of May
Common byMay 15-21mid May
PeakJun 15-21mid June
Most gone bySep 1-7early September

Best: mid June. First arrivals the second week of May; most are gone by early September. Peak: on about 24% of Montana checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprnot usually seen
  5. Maycommon
  6. Junpeak season
  7. Julpeak season
  8. Augcommon
  9. Sepuncommon
  10. Octnot usually seen
  11. Novnot usually seen
  12. Decnot usually seen

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

0%10%20%30%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% of 6110 checklistsMar 8-14: 0% of 6623 checklistsMar 15-21: 0% of 7687 checklistsMar 22-31: 0% of 11095 checklistsApr 1-7: 0% of 7774 checklistsApr 8-14: 0% of 8785 checklistsApr 15-21: 0% of 9684 checklistsApr 22-30: 0% of 13805 checklistsMay 1-7: 0.2% of 11847 checklistsMay 8-14: 2.3% of 13547 checklistsMay 15-21: 7.1% of 13019 checklistsMay 22-31: 13% of 20456 checklistsJun 1-7: 20% of 12993 checklistsJun 8-14: 24% of 11594 checklistsJun 15-21: 24% of 11159 checklistsJun 22-30: 23% of 13786 checklistsJul 1-7: 21% of 9584 checklistsJul 8-14: 20% of 9078 checklistsJul 15-21: 15% of 7905 checklistsJul 22-31: 12% of 10906 checklistsAug 1-7: 8.4% of 7335 checklistsAug 8-14: 7.2% of 6868 checklistsAug 15-21: 7.5% of 6866 checklistsAug 22-31: 8.7% of 10076 checklistsSep 1-7: 6.7% of 7670 checklistsSep 8-14: 5.5% of 7490 checklistsSep 15-21: 3.0% of 6804 checklistsSep 22-30: 1.0% of 8016 checklistsOct 1-7: 0.3% of 5996 checklistsOct 8-14: 0.1% of 6156 checklistsOct 15-21: 0% of 5742 checklistsOct 22-31: 0% of 7790 checklistsNov 1-7: 0% 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. Granite CountyBest mid June · 130 checklists that week, 1,737 in all47%
  2. Mineral CountyBest the second week of June · 137 checklists that week, 2,163 in all41%
  3. Missoula CountyBest the second week of June · 1481 checklists that week, 64,368 in all40%
  4. Lincoln CountyBest the second week of June · 260 checklists that week, 5,543 in all39%
  5. Flathead CountyBest the second week of June · 1114 checklists that week, 40,185 in all34%
  6. Silver Bow CountyBest mid June · 64 checklists that week, 3,051 in all33%

Best spots

Share of checklists at the peak
  1. Swamp GulchLewis and Clark County, best early June · 28 checklists that week, 160 in all81%
  2. Gardner ParkGallatin County, best early July · 29 checklists that week, 2,009 in all80%

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

Best time of day

In Montana, the Western Warbling Vireo is most often listed on checklists started between 6 and 8 am (12% of those checklists).

0%5%10%15%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: 15% of 12719 checklists7 am: 11% of 31202 checklists8 am: 8.0% of 47646 checklists9 am: 7.4% of 44624 checklists10 am: 6.8% of 40704 checklists11 am: 5.4% of 33825 checklists12 pm: 4.4% of 29407 checklists1 pm: 3.8% of 27959 checklists2 pm: 3.8% of 26928 checklists3 pm: 3.7% of 25313 checklists4 pm: 3.8% of 22151 checklists5 pm: 5.0% of 16884 checklists6 pm: 5.8% of 13780 checklists7 pm: 6.9% 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%0%0%0%
April0%0%0%0%
May0.2%2.3%7.1%13%
June20%24%24%23%
July21%20%15%12%
August8.4%7.2%7.5%8.7%
September6.7%5.5%3.0%1.0%
October0.3%0.1%0%0%
November0%0%0%0%
December0%0%0%0%

Neighboring states

  • Idaho: arrives early May, 1 week earlier than Montana
  • Wyoming: arrives mid May, 1 week later than Montana
  • Utah: arrives late April, 2 weeks earlier than Montana
  • Washington: arrives mid April, 3 weeks earlier than Montana

Common questions

When do Western Warbling Vireos arrive in Montana?
Western Warbling Vireos reach Montana in the second week of May, are common by mid May, peak in mid June (24% of checklists), and most are gone by early September.
When do Western Warbling Vireos leave Montana?
Most Western Warbling Vireos have left Montana by early September, when reports fall below half their usual rate. Stragglers are still reported until late September.
When is the best time to see a Western Warbling Vireo in Montana?
The Western Warbling Vireo is reported most often in mid June, on about 24% of Montana checklists.
Where in Montana are Western Warbling Vireos seen most often?
By county, Granite County, Mineral County, and Missoula County have the highest peak reporting rates for the Western Warbling Vireo (counties with at least 200 checklists).