WhenToBird

Empidonax traillii · Tyrannidae

When Do Willow Flycatchers Arrive in Wyoming?

Adult Willow Flycatcher
Photo: Steven Smethurst, CC0 1.0 via iNaturalist

Willow Flycatchers arrive in Wyoming in mid May, peak in the second week of June (2.5% of checklists), and most are gone by early September.

When to look

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

Best: the second week of June. First arrivals mid May; most are gone by early September. Peak: on about 2.5% of Wyoming 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%1%2%3%Jan 1-7: 0% of 2543 checklistsJan 8-14: 0% of 2114 checklistsJan 15-21: 0% of 1984 checklistsJan 22-31: 0% of 2605 checklistsFeb 1-7: 0% of 1940 checklistsFeb 8-14: 0% of 1954 checklistsFeb 15-21: 0% of 2575 checklistsFeb 22-28: 0% of 1932 checklistsMar 1-7: 0% of 2486 checklistsMar 8-14: 0% of 2535 checklistsMar 15-21: 0% of 2726 checklistsMar 22-31: 0% of 4349 checklistsApr 1-7: 0% of 3300 checklistsApr 8-14: 0% of 3500 checklistsApr 15-21: 0% of 3701 checklistsApr 22-30: 0% of 5887 checklistsMay 1-7: 0.1% of 5341 checklistsMay 8-14: 0.1% of 6910 checklistsMay 15-21: 0.7% of 6884 checklistsMay 22-31: 1.6% of 10652 checklistsJun 1-7: 2.4% of 6807 checklistsJun 8-14: 2.8% of 6714 checklistsJun 15-21: 2.2% of 6708 checklistsJun 22-30: 2.2% of 8160 checklistsJul 1-7: 1.9% of 5755 checklistsJul 8-14: 1.4% of 5379 checklistsJul 15-21: 1.2% of 5299 checklistsJul 22-31: 1.6% of 6830 checklistsAug 1-7: 1.5% of 4581 checklistsAug 8-14: 1.2% of 4625 checklistsAug 15-21: 1.2% of 4466 checklistsAug 22-31: 1.2% of 6562 checklistsSep 1-7: 0.7% of 4543 checklistsSep 8-14: 0.4% of 4652 checklistsSep 15-21: 0.1% of 4186 checklistsSep 22-30: 0.1% of 5301 checklistsOct 1-7: 0% of 3248 checklistsOct 8-14: 0% of 3010 checklistsOct 15-21: 0% of 2624 checklistsOct 22-31: 0% of 3170 checklistsNov 1-7: 0% of 2110 checklistsNov 8-14: 0% of 2153 checklistsNov 15-21: 0% of 1971 checklistsNov 22-30: 0% of 2136 checklistsDec 1-7: 0% of 1646 checklistsDec 8-14: 0% of 1609 checklistsDec 15-21: 0% of 1954 checklistsDec 22-31: 0% of 2392 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 Wyoming 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 Wyoming

Best counties

Share of checklists at the peak
  1. Sublette CountyBest mid June · 208 checklists that week, 6,738 in all6.5%
  2. Lincoln CountyBest the second week of June · 150 checklists that week, 3,169 in all6.1%
  3. Laramie CountyBest early June · 327 checklists that week, 15,593 in all5.5%
  4. Johnson CountyBest mid June · 133 checklists that week, 5,977 in all4.3%
  5. Teton CountyBest mid June · 1835 checklists that week, 34,686 in all4.2%
  6. Sheridan CountyBest the second week of June · 191 checklists that week, 6,459 in all4.0%

Best spots

Share of checklists at the peak
  1. South Park Wildlife Habitat Management AreaTeton County, best early August · 22 checklists that week, 756 in all53%
  2. Blacktail PondsTeton County, best late June · 37 checklists that week, 338 in all36%
  3. Usbr (southeast)Lincoln County, best late May · 21 checklists that week, 115 in all32%
  4. Christian Pond (Lunch Tree Hill)Teton County, best mid June · 23 checklists that week, 140 in all21%
  5. French CreekJohnson County, best late May · 21 checklists that week, 397 in all20%

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

Best time of day

In Wyoming, the Willow Flycatcher is most often listed on checklists started between 6 and 8 am (1.3% of those checklists).

0%0.5%1%1.5%2%12 am: too few checklists (59) to judge1 am: too few checklists (76) to judge2 am: too few checklists (86) to judge3 am: too few checklists (79) to judge4 am: too few checklists (326) to judge5 am: too few checklists (2271) to judge6 am: 1.8% of 8808 checklists7 am: 1.1% of 18458 checklists8 am: 1.0% of 22143 checklists9 am: 0.9% of 21499 checklists10 am: 1.0% of 19425 checklists11 am: 0.6% of 16017 checklists12 pm: 0.4% of 13868 checklists1 pm: 0.5% of 12984 checklists2 pm: 0.5% of 12605 checklists3 pm: 0.6% of 11821 checklists4 pm: 0.5% of 10571 checklists5 pm: 0.6% of 8746 checklists6 pm: 0.4% of 6707 checklists7 pm: 0.5% of 4890 checklists8 pm: too few checklists (2323) to judge9 pm: too few checklists (554) to judge10 pm: too few checklists (134) to judge11 pm: too few checklists (59) 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%
May0.1%0.1%0.7%1.6%
June2.4%2.8%2.2%2.2%
July1.9%1.4%1.2%1.6%
August1.5%1.2%1.2%1.2%
September0.7%0.4%0.1%0.1%
October0%0%0%0%
November0%0%0%0%
December0%0%0%0%

Neighboring states

  • Colorado: arrives the second week of May, 1 week earlier than Wyoming
  • Utah: arrives mid May, in the same week than Wyoming
  • Montana: arrives mid May, in the same week than Wyoming
  • Idaho: arrives mid May, in the same week than Wyoming

Common questions

When do Willow Flycatchers arrive in Wyoming?
Willow Flycatchers arrive in Wyoming in mid May, peak in the second week of June (2.5% of checklists), and most are gone by early September.
When do Willow Flycatchers leave Wyoming?
Most Willow Flycatchers have left Wyoming by early September, when reports fall below half their usual rate.
When is the best time to see a Willow Flycatcher in Wyoming?
The Willow Flycatcher is reported most often in the second week of June, on about 2.5% of Wyoming checklists.
Where in Wyoming are Willow Flycatchers seen most often?
By county, Sublette County, Lincoln County, and Laramie County have the highest peak reporting rates for the Willow Flycatcher (counties with at least 200 checklists).