WhenToBird

Falco columbarius · Falconidae

When Do Merlins Arrive in Wyoming?

Adult female Merlin
Photo: Cricket Raspet, CC BY 4.0 via iNaturalist

Merlins are winter birds in Wyoming: they arrive in early September, peak in mid December (1.6% of checklists), and most are gone by the second week of March.

When to look

First arrivalsSep 1-7early September
Common bySep 1-7early September
PeakDec 15-21mid December
Most gone byMar 8-14the second week of March

Best: mid December. First arrivals early September; most are gone by the second week of March. Peak: on about 1.6% of Wyoming checklists.

  1. Janpeak season
  2. Febcommon
  3. Marcommon
  4. Apruncommon
  5. Mayuncommon
  6. Junrare
  7. Julrare
  8. Auguncommon
  9. Sepcommon
  10. Octpeak season
  11. Novpeak season
  12. Decpeak season

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

0%0.5%1%1.5%2%Jan 1-7: 1.3% of 2543 checklistsJan 8-14: 1.2% of 2114 checklistsJan 15-21: 1.3% of 1984 checklistsJan 22-31: 1.1% of 2605 checklistsFeb 1-7: 1.5% of 1940 checklistsFeb 8-14: 0.8% of 1954 checklistsFeb 15-21: 1.0% of 2575 checklistsFeb 22-28: 1.1% of 1932 checklistsMar 1-7: 0.6% of 2486 checklistsMar 8-14: 0.6% of 2535 checklistsMar 15-21: 0.6% of 2726 checklistsMar 22-31: 0.4% of 4349 checklistsApr 1-7: 0.7% of 3300 checklistsApr 8-14: 0.5% of 3500 checklistsApr 15-21: 0.7% of 3701 checklistsApr 22-30: 0.6% of 5887 checklistsMay 1-7: 0.4% of 5341 checklistsMay 8-14: 0.2% of 6910 checklistsMay 15-21: 0.2% of 6884 checklistsMay 22-31: 0.2% of 10652 checklistsJun 1-7: 0.1% of 6807 checklistsJun 8-14: 0.1% of 6714 checklistsJun 15-21: 0.1% of 6708 checklistsJun 22-30: 0.1% of 8160 checklistsJul 1-7: 0.1% of 5755 checklistsJul 8-14: 0.1% of 5379 checklistsJul 15-21: 0.2% of 5299 checklistsJul 22-31: 0.1% of 6830 checklistsAug 1-7: 0.2% of 4581 checklistsAug 8-14: 0.2% of 4625 checklistsAug 15-21: 0.5% of 4466 checklistsAug 22-31: 0.4% of 6562 checklistsSep 1-7: 0.7% of 4543 checklistsSep 8-14: 0.8% of 4652 checklistsSep 15-21: 0.8% of 4186 checklistsSep 22-30: 1.0% of 5301 checklistsOct 1-7: 0.9% of 3248 checklistsOct 8-14: 1.5% of 3010 checklistsOct 15-21: 1.8% of 2624 checklistsOct 22-31: 1.2% of 3170 checklistsNov 1-7: 1.2% of 2110 checklistsNov 8-14: 1.2% of 2153 checklistsNov 15-21: 1.2% of 1971 checklistsNov 22-30: 1.2% of 2136 checklistsDec 1-7: 1.5% of 1646 checklistsDec 8-14: 1.4% of 1609 checklistsDec 15-21: 1.8% of 1954 checklistsDec 22-31: 1.7% 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. Goshen CountyBest mid October · 12 checklists that week, 1,920 in all7.3%
  2. Weston CountyBest the second week of December · 20 checklists that week, 2,297 in all7.0%
  3. Carbon CountyBest mid December · 25 checklists that week, 6,429 in all6.6%
  4. Lincoln CountyBest the second week of October · 37 checklists that week, 3,169 in all5.5%
  5. Big Horn CountyBest early January · 35 checklists that week, 2,023 in all4.1%
  6. Albany CountyBest the second week of December · 202 checklists that week, 21,857 in all3.7%

Best spots

Share of checklists at the peak
  1. Optomist ParkAlbany County, best early December · 33 checklists that week, 2,101 in all11%
  2. Camplex ParkCampbell County, best early October · 20 checklists that week, 659 in all9.2%
  3. LaBonte ParkAlbany County, best late September · 22 checklists that week, 1,107 in all6.8%
  4. French CreekJohnson County, best late April · 27 checklists that week, 397 in all6.3%
  5. Reshaw ParkNatrona County, best mid May · 20 checklists that week, 291 in all5.9%

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

Best time of day

In Wyoming, the Merlin is most often listed on checklists started between 7 and 9 am (0.7% of those checklists).

0%0.5%1%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: 0.4% of 8808 checklists7 am: 0.7% of 18458 checklists8 am: 0.8% of 22143 checklists9 am: 0.6% of 21499 checklists10 am: 0.6% of 19425 checklists11 am: 0.5% of 16017 checklists12 pm: 0.5% of 13868 checklists1 pm: 0.5% of 12984 checklists2 pm: 0.6% of 12605 checklists3 pm: 0.7% of 11821 checklists4 pm: 0.6% of 10571 checklists5 pm: 0.5% of 8746 checklists6 pm: 0.4% of 6707 checklists7 pm: 0.2% 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
January1.3%1.2%1.3%1.1%
February1.5%0.8%1.0%1.1%
March0.6%0.6%0.6%0.4%
April0.7%0.5%0.7%0.6%
May0.4%0.2%0.2%0.2%
June0.1%0.1%0.1%0.1%
July0.1%0.1%0.2%0.1%
August0.2%0.2%0.5%0.4%
September0.7%0.8%0.8%1.0%
October0.9%1.5%1.8%1.2%
November1.2%1.2%1.2%1.2%
December1.5%1.4%1.8%1.7%

Neighboring states

  • Colorado: arrives the second week of September, 1 week later than Wyoming
  • Utah: arrives the second week of October, 5 weeks later than Wyoming
  • Montana: arrives mid August, 2 weeks earlier than Wyoming
  • Idaho: arrives the second week of September, 1 week later than Wyoming

Common questions

When do Merlins arrive in Wyoming?
Merlins are winter birds in Wyoming: they arrive in early September, peak in mid December (1.6% of checklists), and most are gone by the second week of March.
When do Merlins leave Wyoming?
Most Merlins have left Wyoming by the second week of March, when reports fall below half their usual rate.
When is the best time to see a Merlin in Wyoming?
The Merlin is reported most often in mid December, on about 1.6% of Wyoming checklists.
Where in Wyoming are Merlins seen most often?
By county, Goshen County, Weston County, and Carbon County have the highest peak reporting rates for the Merlin (counties with at least 200 checklists).