WhenToBird

Pandion haliaetus · Pandionidae

When Do Ospreys Arrive in Colorado?

Adult female Osprey
Photo: Bill Levine, CC BY 4.0 via iNaturalist

Ospreys reach Colorado in mid March, are common by late March, peak in mid April (11% of checklists), and most are gone by early October.

When to look

First arrivalsMar 15-21mid March
Common byMar 22-31late March
PeakApr 15-21mid April
Most gone byOct 1-7early October

Best: mid April. First arrivals mid March; most are gone by early October. Peak: on about 11% of Colorado checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marcommon
  4. Aprpeak season
  5. Maypeak season
  6. Juncommon
  7. Julcommon
  8. Augpeak season
  9. Sepcommon
  10. Octuncommon
  11. Novrare
  12. Decnot usually seen

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

0%5%10%15%Jan 1-7: 0.1% of 32254 checklistsJan 8-14: 0% of 23278 checklistsJan 15-21: 0% of 22933 checklistsJan 22-31: 0% of 30856 checklistsFeb 1-7: 0% of 21464 checklistsFeb 8-14: 0% of 22910 checklistsFeb 15-21: 0% of 28739 checklistsFeb 22-28: 0.1% of 21833 checklistsMar 1-7: 0.1% of 23066 checklistsMar 8-14: 0.3% of 23783 checklistsMar 15-21: 1.3% of 24797 checklistsMar 22-31: 5.6% of 38439 checklistsApr 1-7: 8.7% of 31676 checklistsApr 8-14: 10% of 35092 checklistsApr 15-21: 13% of 36778 checklistsApr 22-30: 11% of 50885 checklistsMay 1-7: 9.5% of 44186 checklistsMay 8-14: 8.7% of 49011 checklistsMay 15-21: 8.5% of 40784 checklistsMay 22-31: 7.9% of 53073 checklistsJun 1-7: 7.3% of 32432 checklistsJun 8-14: 6.2% of 29978 checklistsJun 15-21: 6.2% of 29457 checklistsJun 22-30: 6.1% of 36072 checklistsJul 1-7: 6.4% of 28857 checklistsJul 8-14: 5.6% of 27224 checklistsJul 15-21: 5.9% of 27629 checklistsJul 22-31: 6.8% of 37318 checklistsAug 1-7: 7.3% of 25893 checklistsAug 8-14: 7.2% of 24870 checklistsAug 15-21: 8.4% of 24035 checklistsAug 22-31: 8.9% of 35691 checklistsSep 1-7: 8.4% of 27068 checklistsSep 8-14: 7.5% of 26709 checklistsSep 15-21: 5.9% of 26098 checklistsSep 22-30: 4.8% of 31550 checklistsOct 1-7: 3.4% of 24110 checklistsOct 8-14: 2.6% of 23352 checklistsOct 15-21: 2.0% of 21895 checklistsOct 22-31: 1.0% of 28319 checklistsNov 1-7: 0.5% of 21698 checklistsNov 8-14: 0.2% of 21061 checklistsNov 15-21: 0.1% of 19855 checklistsNov 22-30: 0.1% of 25798 checklistsDec 1-7: 0.1% of 18626 checklistsDec 8-14: 0.1% of 19004 checklistsDec 15-21: 0.1% of 23103 checklistsDec 22-31: 0.1% of 30802 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 Colorado 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 Colorado

Best counties

Share of checklists at the peak
  1. Pueblo CountyBest the second week of April · 668 checklists that week, 26,547 in all45%
  2. La Plata CountyBest mid April · 567 checklists that week, 21,744 in all28%
  3. Mesa CountyBest late April · 1841 checklists that week, 45,553 in all26%
  4. Rio Blanco CountyBest late April · 171 checklists that week, 2,806 in all25%
  5. Grand CountyBest late August · 511 checklists that week, 11,286 in all25%
  6. Moffat CountyBest late August · 164 checklists that week, 5,700 in all24%

Best spots

Share of checklists at the peak
  1. North Mills Clarifying PondPueblo County, best late July · 37 checklists that week, 1,694 in all99%
  2. James M. Robb - Colorado River State ParkMesa County, best mid July · 23 checklists that week, 1,898 in all99%
  3. St. Vrain State ParkWeld County, best mid April · 20 checklists that week, 1,146 in all93%
  4. James M. Robb - Colorado River State Park - Connected Lakes (Red Canyon)Mesa County, best early May · 42 checklists that week, 601 in all91%
  5. Lake PuebloPueblo County, best early June · 30 checklists that week, 1,695 in all90%

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

Best time of day

In Colorado, the Osprey is most often listed on checklists started between 5 and 7 pm (6.0% of those checklists).

0%2%4%6%8%12 am: too few checklists (512) to judge1 am: too few checklists (468) to judge2 am: too few checklists (513) to judge3 am: too few checklists (656) to judge4 am: too few checklists (1918) to judge5 am: too few checklists (16045) to judge6 am: 6.1% of 71991 checklists7 am: 5.9% of 159189 checklists8 am: 6.1% of 177206 checklists9 am: 5.5% of 165269 checklists10 am: 4.6% of 141029 checklists11 am: 4.1% of 115283 checklists12 pm: 3.6% of 96068 checklists1 pm: 3.8% of 89512 checklists2 pm: 3.8% of 86319 checklists3 pm: 4.0% of 82496 checklists4 pm: 4.7% of 71648 checklists5 pm: 6.1% of 52445 checklists6 pm: 6.0% of 40199 checklists7 pm: too few checklists (24246) to judge8 pm: too few checklists (7986) to judge9 pm: too few checklists (2004) to judge10 pm: too few checklists (888) to judge11 pm: too few checklists (450) 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
January0.1%0%0%0%
February0%0%0%0.1%
March0.1%0.3%1.3%5.6%
April8.7%10%13%11%
May9.5%8.7%8.5%7.9%
June7.3%6.2%6.2%6.1%
July6.4%5.6%5.9%6.8%
August7.3%7.2%8.4%8.9%
September8.4%7.5%5.9%4.8%
October3.4%2.6%2.0%1.0%
November0.5%0.2%0.1%0.1%
December0.1%0.1%0.1%0.1%

Neighboring states

  • Wyoming: arrives early April, 2 weeks later than Colorado
  • New Mexico: arrives mid March, in the same week than Colorado
  • Utah: arrives mid March, in the same week than Colorado
  • Nebraska: arrives the second week of August, 19 weeks later than Colorado

Common questions

When do Ospreys arrive in Colorado?
Ospreys reach Colorado in mid March, are common by late March, peak in mid April (11% of checklists), and most are gone by early October.
When do Ospreys leave Colorado?
Most Ospreys have left Colorado by early October, when reports fall below half their usual rate. Stragglers are still reported until late October.
When is the best time to see a Osprey in Colorado?
The Osprey is reported most often in mid April, on about 11% of Colorado checklists.
Where in Colorado are Ospreys seen most often?
By county, Pueblo County, La Plata County, and Mesa County have the highest peak reporting rates for the Osprey (counties with at least 200 checklists).