WhenToBird

Cyanocitta cristata · Corvidae

When Do Blue Jays Arrive in Colorado?

Adult Blue Jay
Photo: Texas Bird Family, CC BY 4.0 via iNaturalist

The Blue Jay is in Colorado all year. It turns up on about 35% of checklists at its peak (early October) and on 17% in its quietest week (early July).

When to look

PresentAll year
Peak weekOct 1-7early October
Quietest weekJul 1-7early July

Best: early October. Here all year. Peak: on about 35% of Colorado checklists.

  1. Jancommon
  2. Febcommon
  3. Marcommon
  4. Aprcommon
  5. Maypeak season
  6. Juncommon
  7. Julcommon
  8. Augcommon
  9. Seppeak season
  10. Octpeak season
  11. Novpeak season
  12. Deccommon

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

0%10%20%30%40%Jan 1-7: 18% of 32254 checklistsJan 8-14: 18% of 23278 checklistsJan 15-21: 18% of 22933 checklistsJan 22-31: 18% of 30856 checklistsFeb 1-7: 18% of 21464 checklistsFeb 8-14: 18% of 22910 checklistsFeb 15-21: 18% of 28739 checklistsFeb 22-28: 19% of 21833 checklistsMar 1-7: 20% of 23066 checklistsMar 8-14: 19% of 23783 checklistsMar 15-21: 20% of 24797 checklistsMar 22-31: 21% of 38439 checklistsApr 1-7: 18% of 31676 checklistsApr 8-14: 18% of 35092 checklistsApr 15-21: 19% of 36778 checklistsApr 22-30: 23% of 50885 checklistsMay 1-7: 28% of 44186 checklistsMay 8-14: 28% of 49011 checklistsMay 15-21: 27% of 40784 checklistsMay 22-31: 22% of 53073 checklistsJun 1-7: 19% of 32432 checklistsJun 8-14: 18% of 29978 checklistsJun 15-21: 17% of 29457 checklistsJun 22-30: 16% of 36072 checklistsJul 1-7: 18% of 28857 checklistsJul 8-14: 16% of 27224 checklistsJul 15-21: 18% of 27629 checklistsJul 22-31: 19% of 37318 checklistsAug 1-7: 20% of 25893 checklistsAug 8-14: 20% of 24870 checklistsAug 15-21: 22% of 24035 checklistsAug 22-31: 24% of 35691 checklistsSep 1-7: 28% of 27068 checklistsSep 8-14: 31% of 26709 checklistsSep 15-21: 34% of 26098 checklistsSep 22-30: 35% of 31550 checklistsOct 1-7: 35% of 24110 checklistsOct 8-14: 35% of 23352 checklistsOct 15-21: 33% of 21895 checklistsOct 22-31: 32% of 28319 checklistsNov 1-7: 30% of 21698 checklistsNov 8-14: 27% of 21061 checklistsNov 15-21: 28% of 19855 checklistsNov 22-30: 26% of 25798 checklistsDec 1-7: 23% of 18626 checklistsDec 8-14: 24% of 19004 checklistsDec 15-21: 22% of 23103 checklistsDec 22-31: 21% 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. Broomfield CountyBest mid September · 289 checklists that week, 16,139 in all65%
  2. Morgan CountyBest mid October · 78 checklists that week, 5,181 in all57%
  3. Boulder CountyBest late September · 3785 checklists that week, 180,634 in all56%
  4. Elbert CountyBest late October · 60 checklists that week, 5,660 in all55%
  5. Yuma CountyBest mid September · 66 checklists that week, 3,844 in all53%
  6. Pueblo CountyBest early October · 375 checklists that week, 26,547 in all52%

Best spots

Share of checklists at the peak
  1. George Rist ReservoirLarimer County, best early September · 23 checklists that week, 1,076 in all100%
  2. Lon Hagler ReservoirLarimer County, best early September · 26 checklists that week, 1,172 in all98%
  3. Horseshoe Natural AreaArapahoe County, best late August · 20 checklists that week, 523 in all98%
  4. North Shields Pond Natural AreaLarimer County, best early August · 25 checklists that week, 2,028 in all96%
  5. Old St. Louis Natural AreaLarimer County, best the second week of September · 20 checklists that week, 934 in all95%

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

Best time of day

In Colorado, the Blue Jay is most often listed on checklists started between 6 and 8 am (36% of those checklists).

0%10%20%30%40%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: 37% of 71991 checklists7 am: 35% of 159189 checklists8 am: 31% of 177206 checklists9 am: 25% of 165269 checklists10 am: 20% of 141029 checklists11 am: 16% of 115283 checklists12 pm: 16% of 96068 checklists1 pm: 15% of 89512 checklists2 pm: 15% of 86319 checklists3 pm: 15% of 82496 checklists4 pm: 16% of 71648 checklists5 pm: 20% of 52445 checklists6 pm: 18% 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
January18%18%18%18%
February18%18%18%19%
March20%19%20%21%
April18%18%19%23%
May28%28%27%22%
June19%18%17%16%
July18%16%18%19%
August20%20%22%24%
September28%31%34%35%
October35%35%33%32%
November30%27%28%26%
December23%24%22%21%

Neighboring states

  • Wyoming: winter visitor, peaks late October
  • New Mexico: winter visitor, peaks the second week of October
  • Nebraska: all year, most in fall, peaks the second week of September
  • South Dakota: all year, most in fall, peaks late September

Common questions

When do Blue Jays arrive in Colorado?
The Blue Jay is in Colorado all year. It turns up on about 35% of checklists at its peak (early October) and on 17% in its quietest week (early July).
When do Blue Jays leave Colorado?
The Blue Jay does not leave Colorado: it is reported all year, from 17% of checklists in early July to 35% in early October.
When is the best time to see a Blue Jay in Colorado?
The Blue Jay is reported most often in early October, on about 35% of Colorado checklists.
Where in Colorado are Blue Jays seen most often?
By county, Broomfield County, Morgan County, and Boulder County have the highest peak reporting rates for the Blue Jay (counties with at least 200 checklists).