WhenToBird

Pica hudsonia · Corvidae

When Do Black-billed Magpies Arrive in Colorado?

Adult Black-billed Magpie
Photo: Mayela y Ramón, CC BY-SA 4.0 via iNaturalist

The Black-billed Magpie is in Colorado all year. It turns up on about 40% of checklists at its peak (early November) and on 18% in its quietest week (early August).

When to look

PresentAll year
Peak weekNov 1-7early November
Quietest weekAug 1-7early August

Best: early November. Here all year. Peak: on about 40% of Colorado checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Aprcommon
  5. Maycommon
  6. Juncommon
  7. Julcommon
  8. Augcommon
  9. Seppeak season
  10. Octpeak season
  11. Novpeak season
  12. Decpeak season

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

0%20%40%60%Jan 1-7: 32% of 32254 checklistsJan 8-14: 32% of 23278 checklistsJan 15-21: 31% of 22933 checklistsJan 22-31: 32% of 30856 checklistsFeb 1-7: 30% of 21464 checklistsFeb 8-14: 31% of 22910 checklistsFeb 15-21: 30% of 28739 checklistsFeb 22-28: 31% of 21833 checklistsMar 1-7: 31% of 23066 checklistsMar 8-14: 31% of 23783 checklistsMar 15-21: 32% of 24797 checklistsMar 22-31: 30% of 38439 checklistsApr 1-7: 29% of 31676 checklistsApr 8-14: 27% of 35092 checklistsApr 15-21: 27% of 36778 checklistsApr 22-30: 28% of 50885 checklistsMay 1-7: 27% of 44186 checklistsMay 8-14: 27% of 49011 checklistsMay 15-21: 29% of 40784 checklistsMay 22-31: 29% of 53073 checklistsJun 1-7: 28% of 32432 checklistsJun 8-14: 27% of 29978 checklistsJun 15-21: 26% of 29457 checklistsJun 22-30: 25% of 36072 checklistsJul 1-7: 23% of 28857 checklistsJul 8-14: 20% of 27224 checklistsJul 15-21: 19% of 27629 checklistsJul 22-31: 18% of 37318 checklistsAug 1-7: 18% of 25893 checklistsAug 8-14: 19% of 24870 checklistsAug 15-21: 20% of 24035 checklistsAug 22-31: 22% of 35691 checklistsSep 1-7: 24% of 27068 checklistsSep 8-14: 27% of 26709 checklistsSep 15-21: 31% of 26098 checklistsSep 22-30: 34% of 31550 checklistsOct 1-7: 38% of 24110 checklistsOct 8-14: 39% of 23352 checklistsOct 15-21: 39% of 21895 checklistsOct 22-31: 40% of 28319 checklistsNov 1-7: 41% of 21698 checklistsNov 8-14: 39% of 21061 checklistsNov 15-21: 38% of 19855 checklistsNov 22-30: 37% of 25798 checklistsDec 1-7: 36% of 18626 checklistsDec 8-14: 36% of 19004 checklistsDec 15-21: 36% of 23103 checklistsDec 22-31: 35% 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. Rio Blanco CountyBest late February · 27 checklists that week, 2,806 in all78%
  2. Eagle CountyBest mid October · 222 checklists that week, 15,893 in all76%
  3. Conejos CountyBest late December · 13 checklists that week, 1,636 in all74%
  4. Grand CountyBest the second week of November · 78 checklists that week, 11,286 in all70%
  5. Rio Grande CountyBest mid December · 28 checklists that week, 4,655 in all65%
  6. Gunnison CountyBest early March · 34 checklists that week, 9,894 in all63%

Best spots

Share of checklists at the peak
  1. City LandArapahoe County, best late March · 30 checklists that week, 802 in all99%
  2. Chatfield Lake (Fairview Reservoir Number 2)Jefferson County, best late February · 20 checklists that week, 1,041 in all98%
  3. Colorado River Segment 7Eagle County, best late April · 23 checklists that week, 499 in all98%
  4. William Frederick Hayden Green Mountain ParkJefferson County, best mid May · 24 checklists that week, 318 in all98%
  5. Rampart ParkEl Paso County, best late February · 31 checklists that week, 255 in all98%

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

Best time of day

In Colorado, the Black-billed Magpie is most often listed on checklists started between 7 and 9 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: 32% of 71991 checklists7 am: 36% of 159189 checklists8 am: 35% of 177206 checklists9 am: 33% of 165269 checklists10 am: 30% of 141029 checklists11 am: 27% of 115283 checklists12 pm: 25% of 96068 checklists1 pm: 26% of 89512 checklists2 pm: 26% of 86319 checklists3 pm: 26% of 82496 checklists4 pm: 24% of 71648 checklists5 pm: 24% of 52445 checklists6 pm: 21% 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
January32%32%31%32%
February30%31%30%31%
March31%31%32%30%
April29%27%27%28%
May27%27%29%29%
June28%27%26%25%
July23%20%19%18%
August18%19%20%22%
September24%27%31%34%
October38%39%39%40%
November41%39%38%37%
December36%36%36%35%

Neighboring states

  • Wyoming: all year, most in winter, peaks early January
  • New Mexico: year-round, peaks the second week of October
  • Utah: year-round, peaks the second week of January
  • Nebraska: summer visitor, peaks mid June

Common questions

When do Black-billed Magpies arrive in Colorado?
The Black-billed Magpie is in Colorado all year. It turns up on about 40% of checklists at its peak (early November) and on 18% in its quietest week (early August).
When do Black-billed Magpies leave Colorado?
The Black-billed Magpie does not leave Colorado: it is reported all year, from 18% of checklists in early August to 40% in early November.
When is the best time to see a Black-billed Magpie in Colorado?
The Black-billed Magpie is reported most often in early November, on about 40% of Colorado checklists.
Where in Colorado are Black-billed Magpies seen most often?
By county, Rio Blanco County, Eagle County, and Conejos County have the highest peak reporting rates for the Black-billed Magpie (counties with at least 200 checklists).