WhenToBird

Chroicocephalus philadelphia · Laridae

When Do Bonaparte's Gulls Arrive in Michigan?

Adult Bonaparte's Gull
Photo: Kevin Krebs, CC BY 4.0 via iNaturalist

Bonaparte's Gulls are winter birds in Michigan: they arrive in late July, peak in the second week of November (7.3% of checklists), and most are gone by mid December.

When to look

First arrivalsJul 22-31late July
Common byJul 22-31late July
PeakNov 8-14the second week of November
Most gone byDec 15-21mid December

Best: the second week of November. First arrivals late July; most are gone by mid December. Peak: on about 7.3% of Michigan checklists.

  1. Janrare
  2. Febnot usually seen
  3. Maruncommon
  4. Aprcommon
  5. Mayuncommon
  6. Junrare
  7. Juluncommon
  8. Auguncommon
  9. Sepuncommon
  10. Octpeak season
  11. Novpeak season
  12. Deccommon

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

0%5%10%Jan 1-7: 1.0% of 38160 checklistsJan 8-14: 0.6% of 24696 checklistsJan 15-21: 0.2% of 23771 checklistsJan 22-31: 0.1% of 31347 checklistsFeb 1-7: 0.1% of 23225 checklistsFeb 8-14: 0.1% of 27398 checklistsFeb 15-21: 0.1% of 36606 checklistsFeb 22-28: 0.1% of 27127 checklistsMar 1-7: 0.1% of 29700 checklistsMar 8-14: 0.1% of 31587 checklistsMar 15-21: 0.5% of 32118 checklistsMar 22-31: 1.9% of 47777 checklistsApr 1-7: 3.1% of 38557 checklistsApr 8-14: 4.2% of 42207 checklistsApr 15-21: 4.9% of 42759 checklistsApr 22-30: 3.5% of 64458 checklistsMay 1-7: 2.0% of 60998 checklistsMay 8-14: 1.7% of 72091 checklistsMay 15-21: 2.7% of 59058 checklistsMay 22-31: 1.3% of 64724 checklistsJun 1-7: 0.7% of 35990 checklistsJun 8-14: 0.4% of 32595 checklistsJun 15-21: 0.7% of 30017 checklistsJun 22-30: 0.7% of 33988 checklistsJul 1-7: 0.5% of 28708 checklistsJul 8-14: 0.6% of 25175 checklistsJul 15-21: 0.8% of 24084 checklistsJul 22-31: 1.1% of 33522 checklistsAug 1-7: 1.6% of 25098 checklistsAug 8-14: 1.9% of 24353 checklistsAug 15-21: 2.2% of 25059 checklistsAug 22-31: 2.2% of 37489 checklistsSep 1-7: 1.9% of 28410 checklistsSep 8-14: 1.9% of 27887 checklistsSep 15-21: 1.7% of 26614 checklistsSep 22-30: 1.8% of 32557 checklistsOct 1-7: 1.8% of 25844 checklistsOct 8-14: 2.7% of 27741 checklistsOct 15-21: 4.4% of 24693 checklistsOct 22-31: 6.4% of 32460 checklistsNov 1-7: 8.0% of 23660 checklistsNov 8-14: 7.2% of 21542 checklistsNov 15-21: 6.6% of 19922 checklistsNov 22-30: 5.6% of 25069 checklistsDec 1-7: 3.8% of 18272 checklistsDec 8-14: 2.8% of 18961 checklistsDec 15-21: 1.2% of 24171 checklistsDec 22-31: 0.9% of 30908 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 Michigan 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 Michigan

Best counties

Share of checklists at the peak
  1. Huron CountyBest the second week of November · 95 checklists that week, 4,733 in all49%
  2. Sanilac CountyBest the second week of November · 73 checklists that week, 4,539 in all44%
  3. Branch CountyBest early November · 63 checklists that week, 2,279 in all43%
  4. Iosco CountyBest early November · 319 checklists that week, 31,409 in all38%
  5. Roscommon CountyBest early November · 66 checklists that week, 7,054 in all37%
  6. Arenac CountyBest the second week of November · 41 checklists that week, 4,464 in all34%

Best spots

Share of checklists at the peak
  1. GibraltarWayne County, best mid November · 25 checklists that week, 135 in all100%
  2. Little Portage LakeWashtenaw County, best late November · 29 checklists that week, 620 in all81%
  3. Tierney ParkSanilac County, best late October · 25 checklists that week, 402 in all81%

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

Best time of day

In Michigan, the Bonaparte's Gull is most often listed on checklists started between 6 and 8 am (2.3% of those checklists).

0%1%2%3%12 am: too few checklists (712) to judge1 am: too few checklists (592) to judge2 am: too few checklists (532) to judge3 am: too few checklists (516) to judge4 am: too few checklists (1592) to judge5 am: too few checklists (6849) to judge6 am: 2.2% of 39298 checklists7 am: 2.3% of 120344 checklists8 am: 2.1% of 180109 checklists9 am: 2.1% of 171966 checklists10 am: 2.1% of 156332 checklists11 am: 2.2% of 134964 checklists12 pm: 2.1% of 120967 checklists1 pm: 2.3% of 113852 checklists2 pm: 2.3% of 110773 checklists3 pm: 2.1% of 105530 checklists4 pm: 1.9% of 100958 checklists5 pm: 1.6% of 80085 checklists6 pm: 1.6% of 62883 checklists7 pm: 1.3% of 44912 checklists8 pm: too few checklists (21062) to judge9 pm: too few checklists (5920) to judge10 pm: too few checklists (1629) to judge11 pm: too few checklists (775) 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
January1.0%0.6%0.2%0.1%
February0.1%0.1%0.1%0.1%
March0.1%0.1%0.5%1.9%
April3.1%4.2%4.9%3.5%
May2.0%1.7%2.7%1.3%
June0.7%0.4%0.7%0.7%
July0.5%0.6%0.8%1.1%
August1.6%1.9%2.2%2.2%
September1.9%1.9%1.7%1.8%
October1.8%2.7%4.4%6.4%
November8.0%7.2%6.6%5.6%
December3.8%2.8%1.2%0.9%

Neighboring states

  • Ohio: arrives early August, 1 week later than Michigan
  • Indiana: arrives early October, 9 weeks later than Michigan
  • Illinois: arrives early October, 9 weeks later than Michigan
  • Wisconsin: arrives late March, 16 weeks earlier than Michigan

Common questions

When do Bonaparte's Gulls arrive in Michigan?
Bonaparte's Gulls are winter birds in Michigan: they arrive in late July, peak in the second week of November (7.3% of checklists), and most are gone by mid December.
When do Bonaparte's Gulls leave Michigan?
Most Bonaparte's Gulls have left Michigan by mid December, when reports fall below half their usual rate.
When is the best time to see a Bonaparte's Gull in Michigan?
The Bonaparte's Gull is reported most often in the second week of November, on about 7.3% of Michigan checklists.
Where in Michigan are Bonaparte's Gulls seen most often?
By county, Huron County, Sanilac County, and Branch County have the highest peak reporting rates for the Bonaparte's Gull (counties with at least 200 checklists).