WhenToBird

Setophaga caerulescens · Parulidae

When Do Black-throated Blue Warblers Arrive in Wisconsin?

Adult male Black-throated Blue Warbler
Photo: Dan Vickers, CC BY 4.0 via iNaturalist

Black-throated Blue Warblers arrive in Wisconsin in late April, peak in the second week of May (1.9% of checklists), and most are gone by the second week of July.

When to look

First arrivalsApr 22-30late April
Common byApr 22-30late April
PeakMay 8-14the second week of May
Most gone byJul 8-14the second week of July

Best: the second week of May. First arrivals late April; most are gone by the second week of July. Peak: on about 1.9% of Wisconsin checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprrare
  5. Maypeak season
  6. Jununcommon
  7. Juluncommon
  8. Auguncommon
  9. Sepcommon
  10. Octuncommon
  11. Novnot usually seen
  12. Decnot usually seen

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

0%1%2%3%Jan 1-7: 0% of 27925 checklistsJan 8-14: 0% of 18337 checklistsJan 15-21: 0% of 17370 checklistsJan 22-31: 0% of 23777 checklistsFeb 1-7: 0% of 16656 checklistsFeb 8-14: 0% of 18286 checklistsFeb 15-21: 0% of 24739 checklistsFeb 22-28: 0% of 20113 checklistsMar 1-7: 0% of 24024 checklistsMar 8-14: 0% of 26722 checklistsMar 15-21: 0% of 27238 checklistsMar 22-31: 0% of 40171 checklistsApr 1-7: 0% of 34961 checklistsApr 8-14: 0% of 39128 checklistsApr 15-21: 0% of 38887 checklistsApr 22-30: 0.1% of 57231 checklistsMay 1-7: 0.7% of 55115 checklistsMay 8-14: 2.6% of 63098 checklistsMay 15-21: 2.5% of 49821 checklistsMay 22-31: 0.7% of 56796 checklistsJun 1-7: 0.4% of 33621 checklistsJun 8-14: 0.3% of 31282 checklistsJun 15-21: 0.5% of 30186 checklistsJun 22-30: 0.5% of 35128 checklistsJul 1-7: 0.4% of 27088 checklistsJul 8-14: 0.3% of 23293 checklistsJul 15-21: 0.3% of 20933 checklistsJul 22-31: 0.2% of 27595 checklistsAug 1-7: 0.1% of 19147 checklistsAug 8-14: 0.1% of 18286 checklistsAug 15-21: 0.1% of 19195 checklistsAug 22-31: 0.4% of 28229 checklistsSep 1-7: 1.1% of 22408 checklistsSep 8-14: 1.4% of 20857 checklistsSep 15-21: 1.2% of 20707 checklistsSep 22-30: 1.0% of 26469 checklistsOct 1-7: 0.7% of 21069 checklistsOct 8-14: 0.2% of 21011 checklistsOct 15-21: 0.1% of 20006 checklistsOct 22-31: 0.1% of 26362 checklistsNov 1-7: 0.1% of 18928 checklistsNov 8-14: 0.1% of 17052 checklistsNov 15-21: 0% of 16291 checklistsNov 22-30: 0% of 20564 checklistsDec 1-7: 0% of 15354 checklistsDec 8-14: 0% of 16294 checklistsDec 15-21: 0% of 21430 checklistsDec 22-31: 0.1% of 26314 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 Wisconsin 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 Wisconsin

Best counties

Share of checklists at the peak
  1. Menominee CountyBest late May · 56 checklists that week, 745 in all11%
  2. Iron CountyBest late June · 254 checklists that week, 5,981 in all8.2%
  3. Milwaukee CountyBest mid May · 4529 checklists that week, 114,667 in all7.4%
  4. Forest CountyBest late May · 374 checklists that week, 7,461 in all6.1%
  5. Calumet CountyBest the second week of May · 959 checklists that week, 12,359 in all4.9%
  6. Brown CountyBest the second week of May · 1683 checklists that week, 36,306 in all4.7%

Best spots

Share of checklists at the peak
  1. Nature PreserveMilwaukee County, best late May · 51 checklists that week, 875 in all29%
  2. Sheridan Park (south)Milwaukee County, best the second week of September · 35 checklists that week, 349 in all24%
  3. Lake ParkMilwaukee County, best mid May · 333 checklists that week, 3,271 in all22%
  4. Warnimont ParkMilwaukee County, best mid May · 149 checklists that week, 2,226 in all22%
  5. Grant Park (northwest)Milwaukee County, best late May · 21 checklists that week, 383 in all21%
  6. Bay Beach Wildlife SanctuaryBrown County, best mid May · 251 checklists that week, 2,385 in all21%

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

Best time of day

In Wisconsin, the Black-throated Blue Warbler is most often listed on checklists started between 5 and 7 am (0.9% of those checklists).

0%0.5%1%12 am: too few checklists (993) to judge1 am: too few checklists (844) to judge2 am: too few checklists (839) to judge3 am: too few checklists (1488) to judge4 am: too few checklists (5344) to judge5 am: 0.9% of 27016 checklists6 am: 0.9% of 83973 checklists7 am: 0.7% of 160717 checklists8 am: 0.6% of 160531 checklists9 am: 0.4% of 136968 checklists10 am: 0.5% of 119110 checklists11 am: 0.4% of 99116 checklists12 pm: 0.3% of 85078 checklists1 pm: 0.3% of 80688 checklists2 pm: 0.3% of 79140 checklists3 pm: 0.2% of 78599 checklists4 pm: 0.3% of 69767 checklists5 pm: 0.3% of 53229 checklists6 pm: 0.2% of 38769 checklists7 pm: too few checklists (24396) to judge8 pm: too few checklists (10155) to judge9 pm: too few checklists (4990) to judge10 pm: too few checklists (2463) to judge11 pm: too few checklists (1281) 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%0%0%0%
February0%0%0%0%
March0%0%0%0%
April0%0%0%0.1%
May0.7%2.6%2.5%0.7%
June0.4%0.3%0.5%0.5%
July0.4%0.3%0.3%0.2%
August0.1%0.1%0.1%0.4%
September1.1%1.4%1.2%1.0%
October0.7%0.2%0.1%0.1%
November0.1%0.1%0%0%
December0%0%0%0.1%

Neighboring states

  • Illinois: arrives late August, 16 weeks later than Wisconsin
  • Michigan: arrives late April, in the same week than Wisconsin
  • Indiana: arrives late April, in the same week than Wisconsin
  • Ohio: arrives late April, in the same week than Wisconsin

Common questions

When do Black-throated Blue Warblers arrive in Wisconsin?
Black-throated Blue Warblers arrive in Wisconsin in late April, peak in the second week of May (1.9% of checklists), and most are gone by the second week of July.
When do Black-throated Blue Warblers leave Wisconsin?
Most Black-throated Blue Warblers have left Wisconsin by the second week of July, when reports fall below half their usual rate.
When is the best time to see a Black-throated Blue Warbler in Wisconsin?
The Black-throated Blue Warbler is reported most often in the second week of May, on about 1.9% of Wisconsin checklists.
Where in Wisconsin are Black-throated Blue Warblers seen most often?
By county, Menominee County, Iron County, and Milwaukee County have the highest peak reporting rates for the Black-throated Blue Warbler (counties with at least 200 checklists).