WhenToBird

Setophaga pensylvanica · Parulidae

When Do Chestnut-sided Warblers Arrive in Wisconsin?

Adult male Chestnut-sided Warbler
Photo: Matt Felperin, CC BY 4.0 via iNaturalist

Chestnut-sided Warblers arrive in Wisconsin in early May, peak in mid May (16% of checklists), and most are gone by mid September.

When to look

First arrivalsMay 1-7early May
Common byMay 1-7early May
PeakMay 15-21mid May
Most gone bySep 15-21mid September

Best: mid May. First arrivals early May; most are gone by mid September. Peak: on about 16% of Wisconsin checklists.

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

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

0%10%20%30%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: 0.1% of 39128 checklistsApr 15-21: 0% of 38887 checklistsApr 22-30: 0.1% of 57231 checklistsMay 1-7: 2.6% of 55115 checklistsMay 8-14: 15% of 63098 checklistsMay 15-21: 21% of 49821 checklistsMay 22-31: 13% of 56796 checklistsJun 1-7: 8.6% of 33621 checklistsJun 8-14: 9.2% of 31282 checklistsJun 15-21: 10% of 30186 checklistsJun 22-30: 9.7% of 35128 checklistsJul 1-7: 8.9% of 27088 checklistsJul 8-14: 6.3% of 23293 checklistsJul 15-21: 3.9% of 20933 checklistsJul 22-31: 2.5% of 27595 checklistsAug 1-7: 1.8% of 19147 checklistsAug 8-14: 1.9% of 18286 checklistsAug 15-21: 2.8% of 19195 checklistsAug 22-31: 5.4% of 28229 checklistsSep 1-7: 6.7% of 22408 checklistsSep 8-14: 7.4% of 20857 checklistsSep 15-21: 5.4% of 20707 checklistsSep 22-30: 2.5% of 26469 checklistsOct 1-7: 0.6% of 21069 checklistsOct 8-14: 0.1% of 21011 checklistsOct 15-21: 0% of 20006 checklistsOct 22-31: 0.1% of 26362 checklistsNov 1-7: 0% of 18928 checklistsNov 8-14: 0% 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% 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. Washburn CountyBest mid June · 382 checklists that week, 7,099 in all59%
  2. Sawyer CountyBest late May · 339 checklists that week, 7,502 in all53%
  3. Menominee CountyBest late May · 56 checklists that week, 745 in all50%
  4. Price CountyBest late May · 254 checklists that week, 5,795 in all49%
  5. Florence CountyBest the second week of June · 308 checklists that week, 10,179 in all44%
  6. Forest CountyBest early June · 333 checklists that week, 7,461 in all40%

Best spots

Share of checklists at the peak
  1. Spread Eagle Barrens Natural AreaFlorence County, best the second week of June · 22 checklists that week, 215 in all94%
  2. Statenaker LakeVilas County, best late June · 60 checklists that week, 2,030 in all81%
  3. Colonial ParkRacine County, best late May · 33 checklists that week, 379 in all69%
  4. Lake ParkMilwaukee County, best late May · 176 checklists that week, 3,271 in all67%
  5. Red Cedar State TrailDunn County, best early September · 20 checklists that week, 444 in all67%

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

Best time of day

In Wisconsin, the Chestnut-sided Warbler is most often listed on checklists started between 5 and 7 am (10% of those checklists).

0%5%10%15%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: 12% of 27016 checklists6 am: 9.2% of 83973 checklists7 am: 6.0% of 160717 checklists8 am: 5.0% of 160531 checklists9 am: 4.2% of 136968 checklists10 am: 3.6% of 119110 checklists11 am: 2.9% of 99116 checklists12 pm: 2.6% of 85078 checklists1 pm: 2.3% of 80688 checklists2 pm: 2.2% of 79140 checklists3 pm: 2.0% of 78599 checklists4 pm: 2.5% of 69767 checklists5 pm: 2.9% of 53229 checklists6 pm: 2.5% 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%0.1%0%0.1%
May2.6%15%21%13%
June8.6%9.2%10%9.7%
July8.9%6.3%3.9%2.5%
August1.8%1.9%2.8%5.4%
September6.7%7.4%5.4%2.5%
October0.6%0.1%0%0.1%
November0%0%0%0%
December0%0%0%0%

Neighboring states

  • Illinois: arrives late April, 1 week earlier than Wisconsin
  • Iowa: arrives the second week of August, 13 weeks later than Wisconsin
  • Michigan: arrives early May, in the same week than Wisconsin
  • Minnesota: arrives early May, in the same week than Wisconsin

Common questions

When do Chestnut-sided Warblers arrive in Wisconsin?
Chestnut-sided Warblers arrive in Wisconsin in early May, peak in mid May (16% of checklists), and most are gone by mid September.
When do Chestnut-sided Warblers leave Wisconsin?
Most Chestnut-sided Warblers have left Wisconsin by mid September, when reports fall below half their usual rate. Stragglers are still reported until early October.
When is the best time to see a Chestnut-sided Warbler in Wisconsin?
The Chestnut-sided Warbler is reported most often in mid May, on about 16% of Wisconsin checklists.
Where in Wisconsin are Chestnut-sided Warblers seen most often?
By county, Washburn County, Sawyer County, and Menominee County have the highest peak reporting rates for the Chestnut-sided Warbler (counties with at least 200 checklists).