WhenToBird

Melospiza georgiana · Passerellidae

When Do Swamp Sparrows Arrive in Wisconsin?

Adult Swamp Sparrow
Photo: Sandra Keller, CC BY 4.0 via iNaturalist

Swamp Sparrows reach Wisconsin in late March, are common by the second week of April, peak in early May (15% of checklists), and most are gone by late October.

When to look

First arrivalsMar 22-31late March
Common byApr 8-14the second week of April
PeakMay 1-7early May
Most gone byOct 22-31late October

Best: early May. First arrivals late March; most are gone by late October. Peak: on about 15% of Wisconsin checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marrare
  4. Aprpeak season
  5. Maypeak season
  6. Junpeak season
  7. Julpeak season
  8. Augcommon
  9. Seppeak season
  10. Octpeak season
  11. Novuncommon
  12. Decnot usually seen

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

0%5%10%15%20%Jan 1-7: 0.5% of 27925 checklistsJan 8-14: 0.4% of 18337 checklistsJan 15-21: 0.3% of 17370 checklistsJan 22-31: 0.4% of 23777 checklistsFeb 1-7: 0.2% of 16656 checklistsFeb 8-14: 0.1% of 18286 checklistsFeb 15-21: 0.1% of 24739 checklistsFeb 22-28: 0.1% of 20113 checklistsMar 1-7: 0.2% of 24024 checklistsMar 8-14: 0.3% of 26722 checklistsMar 15-21: 0.4% of 27238 checklistsMar 22-31: 0.9% of 40171 checklistsApr 1-7: 2.1% of 34961 checklistsApr 8-14: 5.6% of 39128 checklistsApr 15-21: 10% of 38887 checklistsApr 22-30: 15% of 57231 checklistsMay 1-7: 16% of 55115 checklistsMay 8-14: 13% of 63098 checklistsMay 15-21: 12% of 49821 checklistsMay 22-31: 10% of 56796 checklistsJun 1-7: 9.8% of 33621 checklistsJun 8-14: 9.7% of 31282 checklistsJun 15-21: 11% of 30186 checklistsJun 22-30: 11% of 35128 checklistsJul 1-7: 12% of 27088 checklistsJul 8-14: 12% of 23293 checklistsJul 15-21: 13% of 20933 checklistsJul 22-31: 11% of 27595 checklistsAug 1-7: 9.1% of 19147 checklistsAug 8-14: 6.7% of 18286 checklistsAug 15-21: 5.1% of 19195 checklistsAug 22-31: 4.2% of 28229 checklistsSep 1-7: 4.9% of 22408 checklistsSep 8-14: 6.0% of 20857 checklistsSep 15-21: 8.2% of 20707 checklistsSep 22-30: 12% of 26469 checklistsOct 1-7: 13% of 21069 checklistsOct 8-14: 13% of 21011 checklistsOct 15-21: 9.2% of 20006 checklistsOct 22-31: 5.1% of 26362 checklistsNov 1-7: 2.5% of 18928 checklistsNov 8-14: 1.4% of 17052 checklistsNov 15-21: 0.8% of 16291 checklistsNov 22-30: 0.6% of 20564 checklistsDec 1-7: 0.4% of 15354 checklistsDec 8-14: 0.4% of 16294 checklistsDec 15-21: 0.7% of 21430 checklistsDec 22-31: 0.3% 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.

Embed this map on your site

Where in Wisconsin

Best counties

Share of checklists at the peak
  1. Dodge CountyBest the second week of July · 794 checklists that week, 34,980 in all41%
  2. Lafayette CountyBest the second week of October · 19 checklists that week, 1,911 in all34%
  3. Price CountyBest the second week of May · 138 checklists that week, 5,795 in all29%
  4. Ashland CountyBest mid July · 308 checklists that week, 16,576 in all26%
  5. Bayfield CountyBest early October · 409 checklists that week, 21,381 in all26%
  6. Dunn CountyBest the second week of October · 117 checklists that week, 8,247 in all26%

Best spots

Share of checklists at the peak
  1. Mud Lake (northeast)Ozaukee County, best late May · 26 checklists that week, 355 in all95%
  2. Prentice ParkAshland County, best late June · 70 checklists that week, 3,508 in all92%
  3. Mullet Marsh 15 ReservoirFond du Lac County, best the second week of May · 22 checklists that week, 457 in all91%
  4. Glacial Habitat Restoration - LmWinnebago County, best late May · 22 checklists that week, 269 in all84%
  5. Glacial Drumlin State TrailJefferson County, best early May · 23 checklists that week, 346 in all84%

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

Best time of day

In Wisconsin, the Swamp Sparrow is most often listed on checklists started between 5 and 7 am (13% 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: 15% of 27016 checklists6 am: 13% of 83973 checklists7 am: 9.6% of 160717 checklists8 am: 8.2% of 160531 checklists9 am: 7.2% of 136968 checklists10 am: 6.1% of 119110 checklists11 am: 5.3% of 99116 checklists12 pm: 4.6% of 85078 checklists1 pm: 4.4% of 80688 checklists2 pm: 4.1% of 79140 checklists3 pm: 4.2% of 78599 checklists4 pm: 4.9% of 69767 checklists5 pm: 6.1% of 53229 checklists6 pm: 7.1% 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
January0.5%0.4%0.3%0.4%
February0.2%0.1%0.1%0.1%
March0.2%0.3%0.4%0.9%
April2.1%5.6%10%15%
May16%13%12%10%
June9.8%9.7%11%11%
July12%12%13%11%
August9.1%6.7%5.1%4.2%
September4.9%6.0%8.2%12%
October13%13%9.2%5.1%
November2.5%1.4%0.8%0.6%
December0.4%0.4%0.7%0.3%

Neighboring states

  • Illinois: arrives the second week of September, 22 weeks later than Wisconsin
  • Iowa: arrives the second week of September, 22 weeks later than Wisconsin
  • Michigan: arrives late March, in the same week than Wisconsin
  • Minnesota: arrives early April, 1 week later than Wisconsin

Common questions

When do Swamp Sparrows arrive in Wisconsin?
Swamp Sparrows reach Wisconsin in late March, are common by the second week of April, peak in early May (15% of checklists), and most are gone by late October.
When do Swamp Sparrows leave Wisconsin?
Most Swamp Sparrows have left Wisconsin by late October, when reports fall below half their usual rate. Stragglers are still reported until the second week of November.
When is the best time to see a Swamp Sparrow in Wisconsin?
The Swamp Sparrow is reported most often in early May, on about 15% of Wisconsin checklists.
Where in Wisconsin are Swamp Sparrows seen most often?
By county, Dodge County, Lafayette County, and Price County have the highest peak reporting rates for the Swamp Sparrow (counties with at least 200 checklists).