WhenToBird

Spizelloides arborea · Passerellidae

When Do American Tree Sparrows Arrive in Wisconsin?

Adult American Tree Sparrow
Photo: Michael, CC BY 4.0 via iNaturalist

American Tree Sparrows are winter birds in Wisconsin: the first arrive in the second week of October, they are common by late October, peak in late January (18% of checklists), and most are gone by mid April.

When to look

First arrivalsOct 8-14the second week of October
Common byOct 22-31late October
PeakJan 22-31late January
Most gone byApr 15-21mid April

Best: late January. First arrivals the second week of October; most are gone by mid April. Peak: on about 18% of Wisconsin checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Aprcommon
  5. Mayrare
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Sepnot usually seen
  10. Octcommon
  11. Novpeak season
  12. Decpeak season

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

0%10%20%30%Jan 1-7: 17% of 27925 checklistsJan 8-14: 17% of 18337 checklistsJan 15-21: 18% of 17370 checklistsJan 22-31: 19% of 23777 checklistsFeb 1-7: 18% of 16656 checklistsFeb 8-14: 18% of 18286 checklistsFeb 15-21: 16% of 24739 checklistsFeb 22-28: 15% of 20113 checklistsMar 1-7: 14% of 24024 checklistsMar 8-14: 15% of 26722 checklistsMar 15-21: 14% of 27238 checklistsMar 22-31: 15% of 40171 checklistsApr 1-7: 14% of 34961 checklistsApr 8-14: 12% of 39128 checklistsApr 15-21: 9.7% of 38887 checklistsApr 22-30: 5.2% of 57231 checklistsMay 1-7: 1.2% of 55115 checklistsMay 8-14: 0.1% of 63098 checklistsMay 15-21: 0.1% of 49821 checklistsMay 22-31: 0.1% of 56796 checklistsJun 1-7: 0% of 33621 checklistsJun 8-14: 0% of 31282 checklistsJun 15-21: 0% of 30186 checklistsJun 22-30: 0% of 35128 checklistsJul 1-7: 0% of 27088 checklistsJul 8-14: 0% of 23293 checklistsJul 15-21: 0% of 20933 checklistsJul 22-31: 0% of 27595 checklistsAug 1-7: 0% of 19147 checklistsAug 8-14: 0% of 18286 checklistsAug 15-21: 0% of 19195 checklistsAug 22-31: 0% of 28229 checklistsSep 1-7: 0% of 22408 checklistsSep 8-14: 0% of 20857 checklistsSep 15-21: 0% of 20707 checklistsSep 22-30: 0.1% of 26469 checklistsOct 1-7: 0.6% of 21069 checklistsOct 8-14: 2.5% of 21011 checklistsOct 15-21: 5.8% of 20006 checklistsOct 22-31: 11% of 26362 checklistsNov 1-7: 15% of 18928 checklistsNov 8-14: 16% of 17052 checklistsNov 15-21: 16% of 16291 checklistsNov 22-30: 14% of 20564 checklistsDec 1-7: 14% of 15354 checklistsDec 8-14: 16% of 16294 checklistsDec 15-21: 20% of 21430 checklistsDec 22-31: 18% 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. Iowa CountyBest early February · 226 checklists that week, 18,836 in all43%
  2. Green CountyBest late January · 59 checklists that week, 4,387 in all42%
  3. Clark CountyBest late January · 30 checklists that week, 2,369 in all41%
  4. Lafayette CountyBest the second week of December · 26 checklists that week, 1,911 in all40%
  5. Columbia CountyBest the second week of January · 169 checklists that week, 15,761 in all38%
  6. Washington CountyBest the second week of December · 146 checklists that week, 15,206 in all37%

Best spots

Share of checklists at the peak
  1. Duck CreekBrown County, best early December · 56 checklists that week, 4,031 in all93%
  2. Paradise Valley Wildlife AreaWaukesha County, best late November · 22 checklists that week, 848 in all91%
  3. Mequon Nature PreserveOzaukee County, best late January · 26 checklists that week, 1,745 in all87%
  4. 1 ReservoirDodge County, best late January · 31 checklists that week, 2,770 in all83%
  5. Lake Mills Wildlife AreaJefferson County, best early January · 36 checklists that week, 1,592 in all79%

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

Best time of day

In Wisconsin, the American Tree Sparrow is most often listed on checklists started between 7 and 9 am (8.5% of those checklists).

0%5%10%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: 1.2% of 27016 checklists6 am: 4.5% of 83973 checklists7 am: 8.3% of 160717 checklists8 am: 8.7% of 160531 checklists9 am: 8.2% of 136968 checklists10 am: 8.0% of 119110 checklists11 am: 7.8% of 99116 checklists12 pm: 7.7% of 85078 checklists1 pm: 7.7% of 80688 checklists2 pm: 7.5% of 79140 checklists3 pm: 7.8% of 78599 checklists4 pm: 6.5% of 69767 checklists5 pm: 4.1% of 53229 checklists6 pm: 2.8% 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
January17%17%18%19%
February18%18%16%15%
March14%15%14%15%
April14%12%9.7%5.2%
May1.2%0.1%0.1%0.1%
June0%0%0%0%
July0%0%0%0%
August0%0%0%0%
September0%0%0%0.1%
October0.6%2.5%5.8%11%
November15%16%16%14%
December14%16%20%18%

Neighboring states

  • Illinois: arrives mid October, 1 week later than Wisconsin
  • Iowa: arrives mid October, 1 week later than Wisconsin
  • Michigan: arrives the second week of October, in the same week than Wisconsin
  • Minnesota: arrives early October, 1 week earlier than Wisconsin

Common questions

When do American Tree Sparrows arrive in Wisconsin?
American Tree Sparrows are winter birds in Wisconsin: the first arrive in the second week of October, they are common by late October, peak in late January (18% of checklists), and most are gone by mid April.
When do American Tree Sparrows leave Wisconsin?
Most American Tree Sparrows have left Wisconsin by mid April, when reports fall below half their usual rate. Stragglers are still reported until early May.
When is the best time to see a American Tree Sparrow in Wisconsin?
The American Tree Sparrow is reported most often in late January, on about 18% of Wisconsin checklists.
Where in Wisconsin are American Tree Sparrows seen most often?
By county, Iowa County, Green County, and Clark County have the highest peak reporting rates for the American Tree Sparrow (counties with at least 200 checklists).