WhenToBird

Ammospiza nelsoni · Passerellidae

When Do Nelson's Sparrows Arrive in Illinois?

Adult Nelson's Sparrow
Photo: Kathy Richardson, CC BY 4.0 via iNaturalist

Nelson's Sparrows mostly pass through Illinois: they arrive in mid September, peak in early October (1.4% of checklists), and most are gone by mid October.

When to look

First arrivalsSep 15-21mid September
Common bySep 15-21mid September
PeakOct 1-7early October
Most gone byOct 15-21mid October

Best: early October. First arrivals mid September; most are gone by mid October. Peak: on about 1.4% of Illinois checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprnot usually seen
  5. Maynot usually seen
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Seppeak season
  10. Octpeak season
  11. Novrare
  12. Decnot usually seen

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

0%0.5%1%1.5%2%Jan 1-7: 0% of 29700 checklistsJan 8-14: 0% of 20189 checklistsJan 15-21: 0% of 19784 checklistsJan 22-31: 0% of 26641 checklistsFeb 1-7: 0% of 20478 checklistsFeb 8-14: 0% of 21967 checklistsFeb 15-21: 0% of 28735 checklistsFeb 22-28: 0% of 24223 checklistsMar 1-7: 0% of 26775 checklistsMar 8-14: 0% of 27579 checklistsMar 15-21: 0% of 27193 checklistsMar 22-31: 0% of 42278 checklistsApr 1-7: 0% of 34579 checklistsApr 8-14: 0% of 38290 checklistsApr 15-21: 0% of 39261 checklistsApr 22-30: 0% of 59584 checklistsMay 1-7: 0.1% of 60485 checklistsMay 8-14: 0.1% of 59647 checklistsMay 15-21: 0.1% of 43173 checklistsMay 22-31: 0.1% of 47913 checklistsJun 1-7: 0% of 31151 checklistsJun 8-14: 0% of 27692 checklistsJun 15-21: 0% of 23983 checklistsJun 22-30: 0% of 28448 checklistsJul 1-7: 0% of 21273 checklistsJul 8-14: 0% of 19284 checklistsJul 15-21: 0% of 17712 checklistsJul 22-31: 0% of 24500 checklistsAug 1-7: 0% of 18498 checklistsAug 8-14: 0% of 19331 checklistsAug 15-21: 0% of 19983 checklistsAug 22-31: 0% of 31892 checklistsSep 1-7: 0.1% of 26396 checklistsSep 8-14: 0.1% of 25011 checklistsSep 15-21: 0.3% of 23597 checklistsSep 22-30: 1.3% of 30638 checklistsOct 1-7: 1.9% of 23949 checklistsOct 8-14: 1.1% of 24412 checklistsOct 15-21: 0.6% of 22359 checklistsOct 22-31: 0.2% of 29794 checklistsNov 1-7: 0.1% of 21877 checklistsNov 8-14: 0.1% of 19742 checklistsNov 15-21: 0.1% of 18989 checklistsNov 22-30: 0% of 23905 checklistsDec 1-7: 0% of 16935 checklistsDec 8-14: 0% of 16687 checklistsDec 15-21: 0% of 20931 checklistsDec 22-31: 0% of 29011 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 Illinois 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 Illinois

Best counties

Share of checklists at the peak
  1. Ford CountyBest the second week of October · 14 checklists that week, 762 in all12%
  2. Jasper CountyBest mid October · 12 checklists that week, 1,292 in all8.6%
  3. Winnebago CountyBest early October · 323 checklists that week, 18,333 in all2.8%
  4. Cook CountyBest early October · 8669 checklists that week, 432,644 in all2.5%
  5. Lake CountyBest early October · 1814 checklists that week, 113,940 in all2.4%
  6. McLean CountyBest the second week of October · 484 checklists that week, 24,517 in all1.9%

Best spots

Share of checklists at the peak
  1. Rainbow BeachCook County, best early October · 220 checklists that week, 2,955 in all54%
  2. Pine Dunes Forest PreserveLake County, best early October · 93 checklists that week, 1,184 in all21%
  3. Rollins Savanna Forest Preserve (southeast)Lake County, best late September · 44 checklists that week, 924 in all20%
  4. Whispering Willows ParkKankakee County, best late October · 35 checklists that week, 1,147 in all20%
  5. Carl and Myrna Nygren Wetland PreserveWinnebago County, best late September · 50 checklists that week, 1,834 in all19%

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

Best time of day

In Illinois, the Nelson's Sparrow is most often listed on checklists started between 6 and 8 am (0.2% of those checklists).

0%0.5%12 am: too few checklists (484) to judge1 am: too few checklists (631) to judge2 am: too few checklists (485) to judge3 am: too few checklists (610) to judge4 am: too few checklists (2321) to judge5 am: too few checklists (23536) to judge6 am: 0.3% of 95511 checklists7 am: 0.2% of 164584 checklists8 am: 0.1% of 163654 checklists9 am: 0.1% of 141804 checklists10 am: 0.1% of 122882 checklists11 am: 0.1% of 100640 checklists12 pm: 0.1% of 89894 checklists1 pm: 0.1% of 82729 checklists2 pm: 0.1% of 79801 checklists3 pm: 0.1% of 82169 checklists4 pm: 0.1% of 75124 checklists5 pm: 0.1% of 57708 checklists6 pm: 0.1% of 41843 checklists7 pm: too few checklists (20943) to judge8 pm: too few checklists (6131) to judge9 pm: too few checklists (1677) to judge10 pm: too few checklists (843) to judge11 pm: too few checklists (448) 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%
May0.1%0.1%0.1%0.1%
June0%0%0%0%
July0%0%0%0%
August0%0%0%0%
September0.1%0.1%0.3%1.3%
October1.9%1.1%0.6%0.2%
November0.1%0.1%0.1%0%
December0%0%0%0%

Neighboring states

  • Iowa: arrives late September, 1 week later than Illinois
  • Nebraska: arrives late September, 1 week later than Illinois
  • Mississippi: arrives early October, 2 weeks later than Illinois
  • North Dakota: arrives late May, 15 weeks earlier than Illinois

Common questions

When do Nelson's Sparrows arrive in Illinois?
Nelson's Sparrows mostly pass through Illinois: they arrive in mid September, peak in early October (1.4% of checklists), and most are gone by mid October.
When do Nelson's Sparrows leave Illinois?
Most Nelson's Sparrows have left Illinois by mid October, when reports fall below half their usual rate.
When is the best time to see a Nelson's Sparrow in Illinois?
The Nelson's Sparrow is reported most often in early October, on about 1.4% of Illinois checklists.
Where in Illinois are Nelson's Sparrows seen most often?
By county, Ford County, Jasper County, and Winnebago County have the highest peak reporting rates for the Nelson's Sparrow (counties with at least 200 checklists).