WhenToBird

Ammospiza nelsoni · Passerellidae

When Do Nelson's Sparrows Arrive in Connecticut?

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

Nelson's Sparrows mostly pass through Connecticut: they arrive in late September, peak in the second week of October (1.7% of checklists), and most are gone by early November.

When to look

First arrivalsSep 22-30late September
Common bySep 22-30late September
PeakOct 8-14the second week of October
Most gone byNov 1-7early November

Best: the second week of October. First arrivals late September; most are gone by early November. Peak: on about 1.7% of Connecticut 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. Sepcommon
  10. Octpeak season
  11. Novuncommon
  12. Decnot usually seen

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

0%1%2%3%Jan 1-7: 0.1% of 18950 checklistsJan 8-14: 0% of 13676 checklistsJan 15-21: 0% of 13377 checklistsJan 22-31: 0.1% of 17004 checklistsFeb 1-7: 0% of 10218 checklistsFeb 8-14: 0% of 11568 checklistsFeb 15-21: 0% of 15916 checklistsFeb 22-28: 0% of 11413 checklistsMar 1-7: 0% of 10754 checklistsMar 8-14: 0% of 12051 checklistsMar 15-21: 0% of 12616 checklistsMar 22-31: 0% of 17801 checklistsApr 1-7: 0% of 13186 checklistsApr 8-14: 0% of 14428 checklistsApr 15-21: 0% of 14738 checklistsApr 22-30: 0% of 21753 checklistsMay 1-7: 0% of 22494 checklistsMay 8-14: 0% of 23363 checklistsMay 15-21: 0.1% of 20219 checklistsMay 22-31: 0.1% of 20778 checklistsJun 1-7: 0.1% of 12234 checklistsJun 8-14: 0% of 12491 checklistsJun 15-21: 0% of 10856 checklistsJun 22-30: 0% of 11964 checklistsJul 1-7: 0% of 9437 checklistsJul 8-14: 0% of 8599 checklistsJul 15-21: 0% of 8252 checklistsJul 22-31: 0% of 11329 checklistsAug 1-7: 0% of 8116 checklistsAug 8-14: 0% of 8051 checklistsAug 15-21: 0% of 8502 checklistsAug 22-31: 0% of 13673 checklistsSep 1-7: 0% of 9873 checklistsSep 8-14: 0.1% of 9735 checklistsSep 15-21: 0.1% of 10120 checklistsSep 22-30: 1.1% of 12543 checklistsOct 1-7: 2.1% of 10735 checklistsOct 8-14: 1.5% of 10869 checklistsOct 15-21: 1.4% of 10436 checklistsOct 22-31: 0.9% of 13808 checklistsNov 1-7: 0.5% of 10507 checklistsNov 8-14: 0.4% of 9827 checklistsNov 15-21: 0.1% of 9904 checklistsNov 22-30: 0% of 13396 checklistsDec 1-7: 0% of 8974 checklistsDec 8-14: 0% of 9468 checklistsDec 15-21: 0% of 11614 checklistsDec 22-31: 0.1% of 16616 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 Connecticut 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 Connecticut

Best counties

Share of checklists at the peak
  1. New Haven CountyBest the second week of October · 2651 checklists that week, 139,721 in all4.7%
  2. Fairfield CountyBest the second week of October · 2477 checklists that week, 139,848 in all1.8%
  3. New London CountyBest early October · 1011 checklists that week, 65,205 in all0.5%
  4. Middlesex CountyBest early October · 629 checklists that week, 39,919 in all0.4%
  5. Tolland CountyBest late September · 873 checklists that week, 39,004 in all0.3%
  6. Hartford CountyBest early October · 1760 checklists that week, 105,735 in all0.1%

Best spots

Share of checklists at the peak
  1. Southport BeachFairfield County, best the second week of October · 20 checklists that week, 848 in all58%
  2. Morse ParkNew Haven County, best early October · 68 checklists that week, 3,681 in all36%
  3. Beard Cove (historical)New Haven County, best the second week of October · 203 checklists that week, 8,925 in all27%
  4. Great MeadowsFairfield County, best late September · 36 checklists that week, 3,190 in all26%
  5. Mohawk SwampNew Haven County, best the second week of October · 120 checklists that week, 3,247 in all18%
  6. Chaffinch IslandNew Haven County, best early October · 21 checklists that week, 479 in all18%

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

Best time of day

In Connecticut, the Nelson's Sparrow is most often listed on checklists started between 7 and 9 am (0.2% of those checklists).

0%0.5%12 am: too few checklists (325) to judge1 am: too few checklists (367) to judge2 am: too few checklists (488) to judge3 am: too few checklists (792) to judge4 am: too few checklists (2722) to judge5 am: too few checklists (9489) to judge6 am: 0.1% of 33657 checklists7 am: 0.2% of 62964 checklists8 am: 0.2% of 70645 checklists9 am: 0.2% of 64870 checklists10 am: 0.2% of 58827 checklists11 am: 0.2% of 51689 checklists12 pm: 0.1% of 45288 checklists1 pm: 0.1% of 44765 checklists2 pm: 0.2% of 44173 checklists3 pm: 0.1% of 41979 checklists4 pm: 0.1% of 33219 checklists5 pm: 0.1% of 24828 checklists6 pm: 0.1% of 15856 checklists7 pm: too few checklists (8126) to judge8 pm: too few checklists (1994) to judge9 pm: too few checklists (533) to judge10 pm: too few checklists (349) to judge11 pm: too few checklists (286) 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
January0.1%0%0%0.1%
February0%0%0%0%
March0%0%0%0%
April0%0%0%0%
May0%0%0.1%0.1%
June0.1%0%0%0%
July0%0%0%0%
August0%0%0%0%
September0%0.1%0.1%1.1%
October2.1%1.5%1.4%0.9%
November0.5%0.4%0.1%0%
December0%0%0%0.1%

Neighboring states

  • Rhode Island: arrives late September, in the same week than Connecticut
  • Maine: arrives early June, 15 weeks earlier than Connecticut
  • Illinois: arrives mid September, 1 week earlier than Connecticut
  • Iowa: arrives late September, in the same week than Connecticut

Common questions

When do Nelson's Sparrows arrive in Connecticut?
Nelson's Sparrows mostly pass through Connecticut: they arrive in late September, peak in the second week of October (1.7% of checklists), and most are gone by early November.
When do Nelson's Sparrows leave Connecticut?
Most Nelson's Sparrows have left Connecticut by early November, when reports fall below half their usual rate.
When is the best time to see a Nelson's Sparrow in Connecticut?
The Nelson's Sparrow is reported most often in the second week of October, on about 1.7% of Connecticut checklists.
Where in Connecticut are Nelson's Sparrows seen most often?
By county, New Haven County, Fairfield County, and New London County have the highest peak reporting rates for the Nelson's Sparrow (counties with at least 200 checklists).