WhenToBird

Circus hudsonius · Accipitridae

When Do Northern Harriers Arrive in Connecticut?

Northern Harriers reach Connecticut in mid August, are common by late August, peak in late September (6.5% of checklists), and most are gone by late March.

When to look

First arrivalsAug 15-21mid August
Common byAug 22-31late August
PeakSep 22-30late September
Most gone byMar 22-31late March

Best: late September. First arrivals mid August; most are gone by late March. Peak: on about 6.5% of Connecticut checklists.

  1. Janpeak season
  2. Febcommon
  3. Marcommon
  4. Apruncommon
  5. Mayrare
  6. Junnot usually seen
  7. Julnot usually seen
  8. Auguncommon
  9. Seppeak season
  10. Octpeak season
  11. Novpeak season
  12. Deccommon

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

0%2%4%6%8%Jan 1-7: 4.2% of 18950 checklistsJan 8-14: 5.1% of 13676 checklistsJan 15-21: 4.5% of 13377 checklistsJan 22-31: 5.0% of 17004 checklistsFeb 1-7: 4.3% of 10218 checklistsFeb 8-14: 3.6% of 11568 checklistsFeb 15-21: 2.8% of 15916 checklistsFeb 22-28: 3.5% of 11413 checklistsMar 1-7: 3.4% of 10754 checklistsMar 8-14: 2.9% of 12051 checklistsMar 15-21: 2.8% of 12616 checklistsMar 22-31: 2.5% of 17801 checklistsApr 1-7: 2.2% of 13186 checklistsApr 8-14: 1.7% of 14428 checklistsApr 15-21: 1.4% of 14738 checklistsApr 22-30: 0.7% of 21753 checklistsMay 1-7: 0.7% of 22494 checklistsMay 8-14: 0.6% of 23363 checklistsMay 15-21: 0.3% of 20219 checklistsMay 22-31: 0.2% of 20778 checklistsJun 1-7: 0.1% of 12234 checklistsJun 8-14: 0.1% of 12491 checklistsJun 15-21: 0.1% of 10856 checklistsJun 22-30: 0.1% of 11964 checklistsJul 1-7: 0.1% of 9437 checklistsJul 8-14: 0.1% of 8599 checklistsJul 15-21: 0.1% of 8252 checklistsJul 22-31: 0.1% of 11329 checklistsAug 1-7: 0.3% of 8116 checklistsAug 8-14: 0.4% of 8051 checklistsAug 15-21: 1.1% of 8502 checklistsAug 22-31: 2.6% of 13673 checklistsSep 1-7: 3.1% of 9873 checklistsSep 8-14: 4.2% of 9735 checklistsSep 15-21: 7.4% of 10120 checklistsSep 22-30: 6.5% of 12543 checklistsOct 1-7: 5.6% of 10735 checklistsOct 8-14: 6.1% of 10869 checklistsOct 15-21: 5.9% of 10436 checklistsOct 22-31: 5.4% of 13808 checklistsNov 1-7: 5.6% of 10507 checklistsNov 8-14: 6.0% of 9827 checklistsNov 15-21: 5.3% of 9904 checklistsNov 22-30: 4.4% of 13396 checklistsDec 1-7: 4.6% of 8974 checklistsDec 8-14: 4.3% of 9468 checklistsDec 15-21: 3.9% of 11614 checklistsDec 22-31: 4.2% 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 late September · 2996 checklists that week, 139,721 in all13%
  2. Fairfield CountyBest the second week of November · 2105 checklists that week, 139,848 in all6.8%
  3. New London CountyBest early February · 1468 checklists that week, 65,205 in all4.8%
  4. Windham CountyBest late October · 337 checklists that week, 19,034 in all4.7%
  5. Tolland CountyBest late January · 736 checklists that week, 39,004 in all4.7%
  6. Middlesex CountyBest late December · 1030 checklists that week, 39,919 in all4.3%

Best spots

Share of checklists at the peak
  1. Griswold CoveNew London County, best the second week of February · 28 checklists that week, 896 in all68%
  2. Hammonasset Natural Area Preserve (Willard Island)New Haven County, best early January · 48 checklists that week, 1,363 in all54%
  3. Glastonbury MeadowsHartford County, best mid September · 32 checklists that week, 683 in all53%
  4. Beard Cove (historical)New Haven County, best the second week of December · 58 checklists that week, 8,925 in all53%
  5. Swan LakeTolland County, best mid November · 30 checklists that week, 1,732 in all52%

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

Best time of day

In Connecticut, the Northern Harrier is most often listed on checklists started between 10 am and 12 pm (3.5% of those checklists).

0%1%2%3%4%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: 1.6% of 33657 checklists7 am: 2.4% of 62964 checklists8 am: 3.1% of 70645 checklists9 am: 3.3% of 64870 checklists10 am: 3.5% of 58827 checklists11 am: 3.4% of 51689 checklists12 pm: 3.2% of 45288 checklists1 pm: 3.3% of 44765 checklists2 pm: 3.5% of 44173 checklists3 pm: 2.9% of 41979 checklists4 pm: 2.3% of 33219 checklists5 pm: 1.3% of 24828 checklists6 pm: 0.7% 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
January4.2%5.1%4.5%5.0%
February4.3%3.6%2.8%3.5%
March3.4%2.9%2.8%2.5%
April2.2%1.7%1.4%0.7%
May0.7%0.6%0.3%0.2%
June0.1%0.1%0.1%0.1%
July0.1%0.1%0.1%0.1%
August0.3%0.4%1.1%2.6%
September3.1%4.2%7.4%6.5%
October5.6%6.1%5.9%5.4%
November5.6%6.0%5.3%4.4%
December4.6%4.3%3.9%4.2%

Neighboring states

  • Rhode Island: arrives the second week of August, 1 week earlier than Connecticut
  • Massachusetts: arrives late July, 3 weeks earlier than Connecticut
  • New Jersey: arrives late August, 1 week later than Connecticut
  • New York: arrives mid August, in the same week than Connecticut

Common questions

When do Northern Harriers arrive in Connecticut?
Northern Harriers reach Connecticut in mid August, are common by late August, peak in late September (6.5% of checklists), and most are gone by late March.
When do Northern Harriers leave Connecticut?
Most Northern Harriers have left Connecticut by late March, when reports fall below half their usual rate. Stragglers are still reported until mid April.
When is the best time to see a Northern Harrier in Connecticut?
The Northern Harrier is reported most often in late September, on about 6.5% of Connecticut checklists.
Where in Connecticut are Northern Harriers seen most often?
By county, New Haven County, Fairfield County, and New London County have the highest peak reporting rates for the Northern Harrier (counties with at least 200 checklists).