WhenToBird

Circus hudsonius · Accipitridae

When Do Northern Harriers Arrive in New Hampshire?

Northern Harriers arrive in New Hampshire in the second week of August, peak in late September (3.0% of checklists), and most are gone by mid May.

When to look

First arrivalsAug 8-14the second week of August
Common byAug 8-14the second week of August
PeakSep 22-30late September
Most gone byMay 15-21mid May

Best: late September. First arrivals the second week of August; most are gone by mid May. Peak: on about 3.0% of New Hampshire checklists.

  1. Jancommon
  2. Febuncommon
  3. Marcommon
  4. Aprcommon
  5. Maycommon
  6. Junrare
  7. Julrare
  8. Augcommon
  9. Seppeak season
  10. Octpeak season
  11. Novpeak season
  12. Deccommon

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

0%1%2%3%4%Jan 1-7: 0.8% of 8253 checklistsJan 8-14: 0.9% of 5998 checklistsJan 15-21: 1.1% of 5734 checklistsJan 22-31: 1.4% of 7776 checklistsFeb 1-7: 1.1% of 5253 checklistsFeb 8-14: 0.6% of 6802 checklistsFeb 15-21: 0.7% of 8852 checklistsFeb 22-28: 0.7% of 5792 checklistsMar 1-7: 1.3% of 6187 checklistsMar 8-14: 1.0% of 6977 checklistsMar 15-21: 1.0% of 7863 checklistsMar 22-31: 1.5% of 11746 checklistsApr 1-7: 1.9% of 9329 checklistsApr 8-14: 2.2% of 10499 checklistsApr 15-21: 1.7% of 10376 checklistsApr 22-30: 1.5% of 13086 checklistsMay 1-7: 1.2% of 13198 checklistsMay 8-14: 1.3% of 14980 checklistsMay 15-21: 0.7% of 12487 checklistsMay 22-31: 0.4% of 14294 checklistsJun 1-7: 0.2% of 8974 checklistsJun 8-14: 0.2% of 8395 checklistsJun 15-21: 0.3% of 7670 checklistsJun 22-30: 0.2% of 9188 checklistsJul 1-7: 0.2% of 7707 checklistsJul 8-14: 0.2% of 6554 checklistsJul 15-21: 0.3% of 6636 checklistsJul 22-31: 0.3% of 9599 checklistsAug 1-7: 0.3% of 6436 checklistsAug 8-14: 0.8% of 6477 checklistsAug 15-21: 1.0% of 6510 checklistsAug 22-31: 1.2% of 9762 checklistsSep 1-7: 1.7% of 6700 checklistsSep 8-14: 2.4% of 6012 checklistsSep 15-21: 3.0% of 6238 checklistsSep 22-30: 3.1% of 7619 checklistsOct 1-7: 2.8% of 6702 checklistsOct 8-14: 2.5% of 6863 checklistsOct 15-21: 2.9% of 6284 checklistsOct 22-31: 2.8% of 8287 checklistsNov 1-7: 2.3% of 7584 checklistsNov 8-14: 1.9% of 6056 checklistsNov 15-21: 1.9% of 5597 checklistsNov 22-30: 1.3% of 7140 checklistsDec 1-7: 0.9% of 4623 checklistsDec 8-14: 1.3% of 4920 checklistsDec 15-21: 1.1% of 6416 checklistsDec 22-31: 1.2% of 7659 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 New Hampshire 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 New Hampshire

Best counties

Share of checklists at the peak
  1. Sullivan CountyBest the second week of April · 350 checklists that week, 13,105 in all5.1%
  2. Coos CountyBest early May · 724 checklists that week, 27,719 in all5.0%
  3. Rockingham CountyBest the second week of November · 1414 checklists that week, 84,864 in all4.6%
  4. Hillsborough CountyBest late September · 1038 checklists that week, 50,125 in all4.3%
  5. Merrimack CountyBest late September · 858 checklists that week, 36,980 in all3.9%
  6. Cheshire CountyBest late September · 699 checklists that week, 39,834 in all3.6%

Best spots

Share of checklists at the peak
  1. Chapman's Landing - Stratham Boat LaunchRockingham County, best the second week of November · 23 checklists that week, 1,876 in all48%
  2. UNH PropertyStrafford County, best mid October · 29 checklists that week, 905 in all37%
  3. Haydens MillpondHillsborough County, best mid September · 38 checklists that week, 1,099 in all37%
  4. Copps PondCarroll County, best late August · 42 checklists that week, 473 in all35%
  5. Horseshoe PondMerrimack County, best late September · 33 checklists that week, 2,088 in all35%

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

Best time of day

In New Hampshire, the Northern Harrier is most often listed on checklists started between 8 and 10 am (1.5% of those checklists).

0%0.5%1%1.5%2%12 am: too few checklists (219) to judge1 am: too few checklists (192) to judge2 am: too few checklists (176) to judge3 am: too few checklists (234) to judge4 am: too few checklists (1042) to judge5 am: too few checklists (6352) to judge6 am: 0.8% of 23140 checklists7 am: 1.1% of 43401 checklists8 am: 1.5% of 48039 checklists9 am: 1.5% of 43328 checklists10 am: 1.5% of 37073 checklists11 am: 1.4% of 32028 checklists12 pm: 1.3% of 27396 checklists1 pm: 1.2% of 25182 checklists2 pm: 1.4% of 24318 checklists3 pm: 1.2% of 21974 checklists4 pm: 1.3% of 17958 checklists5 pm: 1.2% of 14528 checklists6 pm: 0.5% of 9144 checklists7 pm: too few checklists (5341) to judge8 pm: too few checklists (1845) to judge9 pm: too few checklists (578) to judge10 pm: too few checklists (346) to judge11 pm: too few checklists (256) 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
January0.8%0.9%1.1%1.4%
February1.1%0.6%0.7%0.7%
March1.3%1.0%1.0%1.5%
April1.9%2.2%1.7%1.5%
May1.2%1.3%0.7%0.4%
June0.2%0.2%0.3%0.2%
July0.2%0.2%0.3%0.3%
August0.3%0.8%1.0%1.2%
September1.7%2.4%3.0%3.1%
October2.8%2.5%2.9%2.8%
November2.3%1.9%1.9%1.3%
December0.9%1.3%1.1%1.2%

Neighboring states

  • Massachusetts: arrives late July, 2 weeks earlier than New Hampshire
  • Vermont: arrives early August, 1 week earlier than New Hampshire
  • Rhode Island: arrives the second week of August, in the same week than New Hampshire
  • Maine: arrives the second week of August, in the same week than New Hampshire

Common questions

When do Northern Harriers arrive in New Hampshire?
Northern Harriers arrive in New Hampshire in the second week of August, peak in late September (3.0% of checklists), and most are gone by mid May.
When do Northern Harriers leave New Hampshire?
Most Northern Harriers have left New Hampshire by mid May, when reports fall below half their usual rate.
When is the best time to see a Northern Harrier in New Hampshire?
The Northern Harrier is reported most often in late September, on about 3.0% of New Hampshire checklists.
Where in New Hampshire are Northern Harriers seen most often?
By county, Sullivan County, Coos County, and Rockingham County have the highest peak reporting rates for the Northern Harrier (counties with at least 200 checklists).