WhenToBird

Circus hudsonius · Accipitridae

When Do Northern Harriers Arrive in Maine?

Northern Harriers arrive in Maine in the second week of August, peak in mid September (4.1% of checklists), and most are gone by early January.

When to look

First arrivalsAug 8-14the second week of August
Common byAug 8-14the second week of August
PeakSep 15-21mid September
Most gone byJan 1-7early January

Best: mid September. First arrivals the second week of August; most are gone by early January. Peak: on about 4.1% of Maine checklists.

  1. Januncommon
  2. Febuncommon
  3. Marcommon
  4. Aprpeak season
  5. Maycommon
  6. Junrare
  7. Julrare
  8. Augcommon
  9. Seppeak season
  10. Octpeak season
  11. Novcommon
  12. Deccommon

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

0%2%4%6%Jan 1-7: 0.9% of 15499 checklistsJan 8-14: 1.0% of 11141 checklistsJan 15-21: 0.9% of 10729 checklistsJan 22-31: 0.7% of 15084 checklistsFeb 1-7: 0.7% of 9403 checklistsFeb 8-14: 0.6% of 11268 checklistsFeb 15-21: 0.5% of 14061 checklistsFeb 22-28: 0.6% of 9977 checklistsMar 1-7: 0.6% of 9649 checklistsMar 8-14: 1.1% of 11781 checklistsMar 15-21: 1.3% of 11613 checklistsMar 22-31: 2.7% of 17798 checklistsApr 1-7: 4.1% of 14638 checklistsApr 8-14: 3.8% of 16511 checklistsApr 15-21: 3.6% of 17164 checklistsApr 22-30: 2.5% of 22602 checklistsMay 1-7: 2.0% of 22556 checklistsMay 8-14: 1.5% of 27842 checklistsMay 15-21: 1.1% of 27748 checklistsMay 22-31: 0.6% of 38715 checklistsJun 1-7: 0.6% of 26916 checklistsJun 8-14: 0.4% of 23737 checklistsJun 15-21: 0.4% of 22733 checklistsJun 22-30: 0.4% of 28248 checklistsJul 1-7: 0.4% of 20290 checklistsJul 8-14: 0.6% of 18534 checklistsJul 15-21: 0.6% of 17319 checklistsJul 22-31: 0.6% of 22815 checklistsAug 1-7: 0.7% of 15004 checklistsAug 8-14: 0.9% of 14603 checklistsAug 15-21: 1.7% of 14972 checklistsAug 22-31: 2.6% of 19813 checklistsSep 1-7: 3.2% of 14567 checklistsSep 8-14: 3.9% of 14520 checklistsSep 15-21: 4.7% of 14339 checklistsSep 22-30: 3.6% of 16879 checklistsOct 1-7: 2.8% of 12959 checklistsOct 8-14: 3.1% of 13168 checklistsOct 15-21: 2.8% of 11184 checklistsOct 22-31: 2.8% of 13717 checklistsNov 1-7: 2.4% of 9823 checklistsNov 8-14: 2.1% of 9007 checklistsNov 15-21: 2.1% of 8528 checklistsNov 22-30: 1.9% of 10228 checklistsDec 1-7: 1.4% of 7505 checklistsDec 8-14: 1.5% of 7982 checklistsDec 15-21: 1.1% of 10455 checklistsDec 22-31: 1.1% of 14285 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 Maine 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 Maine

Best counties

Share of checklists at the peak
  1. Oxford CountyBest late September · 197 checklists that week, 15,115 in all11%
  2. Cumberland CountyBest the second week of September · 2687 checklists that week, 169,501 in all6.4%
  3. Penobscot CountyBest the second week of April · 1591 checklists that week, 56,895 in all6.1%
  4. Knox CountyBest mid September · 626 checklists that week, 34,453 in all6.0%
  5. York CountyBest mid October · 1582 checklists that week, 101,844 in all5.8%
  6. Aroostook CountyBest the second week of October · 338 checklists that week, 16,817 in all4.6%

Best spots

Share of checklists at the peak
  1. Bradbury Mountain State ParkCumberland County, best the second week of April · 50 checklists that week, 377 in all46%
  2. Scarborough Marsh Wildlife Management Area (northeast)Cumberland County, best early September · 20 checklists that week, 719 in all45%
  3. Scarborough Marsh Wildlife Management AreaCumberland County, best early September · 131 checklists that week, 4,768 in all45%
  4. City of Bangor (Stillwater Avenue)Penobscot County, best mid April · 26 checklists that week, 374 in all39%
  5. Jagger PondYork County, best early November · 49 checklists that week, 1,870 in all35%

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

Best time of day

In Maine, the Northern Harrier is most often listed on checklists started between 3 and 5 pm (1.8% of those checklists).

0%0.5%1%1.5%2%12 am: too few checklists (510) to judge1 am: too few checklists (517) to judge2 am: too few checklists (581) to judge3 am: too few checklists (3242) to judge4 am: too few checklists (7221) to judge5 am: 1.1% of 19895 checklists6 am: 1.6% of 54578 checklists7 am: 1.5% of 92775 checklists8 am: 1.8% of 86962 checklists9 am: 1.8% of 78989 checklists10 am: 1.7% of 70954 checklists11 am: 1.6% of 59331 checklists12 pm: 1.7% of 50943 checklists1 pm: 1.7% of 49775 checklists2 pm: 1.7% of 49001 checklists3 pm: 1.8% of 43252 checklists4 pm: 1.9% of 33413 checklists5 pm: 1.6% of 25547 checklists6 pm: 1.2% of 18309 checklists7 pm: too few checklists (14287) to judge8 pm: too few checklists (5336) to judge9 pm: too few checklists (2253) to judge10 pm: too few checklists (1518) to judge11 pm: too few checklists (720) 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
January0.9%1.0%0.9%0.7%
February0.7%0.6%0.5%0.6%
March0.6%1.1%1.3%2.7%
April4.1%3.8%3.6%2.5%
May2.0%1.5%1.1%0.6%
June0.6%0.4%0.4%0.4%
July0.4%0.6%0.6%0.6%
August0.7%0.9%1.7%2.6%
September3.2%3.9%4.7%3.6%
October2.8%3.1%2.8%2.8%
November2.4%2.1%2.1%1.9%
December1.4%1.5%1.1%1.1%

Neighboring states

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

Common questions

When do Northern Harriers arrive in Maine?
Northern Harriers arrive in Maine in the second week of August, peak in mid September (4.1% of checklists), and most are gone by early January.
When do Northern Harriers leave Maine?
Most Northern Harriers have left Maine by early January, when reports fall below half their usual rate.
When is the best time to see a Northern Harrier in Maine?
The Northern Harrier is reported most often in mid September, on about 4.1% of Maine checklists.
Where in Maine are Northern Harriers seen most often?
By county, Oxford County, Cumberland County, and Penobscot County have the highest peak reporting rates for the Northern Harrier (counties with at least 200 checklists).