WhenToBird

Lophodytes cucullatus · Anatidae

When Do Hooded Mergansers Arrive in New Hampshire?

Adult male Hooded Merganser
Photo: Justin Flint, CC BY 4.0 via iNaturalist

Hooded Mergansers are in New Hampshire all year, but most are here in spring: numbers build from early March, peak in late March (13% of checklists), and fall back by mid April. In the quietest week (late July) they are still on about 2.4% of checklists.

When to look

Numbers buildMar 1-7early March
PeakMar 22-31late March
Fall back byApr 15-21mid April
FewestJul 22-31late July

Best: late March. Here all year; numbers build from early March and fall back by mid April. Peak: on about 13% of New Hampshire checklists.

  1. Januncommon
  2. Febuncommon
  3. Marpeak season
  4. Aprpeak season
  5. Mayuncommon
  6. Jununcommon
  7. Juluncommon
  8. Auguncommon
  9. Sepuncommon
  10. Octcommon
  11. Novpeak season
  12. Deccommon

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

0%5%10%15%Jan 1-7: 5.0% of 8253 checklistsJan 8-14: 4.6% of 5998 checklistsJan 15-21: 3.8% of 5734 checklistsJan 22-31: 4.0% of 7776 checklistsFeb 1-7: 4.3% of 5253 checklistsFeb 8-14: 3.1% of 6802 checklistsFeb 15-21: 2.8% of 8852 checklistsFeb 22-28: 5.7% of 5792 checklistsMar 1-7: 8.2% of 6187 checklistsMar 8-14: 11% of 6977 checklistsMar 15-21: 13% of 7863 checklistsMar 22-31: 14% of 11746 checklistsApr 1-7: 12% of 9329 checklistsApr 8-14: 11% of 10499 checklistsApr 15-21: 7.7% of 10376 checklistsApr 22-30: 6.2% of 13086 checklistsMay 1-7: 4.9% of 13198 checklistsMay 8-14: 3.6% of 14980 checklistsMay 15-21: 3.4% of 12487 checklistsMay 22-31: 3.7% of 14294 checklistsJun 1-7: 3.2% of 8974 checklistsJun 8-14: 3.2% of 8395 checklistsJun 15-21: 2.5% of 7670 checklistsJun 22-30: 2.8% of 9188 checklistsJul 1-7: 2.6% of 7707 checklistsJul 8-14: 2.7% of 6554 checklistsJul 15-21: 2.4% of 6636 checklistsJul 22-31: 2.5% of 9599 checklistsAug 1-7: 2.4% of 6436 checklistsAug 8-14: 3.4% of 6477 checklistsAug 15-21: 2.9% of 6510 checklistsAug 22-31: 2.6% of 9762 checklistsSep 1-7: 2.8% of 6700 checklistsSep 8-14: 2.6% of 6012 checklistsSep 15-21: 2.6% of 6238 checklistsSep 22-30: 2.4% of 7619 checklistsOct 1-7: 2.5% of 6702 checklistsOct 8-14: 2.5% of 6863 checklistsOct 15-21: 3.5% of 6284 checklistsOct 22-31: 6.7% of 8287 checklistsNov 1-7: 9.8% of 7584 checklistsNov 8-14: 12% of 6056 checklistsNov 15-21: 13% of 5597 checklistsNov 22-30: 12% of 7140 checklistsDec 1-7: 8.1% of 4623 checklistsDec 8-14: 7.2% of 4920 checklistsDec 15-21: 5.3% of 6416 checklistsDec 22-31: 5.6% 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.

Embed this map on your site

Where in New Hampshire

Best counties

Share of checklists at the peak
  1. Belknap CountyBest mid December · 138 checklists that week, 13,295 in all26%
  2. Grafton CountyBest late March · 1278 checklists that week, 45,699 in all24%
  3. Sullivan CountyBest late November · 233 checklists that week, 13,105 in all22%
  4. Coos CountyBest the second week of April · 668 checklists that week, 27,719 in all17%
  5. Merrimack CountyBest late March · 1349 checklists that week, 36,980 in all17%
  6. Cheshire CountyBest mid March · 898 checklists that week, 39,834 in all17%

Best spots

Share of checklists at the peak
  1. Livingston Park - Undeveloped AreaHillsborough County, best late November · 22 checklists that week, 547 in all87%
  2. Airport Marsh ReservoirCoos County, best late April · 67 checklists that week, 1,437 in all87%
  3. Lake WaukewanBelknap County, best late November · 25 checklists that week, 505 in all85%
  4. Keene Forestry ParkCheshire County, best late November · 29 checklists that week, 292 in all84%
  5. Wilder Management AreaGrafton County, best late March · 57 checklists that week, 543 in all84%
  6. Pine Road SiteRockingham County, best mid March · 32 checklists that week, 1,105 in all84%

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

Best time of day

In New Hampshire, the Hooded Merganser is most often listed on checklists started between 1 and 3 pm (6.3% of those checklists).

0%2%4%6%8%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: 4.7% of 23140 checklists7 am: 4.8% of 43401 checklists8 am: 5.8% of 48039 checklists9 am: 5.7% of 43328 checklists10 am: 6.1% of 37073 checklists11 am: 6.1% of 32028 checklists12 pm: 5.7% of 27396 checklists1 pm: 6.4% of 25182 checklists2 pm: 6.3% of 24318 checklists3 pm: 6.2% of 21974 checklists4 pm: 5.6% of 17958 checklists5 pm: 4.8% of 14528 checklists6 pm: 3.7% 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
January5.0%4.6%3.8%4.0%
February4.3%3.1%2.8%5.7%
March8.2%11%13%14%
April12%11%7.7%6.2%
May4.9%3.6%3.4%3.7%
June3.2%3.2%2.5%2.8%
July2.6%2.7%2.4%2.5%
August2.4%3.4%2.9%2.6%
September2.8%2.6%2.6%2.4%
October2.5%2.5%3.5%6.7%
November9.8%12%13%12%
December8.1%7.2%5.3%5.6%

Neighboring states

  • Massachusetts: arrives mid October, 18 weeks earlier than New Hampshire
  • Vermont: arrives mid July, 18 weeks later than New Hampshire
  • Rhode Island: arrives mid October, 18 weeks earlier than New Hampshire
  • Maine: arrives late July, 19 weeks later than New Hampshire

Common questions

When do Hooded Mergansers arrive in New Hampshire?
Hooded Mergansers are in New Hampshire all year, but most are here in spring: numbers build from early March, peak in late March (13% of checklists), and fall back by mid April. In the quietest week (late July) they are still on about 2.4% of checklists.
When do Hooded Mergansers leave New Hampshire?
Hooded Mergansers never fully leave New Hampshire: numbers fall back below half their usual rate by mid April, but some are still reported in every week, about 2.4% of checklists at the low.
When is the best time to see a Hooded Merganser in New Hampshire?
The Hooded Merganser is reported most often in late March, on about 13% of New Hampshire checklists.
Where in New Hampshire are Hooded Mergansers seen most often?
By county, Belknap County, Grafton County, and Sullivan County have the highest peak reporting rates for the Hooded Merganser (counties with at least 200 checklists).