WhenToBird

Mergus merganser · Anatidae

When Do Common Mergansers Arrive in New Mexico?

Adult female Common Merganser
Photo: Christoph Moning, CC BY 4.0 via iNaturalist

Common Mergansers are winter birds in New Mexico: the first arrive in early November, they are common by late November, peak in mid January (8.0% of checklists), and most are gone by late March.

When to look

First arrivalsNov 1-7early November
Common byNov 22-30late November
PeakJan 15-21mid January
Most gone byMar 22-31late March

Best: mid January. First arrivals early November; most are gone by late March. Peak: on about 8.0% of New Mexico checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marcommon
  4. Apruncommon
  5. Mayrare
  6. Junrare
  7. Julrare
  8. Augrare
  9. Seprare
  10. Octrare
  11. Novcommon
  12. Decpeak season

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

0%5%10%Jan 1-7: 7.1% of 11827 checklistsJan 8-14: 8.6% of 9370 checklistsJan 15-21: 8.1% of 9561 checklistsJan 22-31: 7.5% of 12707 checklistsFeb 1-7: 6.8% of 9365 checklistsFeb 8-14: 6.3% of 10141 checklistsFeb 15-21: 5.4% of 12431 checklistsFeb 22-28: 6.9% of 9159 checklistsMar 1-7: 5.4% of 9348 checklistsMar 8-14: 4.2% of 9704 checklistsMar 15-21: 3.6% of 9896 checklistsMar 22-31: 3.1% of 14679 checklistsApr 1-7: 2.5% of 11145 checklistsApr 8-14: 1.6% of 11939 checklistsApr 15-21: 1.1% of 12885 checklistsApr 22-30: 0.9% of 17935 checklistsMay 1-7: 0.6% of 15202 checklistsMay 8-14: 0.5% of 16604 checklistsMay 15-21: 0.6% of 12720 checklistsMay 22-31: 0.4% of 16699 checklistsJun 1-7: 0.5% of 9889 checklistsJun 8-14: 0.6% of 9322 checklistsJun 15-21: 0.4% of 8341 checklistsJun 22-30: 0.4% of 10562 checklistsJul 1-7: 0.4% of 9036 checklistsJul 8-14: 0.3% of 8461 checklistsJul 15-21: 0.4% of 8585 checklistsJul 22-31: 0.3% of 11800 checklistsAug 1-7: 0.4% of 8289 checklistsAug 8-14: 0.5% of 8882 checklistsAug 15-21: 0.5% of 9136 checklistsAug 22-31: 0.5% of 12662 checklistsSep 1-7: 0.6% of 9936 checklistsSep 8-14: 0.4% of 9581 checklistsSep 15-21: 0.4% of 9355 checklistsSep 22-30: 0.5% of 12402 checklistsOct 1-7: 0.4% of 9467 checklistsOct 8-14: 0.6% of 10279 checklistsOct 15-21: 0.7% of 8990 checklistsOct 22-31: 0.8% of 11986 checklistsNov 1-7: 1.4% of 8461 checklistsNov 8-14: 2.3% of 8801 checklistsNov 15-21: 2.8% of 8616 checklistsNov 22-30: 3.2% of 11088 checklistsDec 1-7: 4.2% of 8444 checklistsDec 8-14: 4.9% of 8575 checklistsDec 15-21: 5.7% of 10958 checklistsDec 22-31: 6.1% of 14523 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 Mexico 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 Mexico

Best counties

Share of checklists at the peak
  1. De Baca CountyBest late January · 31 checklists that week, 2,203 in all52%
  2. San Juan CountyBest late January · 74 checklists that week, 5,542 in all35%
  3. Guadalupe CountyBest the second week of January · 51 checklists that week, 2,614 in all35%
  4. Quay CountyBest mid January · 23 checklists that week, 2,220 in all30%
  5. Colfax CountyBest early December · 104 checklists that week, 8,053 in all26%
  6. Rio Arriba CountyBest the second week of January · 82 checklists that week, 8,526 in all24%

Best spots

Share of checklists at the peak
  1. Lake RobertsGrant County, best late December · 23 checklists that week, 669 in all87%
  2. Santa Cruz LakeSanta Fe County, best mid November · 26 checklists that week, 339 in all82%
  3. Quemado LakeCatron County, best late October · 25 checklists that week, 527 in all81%
  4. Santa Rosa Lake State ParkGuadalupe County, best the second week of January · 20 checklists that week, 356 in all81%
  5. AlamedaBernalillo County, best the second week of January · 125 checklists that week, 2,959 in all73%

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

Best time of day

In New Mexico, the Common Merganser is most often listed on checklists started between 1 and 3 pm (3.5% of those checklists).

0%1%2%3%4%12 am: too few checklists (186) to judge1 am: too few checklists (180) to judge2 am: too few checklists (172) to judge3 am: too few checklists (183) to judge4 am: too few checklists (527) to judge5 am: too few checklists (4013) to judge6 am: 1.2% of 29677 checklists7 am: 1.8% of 71785 checklists8 am: 2.5% of 79208 checklists9 am: 3.0% of 61605 checklists10 am: 3.0% of 49588 checklists11 am: 2.9% of 38079 checklists12 pm: 3.1% of 31089 checklists1 pm: 3.4% of 27524 checklists2 pm: 3.6% of 26644 checklists3 pm: 3.1% of 26849 checklists4 pm: 2.6% of 25156 checklists5 pm: 1.4% of 19061 checklists6 pm: 0.7% of 15112 checklists7 pm: too few checklists (9040) to judge8 pm: too few checklists (2738) to judge9 pm: too few checklists (736) to judge10 pm: too few checklists (384) to judge11 pm: too few checklists (208) 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
January7.1%8.6%8.1%7.5%
February6.8%6.3%5.4%6.9%
March5.4%4.2%3.6%3.1%
April2.5%1.6%1.1%0.9%
May0.6%0.5%0.6%0.4%
June0.5%0.6%0.4%0.4%
July0.4%0.3%0.4%0.3%
August0.4%0.5%0.5%0.5%
September0.6%0.4%0.4%0.5%
October0.4%0.6%0.7%0.8%
November1.4%2.3%2.8%3.2%
December4.2%4.9%5.7%6.1%

Neighboring states

  • Arizona: arrives late November, 3 weeks later than New Mexico
  • Colorado: arrives early September, 8 weeks earlier than New Mexico
  • Utah: arrives mid September, 6 weeks earlier than New Mexico
  • Oklahoma: arrives early December, 4 weeks later than New Mexico

Common questions

When do Common Mergansers arrive in New Mexico?
Common Mergansers are winter birds in New Mexico: the first arrive in early November, they are common by late November, peak in mid January (8.0% of checklists), and most are gone by late March.
When do Common Mergansers leave New Mexico?
Most Common Mergansers have left New Mexico 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 Common Merganser in New Mexico?
The Common Merganser is reported most often in mid January, on about 8.0% of New Mexico checklists.
Where in New Mexico are Common Mergansers seen most often?
By county, De Baca County, San Juan County, and Guadalupe County have the highest peak reporting rates for the Common Merganser (counties with at least 200 checklists).