WhenToBird

Sterna forsteri · Laridae

When Do Forster's Terns Arrive in South Dakota?

Adult Forster's Tern
Photo: Aitor, CC BY 4.0 via iNaturalist

Forster's Terns reach South Dakota in the second week of April, are common by mid April, peak in early May (6.2% of checklists), and most are gone by early September.

When to look

First arrivalsApr 8-14the second week of April
Common byApr 15-21mid April
PeakMay 1-7early May
Most gone bySep 1-7early September

Best: early May. First arrivals the second week of April; most are gone by early September. Peak: on about 6.2% of South Dakota checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprpeak season
  5. Maypeak season
  6. Jununcommon
  7. Julcommon
  8. Augcommon
  9. Sepuncommon
  10. Octrare
  11. Novnot usually seen
  12. Decnot usually seen

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

0%2%4%6%8%Jan 1-7: 0% of 1699 checklistsJan 8-14: 0% of 967 checklistsJan 15-21: 0% of 893 checklistsJan 22-31: 0% of 1338 checklistsFeb 1-7: 0% of 898 checklistsFeb 8-14: 0% of 1013 checklistsFeb 15-21: 0% of 1650 checklistsFeb 22-28: 0% of 1011 checklistsMar 1-7: 0% of 1304 checklistsMar 8-14: 0% of 1447 checklistsMar 15-21: 0% of 1524 checklistsMar 22-31: 0% of 2850 checklistsApr 1-7: 0% of 2170 checklistsApr 8-14: 0.4% of 2259 checklistsApr 15-21: 2.7% of 2578 checklistsApr 22-30: 6.4% of 3858 checklistsMay 1-7: 7.5% of 3532 checklistsMay 8-14: 5.1% of 4498 checklistsMay 15-21: 4.7% of 4211 checklistsMay 22-31: 3.3% of 5094 checklistsJun 1-7: 2.3% of 3279 checklistsJun 8-14: 1.5% of 3503 checklistsJun 15-21: 1.2% of 2861 checklistsJun 22-30: 1.9% of 3893 checklistsJul 1-7: 2.3% of 2666 checklistsJul 8-14: 2.1% of 2554 checklistsJul 15-21: 2.3% of 2412 checklistsJul 22-31: 2.8% of 2746 checklistsAug 1-7: 2.9% of 1842 checklistsAug 8-14: 2.8% of 1899 checklistsAug 15-21: 2.8% of 1757 checklistsAug 22-31: 1.5% of 2464 checklistsSep 1-7: 1.6% of 1894 checklistsSep 8-14: 1.3% of 1794 checklistsSep 15-21: 0.7% of 1671 checklistsSep 22-30: 0.3% of 2085 checklistsOct 1-7: 0.5% of 1429 checklistsOct 8-14: 0.3% of 1441 checklistsOct 15-21: 0.4% of 1330 checklistsOct 22-31: 0.1% of 1471 checklistsNov 1-7: 0.1% of 1168 checklistsNov 8-14: 0% of 1068 checklistsNov 15-21: 0% of 985 checklistsNov 22-30: 0% of 1108 checklistsDec 1-7: 0% of 890 checklistsDec 8-14: 0% of 957 checklistsDec 15-21: 0% of 1246 checklistsDec 22-31: 0% of 1514 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 South Dakota 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 South Dakota

Best counties

Share of checklists at the peak
  1. Day CountyBest the second week of June · 23 checklists that week, 794 in all38%
  2. Hutchinson CountyBest the second week of May · 22 checklists that week, 420 in all28%
  3. Edmunds CountyBest the second week of May · 20 checklists that week, 466 in all27%
  4. Aurora CountyBest mid August · 11 checklists that week, 348 in all26%
  5. Kingsbury CountyBest the second week of May · 29 checklists that week, 300 in all25%
  6. Charles Mix CountyBest the second week of May · 81 checklists that week, 2,198 in all25%

Best spots

Share of checklists at the peak
  1. Oahe Downstream Recreation AreaStanley County, best early May · 20 checklists that week, 509 in all51%
  2. Oaha Recreation AreaStanley County, best early May · 20 checklists that week, 247 in all22%
  3. Oakwood Lakes Recreation AreaBrookings County, best the second week of August · 50 checklists that week, 132 in all20%
  4. Lacreek National Wildlife RefugeBennett County, best late August · 23 checklists that week, 255 in all14%
  5. Farm IslandHughes County, best late April · 27 checklists that week, 825 in all13%

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

Best time of day

In South Dakota, the Forster's Tern is most often listed on checklists started between 2 and 4 pm (2.3% of those checklists).

0%1%2%3%12 am: too few checklists (49) to judge1 am: too few checklists (44) to judge2 am: too few checklists (33) to judge3 am: too few checklists (59) to judge4 am: too few checklists (227) to judge5 am: too few checklists (1080) to judge6 am: 1.3% of 3387 checklists7 am: 1.7% of 7718 checklists8 am: 1.9% of 10342 checklists9 am: 2.2% of 10758 checklists10 am: 2.0% of 9123 checklists11 am: 2.1% of 7814 checklists12 pm: 2.1% of 6876 checklists1 pm: 2.1% of 6801 checklists2 pm: 2.3% of 6673 checklists3 pm: 2.3% of 6344 checklists4 pm: 1.8% of 6412 checklists5 pm: 1.9% of 5570 checklists6 pm: 2.4% of 4276 checklists7 pm: 2.0% of 3183 checklists8 pm: too few checklists (1499) to judge9 pm: too few checklists (329) to judge10 pm: too few checklists (82) to judge11 pm: too few checklists (42) 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%0%0%0%
February0%0%0%0%
March0%0%0%0%
April0%0.4%2.7%6.4%
May7.5%5.1%4.7%3.3%
June2.3%1.5%1.2%1.9%
July2.3%2.1%2.3%2.8%
August2.9%2.8%2.8%1.5%
September1.6%1.3%0.7%0.3%
October0.5%0.3%0.4%0.1%
November0.1%0%0%0%
December0%0%0%0%

Neighboring states

  • Nebraska: arrives the second week of April, in the same week than South Dakota
  • North Dakota: arrives mid April, 1 week later than South Dakota
  • Minnesota: arrives mid April, 1 week later than South Dakota
  • Iowa: arrives mid April, 1 week later than South Dakota

Common questions

When do Forster's Terns arrive in South Dakota?
Forster's Terns reach South Dakota in the second week of April, are common by mid April, peak in early May (6.2% of checklists), and most are gone by early September.
When do Forster's Terns leave South Dakota?
Most Forster's Terns have left South Dakota by early September, when reports fall below half their usual rate. Stragglers are still reported until the second week of September.
When is the best time to see a Forster's Tern in South Dakota?
The Forster's Tern is reported most often in early May, on about 6.2% of South Dakota checklists.
Where in South Dakota are Forster's Terns seen most often?
By county, Day County, Hutchinson County, and Edmunds County have the highest peak reporting rates for the Forster's Tern (counties with at least 200 checklists).