WhenToBird

Bulweria bulwerii · Procellariidae

When Do Bulwer's Petrels Arrive in Hawaii?

Bulwer's Petrels arrive in Hawaii in early April, peak in the second week of June (1.5% of checklists), and most are gone by the second week of September.

When to look

First arrivalsApr 1-7early April
Common byApr 1-7early April
PeakJun 8-14the second week of June
Most gone bySep 8-14the second week of September

Best: the second week of June. First arrivals early April; most are gone by the second week of September. Peak: on about 1.5% of Hawaii checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Maruncommon
  4. Aprcommon
  5. Maycommon
  6. Junpeak season
  7. Julcommon
  8. Augpeak season
  9. Sepcommon
  10. Octrare
  11. Novnot usually seen
  12. Decnot usually seen

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

0%0.5%1%1.5%2%Jan 1-7: 0.1% of 5223 checklistsJan 8-14: 0% of 4322 checklistsJan 15-21: 0% of 4791 checklistsJan 22-31: 0% of 6113 checklistsFeb 1-7: 0.1% of 4916 checklistsFeb 8-14: 0.1% of 4778 checklistsFeb 15-21: 0% of 5119 checklistsFeb 22-28: 0% of 5246 checklistsMar 1-7: 0% of 4356 checklistsMar 8-14: 0% of 4127 checklistsMar 15-21: 0.1% of 4584 checklistsMar 22-31: 0.3% of 5941 checklistsApr 1-7: 0.5% of 3596 checklistsApr 8-14: 1.3% of 3301 checklistsApr 15-21: 0.7% of 3268 checklistsApr 22-30: 1.1% of 3732 checklistsMay 1-7: 0.8% of 2628 checklistsMay 8-14: 1.3% of 3151 checklistsMay 15-21: 0.8% of 2566 checklistsMay 22-31: 0.9% of 4054 checklistsJun 1-7: 1.4% of 2703 checklistsJun 8-14: 1.5% of 2731 checklistsJun 15-21: 1.5% of 2826 checklistsJun 22-30: 1.1% of 3671 checklistsJul 1-7: 0.9% of 2692 checklistsJul 8-14: 1.2% of 2734 checklistsJul 15-21: 0.6% of 2412 checklistsJul 22-31: 1.1% of 3581 checklistsAug 1-7: 1.3% of 2426 checklistsAug 8-14: 1.3% of 2669 checklistsAug 15-21: 0.9% of 2605 checklistsAug 22-31: 0.7% of 3159 checklistsSep 1-7: 0.4% of 2502 checklistsSep 8-14: 0.8% of 2975 checklistsSep 15-21: 0.4% of 3090 checklistsSep 22-30: 0.1% of 3424 checklistsOct 1-7: 0.1% of 2897 checklistsOct 8-14: 0.1% of 3420 checklistsOct 15-21: 0.1% of 3802 checklistsOct 22-31: 0.1% of 4531 checklistsNov 1-7: 0.1% of 3215 checklistsNov 8-14: 0% of 3704 checklistsNov 15-21: 0% of 3216 checklistsNov 22-30: 0% of 4153 checklistsDec 1-7: 0% of 3627 checklistsDec 8-14: 0% of 3710 checklistsDec 15-21: 0% of 3731 checklistsDec 22-31: 0% of 6597 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 Hawaii 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 Hawaii

Best counties

Share of checklists at the peak
  1. Northwestern Hawaiian Islands CountyBest early August · 11 checklists that week, 404 in all20%
  2. Kauai CountyBest early June · 428 checklists that week, 32,543 in all2.8%
  3. Hawaii CountyBest the second week of June · 1105 checklists that week, 75,146 in all2.2%
  4. Maui CountyBest late August · 301 checklists that week, 22,729 in all0.7%
  5. Honolulu CountyBest early August · 743 checklists that week, 47,705 in all0.4%

Best spots

Share of checklists at the peak
  1. Keāhole PointHawaii County, best mid June · 27 checklists that week, 1,290 in all46%
  2. Kilauea Point National Wildlife Refuge (Kīlauea Point)Kauai County, best mid April · 21 checklists that week, 770 in all5.5%
  3. Kilauea Point National Wildlife RefugeKauai County, best mid May · 34 checklists that week, 2,548 in all4.7%
  4. Kaiwi State Scenic ShorelineHonolulu County, best late May · 20 checklists that week, 469 in all2.6%
  5. Kēōkea BeachHawaii County, best late August · 46 checklists that week, 1,029 in all2.0%

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

Best time of day

In Hawaii, the Bulwer's Petrel is most often listed on checklists started between 5 and 7 pm (1.3% of those checklists).

0%0.5%1%1.5%12 am: too few checklists (66) to judge1 am: too few checklists (53) to judge2 am: too few checklists (70) to judge3 am: too few checklists (68) to judge4 am: too few checklists (106) to judge5 am: too few checklists (1548) to judge6 am: 0.2% of 10237 checklists7 am: 0.3% of 17935 checklists8 am: 0.4% of 18565 checklists9 am: 0.4% of 19076 checklists10 am: 0.3% of 18179 checklists11 am: 0.3% of 15530 checklists12 pm: 0.4% of 13069 checklists1 pm: 0.1% of 12798 checklists2 pm: 0.2% of 12698 checklists3 pm: 0.3% of 12213 checklists4 pm: 0.7% of 10921 checklists5 pm: 1.3% of 9437 checklists6 pm: 1.2% of 4360 checklists7 pm: too few checklists (1028) to judge8 pm: too few checklists (316) to judge9 pm: too few checklists (182) to judge10 pm: too few checklists (110) to judge11 pm: too few checklists (50) 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
January0.1%0%0%0%
February0.1%0.1%0%0%
March0%0%0.1%0.3%
April0.5%1.3%0.7%1.1%
May0.8%1.3%0.8%0.9%
June1.4%1.5%1.5%1.1%
July0.9%1.2%0.6%1.1%
August1.3%1.3%0.9%0.7%
September0.4%0.8%0.4%0.1%
October0.1%0.1%0.1%0.1%
November0.1%0%0%0%
December0%0%0%0%

Common questions

When do Bulwer's Petrels arrive in Hawaii?
Bulwer's Petrels arrive in Hawaii in early April, peak in the second week of June (1.5% of checklists), and most are gone by the second week of September.
When do Bulwer's Petrels leave Hawaii?
Most Bulwer's Petrels have left Hawaii by the second week of September, when reports fall below half their usual rate.
When is the best time to see a Bulwer's Petrel in Hawaii?
The Bulwer's Petrel is reported most often in the second week of June, on about 1.5% of Hawaii checklists.
Where in Hawaii are Bulwer's Petrels seen most often?
By county, Northwestern Hawaiian Islands County, Kauai County, and Hawaii County have the highest peak reporting rates for the Bulwer's Petrel (counties with at least 200 checklists).