Circus cyaneus
Silhouette: Andy Wilson · PhyloPic
In 3 days ~10% in a week ~30%
The hen harrier (Circus cyaneus) is a bird of prey. It breeds in open areas such as marshes and grasslands in Eurasia and is migratory, moving further south outside of the breeding season. Birds in milder regions, such as France and Great Britain, may be resident year-round, but the higher altitudes are largely deserted in winter. The species is sexually dimorphic; males are smaller and mostly grey and white with black wingtips, whereas females average larger and are predominantly brown and have buff underparts with brown barring. Both sexes have a white rump patch, although it is more noticeable on females and juveniles.
The term "hen harrier" refers to its former habit of preying on free-ranging fowl. The northern harrier (Circus hudsonius) was formerly considered to be a subspecies of the hen harrier. In 1758 the English naturalist George Edwards included an illustration and a description of the hen harrier in the first volume of his Gleanings of Natural History. He used the English name "The blue hawk". Edwards based his hand-coloured etching on a bird that had been shot near London. When in 1766 the Swedish naturalist Carl Linnaeus updated his Systema Naturae for... Wikipedia →
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Novosibirsk | 🇷🇺 Russia | |
| 2 | León | 🇲🇽 México | |
| 3 | Daegu | 🇰🇷 South Korea | |
| 4 | San Francisco | 🇺🇸 United States | |
| 5 | San Diego | 🇺🇸 United States | |
| 6 | Beijing | 🇨🇳 China | |
| 7 | Vancouver | 🇨🇦 Canada | |
| 8 | Mesa | 🇺🇸 United States | |
| 9 | Los Angeles | 🇺🇸 United States | |
| 10 | Toluca | 🇲🇽 México |
| # | Zoo / Centre | Country | |
|---|---|---|---|
| 1 | Birds of prey | 🇨🇦 Canada | |
| 2 | Zoológico del Altiplano | 🇲🇽 Mexico | |
| 3 | California Raptor Center | 🇺🇸 United States | |
| 4 | Carolina Raptor Center | 🇺🇸 United States | |
| 5 | akwarium warszawskiego ZOO | 🇵🇱 Poland | |
| 6 | Chouette à voir! | 🇨🇦 Canada |
Rare
Under 5% of wildlife watchers report a Hen Harrier sighting in San Francisco on a given day, based on 4,869 verified sightings from GBIF citizen-science data. It is the 125th most-seen of the 375 birds we can rate there. Over three days the chance rises to about 10%, and over a week to about 30%, if each day is a fresh chance.
November to March
In those months about 10% of wildlife watchers report a Hen Harrier in San Francisco on a given day, against under 5% in April to October, the lowest months. Those are among San Francisco's wettest months, with about 85 mm of rain a month against almost none in July.
Between 10 am and 1 pm
Across all the parks we cover, that three-hour window holds the most Hen Harrier sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
4th of 55
Of the 55 cities where we can rate Hen Harrier sightings, San Francisco ranks 4th at under 5%. The best odds are in Novosibirsk (Russia, about 10%), León (México, about 10%) and Daegu (South Korea, about 10%).
Same family: Accipitridae
The closest relatives of the Hen Harrier that you can see in San Francisco (family Accipitridae, Hawks, Eagles, and Kites) are Red-tailed Hawk (about 30%) and Red-shouldered Hawk (about 30%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Hen Harrier is recorded against all the birds logged in San Francisco (4,869 verified sightings), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
