Cypseloides senex
Silhouette: vectorized by Rob Sparks · PhyloPic
In 3 days ~80% in a week >90%
The great dusky swift (Cypseloides senex) is a species of bird in subfamily Cypseloidinae of the swift family Apodidae. It is found in Argentina, Brazil, Paraguay, and possibly Bolivia. The great dusky swift is monotypic.
The great dusky swift is the largest member of genus Cypseloides. It is 18 cm (7.1 in) long and weighs 56 to 110 g (2.0 to 3.9 oz). The sexes have the same plumage. Adults have a chocolate brown crown and throat with pale gray edges to the feathers, giving a frosted appearance to the face. Their back is a darker brown, their rump a brown intermediate between the head and back, and their tail blackish brown. Their undersides are a paler brown than the back. The upper side of the wing is mostly brown and the underside somewhat lighter. Juveniles are very similar to adults with the addition on pale fringes to the wing feathers.
The great dusky swift is found in Brazil from southern Pará and much of Mato Grosso east into Bahia and south to Rio Grande do Sul, in eastern Paraguay, and in northeastern Argentina's Misiones Province. Undocumented sight records in Bolivia lead the South American... Wikipedia →
Call0:05
Brazil · 2002
© Dante Buzzetti · XC500223 · CC BY-NC-SA 4.0
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Iguaçu National Park | 🇧🇷 Brazil | |
| 2 | Iguazú National Park | 🇦🇷 Argentina | |
| 3 | Serra da Canastra National Park | 🇧🇷 Brazil | |
| 4 | Chapada dos Guimarães National Park | 🇧🇷 Brazil | |
| 5 | Emas National Park | 🇧🇷 Brazil |
Likely
About 40% of wildlife watchers report a Great Dusky Swift sighting in Iguaçu National Park on a given day, based on 2,386 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 16th most-seen of the 346 birds we can rate there. Over three days the chance rises to about 80%, and over a week to over 90%, if each day is a fresh chance.
October and November
In those months about 60% of wildlife watchers report a Great Dusky Swift in Iguaçu National Park on a given day, against about 30% in January–February, April and July, the lowest months.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Great Dusky Swift sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Yes
Of the 5 parks where we can rate Great Dusky Swift sightings, Iguaçu National Park has the highest daily chance: about 40%. Next come Iguazú National Park (Argentina, about 40%) and Serra da Canastra National Park (Brazil, about 20%).
GBIF citizen-science records
It is estimated from how often the Great Dusky Swift is recorded against all the birds logged in Iguaçu National Park (2,386 verified sightings from 2019 to 2026), 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.
