Phrynops williamsi
Silhouette: Andy Wilson · PhyloPic
In 3 days ~80% in a week >90%
Phrynops williamsi, also known commonly as Williams' side-necked turtle, Williams' South American sideneck turtle, William's [sic] South American side-necked turtle, William's [sic] toadhead turtle, and Williams' toadhead turtle, is a species of turtle in the family Chelidae. The species is endemic to South America.
The specific name, williamsi, is in honor of American herpetologist Ernest E. Williams. P. williamsi is found in southeastern Brazil, Uruguay, and Argentina. The preferred natural habitat of P. williamsi is freshwater wetlands, at altitudes of 80–1,000 m (260–3,280 ft).
Borteiro, Claudio; Kolenc, Francisco; Prigioni, Carlos (2015). "A new noteworthy record of Phrynops williamsi Rhodin & Mittermeier (Testudines, Chelidae) in Uruguay". Cuadernos de Herpetología 29 (1): 95–96. Buskirk, James R. (1989). "Field observations on Phrynops williamsi and other Uruguayan chelonians". Vivarium 1 (4): 8–11.
Cabrera, Mario R. (1993). "Phrynops williamsi (Williams' South American Sideneck Turtle). Argentina: Corrientes". Herpetological Review 24 (2): 65–66. Data related to... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Iguazú National Park | 🇦🇷 Argentina | |
| 2 | Iguaçu National Park | 🇧🇷 Brazil |
| # | Zoo / Centre | Country | |
|---|---|---|---|
| 1 | Reino Animal | 🇲🇽 Mexico |
Likely
About 40% of wildlife watchers report a Williams' South-American Side-necked Turtle sighting in Iguazú National Park on a given day, based on 232 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 4th most-seen of the 18 reptiles 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.
May, August, October and December
In those months about 50% of wildlife watchers report a Williams' South-American Side-necked Turtle in Iguazú National Park on a given day, against about 20% in March, the lowest month.
Between 10 am and 1 pm
Across all the parks we cover, that three-hour window holds the most Williams' South-American Side-necked Turtle 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 2 parks where we can rate Williams' South-American Side-necked Turtle sightings, Iguazú National Park has the highest daily chance: about 40%. Next come Iguaçu National Park (Brazil, about 30%).
GBIF citizen-science records
It is estimated from how often the Williams' South-American Side-necked Turtle is recorded against all the reptiles logged in Iguazú National Park (232 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.
