Trimorphodon lambda
Silhouette: Alex Slavenko · PhyloPic
In 3 days ~20% in a week ~50%
Trimorphodon lambda, the Sonoran lyre snake, is a species of rear-fanged snake in the family Colubridae. Native to the southwestern United States and northwestern Mexico, the species is best known for the distinctive V-shaped or lyre-like marking on the top of its head. Previously classified as a subspecies of the western lyre snake (Trimorphodon biscutatus), it is now widely recognized as a distinct species.
The generic name, Trimorphodon, is derived from Greek and translates to "three-shaped teeth". This refers to the distinct variations of teeth found in the upper jaw: long and recurved front teeth, shorter middle teeth, and elongated, grooved fangs located at the rear of the mouth.
The specific epithet, lambda, refers to the prominent chevron-shaped mark on the snake's head, which resembles the uppercase Greek letter lambda (Λ). Historically, T. lambda was considered a subspecies of Trimorphodon biscutatus (However, modern multivariate statistical analyses of geographic variation and phylogenetic studies resulted in the elevation of the Sonoran lyre snake to full species status.
The Sonoran lyre snake is a medium to large, slender snake... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Saguaro National Park | 🇺🇸 United States |
More parks will be added in future updates.
With luck
About 10% of wildlife watchers report a Sonoran Lyre Snake sighting in Saguaro National Park on a given day, based on 87 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 31st most-seen of the 51 reptiles we can rate there. Over three days the chance rises to about 20%, and over a week to about 50%, if each day is a fresh chance.
August
In that month about 20% of wildlife watchers report a Sonoran Lyre Snake in Saguaro National Park on a given day, against under 5% in January–February and October, the lowest months. That is one of Saguaro National Park's wettest months, with about 45 mm of rain against almost none in May.
Between 7 and 10 pm
Across all the parks we cover, that three-hour window holds the most Sonoran Lyre Snake sightings with a recorded time, and about 8 in 10 of them come between 6 pm and 6 am: it is mostly seen at night.
Only Saguaro National Park, in our data
Saguaro National Park is the only park on Wallace's Line with enough records to rate Sonoran Lyre Snake sightings: about 10% of wildlife watchers there report one on a given day.
Same family: Colubridae
The closest relatives of the Sonoran Lyre Snake that you can see in Saguaro National Park (family Colubridae, Colubrid Snakes) are Gopher Snake (about 30%), Coachwhip (about 20%) and Long-nosed Snake (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Sonoran Lyre Snake is recorded against all the reptiles logged in Saguaro National Park (87 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.
