Tantilla hobartsmithi
Silhouette: Jessica Tingle · PhyloPic
In 3 days ~10% in a week ~30%
Tantilla hobartsmithi, commonly known as Smith's black-headed snake and the southwestern blackhead snake, is a species of small snake in the subfamily Colubrinae of the family Colubridae. The species is native to the southwestern United States and adjacent northern Mexico.
The specific name or epithet, hobartsmithi, is in honor of American zoologist and herpetologist Hobart M. Smith (1912–2013). Tantilla hobartsmithi was first described by Edward Harrison Taylor in 1936. The southwestern blackhead snake is a small snake, growing to a maximum total length (tail included) of 15 in (38 cm), but typically averaging around 8 in (20 cm) in total length.
Dorsally, it is uniformly brown in color, except for the black-colored head, which gives it its common name, and a cream-colored or white collar. On the belly, there is a broad reddish stripe, which runs down the center of the ventral scales.
Tantilla hobartsmithi is rear-fanged, having enlarged rear teeth and a modified saliva, which while harmless to mammals, is believed to be toxic to arthropods, its primary prey. Blackhead snakes (genus Tantilla... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Big Bend National Park | 🇺🇸 United States | |
| 2 | Saguaro National Park | 🇺🇸 United States |
Rare
Under 5% of wildlife watchers report a Southwestern Blackhead Snake sighting in Saguaro National Park on a given day, based on 6 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 49th most-seen of the 51 reptiles 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.
July–September and November
In those months about 10% of wildlife watchers report a Southwestern Blackhead Snake in Saguaro National Park on a given day, against under 5% in October and December–June, the lowest months. Those are among Saguaro National Park's wettest months, with about 40 mm of rain a month against almost none in May.
Between 9 pm and midnight
Across all the parks we cover, that three-hour window holds the most Southwestern Blackhead Snake sightings with a recorded time, and about half of them come between 6 am and 6 pm: it is seen both by day and at night.
2nd of 2
Of the 2 parks where we can rate Southwestern Blackhead Snake sightings, Saguaro National Park ranks 2nd at under 5%. The best odds are in Big Bend National Park (United States, about 10%).
Same family: Colubridae
The closest relatives of the Southwestern Blackhead 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 Southwestern Blackhead Snake is recorded against all the reptiles logged in Saguaro National Park (6 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.
