Nyctomys sumichrasti
Silhouette: T. Michael Keesey · PhyloPic
In 3 days ~20% in a week ~40%
Sumichrast's vesper rat (Nyctomys sumichrasti) is a rodent of the family Cricetidae found from southern Mexico to Panama. It is named for François Sumichrast, the collector of the first specimen, and its closest relative is probably Hatt's vesper rat, a similar, but slightly smaller, species from the Yucatán Peninsula.
Sumichrast's vesper rat is a relatively small rat, with an adult length of 10 to 13 cm (3.9 to 5.1 in), not including the tail, which is only slightly shorter. Males and females are of similar size, with both weighing between 220 to 245 g (7.8 to 8.6 oz). It is one of the more brightly coloured rats, with a reddish or orange back and creamy to white underparts. The rats have a thick pelt of soft fur, which extends over the entire length of the tail, and is absent only on the soles of the feet. The eyes are relatively large, and surrounded by a narrow ring of black hair, while the whiskers are long and the ears small.
To aid in climbing, the claws are compressed and curved, and the first toe on each foot is thumb-like. Sumichrast's vesper rat is found from southern Jalisco and Veracruz in Mexico through much of Central... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Braulio Carrillo National Park | 🇨🇷 Costa Rica | |
| 2 | Arenal Volcano National Park | 🇨🇷 Costa Rica | |
| 3 | Monteverde Cloud Forest Reserve | 🇨🇷 Costa Rica |
With luck
About 10% of wildlife watchers report a Sumichrast's Vesper Rat sighting in Arenal Volcano National Park on a given day, based on 8 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 15th most-seen of the 25 mammals we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
May and December–February
In those months about 10% of wildlife watchers report a Sumichrast's Vesper Rat in Arenal Volcano National Park on a given day, against under 5% in March–April and June–November, the lowest months.
Between 7 and 10 pm
Across all the parks we cover, that three-hour window holds the most Sumichrast's Vesper Rat sightings with a recorded time, and about 7 in 10 of them come between 6 pm and 6 am: it is mostly seen at night.
Among the best
Of the 3 parks where we can rate Sumichrast's Vesper Rat sightings, Arenal Volcano National Park ranks 2nd at about 10%, level with the leaders once rounded. The best odds are in Braulio Carrillo National Park (Costa Rica, about 10%).
Same order: Rodentia
The closest relatives of the Sumichrast's Vesper Rat that you can see in Arenal Volcano National Park (order Rodentia, Rodents) are Variegated Squirrel (about 40%), Central American Agouti (about 40%) and Red-tailed Squirrel (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Sumichrast's Vesper Rat is recorded against all the mammals logged in Arenal Volcano National Park (8 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.
