Researchers have followed, counted and measured Nile crocodiles. In Ndumo Game Reserve, South Africa, researchers followed 50 Nile crocodiles, which were 202 to 472 cm long, for 18 months, using mark-resight, radio and satellite telemetry.

At Ndumo, larger crocodiles moved farther and more often than smaller ones. Adults over 2.5 m had the largest home ranges. Sub-adult crocodiles of 1.5 to 2.5 m had smaller, more localised home ranges than those adults.

Home ranges of the Ndumo crocodiles overlapped a lot in the dry season, so territory, if present, did not make separate home ranges.

As of November 2026, Ndumo Game Reserve is a winter refuge and spring breeding site for an estimated 846 Nile crocodiles. They move into the Rio Maputo from November and return as floodplain water recedes in May.

As of November 2026, Ndumo Game Reserve has the third largest Nile crocodile population in South Africa.

Researchers usually count Nile crocodiles in the morning, when the animals are out of the water on the shore.

The preferred temperature range for crocodiles and alligators is 25 to 35 degrees Celsius (77 to 95 degrees Fahrenheit). Researchers who implanted temperature sensors in Nile crocodiles saw their body temperatures vary continuously, not settle on one target temperature.

In 2012 researchers measured bite forces in all 23 living crocodilian species, finding molariform bite forces from 900 to 8,983 newtons. Two Nile crocodiles about 2.5 meters long had a mean molariform bite force of 3,043 newtons, measured directly.

As of November 2026, an estimated 50,000 to 70,000 mature Nile crocodiles live in the wild.

Words to know

• telemetry: tracking by radio
• territory: defended area
• floodplain: land that floods
• refuge: safe place