In de south border of the province of Entre Ríos, in Ceibas, there is a transition between the Delta and Espinal environments. The scenery consists of extended grasslands over dunes, where there are low xerophilous woods in the higher lands. Soft wood trees such as the Ceibo and Curupí are found by small rivers and marshes.

In this environment, especially over the dunes, intense life is developed, and a small part of it has been registered in this video. Dusk is the ideal moment to detect most of activity carried out by biodiversity. As soon as the broiling heat of summer diminishes in the evening, many species go out to get food.

Cuises, tucu-tucus and field mice leave their earths, searching for tender vegetables and birds like the Canastero Chaqueño (Asthenes baeri) wander on land looking for insects, and at the same time, the atajacaminos wake up from their long sleep to start acting during the twilight and most of the night.

Just then, a predatory species is very active as well. The rest of the animals are extremely afraid of it: it is de Big Pit Viper or Viper of the Cross (Bothrops alternatus). This viper uses its lethal bite to paralyse its preys, which will be wholly swallowed later on.

This species means a great worry to the people who live in the country, given that most of the 95% of the bites are caused by the Big Pit Viper. It is not aggressive to the human being; however, people who go for a careless walk in the grazing land or country may tragically come across these snakes.