[2] Maroon leaf monkeys (Presbytis rubicunda) are endemic to the island of Borneo in Southeast Asia.

They are selective feeders, as food becomes limited they will feed on certain types of plant matter or seeds during their time of abundance.

[5] Their primary food is the young parts of leaves, feeding less frequently on seeds and whole fruits, and occasionally on flowers.

During this time of abundance, Maroon leaf monkeys feed on large amounts of seeds and fruits.

Food becomes scarce during the rainy season, and at this time of year maroon leaf monkeys feed on mature leaves.

[5] During April, June, and August, maroon leaf monkeys consume the topsoil of termite mounds to obtain the minerals needed for a balanced diet.

The termite mound soil has high levels of calcium and magnesium and is also a source of potassium and phosphorus.

"[6] The Danum Valley of eastern Sabah, northern Borneo, had a rainfall of 3,115 millimetres (122.6 in) between the year 2007 and 2008, with temperature ranging from 31.4 °C (88.5 °F) to 22.5 °C (72.5 °F), with a mean of almost 27 °C (81 °F).