Mautâm is a cyclic ecological phenomenon that occurs every 48–50 years in the northeastern Indian states of Tripura, Mizoram and Manipur, as well as in many places of Assam which are 30% covered by wild bamboo forests, and Chin State in Myanmar, particularly Hakha, Thantlang, Falam, Paletwa and Matupi Townships. It begins with a rat population boom, which in turn creates a widespread famine in those areas.^[1]

During mautâm, Melocanna baccifera, a species of bamboo, flowers at one time across a wide area. This event is followed invariably by a plague of black rats in what is called a rat flood.^[2][3] The bamboo flowering brings a temporary windfall of seeds, and rats multiply, exhaust the bamboo seeds, leave the forests, forage on stored grain, and cause devastating famine.^[4]

During the mautam period of 1958 and 1959 the Mizo National Famine Front (MNFF) was set up to provide relief to the far-flung areas. This body later became the Mizo National Front (MNF), which staged a major uprising in 1966. Under its leader Laldenga (who later became the chief minister of Mizoram), MNF fought a bitter separatist struggle for 20 years against the Indian Army until an accord that guaranteed Mizoram's autonomy as a separate state was signed in 1986.^[5]

Regular rodent outbreaks associated with bamboo flowering (and subsequent fruiting and seeding) also occur in the nearby Indian states of Arunachal Pradesh, Assam, Manipur, and Nagaland,^[6] as well as in Laos, Japan, Madagascar, and South America.^[7] Thingtâm, a similar famine, occurs with the flowering of another species of bamboo, Bambusa tulda.^[8]

Mautam and thingtam have been observed to strictly alternate, with a gap of 18 years from mautam to thingtam and a gap of 30 years from thingtam to mautam.^[9] Recorded instances of mautam include 1864, 1910–1912, 1958–1959, and 2007–2008 and those of thingtam include 1880–1884, 1928–1929, and 1976–1977. The next predicted events if this pattern continues are thingtam in 2025–2026 and mautam in 2055–2056.^[9]

• Bamboo blossom
• Population cycle

• Indian army's new enemy is rats, UK: BBC, 3 June 2006, troops in the six north-eastern states of the country are used to dealing with insurgencies" but are now dealing with "an infestation of rats.
• Bamboo the life blood of the people: Alarm to Ecosystem, SOS arsenic.
• Mautaam in Manipur, archived from the original on 25 October 2011, retrieved 9 September 2013.
• "Rat Attack, Plant vs. Predator", NOVA (interview), PBS, 30 September 2008, noted ecologist Daniel Janzen describes how Melocanna […] bamboo's strategy came about.