World’s biggest bat colony gathers in Zambia every year: we used artificial intelligence to count them

nature & planetanalysisThe Conversation (Africa)2019 · Kasanka National Park, Zambia

World’s biggest bat colony gathers in Zambia every year: we used artificial intelligence to count them

the gist

Every year around October, straw-coloured fruit bats gather at Kasanka National Park in Zambia, and researchers have now counted them with cameras and artificial intelligence. Nine cameras filmed the emergence from below, and software tracked the bats across a centre line, with a check showing it detected about 95% of them. The average estimate for November 2019 was about 857,000 bats, with a peak day of 987,114. Past visual counts had ranged from 1 million to 10 million, which shows how hard the task is. These bats disperse seeds up to 75 km a night, which is three times further than African elephants do.

how it works

Cameras filmed the bats from below against the evening sky, and software tracked each animal frame by frame and counted it when it crossed the centre line. The team then used trigonometry to estimate what fraction of the colony was passing the cameras and scaled that up to the whole roost.

so what

The colony is one of the biggest in the world and the most important in Africa, so monitoring it helps protect bats across the region. Counting consistently lets scientists tell whether shifts come from disturbance or real population declines, which matters as farming and wind power expand nearby.

fun fact

Bats are the only mammals capable of true sustained flight.

Trump and Netanyahu reportedly clash over whether to resume military action against Iran

the gist

Israeli reports also say the cabinet directed the military to prepare for a possible new attack on Iran.

so what

The United States and Israel have been closely aligned on Iran's nuclear programme and regional threats, so open disagreement between their leaders over military strategy is unusual and closely watched. Whether to resume strikes is a decision with consequences for shipping, oil markets and the wider Middle East.

fun fact

Benjamin Netanyahu has served as Prime Minister of Israel for more years in total than any other person.

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Data: GDELT Project

Illustrative photo · Israel Belkind and Fanny Abramovitch (original) “The Provis…, Public domain, via Wikimedia Commons

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supplementary video · Epimetheus on YouTube ↗

world cultures & travelWikivoyageclassic9th–15th century · Siem Reap, Cambodia

Angkor was the largest pre-industrial city on Earth, covering about 3,000 square kilometres

the gist

Angkor, near Siem Reap in northern Cambodia, was the capital of the Khmer Empire, which ruled much of mainland Southeast Asia between roughly the 9th and 15th centuries. At its height the city spread across about 3,000 square kilometres, making it the largest pre-industrial city on Earth by area. Its growth depended on water: huge reservoirs called barays, along with canals and embankments, stored monsoon rain and carried it to rice fields. That system let farmers harvest more than once a year and fed a very large population through the dry season. The temple complex of Angkor Wat, built in the early 12th century, is the best-known monument and still stands at the heart of the park.

how it works

The Khmer kings built enormous rectangular reservoirs that caught monsoon rain during the wet season. Earthen dykes and canals moved that water into rice paddies, so farmers could grow crops across much of the year. The surplus food supported craftsmen, builders and the workforce that raised the temples.

so what

Angkor shows how a society without industrial machinery could build a city on a scale that rivals modern metropolises, using engineering and water management instead. Some historians link its decline to drought, flooding and shifts in its water systems, which makes it a long-running case study in how cities depend on managing water. The site is a UNESCO World Heritage Site and one of the most important archaeological landscapes in Southeast Asia.

fun fact

The outline of Angkor Wat appears on the national flag of Cambodia.