A survey of a single backyard in Australia reveals over a thousand species

Photo: Pexels/Max Rahubovskiy

When many of us think of biodiversity, we tend to think of forests, coral reefs and savannas, but even our backyards can be home, whether permanent or temporary, to numerous creatures. In fact, say scientists, urban landscapes can host plenty of biodiversity even if much of it may escape our attention.

Three experts at the University of Queensland in Australia realized this after conducting a thorough survey of their shared house in Brisbane and and its backyard during the COVID-19 lockdowns in 2020.

They discovered as many as 1,150 unique species of animals, plants and fungi over a one-year period as they document in a study aptly titled “The house of a thousand species.”

This large number came as a complete surprise not only to them but to other scientists as well.

“We asked a large number of ecologists and conservation scientists how many species they’d expect to find in this setting and they predicted only 200,” says Matt Holden, a mathematician who was one of the researchers.

“But after 60 days of surveying, we’d already discovered 777 species,” Holden explains. “It shows suburban houses and apartments could have far more biodiversity than ever imagined, especially when it comes to insects.”

The scientists say they came up with the idea of counting all the the species around the house when one of them, ecologist Andrew Rogers, went to vacuum cobwebs in his room and wondered how many species of spider were on the property. The answer would prove to be 56.

“The three of us soon envisioned a plan to comb through the house and backyard in search of other critters that resided alongside us,” Holden recalls.

In time, the scientists discovered a rich biodiversity of creatures on the premises, including 436 moth and butterfly species, 56 birds and eight reptiles as well as the dozens of spiders over a 12-month period. “The bird species included tawny frogmouths, laughing kookaburras, blue-faced honeyeaters, rainbow lorikeets, spotted doves and Brisbane favourite, the Australian white ibis,” they write.

“Blue-tongued skinks hibernated under the garage and at night blue-banded and teddy-bear bees slept in the hedges under the front window,” Holden explains.

Among the numerous species were three species previously unrecorded in The Atlas of Living Australia, the country’s leading biodiversity database. They were a mosquito, a sandfly, and an invasive flatworm called Platydemus manokwari.

“The house was a complex ecosystem of species interacting. We stumbled upon the moth Scatochresis innumera, which as a caterpillar spends its whole time feeding inside the dung of a brushtail possum before emerging as an adult,” Holden says. “The Parilyrgis concolor is another moth species whose caterpillar lives in spider webs and devours spider poop to survive.”

Obviously, this house was not unique, which means that many other houses with their backyards and gardens are home to a similarly rich biodiversity too even if it may remain unseen by their residents.

That said, certain factors can boost biodiversity on urban properties, Holden notes. “It depends on how people tend to their homes and gardens, keeping low maintenance trees and shrubs and eliminating manicured lawns and pesticides will significantly boost the number of critters found,” he explains.