The concrete sprawl of Los Angeles isn't exactly where you would expect to find 30 new species of wildlife. New York City and Singapore don't exactly seem like oases of non-human life either. New research, however, shows that life in big urban centers is a lot more diverse than some city-dwellers might think.
"Everyone expects for there to be a lot of biodiversity in the tropics," Emily Hartop, lead author of a study to be published next month in the journal Zootaxa, told NBC News.
"When you find new species in the city, that is surprising," she said. "Finding dozens of new species in a city, that is quite startling."
A new study conducted by Hartop and her colleagues at the Natural History Museum of Los Angeles County discovered the 30 new species of flies from the same genus, Megaselia. They were collected from 30 different sites (mostly located in private backyards).
Urban biodiversity isn't just limited to buzzing insects. Last year, a study found that 54 cities are home to 20 percent of the world's bird species. In the city of Lyon, scientists found nearly a third of all the bee species native to France. It turns out that cities are a good place for some animals to live — and how humans decide to manage their cities can make those habitats better or worse for the local fauna.
A fly in the family
Inside Natalie Brejcha's home in the Highland Park neighborhood of Los Angeles, a framed photograph of a fly sits on the mantle next to the family photos. It's named after them, Megaselia brejchaorum, and was discovered in Brejcha's backyard.
In most biodiversity studies, samples are found in public places or areas owned by research institutions. Hartop and her colleagues, however, wanted to get a more complete picture of L.A.'s environment.
When Brejcha, a classical violinist with two daughters, saw the call for volunteers on Facebook, she was a little bit skeptical.
"I thought, if you're going to find a new species, you have to go the Amazon, right?" she told NBC News.
She set up what she described as a small tent-like structure in her "stereotypical L.A. yard." Insects flew into it, got trapped, and dropped into a bottle filled with alcohol. Once a week, she takes the bottle and its unfortunate residents to the researchers at the Natural History Museum.
Her daughters, Tenney, 7, and Marin, 5, have embraced the project.
"The girls are really proud," Brejcha said. Meeting the entomologists even inspired Tenney to ask for some special equipment.
"My girl asked for a microscope for Christmas because of this, and she told me, 'Mom, I want to be a scientist.'"
A bet pays off
The idea for the study came about, according to Hartop, when her boss, curator of entomology Brian Brown, bet a Natural History Museum board member that he could find a new species anywhere in the city.
They set a trap in the board member's backyard and the first bug they pulled out was something new.
While L.A. might have some famous public spaces, like Griffith Park, most of the plant and animal life is located on private property. Putting a call out to regular people meant getting a better picture of what insect life was out there and, eventually, how personal landscaping decisions might affect a city's biodiversity. It also meant there was less of chance of someone knocking down or messing with the traps.
So far, Hartop has examined more than 35,000 flies, and she still has more to go until she finishes going through all of the samples collected in 2014. She hopes that similar studies can be conducted in other cities.
But why flies?
"We get that a lot: 'You just study flies!'" she said. "The reality is that when you look around you, there are so many invisible processes going on under your feet, and most of those processes are the result of insects, microbes and fungi. By knowing what kind of flies are out there, we can know what is going on in our ecosystems."
The birds and the bees
Anyone who has ever walked through a flock of pigeons knows birds do pretty well in cities, too. That isn't to say that birds prefer cities — urban areas only retain about 8 percent of the bird species that otherwise would have lived in the area, according to a study led by Myla Aronson of Rutgers University.
But cities are still filled with a rich variety of birds. Aronson and her team looked at 54 cities around the world and found that 20 percent of known bird species can be found flying in urban centers. New York City and Singapore stood out as particularly diverse, the former because of its large city parks and the latter because of the lush national park that sits right outside of its borders.
"From city to city, across the world, maintaining natural habitat within a city is important for biodiversity," Aronson told NBC News.
And while pigeons are a common sight, most birds found in cities reflect the species that live in the surrounding natural habitat. To keep biodiversity high, she said, it's important for cities to plant other things than just grass and trees. Native shrubs and other less fashionable flora are important to keeping local insects like bees (which, according to a study by the French National Institute for Agricultural Research, are abundant in cities) and birds alive.
As for the flies, Hartop now wants to examine what the ideal mix of backyard plants is to encourage a wider variety of insects.
"You as a citizen can actually do things on your private land that affects the biodiversity," she said, "not only in your backyard, but in your neighborhood and beyond."