Bats have a housing crisis. And it's getting worse

There's a lesser-known housing crisis happening right here in B.C., and some of the homes built to solve it are actually turning into deadly heat traps. And did I mention the residents are bats? Just outside Vancouver, hundreds of bats spend their summers living in these wooden boxes. And they aren't just any bats. They have a high fidelity for coming back to the same spot year after year. And they will teach their daughters and their daughters to come back here. This is a ladies only. That's right. It's a maternity colony. Hundreds of bat moms gather here every summer to give birth and raise their babies. And they actually need warm homes. It takes a lot of energy to be pregnant, produce milk and raise a pup, right? But in July 2018, something went terribly wrong. We came out here and I was just devastated to find 65 dead bats. The bats were dying inside the very homes designed to protect them. And John and other volunteers were desperate to figure out why. It turns out temperatures inside these boxes had climbed to a staggering 46 degrees Celsius. But there's something even more surprising about what happened. There had been another heat wave just a month earlier without the same mass die-off. So what was different with this one? What we think happened is the colony was going through parturition, which is where all the babies to all these female bats are born at the same time. and they're really small. They're really vulnerable. So the bats had these vulnerable pups and they didn't want to leave the roost, even though the conditions were too hot. Instead of fleeing, these mothers stayed to protect their babies, even as temperatures turned deadly. And with climate change making extreme heat more intense and frequent, that creates a growing problem. Because bats actually like the heat, they just need it to be the right amount. And a wooden box sitting in direct sunlight can go from perfectly comfortable to dangerously hot. So how do you build a bat home that can handle both? One team has come up with some pretty ingenious designs. You made an emergency exit. Exactly. Made out of PVC pipes. A bat mini condo. More room, more temperatures to choose from. Different types of boxes facing different directions with different temperatures inside. Some are warm when they need it, some are cooler when they don't. That tries to simulate an attic in terms of different temperatures, different humidity levels. But there's another problem. Most bat species in BC don't live in buildings or bat boxes at all. They depend on forests, especially older trees with cracks and cavities and loose bark where they can shelter. And as those habitats disappear, researchers are also getting creative. They're experimenting with artificial bark that wraps around trees, creating new places for bats to roost. In BC, researchers working with the Okanagan Nation Alliance have even developed smaller versions called mini barks and bats have been moving into some of them remarkably quickly. But these are still experimental solutions and researchers say there's no substitute for protecting the forests bats already call home. So it turns out solving the bat housing crisis isn't about building the perfect bat house, it's about giving them options because bats play a vital role in so many ecosystems and making sure that they have somewhere safe to call home matters more than ever.