The rich tapestry of life on Earth is fraying, due in large part to human-caused habitat loss and climate change. As more species disappear, researchers are racing to track this global decline in biodiversity to understand its consequences and counteract it through conservation initiatives. Those efforts rely on accurate animal monitoring, which can be difficult, time-consuming and costly. Now, in new research published in the journal iScience, researchers present evidence for a new low-cost, noninvasive tool that can be used to monitor animals: spiderwebs. They're using environmental DNA, or eDNA, which is simply different creatures' DNA just lying around in the environment. Previous work showed that webs are good sources of insect DNA, including what spiders are gorging on. But [evolutionary biologist Morton] Allentoft and [student Josh] Newton wanted to see whether the webs were also trapping DNA from vertebrate animals. So Newton ... collected spiderwebs. Back in the lab, Newton amplified the small amounts of DNA from the webs. They were filled with genetic material from animals. "It was wonderful," says Allentoft. "We could see these kangaroos [and] wallabies." There were nine other mammals, 13 species of birds, the motorbike frog and the snake-eyed skink. In other words, the technique worked. It represents a new way of tracking animal biodiversity and alerting us when we should intervene to conserve native species.