Wildlife Science: Urban Moths, Water Features, Spring Songbirds

How moths benefit urban plants and water features boost biodiversity; spring outpaces songbirds; the more monarch spots the better

By Mark Wexler
Science News
Mar 28, 2024

Water Features Boost Biodiversity

For urban wildlife that rely on water, backyard ponds (above, with green frog) and other water features can be just as beneficial as lakes, a team of British and Australian researchers has discovered. In England’s Hertfordshire county, located on the northern border of London, the scientists surveyed residents and discovered that 70 percent of survey respondents had one or more birdbaths, ponds or other water sources in their yards. The researchers compared the quantity and variety of wildlife visiting those sources with the wildlife that inhabited community lakes. In Urban Ecosystems, they report few differences between the overall number and diversity of insects, birds, amphibians and other small animals that visited the lakes and those that visited garden water features—with a total of 43 species inhabiting both locations. “These results demonstrate that garden water sources, especially for smaller-bodied animals, can supplement water-dependent biodiversity across the urbanized landscape, particularly during periods of hot, dry weather,” says co-author Nicola Rooney, a senior lecturer at the University of Bristol.

An image of a cinnabar moth on a yellow flower.

Why Cities Need Moths

More than 2,500 moth species range across Great Britain, where they play a key role supporting urban plant communities. In a recent study during the growing season in the city of Leeds, scientists from the University of Sheffield discovered that nectar-feeding moths (such as the cinnabar moth, above) account for a third of all pollination of urban flowering plants, including crops and trees. The insects carried more pollen and visited more plant species than previous studies had found. “People don’t generally appreciate moths, so they often can be overlooked compared to bees when considering protection and conservation measures,” says ecologist and project leader Emilie Ellis. Using DNA sequencing to analyze pollen attached to moths, she and her colleagues also found that moths feed on different plant communities—including more night-blooming species—than bees do. In Ecology Letters, the scientists recommend including plants such as borage and comfrey—which benefit both moths and native bees—when developing or enhancing residential gardens and other green spaces. “This will become increasingly important for the future health of urban ecosystems,” Ellis says.

An image of a yellow warbler male singing while perched amid crabapple flowers.

Songbirds Can’t Keep Pace

As climate change pushes spring to arrive sooner in many places, scientists worry about impacts on wildlife that rely on the timing of spring leaf out. To investigate such potential effects on breeding songbirds (like the yellow warbler, above), UCLA and Michigan State University researchers analyzed nearly two decades of data on spring leaf out and breeding dates along with the number of young produced by 41 songbird species. In the Proceedings of the National Academy of Sciences, they report that breeding dates were not keeping pace with spring’s earlier arrival—and that birds produced fewer young in years they were out of sync with peak leaf out. This mismatch will worsen: “By the end of the 21st century, spring is likely to arrive about 25 days earlier, with birds breeding only about 6.75 days earlier,” says lead author Casey Youngflesh, now at Clemson University. He and his colleagues urge conservation action to boost North American breeding bird numbers, which have fallen by nearly 30 percent since the 1970s.

Microscope

Hitting the Right Spots

Monarch butterflies with more white spots on their wings are more successful at reaching their winter habitats in Mexico than monarchs that have more black pigment, report ecologists from the University of Georgia in PLOS One.