As if birds didn’t already have enough problems in this world, now it turns out that there is a large European bat (up to 18 inch wingspan) that catches and eats migrating birds on the wing.  By attaching biologging tags to 14 greater noctule bats in Spain and recording the variability of the bats’ echolocation buzzing and the altitudes where they were foraging, researchers were able to determine that the bats mostly pursued and ate insects at lower altitudes under about 300 ft.  But on two occasions, tagged bats were recorded flying up to nearly 4000 ft. where the intense buzzing of their echo locations showed prey pursuit.  In one case, the pursuit was short as the prey apparently escaped.  In the other case, the bat followed its prey (identified by vocalizations as a European robin) down close to the ground, captured, killed, and ate it (masticating sounds were recorded for 23 minutes)—all while still on the wing!  

A few wings of other birds were found on the ground below the greater noctule bats’ hunting grounds, but this bat is rare and it is not known what impact their bird hunting capabilities might have on migrating European songbirds.

Based on an article in Science, 9 October 2025

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Next time you have a chance to view a total solar eclipse, watch and listen to what the birds around you are doing!  That is what several researchers in Indiana did in April of 2024 when the path of a total solar eclipse passed across their area during the period when vocalizations relating to territorial establishment and mate attraction are leading up to breeding season. They set up microphones to record bird vocalizations the day before, the day of, and the day after the eclipse for a period each day centering on the time of totality. But that isn’t all they did. In an excellent example of encouraging active public engagement in science (“citizen or participatory science”), they created a smartphone app that allowed users to record observed behaviors (such as singing, flying, eating) and they recruited observers not only in the path of totality from Mexico to Maine, but elsewhere across the continent.  Extensive statistical and AI analysis of thousands of observations showed that the behavior of 29 of 52 species was significantly affected by the brief darkness, but with considerable variation.  Nineteen species produced a “dawn chorus” as light returned (notably American robins and a barred owl), fewer species (11) responded with a dusk chorus as daylight dimmed, and during totality 6 of 12 species increased vocalizations and 6 decreased.   Movement dropped noticeably during totality. 

This natural experiment shows that the biological rhythms of most birds are indeed affected by light/dark cycles—even when “night” lasts for just 4 minutes—and that citizen science can be a powerful tool for understanding the natural world.

Based on an article in Science, 9 October 2025

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People in the US have been feeding hummingbirds for at least a century but the pastime really took off after WWII when commercially-made feeders became available.  Curious about a range expansion of Anna’s hummingbirds northward in California, Nicolas Alexandre, then a graduate student at the University of California Berkeley, turned to Audubon Christmas Bird Counts from 1938 to 2019 to document the Annas’ movement north. The research team also looked at US Census records to show human population density and looked at newspaper ads for feeders as a proxy for feeder density.  Analysis of museum specimens quantified changes in Anna’s hummingbird beaks over time and found that beaks got longer and larger as feeders proliferated–a noticeable difference in a surprisingly short time span. 

But science is never simple and straightforward.  In California, the widespread planting of non-native eucalyptus trees, which provide nectar throughout the year, likely also contributed to the range expansion of Anna’s hummingbirds.   In colder regions north of the species’ historical range, beaks became smaller and shorter, which seems counter to the trend of larger bills.  But it turns out hummers use their beak to dissipate heat and a smaller beak with less surface area would help conserve heat in colder areas.  Another interesting finding—where feeders were very dense, male hummingbirds also developed pointier and sharper beaks.  Anybody who has watched hummers at feeders can relate to how some are very aggressive in defending a food source and understand that a sharper bill might help intimidate other hungry hummers.

–Based on an article in Science, 29 May 2025

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