The Observer's Book of Birds. 1965

Product Information

The two studies raise questions about the navigational decisions that birds make, says University of California, Irvine, biophysicist Thorsten Ritz, who was not involved in either study.

In the other study, in Scientific Reports, ecologist Morgan Tingley of the University of California, Los Angeles, correlated bird vagrancy with geomagnetic disturbances and solar activity. Over the course of 60 years, scientists at the Bird Banding Laboratory captured and banded two million birds in the United States and Canada, recording their species and location. Using these records, Tingley calculated a vagrancy index for each capture by juxtaposing the bird’s documented location with the expected range of its species for that season. He took the number of sunspots and a daily measure of geomagnetic disturbance and averaged each over the three weeks prior to a bird’s capture, to account for the lag period between a bird veering off course and being caught.There is a signal across very different data sources, very different methods, suggesting that these extraterrestrial phenomena have real-time impacts on the organisms that can sense them,” says Eric Gulson-Castillo, a University of Michigan graduate student who led a study into the effects of space disturbances on bird migration. “We ourselves cannot directly sense them, but the birds can.” Tingley found that during fall migrations, geomagnetic disturbances were strongly associated with vagrancy. Armed with this correlation, Benjamin Tonelli—the first author of the research and Tingley’s graduate student—zeroed in on the peculiar birds found in the U.K. Now, 65 years later, new research into avian navigation gives scientists another hunch about what might have happened. They’ve found that Earth’s weather isn’t the only thing that can cause birds to veer off course—space weather seems to impact birds’ internal GPS. Bursts of energy from the sun in the form of sunspots, solar flares and coronal mass ejections are becoming more frequent and may affect how birds navigate. During the first week of September 1958, keen observers spotted hundreds of rare birds in the British Isles. According to a report at the time, they saw melodious warblers, tree pipits and, most surprisingly, a “remarkable influx” of red-breasted flycatchers. Very few of these flycatchers typically visit the United Kingdom annually as they make their way from central Europe to their wintering grounds in South Asia. Those who do wind up in the U.K. are termed “vagrants,” since they are well outside their expected range.

The studies both offer evidence that contradicts findings from controlled-lab experiments. In some of these prior studies, researchers concluded that magnetic disturbances 1,000 times stronger than the natural geomagnetic ones had no effect on birds’ internal bearings. In both studies, the disruptive effects of altered geomagnetism were strongest during fall migration. In the fall and not the spring, more birds drifted with the wind, and geomagnetic disturbances were associated with vagrancy. The seasonality of these effects may not be a coincidence, Gulson-Castillo says, but rather a reflection of a younger, less-savvy migratory population in the fall. Juvenile birds that hatched in the spring would be taking their first migratory journeys then, and their internal sense of direction might not be as fine-tuned as for older birds that have flown the route before. Still, scientists don’t have a clear reason why these younger birds would leave more up to the wind, or how small errors could compound and lead to a vagrant bird.Our terrestrial magnetic field is formed when heat energy from molten iron in Earth’s outer core is converted into electrical and magnetic energy. This ever-changing, fluid process leads to a slightly variable magnetic field and, at times, results in an odd outcome: Every 300,000 years or so, Earth’s magnetic poles flip locations—the North Pole becomes the South Pole and vice versa. When space weather enters this equation, it temporarily puts Earth’s magnetic field on the fritz. Yong’s research has shaped how he has raised his own pet corgi, Typo, particularly when he learned of a study which found dogs become more optimistic when they are given two weeks of sniffing tasks – they thrive when permitted to fully utilise their powerful sense of smell. There’s a surprising number of sensory biologists who are themselves neuro-atypical – they have something like face blindness or colour blindness,” he says. “Their different than ‘normal’ way of experiencing the world themselves might help them better empathise with other creatures who have those experiences. The core of this book is curiosity and empathy, understanding and valuing animals for their own sake, and trying to put ourselves in the shoes of creatures who are very different to us.” NASA’s Solar Dynamics Observatory captured these images of a solar flare on April 17, 2016. Intense solar flares can affect the Earth’s magnetic field.