For animals unlucky enough to run into a carnivorous songbird known as the shrike, a quiet scurry through the woods can quickly morph into a dance with death. Loggerhead shrikes (Lanius ludovicianus), aka butcherbirds, impale their prey on spiky plants or barbed wire before delivering a death blow to the neck with their hooked beaks. Now, a new study shows how the birds can take down lizards and mice with body masses up to 40% of their own.
Scientists used a high-speed video camera to film 28 shrikes attacking large vertebrate prey at a zoological research center on San Clemente Island in California. When the researchers examined the slowed-down footage, they found that in nearly all fatal attacks, the shrikes would first latch onto the necks of their prey, vigorously shaking them up and down.
By using their prey’s neck as a pivot to whip them in wavelike motion, the shrikes could cause fatal damage to cervical vertebrae and spinal cords, the researchers report today in Biology Letters.
When the team analyzed the shaking motions, they found that the shrikes could exert up to 6 gs of accelerative force. By comparison, humans in low-speed, rear-end car crashes can experience head accelerations of 2 to 12 gs, enough to cause whiplash. On a mouse’s smaller spine, these forces can be fatal.
The results could help explain how shrikes—and other species like snakes and lizards—tackle prey larger than they are, by using the weight of their prey’s own bodies against them. For now, add another brutal move to the butcherbird’s vicious arsenal.
*Correction, 5 September, 2:25 p.m.: This story has been updated to note that the loggerhead shrikes in this study were observed catching prey up to 40% of their body mass.