Bite a mouse in the back of the neck and don’t let go. Now shake your head at a frenzied 11 turns per second, as if saying “No, no, no, no, no!”
You have just imitated a hunting loggerhead shrike (Lanius ludovicianus), already considered one of North America’s more ghoulish songbirds for the way it impales its prey carcasses on thorns and barbed wire.
Once the shrike hoists its prey onto some prong, the bird will tug it downward “so it’s on there to stay,” says vertebrate biologist Diego Sustaita. He has witnessed a shrike, about the size of a mockingbird, steadying a skewered frog like a kabob for the grill. A bird might dig in right away, keep the meal for later or just let it sit around and demonstrate sex appeal (SN Online: 12/13/13).
Shrikes eat a lot of hefty insects, mixing in rodents, lizards, snakes and even small birds. The limit may be close to the shrike’s own weight. A 1987 paper reported on a shrike killing a cardinal not quite two grams lighter than its own weight and then struggling to lift off with its prize. Recently, Sustaita got a rare chance to study how the loggerheads kill their prey to begin with.
Conservation managers breed one loggerhead subspecies on San Clemente Island. That’s about 120 kilometers west of where Sustaita works at California State University San Marcos. Sustaita set up cameras around a caged feeding arena and filmed shrikes, beak open, lunging to catch dinner. “They’re aiming for the prey’s neck,” he says.
夜上海论坛419
That’s a very shrikey thing. Falcons and hawks attack with their talons, but shrikes evolved on the songbird branch of the bird tree — without such powerful grips. Instead, shrikes land on their feet and attack with their hooked bills. “The bite happens at the same time the feet hit the ground,” Sustaita says. If the mouse somehow dodges, the shrike pounces again, “feet first, mouth agape.”
Reading several decades of gruesome shrike papers, Sustaita first believed the real killing power came from the bird’s bill, with bumps on the side, wedging itself between neck vertebrae and biting into the spine. Shrikes definitely bite, but based on videos, he now proposes that shaking may help immobilize, or even kill, prey.
Sustaita and colleagues discovered that the San Clemente shrikes fling their mouse prey with a ferocity that reached six times the acceleration due to Earth’s gravity, or about what a person’s head would feel in a car crash at 2 to 10 miles per hour, the researchers report September 5 in Biology Letters. “Not superfast,” he acknowledges, but enough to give a person whiplash.
In a small mouse, such shaking looks more damaging. Video analysis showed that the mouse’s body and head were twisting at different speeds. “Buckling,” Sustaita calls it. Just how much damage twisting does versus the neck bite remains unclear. But there’s a whole other question: How does a shrike manage not to shake its own brain to mush?
相关文章China’s agriculture ministry approves more varieties of genetically modified corn, soybeansChinas pilot projects on industrialization of genetically modified (GM) corn and soybeans have shown promising results in terms of increased production and reduced costs, the Ministry of Agriculture and Rural Affairs (MARA) said on Tuesday. China launched the pilot projects in 2021, and by 2023, the projects expanded to cover 20 counties in five provinces […]
China’s state-owned assets regulator vows to increase tech investment in emerging industriesChina said it will increase investment on technological innovation to bolster strategic emerging industries, the State-owned Assets Supervision and Administration Commission of the State Council (SASAC) said on Wednesday, in a move to accelerate countrys technology advancement and foster new productive forces. Zhuang Shuxin, a spokesperson for the SASAC, said on Wednesday that Chinas central […]
Mischief of slandering China’s economy will fail, as it should: SachsEditors Note: Despite facing a complex international situation and multiple headwinds, Chinas economy expanded by 5.2 percent in 2023, surpassing the target. However, a new wave of very negative narratives about Chinas economy has emerged in the Western media lately, attempting to undermine investors confidence in Chinas future. To counter Western medias malicious distortions that […]
Chinese stock markets stage miraculous turnaround, with Shanghai composite index up 0.43% on Thursday
Chinas stock markets staged a miraculous turnaround on Thursday, with the Shanghai Composite Stock Index regaining the psychologically important 2,800 points and closing at 2,845.78. Analysts said the market is expected to stabilize and return to normal operations along with the countrys sustained economic recovery, calling for stepped-up policy support to bolster the economy and […]
还没有评论,来说两句吧...