During the late Cretaceous period, raptors could be found all over the planet, with the exception of modern-day Australia and southern Africa. These dinosaurs varied enormously in size and sometimes in anatomical features: the above-mentioned Microraptor weighed only a few pounds and had four feathered proto-wings, while the fierce, one-ton Utahraptor could have whomped a Deinonychus with one claw tied behind its back.
In between were standard-issue raptors like Dromaeosaurus and Saurornitholestes, swift, fierce, feathered predators that made quick meals out of lizards, bugs, and smaller dinosaurs. As mentioned above, even the brainiest raptor of the Mesozoic Era couldn't hope to outwit a Siamese cat, much less a full-grown human being.
However, it's clear that dromaeosaurs and, for that matter, all theropods must have been slightly smarter than the herbivorous dinosaurs they preyed on, since the tools required for active predation a sharp sense of smell and sight, quick reflexes, hand-eye coordination, etc.
As for those lumbering sauropods and ornithopods, they only had to be slightly smarter than the vegetation they munched on! The debate about whether raptors hunted in packs has yet to be settled conclusively. The fact is, very few modern birds engage in cooperative hunting, and since birds are tens of millions of years farther down the evolutionary line than raptors, that can be taken as indirect evidence that Velociraptor packs are a figment of Hollywood producers' imaginations.
Still, the recent discovery of multiple raptor track marks in the same location hints that at least some of these dinosaurs must have roamed in small packs, so cooperative hunting would certainly have been within the realm of possibility, at least for some genera.
By the way, a recent study has concluded that raptors--and many other small- to medium-sized theropod dinosaurs--most likely hunted at night, as evidenced by their larger-than-usual eyes. Bigger eyes allow a predator to gather in more available light, making it easier to home in on small, quivering dinosaurs, lizards, birds and mammals in near-dark conditions. Hunting at night would also have allowed smaller raptors to escape the attention of larger tyrannosaurs, thus assuring the perpetuation of the raptor family tree!
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Previously Viewed. Stotting also communicates other things to nearby animals. Of course, the slotting warns fellow gazelles of a cheetah in the area. Further, stotting may be part of the courtship behavior of gazelles. Given its utility in avoiding both predation and in saving energy, stotting seems like as good a display of fitness as any other. The many species of gazelle are not the only animals that stot.
Their cloven relatives impalas, antelopes, and wild sheep are all thought to stot. Although domestication seems to have diminished stotting in adult sheep livestock, young lambs are prone to periodically engage in bizarre spastic jumping behavior that seems playful and may be the remnant of the stotting instinct.
Other forms of pursuit-deterrent signal have been discovered in motmot birds, Eurasian jays, rabbits, mice, curly-tailed lizards, and even guppies.
Their vocabulary includes distinct calls for each of their main predators. Interestingly, two of the Diana Monkey predators — leopards and eagles — hunt by surprise attack. Thus, these calls also function as pursuit-deterrents for those predators, not unlike slotting in gazelles. However, chimpanzees also hunt Diana monkeys, but they do so through sustained stalking and chase, not surprise attacks.
Consequently, they are not at all dissuaded by the warning calls. For eagles and leopards, the game is up when they have been spotted and so they give up and move on. Signaling theory depends on the signals being truthful. What if Diana monkeys went around making eagle calls randomly, just to protect themselves in the off-chance that an eagle was nearby?
After a while, the eagles would lose their training and no longer be dissuaded from attacking based on the calls alone. The dishonest Diana monkeys would find themselves to be victims of eagle attacks, possibly even more often than chance alone because the calls might actually attract the eagles. If the cheating behavior were genetic, dishonesty would quickly be bred out of the population and balance would be restored.
Thus, honesty is self-perpetuating in signaling theory. They do, however, respond to the predator-warning calls of a species of flycatcher bird that also lives on the island.
Both the iguanas and the flycatchers are sometimes preyed upon by large raptors—birds of prey. They could just listen out for the calls made by flycatchers. You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account. You are commenting using your Facebook account.
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