Aside from looking similar, Titanis probably had similar hunting behaviour to other phorusrhacids. Titanis itself would probably have been a visually orientated predator, relying upon eyesight for everything from prey identification to gauging distances between itself and prey. Analysis of the brain area of the skull in other phorusrhacids has revealed an underdeveloped sense of smell, and while it is not yet possible to know this for certain with Titanis, it is probably likely that as a member of the group, Titanis would also have had limited olfactory ability. This suggests that Titanis was more actively involved in predation than scavenging carcasses, although it does not mean that Titanis never scavenged as most carnivorous animals do when the opportunity presents itself.
Titanis was probably able to match almost any other animal in its ecosystem for speed. While more robust in build than other terror birds, Titanis still had very long legs, particularly the lower legs and modified metatarsals (foot bones) that added extra length to the leg. This resulted in a digitigrade stance that essentially means that Titanis would have balanced upon its toes rather than the flats of it feet (like humans do). All together the leg construction resulted in increased mechanical advantage from the levering of longer leg and foot bones as well as a longer stride that allowed Titanis to cover more ground with each step. This would have allowed for a very efficient means of locomotion that would have allowed Titanis to run down prey, as well as being potentially more manoeuvrable thanks to its bipedal stance and short frame that would have allowed for tighter turning. Reconstruction of the inner ears also shows that Titanis had a well-developed sense of balance.
Assuming that Titanis’s skull was similar to other phorusrhacids, and currently there is no reason to think that it was not, then the beak would have been the primary killing weapon. The tip of the beak would have been strongly curved down to a sharp point, as can be seen in other carnivorous birds today. In feeding this hook tip pulls at the meat while the lower jaw closes, shearing through the meat so that the bird has a bite sized chunk. In actual killing however the point could be brought down onto the neck or the back of the prey’s skull. This penetrating strike could hit an artery, damage the spine and even pierce the cranium and enter the brain causing instant death to the prey in question.
Smaller prey may have actually been swallowed whole, although observation of seriema birds suggests that small prey may have been thrown against the ground to stun or kill it outright before it was swallowed. Impacts against a hard ground would also break the bones of smaller prey resulting in easier swallowing. It’s also possible that Titanis may have regurgitated gastric pellets, especially after feeding on whole animals. This is seen today in owls which typically swallow rodents whole but are unable to digest the fur and the bones. After the bird has finished digesting the flesh, the bones and fur are packed together inside the stomach and are then brought up and regurgitated in the form of a pellet. The fact that Titanis existed for at least three million years, and also comes from a lineage of birds that lasted even longer, has led to a lot of thought as to what could have caused it to go extinct. Because Titanis was a fast runner and capable of tackling anything from small to medium and possibly even some larger prey, it seems unlikely that the cause could have been a loss of prey species. A possible alternative could be competition from newly evolving predators such as larger big cats as well as new forms of canids including the rising numbers of wolves which would have been hunting in packs. These new predators may have begun to displace Titanis as the top predator of its ecosystem, with other carnivores such as Arctodus (better known as the short faced bear) denying Titanis ready access to carrion from these other predators’ kills as well.
Another possibility that may have had a part in the downfall of Titanis is a changing climate. A trend of global cooling that happened in the Pliocene resulted in the climate of the Americas shifting from forest to drier open savannahs. Titanis was not just big it was tall, and when travelling in open grassland it could have easily been spotted by grazing herbivores who would have had plenty of warning to get away. This meant that Titanis would have steadily become a less successful predator, and even when it was successful it may have had to expend even greater amounts of energy when chasing prey. This situation combined with new predators that were better adapted to make use of the environment in their hunting may have combined to steadily overwhelm Titanis to the point where it could not continue to survive.
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