A group of captive killer whales have come up with a strategy to snack on seagulls to supplement their diet… or boredom.
An enterprising young killer whale began using a new baiting tactic to add seagulls to his menu. After feeding time, when his keepers had fed him with fish, this intelligent mammal would regurgitate some of them onto the water surface and then sink below to wait. If a hungry gull landed on the water, he would rush toward it and catch the unsuspecting bird in one maw.
What’s more, he has taught his fellow whales how to do it. As he set his trap again and again with success, his younger half brother began to adopt the practice after a few months.
‘”It looked liked one was watching while the other tried,” Professor Noonan, who made the discovery, said of the whale’s initial behavior.’
The capacity to come up with the baiting strategy and share the technique with others is known as cultural learning in the scientific world. Once, it was believed to be one of the abilities that separated humans from animals. Now it seems on top of other dolphins and chimpanzees, killer whales are also capable of such gifted behavior.
Playing on the saying “Life’s a ***** (read: female dog) and then you die”, it really did hold true for 6 Pilot Whales in Australia. These poor Long-finned Pilot Whales (Globicephala melas) re-beached themselves barely a day after a mass beaching of about 90 whales and 5 Bottle-nosed Dolphins which resulted in most of the 90 whales dying.
The sight of a fairly overweight friend of mine lying by the poolside and being called a “beached whale” piqued my interest in the topic, and in the course of researching, I stumbled upon the National Geographic video of a news report on the re-beached whales. The video got me thinking about why such humongous mammals would want to wade in the shallow end of the sea and risk getting stranded. Picture this: A real obese guy trying to swim laps in the baby pool. Apart from it not being a pretty sight, it’s absolutely pointless for the guy! Likewise for the whales.
A beached Pilot Whale
According to the scientists interviewed, whales that beach themselves belong to “extremely social groups that follow pod members into danger.” As of today, one can only speculate why whales beach themselves; even the scientists interviewed “cannot explain what draws these deep sea animals so close to shore.” It’s quite a wonder how come they’ve yet to put their finger on it, considering the scientific community has been at it from as far back as 1971.
If anything, this little “research project” has made me more aware of the severity of whlaes beaching themselves, and has got me asking why these gentle giants do what they do. It’s no wonder celebrities like Hayden Panettiere from “Heroes” are campaigning to save the whales. On a side note, that gives me one more reason to admire her, apart from her acting, of course.
Citations:
“Whales Re-Beach Themselves”, by National Geographic (AP), March 26, 2009.
Fehring, W. K., & Wells, R. S., 1976. A series of strandings by a single herd of pilot whales on the west coast of Florida. Journal of Mammalogy, 57(1): 191-194
What made dinosaurs take to the sky is a hotly contested question, and it’s just about to get hotter. Dr Robert Nudds, a biologist at the University of Manchester, has suggested that dinosaurs developed wings to show off to potential mates.
Archaeopteryx
Scientists agree that dinosaurs are ancestors of today’s birds. But just why did some of them sprout wings? Until now, the answers offered have often be referred to a better chance of escaping from predators. But researchers at the University of Manchester have advanced a more subversively romantic notion: they suggested that sexual selection- which gives animals an advantage in choosing a mate- may have been the key factor. In the evolutionary process known as sexual selection, traits viewed as more attractive by the opposite sex become both more common and more pronounced, since mating animals gravitate towards them.
” One theory is that these feathered dinosaurs used their forelimbs in some sort of sexual display, so maybe they ran around with their arms outreached to show off how pretty their feathers were,” Dr Robert Nudds, a biologist at the University if Manchester. He bolstered the idea with research showing that the notion ” learning to fly”, which supposedly helped give the creatures an advantage against predators- by giving them extra thrust to climb away from trouble- was false. Primitive wings, the Manchester research suggested, actually reduced the ability of animals to run fast and were, therefore, inefficient.
Sexual selection may have played a bigger role in the evolution of flight than had been previously thought
The models of Archaeopteryx and two other feathered dinosaurs, Caudipteryx and Protarchaeopteryx, suggest that forelimbs would have been inefficient as early wings, since they provide little thrust and increase drag. As a result, in evolutionary terms, these wings would have given the creatures little competitive advantage over rivals.
However, past research has shown that Archaeopteryx and other birds are homologous and had an aerodynamic function. [ Richard O. Prum, 2003]
It all seems so mind- bloggling, so what is the wings of dinosaurs really for? Dr Paul Barret, a palaeontologist at London’s natural history museum, observed that the truth may be in a mix of factors. But well, no one can say that you are wrong if you give an answer like ” Cause it was sexy.”
Male chimps that are willing to share their meat from hunting expeditions mate twice as often, studies found.
As I opened my browser few days ago, something caught my attention on my BBC homepage, “Chimpanzees exchange meat for sex“. Chimpanzees(Pan troglodytes) had been reported to exchange meat for sex. And that “Male chimps that are willing to share the proceeds of their hunting expeditions mate twice as often as their more selfish counterparts.”
There were several attempts before this one to study this exchange for sex phenomenon, but there were unsuccessful as researchers then, thought that it would be a direct ‘transaction’. Now, this study, done by Dr Cristina Gomes and her colleagues suggested that exchange need not happen immediately but takes days.
Meat, being high in protein is essential for animal’s diet. As female chimpanzees normally do not hunt for food, it is more beneficial for them to share, and in exchange, copulate with the males. On the other hand, by sharing their meat, the males increase the number of times they mate, this also implies the increase chances of fertilising the females, ensuring his genes is passed on to the next generation. Thus, in some sense, it is a win-win situation, where the benefits are higher than its cost.
After conducting this study, Dr Gomes suggested that this chimpanzees exchange may help understand the link of “good hunting skills and reproductive success” during the hunter-gatherers era.
So, maybe human beings used to trade sex for meat?
The flocking behavior of thousands of starlings, flying in incredible aerial formations, to their roosting sites before settling into trees for the night never fail to amaze by-standers. Collective animal behavior of large groups of animals, such as bird flocks, fish school and mammal herds, is a fascinating natural phenomenon. The main goal of collective behavior among individuals is to maintain cohesion of the group. This cohesion is an important requirement for survival: small groups and individuals are significantly more susceptible to predation than animals belonging to large and highly cohesive aggregations. For example, when a flock of starlings is under attack by a falcon, the flock contracts, expands, and even splits. Despite continuously changing its structure and density, no bird remains isolated, and soon, the flock reforms as a whole.
A common starling, sturnus vulgaris
A group of starling in 'aerial display'
The question to answer is: what kind of interaction enables the birds to maintain cohesion in such a robust way? One proposed theory is that individuals align and attract each other base on metric distance [Couzin et al (2002)] which they can estimate by stereovision, retinal image size and optic flow [Goodale et al (1990)]. This means that such interaction would decay when distance between individuals is increased. For example, 2 birds 5metres apart would attract each other less than 2 birds separated by 1metre in between them. However, if such interaction is based on metric distance, changes observed during predator attack cannot be explained. This is because one would expect the loss of cohesiveness of the flock when metric distances between individuals become larger than the interaction range.
An alternative hypothesis has been proposed [Ballerini et al (2008)] regarding collective behavior: individuals attract each other based on topological interactions. This means that each individual interacts and tracks a fixed number of neighbors despite their metric distance. In this case, 2 birds in a sparse flock and separated by 5metres would attract each other as much as 2 birds in a denser flock and separated by 1metre in between them, provided the number of individuals between the 2 birds is the same. The strength of interaction would thus remain the same for flocks at different densities, enabling the flock to stay together during strong density fluctuations (for example in predator attacks).
To test this hypothesis, Ballerini et al (2008) observed and reconstructed the 3D positions of individual birds in flocks of a few thousand members using stereo-metric and computer vision techniques. Computational numeric simulations were also conducted to test the topological hypothesis with the metric distance hypothesis. The research group concluded that cohesion in flocks, interacting based on topological cues, are much more robust under perturbations than metric ones, and that topologically, each bird interacts on average with six to seven neighbors.
In conclusion, collective animal behavior is an interesting phenomenon which allows large groups of animals to maintain cohesion that is necessary for survival. However, the underlying principles of interaction between the animals are still not fully elucidated, and might be attributed to topological cues between individuals.
References:
ID Couzin, J Krause, R James, GD Ruxton and NR Franks. (2002). Collective memory and spatial sorting in animal groups. Journal of Theoretical Biology 218: 1–11.
MA Goodale, CG Ellard and L Booth. (1990). The role of image size and retinal motion in the computation of absolute distance by the Mongolian gerbil (Meriones unguiculatus). Vision Res 30:399–413.
M Ballerini, N Cabibbo, R Candelier, A Cavagna, E Cisbani, I Giardina, V Lecomte, A Orlandi, G Parisi, A Procaccini, M Viale and V Zdravkovic. (2008). Interaction ruling animal collective behavior depends on topological rather than metric distance: evidence from a field study. Proceedings of the National Academy of Sciences, U.S.A. 105: 1232–1237.
