Super-predatory humans

Predators have roamed the planet for 500 million years. The earliest is thought to be some type of simple marine organism, a flatworm maybe or type of crustacean, perhaps a giant shrimp that feasted on ancient trilobites. Much later came the famous predatory dinosaurs such as T. rex, and later still large toothed mammals such as sabre toothed cats or modern wolves.

But one or two hundred thousand years ago, the world’s most powerful predator arrived.

Us.

We lacked big teeth or sharp claws, huge tentacles or venomous bites. But we had intelligence, and the guile to produce tools and artificial weapons. And as we became ever better hunters we started harvesting animals on a great scale.

We wiped out the passenger pigeon, the dodo, the great herds of North American bison. Last century we decimated great whale populations. Today the world’s fishing fleets routinely take more fish than scientists say is sustainable, leading to crashes in cod numbers for example, while people kill more large mammals in North America than all other causes put together.

But out of our mass consumption of the world’s fauna appears a curious conundrum.

Read on:  http://www.bbc.co.uk/blogs/wondermonkey/2012/02/super-predatory-humans.shtml

Honeybees tell hornet predators to buzz off

By Victoria GillScience reporter, BBC Nature

Asian honeybees signal to their enemies - bee-eating hornets - to let them know they have been spotted.

An international team of scientists watched the bees as they guarded the entrance to their hive.

The researchers described how the bees shook their abdomens when a hornet approached, a signal that triggered the hornet to retreat.

They published their findings in the journal Animal Behaviour.

Researchers already knew of this "characteristic shaking signal", in which all the guards bees simultaneously vibrate their abdomens from side-to-side for a few seconds when a hornet approaches the colony.

In the wild, this produces a spectacular "Mexican wave" of vibrating bees.

This study, carried out on a small bee hive, revealed the hornets (Vespa velutina) responded directly to the bees' shaking signal.

Warned wasps would retreat from the colony and try to catch bees in flight instead.

To find this out, the researchers tethered live hornets to lengths of wire and held them at a variety of distances from the hive entrance.

The closer the tethered hornet was held to the hive, the more intensely the bee guards shook their bodies.

To confirm that the bees were specifically "talking to" the hornets with this signal, the team carried out the same tethering experiment with a harmless butterfly species (Papilio xuthus).

This insect is slightly larger than the hornet and has very similar yellow and black markings.

Despite the similarity, the bees did not respond to the butterflies, no matter how close they came to the hive.

Read on:  http://www.bbc.co.uk/nature/16981702

Why Some Animals Are Fatter Than Others

Humans are often obsessed with their weight, but nature seems to know exactly how fat each animal on the planet should be. The perfect weight depends on how each species solves the problem of avoiding both starving to death and being killed by predators, new research suggests.

The study, published in The American Naturalist, explains how these causes of death often exert opposite pressures on animals. Storing a lot of fat, for example, helps animals survive periods without food but also slows their running speeds and so makes getting caught by a predator more likely.

Animals can be stronger to compensate, but the energetic costs of extra muscle mean that the animal would starve more quickly during a food shortage.

Continued:  http://www.livescience.com/18054-animals-fatter-survival.html

Predators Hunt for a Balanced Diet

ScienceDaily (Jan. 10, 2012) — Predators select their prey in order to eat a nutritionally balanced diet and give themselves the best chance of producing healthy offspring.

A University of Exeter and Oxford-led study published in Proceedings of the Royal Society B shows for the first time that predatory animals choose their food on the basis of its nutritional value, rather than just overall calorie content.

An international team of scientists from the Universities of Exeter and Oxford in the UK, University of Sydney (Australia), Aarhus University (Denmark) and Massey University (New Zealand) based their research on the ground beetle, Anchomenus dorsalis, a well-known garden insect that feasts on slugs, aphids, moths, beetle larvae and ants.

The team collected female beetles from the wild and split them into two groups in the laboratory. Half of the beetles were offered a choice of foods, some that were high in protein and some that were high in fat. The other half were not given a choice of what to eat: some were only given food that was higher in protein and others just had higher-fat foods, none of which provided the right nutritional balance. The beetles that were provided with a range of foods selected the balance of protein and fat that was optimal for producing healthy eggs. These beetles produced more eggs than the beetles that did not have the right nutritional balance.

Continued at: http://www.sciencedaily.com/releases/2012/01/120110192942.htm

Before Sounding an Alarm, Chimps Consider Information Available to Their Audience

ScienceDaily (Dec. 29, 2011) — Wild chimpanzees monitor the information available to other chimpanzees and inform their ignorant group members of danger.

Many animals produce alarm calls to predators, and do this more often when kin or mates are present than other audience members. So far, however, there has been no evidence that they take the other group members' knowledge state into account. Researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and the University of St. Andrews, Great Britain, set up a study with wild chimpanzees in Uganda and found that chimpanzees were more likely to alarm call to a snake in the presence of unaware than in the presence of aware group members, suggesting that they recognize knowledge and ignorance in others. Furthermore, to share new information with others by means of communication represents a crucial stage in the evolution of language. This study thus suggests that this stage was already present when our common ancestor split off from chimps 6 million years ago.


Read more at: http://www.sciencedaily.com/releases/2011/12/111229131234.htm

Predators Drive the Evolution of Poison Dart Frogs' Skin Patterns

ScienceDaily (Nov. 21, 2011) — Natural selection has played a role in the development of the many skins patterns of the tiny Ranitomeya imitator poison dart frog, according to a study that will be published in an upcoming edition of American Naturalist by University of Montreal biologist Mathieu Chouteau.

The researcher's methodology was rather unusual: on three occasions over three days, at two different sites, Chouteau investigated the number of attacks that had been made on fake frogs, by counting how many times that had been pecked. Those that were attacked the least looked like local frogs, while those that came from another area had obviously been targeted.

The brightly coloured frogs that we find in tropical forests are in fact sending a clear message to predators: "don't come near me, I'm poisonous!" But why would a single species need multiple patterns when one would do? It appears that when predators do not recognize a poisonous frog as being a member of the local group, it attacks in the hope that it has chanced upon edible prey. "When predators see that their targets are of a different species, they attack. Over the long term, that explains how patterns and colours become uniform in an area," said Bernard Angers, who directed Chouteau's doctoral research.


Read more here ...

Safari Visitors Enjoy A Really Wild Night

10:23am UK, Monday December 28, 2009

David Bowden, in South Africa

The days of the traditional African safari may be numbered after one operator turned to battlefield technology to spice up the game-viewing experience.

Bosses at one of South Africa's most famous Game Lodges, Londolozi, have brought in night vision goggles - more often used to hunt the Taliban in Afghanistan - to stay on the trail of wildlife once the sun sets.

The equipment means that, as other guests head back to their lodges for their evening meal, the night vision crew can stay out as the bush comes to life in the dark.

"The whole idea was to try and get closer in with nature," Londolozi owner Dave Varty said.

"With the night glasses you could see what the lions see because their nocturnal vision is so good."

Using a normal spotlight to view the animals in the dark upsets them and stops them acting naturally.

But with the night vision, they return to bush business as usual with no idea they are being watched.

It means that a hippopotamus which spent the heat of the day cooling off underwater ventures out to graze in the open unknowingly spied on by the nightvision crew.

Buffalo which would steer clear of humans in the full glare of daylight brush close-by the darkened vehicle snorting and blowing.

And lions which have spent the day lazing around digesting last night's victim begin to stir and roar as they ponder tonight's killing spree.

"Predators will get active very late in the evening," head ranger Chris Goodman explained.

"And with the night vision you can follow them and view them as they hunt and mark their territory."

It is not quite Dr Doolittle, but there is no doubt being in the bush when it comes alive at night, and being able to see and hear what is happening, does bring a whole new dimension to game viewing.

http://news.sky.com/skynews/Home/World-News/Safari-Night-Vision-Goggles-Used-In-Londolozi-Game-Lodge-In-South-Africa/Article/200912415509016?f=rss