Burrowing US prairie dogs use complex language

A tiny rodent may have the most sophisticated language of any animal.

This bold claim comes from US-based academic Professor Con Slobodchikoff who has long studied the vocal repertoire of Gunnison's prairie dog.

With a single bark, he says, a prairie dog may warn about the type and direction of an encroaching predator, and even describe its colour.

If confirmed, that means the chattering rodents communicate in a more complex way than even monkeys or dolphins.

Prof Slobodchikoff details the experiments he has done to reveal the hidden structure of the prairie dog's language within the BBC natural history programme "Prairie dogs, talk of the town," broadcast as part of the Natural World documentary series.

Prairie dogs belong to the squirrel family, and live in the prairies and semi-desert grassland of northern Arizona, northern New Mexico and southwest Colorado.

Once existing in their billions, prairie dog numbers have now plummeted as ranchers view them as vermin competing for resources with livestock.

But those remaining still live in huge colonies of hundreds of animals, digging complex underground burrow systems.

Whenever a predator approaches, the small rodents let out a series of barks, squeals and squeaks.

For 30 years, Prof Slobodchikoff and colleagues have been recording these calls.

To analyse them, the scientists set up a series of experiments, dragging models of different predators in front of wary prairie dogs, recording if they respond differently to coyotes, hawks and badgers.

Predatory playback

The researchers found that the prairie dogs are confronted by so many predators that they have evolved different "words" to describe them all.

These words are barks and sounds that contain different numbers of rhythmic chirps and frequency modulations.

Individual prairie dogs have different tonal qualities, just as human voices differ, but different rodents use the same words to describe the same predators, allowing the alarm call to be understood by the rest of the colony.

For example, a single bark may be attuned to say "tall, skinny coyote in distance, moving rapidly towards colony".

Other scientists have challenged this idea, because it would mean that in one short bark, prairie dogs relay information about the size, colour, direction and speed of travel of an encroaching predator.

Prof Slobodchikoff's team believes the prairie dogs include this information by varying the modulation of the call and the harmonics in the bark.

By doing so, they can pack in a vast amount of information into a very short sound.

Prairie dogs are not dogs at all but ground dwelling squirrels, whose name is derived from their dog-like barking calls Compared to other prairie dogs Gunnison's have shorter tails and, although you can't see it, they only have 40 chromosomes - all the others have 50 The rodents is the largest of the mammalian orders, with over 2,000 species in it.

"Prairie dogs have the most complex natural language that has been decoded so far. They have words for different predators, they have descriptive words for describing the individual features of different predators, so it's a pretty complex language that has a lot of elements," says Prof Slobodchikoff.

In the documentary, the scientists record for the first time the prairie dogs' call to warn about badgers.

It is subtly but consistently different to all the other calls.

When the alarm call is played back to a colony of rodents they react differently to when they are played a call warning of coyotes.

Coyotes hunt by surprise so the rodents respond by instantly bolting. Badgers try to dig into burrows, and when the prairie dogs are warned of a badger they become instantly vigilant instead.

Prof Slobodchikoff believes the prairie dogs may have evolved such complex language because they live in a complex, social society housed in a highly engineered and complex burrow system.

Not only do they live in highly organised "towns" of hundreds of individuals, but they also have to compete with squatters, such as cottontail rabbits, rattlesnakes, tarantulas, burrowing owls, badgers and swift foxes, that often move into their burrows.

Climate change causes wolverine decline across Canada

The wolverine, a predator renowned for its strength and tenacious character, may be slowly melting away along with the snowpack upon which it lives.

Research shows wolverine numbers are falling across North America. Their decline has been linked to less snow settling as a result of climate change.

The study is the first to show a decline in the abundance of any land species due to vanishing snowpack.

Details of the wolverine's decline are published in Population Ecology.

The wolverine lives in boreal forest across Scandinavia, northern Russia, northern China, Mongolia and North America, where it ranges mostly across six provinces of western Canada.

This largest member of the weasel family eats carrion and food it hunts itself, including hares, marmots, smaller rodents and young or weakened ungulates.

It has evolved for life on the snowpack, having thick fur and outsized feet that help it move across and hunt on snow.

Striking trend

Wildlife biologist Dr Jedediah Brodie of the University of Montana, in Missoula, US, wondered how climate change might be having an impact on snowpack levels, and on the animals that depend on it.

He had previously researched how declining levels of snow in the US Yellowstone National Park, caused by climate change, was changing the abundance of alpen trees and how elk feed on them.

Dr Brodie and his colleague, Professor Eric Post of Pennsylvania State University, at University Park, US, gathered data on snowpack levels across six provinces of Canada: Alberta, British Columbia, Manitoba, the Northwest Territories, Saskatchewan and the Yukon Territory.

In all bar the Yukon, he found that snowpack depth declined significantly between 1968 and 2004.

Other studies have shown corresponding rising temperatures and declining precipitation across much of the western US.

Wolverines are the largest terrestrial members of the weasel family, weighing about 10-25kg As adaptations to living on snow, they have short legs, outsized feet, stocky bodies and thick, extremely warm fur Reindeer herds around the world are also in decline as a result of industrial development and climate change, but as yet, these declines have not specifically been linked to declines in snow cover

"It occurred to me that a good first place to look for ecological impacts of that snowpack decline would be with a snow-adapted species like the wolverine," Dr Brodie told the BBC.

"Fortuitously, Canada has good records of both snowpack trends over time as well as trends in the harvest of all sorts of fur-bearing animals."

So Dr Brodie and Professor Post examined the records of wolverine numbers caught by fur trappers over the same period.

They found a striking correlation between declining snowpack and falling numbers of the predator.

"In provinces where winter snowpack levels are declining fastest, wolverine populations tend to be declining most rapidly," the researchers wrote in the journal article.

"Spring snowpack also appears to influence wolverine population dynamics."

The researchers found only one province, the Northwest Territories, where wolverine numbers are increasing. There, snowpack levels are declining but they remain much higher and less variable than in most other provinces.

Food scarcity

Dr Brodie cannot be sure why wolverine numbers are falling, but he has his suspicions.

"Recent work shows that wolverines appear to use areas with deep snowpack for dispersal. So reduced snowpack could make dispersal more difficult or dangerous, potentially reducing the success rate with which individuals can establish new home ranges," he says.

"Reduced snowpack may also make it harder for wolverines to get food, for several reasons.

"First, harsh winters and deep snow are major causes of mortality for ungulates like elk, moose, deer and caribou.

"If milder winters mean that fewer of these animals die over the course of the winter, then there will be fewer carcasses for wolverines to feed on," he explains.

"Wolverines also hunt rodents, and this food source may be important for wolverine reproductive success in some areas.

"But shallower snowpack is bad for a lot of rodents because it provides less insulation from the cold.

"So if declining snowpack reduces rodent abundance, that could be bad for wolverines."

Dr Brodie believes that his is the first study to show a decline in species abundance due to a reducing snowpack - for any land animal, not just those in North America.

But he says there are interesting parallels in marine systems.

"For example, sea ice is critical for polar bear foraging."

Polar bear body condition, reproductive rates, and survival have declined significantly in Hudson Bay as sea ice breaks up earlier in the spring, he says.

"At the other end of the globe, Antarctic sea ice has increased over recent decades.

"This may have negative impacts on adelie penguin populations that depend on ice-free areas for breeding and foraging.

"But we don't have to just sit back and watch climate change drive animals extinct," he says.

"As climate change worsens, we should reduce trapping levels and also disturbance to boreal forest habitats.

"Reducing the impact of these anthropogenic stressors could help 'offset' the impacts of climate change on wolverines."

Pregnancy baby brain lapse 'a myth'

Expectant mums need to stop blaming their bump for memory lapses, say experts who want to dispel the "baby brain" myth.

Neither pregnancy nor motherhood addle a woman's brain, say the researchers based on their study of 1,241 women both before and after having babies.

The Australian researchers say we have been misled by a fallacy.

Any absentmindedness might be adaptive, shifting attention to the baby, the British Journal of Psychiatry says.

Lead researcher Professor Christensen said: "Part of the problem is that pregnancy manuals tell women they are likely to experience memory and concentration problems - so women and their partners are primed to attribute any memory lapse to the 'hard to miss' physical sign of pregnancy.

"Pregnant women may also shift their focus away from work issues to help them prepare for the birth of their new baby, while new mothers selectively attend to their baby."

But she said this shift should not be labelled a "cognitive deficit".

Fallacy

Her team from The Australian National University followed up the large group of women at four-year intervals using memory tests.

During the course of the study more than half of the women fell pregnant, but this did not appear to have any impact on memory.

The test scores remained unchanged before and after pregnancy and did not differ greatly between the group of women who became mums and the group of those who did not.

Professor Christensen and her team said: "Not so long ago, pregnancy was 'confinement' and motherhood meant the end of career aspirations.

"Our results challenge the view that mothers are anything other than the intellectual peers of their contemporaries.

"Women and their partners need to be less automatic in their willingness to attribute common memory lapses to a growing or new baby.

"And obstetricians, family doctors and midwives may need to use the findings from this study to promote the fact that 'placenta brain' is not inevitable."

Cathy Warwick of the Royal College of Midwives said: "It is about time that some research lays to rest this notion of pregnant women and the 'baby brain' myth.

"The physical and emotional stresses on a woman's body from pregnancy can make women feel more tired than usual.

"As we all know tiredness - for men as well as women - can make us lose concentration and cause us to function less effectively.

"This is why midwives encourage pregnant women to take appropriate rest breaks, at home and at work. Many pregnant women will need this rest, and all of them deserve it."

Nokia navigation software downloads reach one million

One million people downloaded Nokia's free navigation software during the first week of its launch, the company claims.

Ovi Maps have been downloaded 1.4m times overall since the application became available on January 21 2010.

It has been most popular in China, Italy, the UK, Germany and Spain

The service provides different direction information for drivers and pedestrians in 74 countries and 46 different languages.

"We're averaging a download a second, 24 hours a day," said Anssi Vanjoki, Nokia's executive vice president.

He added that the demand for location-based software was growing more quickly than the company had anticipated.

Research by Strategy Analytics suggests that Nokia has 39% of the global smartphone market.

Both Nokia and Google now offer free-to-download navigation services, which is putting pressure on the sat-nav industry.

Dutch satellite company Nav4All announced that it is shutting down after its contract with Nokia subsidiary Navteq, a digital mapping company, was not renewed.