New research shows that disturbed habitats are resulting in increasingly poor diets for monkeys, and that the additional time and energy required to find food is causing concerning levels of stress in already critically endangered primates.

January 2013. Endangered Mexican howler monkeys are consuming more leaves and less fruit as a result of habitat disturbance by humans which is forcing them to invest much more time foraging for sustenance and leading to increased ‘stress’ levels, as detected through hormone analysis.

The research took place in the tropical rainforests of the Mexican state of Veracruz, which are being deforested and fragmented by human activity – primarily the clearing of forest for cattle raising. It shows that increases in howler monkey ‘travel time’ – the amount of time needed to find requisite nourishment – are leading to increases in levels of stress hormones called glucocorticoids. These hormones are not only indicators of stress, but are also known to relate to diminished reproductive success and lower survival rates.

Researchers believe the study could serve as a model for behavioural change and resulting health implications more generally in primates living in habitats disturbed by human activities, such as deforestation.

Dr Jacob Dunn from Cambridge’s Department of Biological Anthropology, who carried out the research, said “Howlers are arboreal primates, that is to say they spend their wholes lives in the trees. As forests are fragmented, the howlers become cut off, isolated on forest ‘islands’ that increasingly lack the fruit which provide an important component of their natural diet. This has led to the monkeys expending ever more time and effort foraging for food, often increasing leaf consumption when their search is, quite literally, fruitless.”

Fruit cycle

Fruit occurs in natural cycles, and the monkeys will naturally revert to ‘fallback’ foods, including leaves, when fruit is scarce. But as habitats shrink, and fruit is harder to find, leaves from second-choice plants, such as lianas, have increased in the Mexican howlers’ diet.

While leaves may sound like a plentiful resource in a rainforest, many leaves are difficult to digest and can be filled with toxins – a natural defence mechanism in most trees and plants – so the monkeys are actually forced to spend more time seeking out the right foliage to eat, such as new shoots which are generally less toxic.

Fruit is vital to monkey diet

Dunn added “The traditional view was that the leaves exploited by howler monkeys were an abundant food source – but this is not the case. The monkeys rely much more heavily on fruit than previously believed, and when turning to foliage for food – as they are increasingly forced to do – they have to be highly selective in the leaves they consume, visiting lots of different trees. This leads to the increased ‘travel time’ and consequent high levels of stress we are seeing in these primates as their habitats disintegrate.”

Faeces analysed

As trying to catch the howlers to examine them would in itself be highly stressful for the animal, the best way of evaluating stress levels in wild primates is by analysing their faeces for glucocorticoid stress hormones, which are general to all vertebrates. Through statistical modelling, the researchers were able to determine that it is the ‘travel time’ – rather than the increased foliage intake – causing high levels of stress.

“Monkeys in disturbed habitats suffering high levels of stress is in itself unsurprising perhaps, but now we think we know why, the root cause from the primates perspective. Our results also highlight the importance of preserving and planting fruit trees – particularly those species such as figs that can produce fruit during periods of general fruit scarcity – for the conservation of howler monkeys¨ said Dr Jurgi Cristóbal-Azkarate, also from Cambridge, who led the research in collaboration with Dr Joaquim Vea from the University of Barcelona.

The authors say that further studies are required to fully understand the significance of increases in stress in howler monkeys living in disturbed habitats. “Determining the full relevance of our results for the conservation of primates living in forest fragments will require long-term studies of stress hormones and survival”, said Dunn.

The report by Butterfly Conservation and Rothamsted Research revealed that two-thirds of common and widespread larger species (macro-moths) declined in the last 40 years. The losses in abundance were much greater in the southern half of Britain than the north.

Once common moths on the edge

Some once common garden species such as the V-moth, Garden Tiger and the Spinach have decreased by more than 90% from 1968-2007 and now face the real threat of extinction in the future. On-going habitat loss and the deteriorating condition of the countryside are believed to be the major factors behind these declines.

The report is based on continuous records running from 1968 to 2007 on common and widespread species. These records represent the longest running national population trends of insect species known anywhere in the world.

Some two-thirds of the species recorded declined over the 40-year study, 37% of species decreased by at least 50%.

40% decline in all moths in southern Britain

In the southern half of Britain, larger moth populations decreased by an average of 43% in comparison to an average 11% decline in northern Britain. Total abundance of moths decreased by 40% in southern Britain but showed no overall change in the north, where declines of some moth species were balanced out by other moths faring well.

The reason for the disparity between the two regions is likely to be due to higher levels of habitat loss in the south and the beneficial effect of climate warming on some moths in the north.

Key indicator species

Moths are key indicator species for assessing the health of the environment. These findings point strongly to a wider insect biodiversity crisis and mirror declines of butterflies and bees and carabid beetles. The declines could have a knock-on effect for plant pollination and animals reliant on moths for food, such as garden and woodland birds, bats and small mammals.

New moth species influx – 100 new species recorded

While moth populations have declined substantially in the last few decades, the period has also seen an unprecedented influx of new moth species to Britain.

More than 100 species have been recorded for the first time in Britain this century and 27 species have colonised Britain from the year 2000 onwards. Climate change is seen as a major driver for these new colonisers as conditions become more suitable for continental species.

Butterfly Conservation Surveys Manager and lead author of the new report, Richard Fox said: “This report paints a bleak picture about Britain’s biodiversity. Much has been made of the decline of butterflies and honey bees but moths represent the massive, but largely un-noticed diversity of insects that form the vast majority of animal life in Britain.

“The severe declines of once common garden moths and overall decrease in moth abundance that we found are a damning indictment of how recent human activity has devastated our native wildlife.”

Chris Packham, Butterfly Conservation Vice-president said: “Larger moths are key indicator species that let us know how our environment is faring in a period of unprecedented environmental change.

Vital cog in food chain

“As well as being important pollinators, moths are an absolutely vital cog in the food chain for other species such as birds and bats. The dramatic and ongoing loss of moth abundance highlighted in this report signals a potentially catastrophic loss of biodiversity in the British countryside.”

David Brooks, an ecologist at Rothamsted Research who analysed the data, said: “This study highlights the value of long-term investment in monitoring of species populations, for discovering fundamental changes taking place in the ecology of the British landscape. The study would also not have been possible without the help of numerous volunteers and amateur naturalists, who increasingly make invaluable contributions to ecological research.”

This week’s gift of “democracy” to Afghanistan – where US soldiers are being killed with relentless regularity by their Afghan “colleagues” who, of course, they have “trained” – has brought such poverty and desperation that the BBC, usually loyal to a fault to any colonial invasion, is reporting that some families resort to selling one child, in order to gain enough money to feed the others.

“Violence was endemic to the [British] state practices and part of the state practices.”

As the 10th anniversary of the Iraq invasion approaches it is surely time for the invading countries to attempt to amend for the enormity of the illegality of the invasion and for individual sufferings.

In the great food markets of Paris in the build-up to Christmas, Perigord black truffles were selling for €3,000 per kilo – they must be one of the most expensive luxury foodstuff in the world.

Truffles are normally only served on the menus of the best and most expensive restaurants in Paris, Rome or London’s West End.

No wonder for hundreds of years the country folk of the Perigord region of France have hunted these amazingly delicious and valuable delicacies.

Italians too have appreciated the amazing fungus that grows in the forests of Tuscany and other regions of Italy.

Did you know it is perfectly possible to find truffles here in Britain. They are our best and most delicious free food.

And remember, as Communist MP Willie Gallacher used to say: “Nothing is too good for the workers.”

If you are very lucky you can find your own truffles in wild hardwood forests and mature woodland all over Britain.

They are surprisingly common but that doesn’t mean they are easy to find.

Increasingly British private landowners are planting dedicated truffle groves as a lucrative cash crop although getting the valuable fungus established is sometimes a bit hit and miss.

Prince Charles has planted large numbers of them and if his other Duchy Original product prices are anything to go by his will be the most expensive of all.

So how do you find these little subterranean treasures?

Traditionally, the French and Italians have used trained pigs to snuffle the truffle but more and more today dogs are replacing pigs as the preferred hunting animal.

The reason is that pigs eat most of the truffles they find. Guzzling them down before the human hunter can get his hands on them.

However it is possible to hunt down you own truffles even without either a pig or a trained dog and you can do it for nothing.

You will certainly need a lot of patience. The prized epicurean delight grows underground on the roots of ancient hardwood trees.

Oaks are probably best. Look for the telltale column of tiny gnats hovering above a slight swelling in the moss and leaf litter of the forest floor.

Just below the surface, if you are very lucky indeed, you might find the treasure you seek. It will be between the size of an acorn and a plum and black and wrinkled.

The wonderful smell will make it easy to identify – much easier than almost any other fungus.

Even a tiny one, grated, will make the best omelette you ever tasted, or stored in a small jar of virgin olive oil will give you an ingredient that will delight your taste buds every time you cook with it.

For me the best way to enjoy the delicate, fragrant fungi is in tiny slivers served in a smooth duck or goose paté.

The French philosopher Jean-Louis Vaudoyer tells us: “There are two types of people who eat truffles – those who think truffles are good because they are expensive and those who know they are expensive because they are so good.”

Only in France would a philosopher pontificate on a smelly black wrinkled fungus – even one as good as the pride of Perigord.

Keep your eyes open next time you go for a walk in the woods. Finding a truffle or two could make it a real treasure hunt.