Two howler monkeys doing what they do best. (0607278)

BIOLOGICAL diversity in Costa Rica is breathtaking.

Tottering on a tightrope of rain forest vegetation which points at the United States from South America, exotic and colourful creatures are concentrated in a narrow strip of land between the Pacific Ocean and Caribbean.

Some of the wildlife is famous too: poison-arrow frogs are tiny, brightly coloured creatures which hop around in leaf litter.

They do not bother to hide. Their bright colours are a warning to would-be diners that this is a course to be avoided.

The most famous is the ‘Levi’s’ or blue-jeans poison-arrow frog. This has a bright-red body which seems to have been pushed into a pair of denim jeans.

The poison in these frogs’ skin is so lethal that if injected into the bloodstream of a monkey, the creature will be rendered unconscious within a minute. If that does not kill the unfortunate monkey, its fall from the canopy to the ground most certainly does.

Native Mayan-Indian tribesmen use the poison in just this way, daubing it onto the tips of their blow-pipe arrows, which are then fired at whatever bird or mammal they happen to find.

Howler monkeys are easy to trace as their calls echo through Costa Rica’s jungles. Occasionally a female monkey will be killed, leaving its baby to be captured as a pet.

One such animal was gamboling around the trees at La Ensenada, a delightful lowland ranch with stunning views out to sea.

The young howler had become self-sufficient and was quite able to feed itself from the ample fruit trees around the ranch buildings, much to the disgust of our driver who would have liked to eat the poor monkey with pawpaw for dessert.

Using poison to kill one’s food presents a problem. Why don’t the Indians fall victim to the poison? It seems that the cunning plan relies on their digestive system neutralising it before it is absorbed into the bloodstream.

I have swapped the job of journalist for wildlife tour-leader and spend much of my time taking people to see birds and mammals all over the world.

The company which employs me dropped me from Costa Rica several years ago and it was only a month or two ago that the roster came around to me again.

The country has continued to improve its infrastructure, thanks to huge amounts of US investment. Many Americans are buying land out there and building homes in jungle clearings.

They are doing it partly to enjoy the abundant wildlife which will come to their new homes.

It is not unknown for resplendent quetzals (Costa Rica’s national bird) to appear on people’s garden-bird lists. Hummingbirds are easily attracted by hanging special feeders containing sugar solutions which the birds drink.

Nature reserves hold a vast number of birds and seeing more than 100 different species in a morning is possible.

On my trips it is a little unlikely, however. I enjoy watching the activities of some of these species and am quite happy to take things easily and get to know these new birds better.

Poison-arrow frogs – they’re conspicuous… (0607277)

Montezuma oropendolas are a great example. They are not uncommon, although not seen daily.

Colonial breeders, they build huge flask-shaped nests in colonies – each swinging from the same tree.

Their name is Spanish, oro meaning gold and pendola indicating the swinging feature of their lives.

I have anglicised the word and call them ‘gold-swingers’. The males swivel around the branch while holding their nest, flashing golden-yellow tail feathers and making a strangled gurgling sound to attract a mate.

Our Costa Rica tour includes a night spent on the slopes of Mt Arenal, one of the world’s most active volcanoes.

Thick mist had enveloped the mountain previous time I was there and all we could detect were rumbles as landslides rolled down the mountain. We were lucky this year, however, as the night was clear and all our rooms overlooked the volcano.

We gathered on the observation deck of our hotel watching a beautiful sunset on one side and red-hot lava rocks rolling down the mountain like spinning Catherine wheels on the other.

The rocks are thrown out of a vent high in cloud but then roll down the slope at a fantastic speed. Huge boulders the size of cars hurtle down, smashing up and turning into a myriad smaller red-hot rocks. Some members of our group went very short of sleep as they sat up watching the free fireworks show.

Story has it that his ship, Monarch, was making heavy weather coming down from San Francisco empty.

It called into Puntarenas in Costa Rica, where he was offered 5,000 sacks of coffee beans as ballast. If he could sell them in Europe, that would be great… please return with the takings, he was told.

Le Lacheur did just that and opened European markets for the delicious coffee, putting the Guernseyman high up among Costa Rica’s heroes.