Turning a zoo into a habitat

Dublin Zoo is bursting with new and varied life, and much of it is outside the animal enclosures, especially if you have the right person to point it out to you.

There can be few better or more entertaining guides than Stephen Butler, the zoo's curator of horticulture and a key figure in the remarkable transformation of its landscape in recent years, under the directorship of Leo Oosterweghel.

We have barely left the Meercat Cafe when Butler pauses to show me an evergreen shrub with crinkled, waxy leaves. Aristolochia sempervirens , sometimes called Dutchman's pipe, has a persuasive way with insect visitors. Stiff hairs coat the interior of its flower tubes. They are cunningly angled, and force tiny flies to move down and gather pollen from its male sexual organs. Only then do the hairs relax, allowing the insect to leave. It is then tempted to enter another flower, where the hairs again coerce it down the tube, and it transfers the pollen to the plant's female parts.

So there you have it: sex and violence in nature, right under your nose, before you reach a single enclosure. David Attenborough could not ask for more.

This is a Mediterranean plant, but it has found native Irish fly species to assist in its propagation. Right beside it is a plant from the Canaries, and it is now closely associated with a native bird. The tight spaces between the leaves of Echium pininana (giant viper's bugloss) provide a surprising nesting site for wrens, which seem to be singing from every second bush in the May sun.

The abundance of songbirds is indeed remarkable. The zoo holds more nesting bird species than its much larger neighbour, the Phoenix Park. The reason is simple. The park is heavily browsed by deer, which remove most of the shrub-layer habitat, leaving only grassland and trees. The zoo, in contrast, is now quite densely planted.

Indeed, Butler wryly recounts how one irate customer complained they felt they had been “visiting a botanical garden, and could only find the animals with difficulty”.

Most visitors, however, undoubtedly appreciate the diversity of flowers and foliage that has transformed the very bare look the zoo had for most of the last century. Few of us, however, probably appreciate the care and thought that go into deciding which plants are deployed where.

Fast evolution
Butler points out that the zoo has evolved quite quickly from keeping animals in steel cages to holding them in enclosures and, finally, to creating entire habitats, such as the African Savanna, for giraffes, rhinos and ostriches, and the Kaziranga Forest Trail, for Indian elephants.

He is quick to add that there is no attempt to precisely replicate the plant communities in which these animals would live in the wild. Many of these plants would not survive our climate. “My aim,” he says, “is to create an impression of what the animals’ actual habitat looks like. I think of my job as similar to a set designer’s in a theatre.”

You think that lovely little waterfall on the Kaziranga trail, leading to the elephant enclosure, is flowing over real soil and rocks? I certainly always did. But no: Butler points out that it’s all concrete, sprayed on to a frame covered in hessian. Weathering has camouflaged it. So have an abundance of native and exotic plants, which flourish in the damp niches the “rocks” provide. The trail itself is densely shaded, mainly by about 25 types of bamboo. Why so many species? This is an insurance against a peculiarity of bamboo: the parent plants die out collectively after the rare occasions when they flower.

Many of these species would not be found in Indian forests, but they are certainly effective in creating a sense of thick cover, through which the elephants can sometimes be glimpsed only occasionally, if at all. This is more challenging – and exciting – for the visitors, more like how we would see these animals in the wild. There is also less of the pressure of constant scrutiny for the great beasts themselves.

The planting on the African Savanna seeks the opposite visual effect to that of the forest trail: open spaces, big distances. The grasses may come from New Zealand, the acacias and the exquisite grevilleas from Australia, but their shapes, colours and arrangements seek to mimic their African counterparts. “If we limited ourselves to the African plants that could thrive here, our palette would have a very limited range,” says Butler.

Not everything goes according to plan, and it is sometimes native species that send Butler’s best-laid plans awry. Ducks and coots in search of insects have uprooted most of a big aquatic planting in the gorilla enclosure.

More obvious interventions are made daily by the colony of herons that now nests just outside the zoo. Extra fish are needed for the penguins, as the local birds flock in noisily for free food – they’ll grab your burger, too, if you let them.

Incidentally, however, these magnificent birds currently offer visitors bonus views of their spectacular breeding plumage, at ranges closer than one would ever see them outside the zoo boundaries.

The dynamic interplay between exotic and native species at the zoo seems to be mainly healthy, but Butler is very mindful of his obligation to prevent aggressively invasive species such as Gunnera tinctoria (giant rhubarb) from escaping into the wild.

So its seed heads are removed each year before they can spread. Similar careful watches are kept on all the usual – and unusual – suspects to be found in the zoo.

It should never be forgotten that it was from the National Botanic Gardens, now so committed to native plant conservation, that the noxious giant hogweed first leaped into the Tolka many years ago, with disastrous consequences for native species. It’s good to be able to see exotic species in our capital city, but we don’t want to find any more of them overrunning our countryside.

Dublin Zoo is holding a native species weekend on May 25th and 26th