City in a garden, not city in a forest

A feature on the bird ecology study group’s call for contributions to a plant-bird database appeared in the Straits Times on 6 Oct by David Ee (“Matching birds and trees“).

Some responses in the ST Forum today (online and in print, respectively):

What works in the forest may not work in a garden

WHILE it is laudable that the Bird Ecology Study Group will compile an archive listing more than 200 species of flora and detailing birds that frequent them (“Matching trees and birds”; Oct 6), planners such as the National Parks Board should exercise prudence and care when using such resources to decide what and what not to plant in our parks and gardens, in their effort to attract fauna.

The finding that the common mahang, a tree found in our forests here, draws more than 20 bird species to its fruit does not recognise the fact that a tree growing in a forest, when grown in our gardens and parks, might not attract an equal number of bird species.

Birds that are forest-dependent will not visit the same mahang tree grown in a garden or park that is outside the forest.

If the fruits of the mahang tree draw the liking, too, of the noisy Asian glossy starlings or mynahs, we might even inadvertently propagate more roosting sites for these community roosting birds – a scenario we do not want.

The common mahang tree is also well known for attracting ants to its leaf stalks.

The presence of ants and the consequences when one unwittingly touches them, or if they drop on someone standing below the tree, also need to be taken into consideration.

The safety of the public is of paramount concern.

While we would certainly like to see a “City in a Garden” full of life and biodiversity, we must also be cognisant of the fact that what works in one place might not work in another.

No one size fits all.

Even lizards and butterflies have their own niches and will not readily adapt to a habitat unfamiliar and foreign to them.

Certainly, a lot more experimenting and study of what we want to plant has to be done first before we embark on planting any one species of flora.

Chia Yong Soong

Plant the right trees or risk attracting the wrong birds

THE Bird Ecology Study Group should be commended for compiling an archive that will list more than 200 species of flora and detail the birds frequenting them (“Matching trees and birds”; Oct 6).

But planting a common mahang tree outside the forest environment will not attract the same species and number of birds. This is because forest-specific birds like the cream-vented bulbuls, red-eyed bulbuls and red-crowned barbets will not move out of the forest habitats to urban parkland to forage.

Planting food trees outside the reserves may instead attract the more adaptable Asian glossy starlings and mynas, whose populations the Agri-Food and Veterinary Authority is trying to control.

Botanists know that many of the wild scrubs and trees do not grow well or even survive outside the forest without the support of the ecosystem. Such trees are not used in our parks and open spaces. On the other hand, fig trees, with their root systems, are destructive to buildings, homes and roads.

The best way to protect biodiversity is to conserve their habitats, which cannot be replicated. You cannot “grow” back a primary forest.

Hospitals, community development councils, schools and corporations have been drawing from the database of the National Parks Board and the Nature Society (Singapore) for many years now to create butterfly- and bird-friendly trails, gardens and open spaces. Let us hope the Bird Ecology Study Group’s archive can supplement the existing databases for the greater good.

Alan Owyong

My comments:

Another thing about the mahang is that many of them are pioneers, which are fast-growing because they are adapted to tree fall gaps and forest edges, where they need to race to reach the canopy before it closes from the growth of branches in the periphery, or before other fast-growing species shade them out. The trade-off in fast growth is the poor quality of the wood in the trunk. Fast-growing plants therefore are usually shorter-lived and more likely to snap under strong weather conditions. This may make them unsuitable for planting in parks and especially along streetscapes. The common mahang cited, Macaranga bancana, is certainly one of the faster-growing pioneers.

Perhaps better to consider are the so-called climax-type mahang, such as Macaranga conifera. These are slower-growing and are known to persist longer in the forest.

Aside from fruits that attract birds, mahang leaves are also food for caterpillars of some forest butterflies.

Anyway, I think there are many more food plants out there that can attact birds and butterflies. The question is not just what plants to choose to plant, but also how and where we plant them. The messiness of natural vegetation remains essential. As yet, our cultivated plants are not a perfect substitute for natural vegetation as an ecological resource for animals.

Do we want to create a City in a Garden, or a City in a Forest? I prefer the latter.

Update: comprehensive response on 20 Oct 2012 in the ST Forum.

I THANK Mr Chia Yong Soong (“What works in the forest may not work in a garden”; Tuesday) for his interest in the Bird Ecology Study Group’s list of plants and the birds they attract (“Matching trees and birds”; Oct 6).

I would like to reiterate that it is a list compiled from seven years of contributions by birdwatchers interested in bird behaviour. As in any list, it is just a guide that planners need to use with prudence and care. Having said that, let me go into specifics.

The common mahang is a tree of disturbed forests and forest edge, not of the rainforest proper. As such, the birds it attracts need not necessarily be exclusively forest species.

In any case, our extensive park connectors can grow this tree, thus allowing for easy movement of woodland birds into parks that grow the tree.

The tree will also attract urban birds like the yellow-vented bulbul, scarlet-backed flowerpecker and brown-throated sunbird that feed on the nectar and fruits. So there is always the possibility that it will attract more than the 20 species of birds that we document.

Another concern of the writer is the possibility of the tree being used as a roosting site for starlings and mynahs. Birds roost in trees with dense canopies that are grown near food centres and in areas surrounded by tall buildings. Trees in such locations provide some shelter from the weather as well as from predators. So, it is not the species of the tree but where it is grown that attracts roosting birds.

For example, the angsana, a favourite roosting tree along Orchard Road, when grown away from tall buildings, is mostly devoid of roosting birds.

As to the ants scare, the common mahang harbours tiny, harmless ants that live within the hollows of young shoots. These ants mostly emerge when we roughly handle these shoots, and even then they do not swarm over our hands nor drop on to people standing below the tree.

The statement that lizards and butterflies have their own niches and are not readily adapted to an unfamiliar habitat is a fallacy. In the case of native species, given the food source, they will definitely be around. In the case of exotic species, many that arrived became more successful than the local species. An excellent example here is the changeable lizard that is native to countries as far south as the northern states of Peninsular Malaysia.

It was introduced into this country and is currently found all over our urban parks and gardens.

And many of our roadside plants have been introduced from faraway countries and have since adapted to our local conditions and are attracting their complement of local bird and other faunal species.

Singaporeans have, through the years, come to appreciate nature. However, many have yet to have an emotional connect with nature in our Garden City.

There are still people who demand that a tree be cut if its branches grow near their windows for fear of insects moving into their homes.

And I have even met many children who panic when a butterfly flutters near them.

We need to work towards exposing our children, not to mention adults, to the wonders of the biodiversity in our Garden City, otherwise they may not appreciate it when we fully become a City in a Garden.

Wee Yeow Chin (Dr)
Bird Ecology Study Group

Update 2 on 11 November 2012:

I learnt that there was a separate rebuttal to Alan Owyong’s letter, which was not published by ST but is on the BESG blog.

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2 Comments

  1. YC Wee said,

    21 October 2012 at 10:58

    Please refer to http://www.besgroup.org/2012/10/20/matching-trees-and-birds-a-naturalists-response/#comment-52580 for BESG’s response to the the first letter.

  2. YC Wee said,

    9 November 2012 at 00:01

    You may wish to enter BESG’s reply to the second letter by Alan Owyong at this link: http://www.besgroup.org/2012/10/27/%E2%80%9Cmatching-trees-and-birds%E2%80%9D-%E2%80%93-a-birdwatchers-response/ – to make your post complete. It is unfortunate that ST was not willing to publish two separate replies on the same subject.


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