Gardens as good as the bush
Friday, 20 February 2009
Love them or loathe them, there are advantages in having birds fluttering around Nelson home gardens, as Vanessa Phillips reports.
They can drive a gardener crazy with their relentless scratching for food in prized fruit and flower beds, but when it comes to the benefits of having them around, birds can be more than just sweet, singing, pretty faces.
Pollinators, pest eaters and nectar feeders, different birds have different functions, and in the Nelson region we're lucky to be able to attract a reasonable variety in our urban gardens because of nearby bush and forest.
If your garden doesn't seem to attract more than sparrows, there are things you can do to encourage a wider range of native and introduced varieties to stop by, spend time in your garden, and provide the benefits that come with having a more balanced ecosystem.
"To get the native and endemic birds, you need to plant things that will give them food and/or shelter," says Landcare Research Nelson scientist Peter Williams.
While results for Nelson are not yet available, analysis so far of last year's bird survey by Landcare Research, done in conjunction with other agencies, shows that nationally, house sparrows and silvereyes (also known as waxeyes) are still the two most predominant of our feathered friends in our gardens.
Starlings, blackbirds and chaffinches are also high on the list of birds seen in the country's gardens, while birds such as tui, fantails and thrushes were seen in lesser numbers.
Birds are classed in three categories - endemic, which are birds found nowhere else; native, which are birds found in New Zealand and other places in the world; and introduced birds, which are those that were brought to New Zealand from elsewhere.
Peter says that in the immediate Nelson area, bellbirds, kereru (wood pigeons) and tui are endemic birds that visit our gardens.
Fantails and silvereyes, which are also found in Australia, are two of the most common native birds.
On the list of exotic birds that flutter around our gardens are sparrows, blackbirds, thrushes and starlings, and occasionally, Nelson people will see birds such as greenfinches, goldfinches and yellowhammers, Peter says.
Christchurch-based Landcare Research senior scientist Colin Meurk says some birds, such as bellbirds and tui, are nectar feeders that target flowers producing large amounts of nectar, such as kowhai, New Zealand flax, pohutukawa, rata and bush fuschia, and exotic plants such as grevillia, members of the protea family, wattles, gums, camellias and red-hot pokers.
These are the types of flora to plant if you want to try to introduce more tui and bellbirds into your garden.
"They don't have to be natives [plants] but have to produce flowers with nectar," Peter says. "Flaxes are a great source for tui."
As well as being visually stimulating and a joy to listen to, these birds are also performing the important function of pollinating plants, by spreading the pollen among flowers.
Some birds, such as thrushes, blackbirds and starlings, are insect feeders, which provide benefits because they devour pest insects that gardeners might otherwise target with sprays, which can damage the ecosystem.
Such birds also take grass grubs and worms, although they probably don't seriously deplete worm populations, Colin says.
Peter says it's hard to know how much of a difference birds make in reducing the pest populations in urban gardens.
For example, sparrows love the small passion vine hoppers that are such a problem in gardens across the region at the moment, "but I don't think they make a tack of difference to how many there are around", he says.
One of the major benefits of welcoming birds into the garden is the uplifting feeling of hearing them sing and seeing their colours - "That flash of colour when you see them in the sun," Colin says. "This is important in terms of local, regional and national identity."
Birds have important cultural significance in stories and legends, and as a source of food and materials such as feathers for the early inhabitants of New Zealand, Colin says.
Of course, like many things, while there are benefits to having birds around, they can also cause frustrations.
Colin says silvereyes, which eat fruit and insects, are one of the more damaging native birds because they don't have a big bill, so they tend to peck holes in fruit and suck the juice out. With grape vines, they can peck holes in entire rows of grapes, he says.
Blackbirds, in particular, make a huge mess with mulch in gardens as they scratch around for food, as they would do in the wild.
However, there are things you can do to prevent this happening, such as erecting netting or mesh at problem times to keep these birds out; using coarse and heavy mulch, such as pebbles and crushed rock; and placing logs or bricks around newly planted seedlings.
Some gardeners have also had success by putting plenty of small stakes in around new vegetable plantings, saying it seems to deter the birds, because they're wary that the objects might be a trap. Hanging old compact discs in the garden is another common trick, as the shiny surface puts birds off.
Despite the fact that they can be testing at times, tolerating birds, which are just following their instincts in searching for food, is a small price to pay for the enjoyment of having wildlife around home gardens.
Peter warns that when choosing plants to attract birds, don't plant introduced invasive species that have small fruit the birds can eat, such as holly and rowan, as they'll spread them into the forests, where they become problem plants.
"Particularly blackbirds and waxeyes will eat them and spread them into the native vegetation," he says.
"Waxeyes will eat anything that's not tied down."
People plant fewer tall-growing trees in home gardens these days, and that also has an impact on birds, with fewer safe nesting sites for them, Colin says.
"Many of the smaller trees often don't have the same food sources that our native birds require."
One tree that is still commonly grown in home gardens, and which can grow tall and has benefits for the bird population, is kowhai, but more big trees are also needed, such as rimu, kahikatea, miro and totara, Colin says.
Peter adds that woody shrubs can also be beneficial as nesting sites.
Kereru mainly eat vegetation and fruit - and, like other birds, they have trees they particularly like.
"On the edges of Nelson, the thing that really attracts pigeons is tree lucerne," Peter says.
They come down (from the bush) from the early spring and eat that."
In the bush, or in urban environments, birds face their fair share of dangers from predators.
There's no doubt that cats are a real problem, because collectively they kill hundreds of thousands of birds each year. As Colin says, "the jury's still out" on just how bad cats are, and whether they could actually present some benefits for birdlife.
There are observations, he says, which suggest that household moggies may limit more serious predators such as rats, ferrets and stoats from killing birds, by either killing these predators themselves or deterring them.
"One does have to bear in mind that beneficial effect of limiting other, worse predators," Colin says.
In the future, bird populations in Nelson city gardens could also get a boost because of the Brook Waimarama Sanctuary, which is under development in the Brook Valley.
Peter says that if the Brook sanctuary eliminates predators and is as successful as Wellington's Karori bird sanctuary - which has seen kaka become common in parts of the capital city - it should have a huge positive impact on birdlife in Nelson's urban gardens.
Attracting the sticky beaks
How to encourage birds into the garden:
- To attract tui and bellbirds, plant nectar-producing flora such as native flax, kowhai and pohutukawa, and exotics such as camellias and red hot pokers.
- If you have room, plant large trees to give birds a nesting space, particularly natives such as totara and rimu. Also plant bushy shrubs and undergrowth to imitate the bush.
- Link native plantings to your neighbours' trees or to nearby street trees to encourage birds to flutter from there into your garden, as some will not fly large distances over open ground.
- Provide water, such as a birdbath or shallow bowl, in your garden for birds, somewhere where cats won't get them. Keep water sources, which birds use to drink and wash in, free of debris and top them up with fresh water frequently.
- Vary the type of trees and bushes you plant to attract a wider range of birds, from insect and seed eaters to nectar eaters. Try not to keep some areas of the garden too tidy, to encourage more insects that birds target.
- Planting trees that flower or fruit at different times will provide a year-round food supply for birds in your garden.
- Avoid insecticides and chemicals - they kill the insects that some birds eat.
Nelson Mail, New Zealand