Happy together: The co-dependent development of our native birds & plants

That our native birds and native trees share a synergistic history ought to come as not a surprise, offered both have actually been guided by New Zealand’s geographically separated island landscape.

Plant evolutionary biologist Janice Lord, an associate teacher in the Department of Botany at Otago University, says one fine example of how our native plants have actually adjusted to the native bird life remains in fruit size to help guarantee seed dispersal.

“The trees rely on birds to spread the seeds around. We do have some big-seeded plants like the tawa and taraire that rely on kererū for fruit dispersal, but generally in New Zealand bird gapes (the interior of a bird’s open mouth) are smaller. Seeds need to be swallowed whole, so that constrains the size of the fruit,” Lord says.

Interestingly the lack of endemic land mammals in New Zealand, aside from bats, has actually likewise affected the colour and flavour of berries in a lot of our native plant ranges. That’s mostly due to the fact that the majority of our fruit-eating native birds have little or no sense of odor, and try to find food based upon colour, normally purples, reds and black.

FIND OUT MORE:
* 5 methods to make your garden a safe house for native types
* Save these locals – plant them in your garden
* We require to overcome our native plant cultural cringe

Tangled tales: Why we have numerous divaricating native trees and shrubs

Divaricating plants are those that branch at broad angles, frequently producing a twiggy tangle, and, when it comes to New Zealand locals, frequently with little leaves and a significant distinction in their look in between their juvenile and fully grown kinds.

There are a variety of theories around why our native plants might have progressed these functions, Janice says, from it being a method of adjusting to New Zealand’s adjustable environment to safeguarding the plant from frost, and even assisting it handle light.

One concept that’s captured popular creativity is that plants like the toothed lancewood progressed their spiky, interlaced juvenile kinds to fend off starving moa. Once the lancewood reaches about 3m high, positioning its excludes of reach of even the slender moa, it alters shape, ultimately establishing a high straight trunk and upward pointing leaves.

While everybody likes a good moa story, Lord says the theory is still relatively controversial. “Though the moa hypothesis does seem to explain all the different divaricated forms we see, theories around climate and light only account for some forms.”

And while the moa/lancewood relationship may still be up for dispute, Lord says New Zealand’s big, ground birds would have produced disruptions for young native plants which might explain the number of have actually progressed. “There would quite probably have been herds of moa moving through the undergrowth, eating things and generally making a mess of the place, and it’s not just moa. There were other large ground birds as well.”

She indicate Australia where ground-dwelling lyrebirds scrabble in the understorey of regional plants, troubling and in some cases consuming the plants along with accumulating mounds for nests.

“Those kinds of things were probably happening here too. The plant response to that is to not look too tasty when you’re young, small and vulnerable. Lots of our native plants have cryptic colours or very jagged leaves when they’re young, compared with when they’re adult,” Lord includes, pointing out New Zealand jasmine (Parsonsia heterophylla) and mataī (Prumnopitys taxifolia) as locals with a really “scruffy-looking juvenile phase”.

“Even South Island kōwhai is tangled when young, then it sorts itself out into a property tree when it’s bigger.”

In his brand-new book The Story of New Zealand’s Unique Birds (from Adzebill to Yellow-Eyed Penguin), author and bird professional Alan Froggatt discusses New Zealand’s geographical seclusion, and how being the last significant landmass to be occupied by human beings turned our collection of islands into the best life science laboratory.

Our birds progressed to “fill the ecological niches normally filled by mammals elsewhere on the planet”, ending up being larger, much heavier and more powerful than birds discovered anywhere else, Froggatt says in his book. “All were descendants of birds that could fly but many lost the ability to do so. All they needed to do to escape aerial predators was hide on the ground or blend into the background.”

This very same separated, pre-human, science laboratory likewise affected the plants those birds utilized for camouflage. “That isolation has meant we have some really unusual growth forms. We have tree daisies, for example, which are actually not common elsewhere in the world, though we kind of take them for granted. Our tree fuchsia is another one; the largest in the world,” Lord says, mentioning it likewise as an example of a plant with an uncommon action to altering seasons.

While the majority of our locals are evergreen, the tree fuchsia (Fuchsia excorticata) is among our couple of deciduous trees. And while it does lose leaves in winter season, that is likewise when it flowers, with nectar-rich flowers best for pollinating by tūī, bellbirds and silvereyes (tauhou).

“So while the fuchsia loses its leaves, it’s not dormant like other deciduous trees. There’s been a bit of work looking at how when it loses its leaves, those flowers become a lot more visible against that lovely orange bark,” Lord says.

And the factor numerous of our native trees are evergreen? Simply our adjustable environment, she says. “Because we’re an island with an oceanic climate sometimes, for example, the summers aren’t great.

A plant that habitually loses its leaves in winter can miss out on growing opportunities. “With an unpredictable climate, it’s far better to just be evergreen. Being deciduous only serves the plant when there are definite seasons with really different temperatures.”

Welcoming immigrants: eating unique plants

While our native plants and animals have actually mostly had a well suitable history, especially when they had New Zealand to themselves, much of our birdlife has actually adjusted to the arrival of presented plant types too.

Kererū, for instance, are popular for their love of a good plum as numerous annoyed growers can affirm.

But, Lord says, they’re likewise keen on tree lucerne, to the point where the presented types are utilized in some sanctuary to help build up the kererū population. “They’ll eat the fresh flowers and the leaves just as they would with kōwhai because they’re both from the pea family.

“I’ve also seen tūī and bellbirds on red hot poker which is fascinating. The plant is bird-pollinated where it comes from in South Africa but it is very different to a lot of our native flora, with very bright colourful flowers. So it’s really interesting that our birds have learned to visit those flowers.”

Of course while our birds may have adjusted to check out the unique plants; the plants have actually not constantly adjusted to our native birds. Last month, NZ Gardener reported about the flocks of kākā ravaging unique trees in Wellington, consisting of historical northern hemisphere conifers in the Wellington Botanic Gardens.

Native birds in your garden

While you may not desire kākā tearing away at your trees, there are lots of methods to lure more native birds securely into your yard, Janice says.

The apparent one is planting the shrubs and trees that they like. For those that have the space, kōwhai and pōhutukawa (if you have the space)are a good option, as are “any of the lancewoods”, she says. “They don’t all have those odd juvenile leaves, but they all have berries that will attract the birds.”

Places for birds to securely sit and nest are likewise crucial, she says. “Leaving small messy or wild areas in your garden will help bring in the birds. Hedges are also really important and plants like muehlenbeckia – which I know a lot of people don’t like – offer good protection for birds. And don’t cut down big trees!”

In smaller sized garden, she recommends growing nectar feeders as an easy method to bring in birds, or smaller sized types such as Marguerite daisies which likewise interest native bees and hoverflies.

When it concerns planting locals, Lord motivates garden enthusiasts to look beyond popular, easily available types to attempt brand-new things. “There are a lot more natives out there than you might realise that will work in home gardens. If you go to a nursery that specialises in natives, you’ll be amazed at the diversity of foliage shapes and forms. They’re easy to grow. It’s just a matter of the right plant in the right place. And they will help bring native birds into the garden, as well as bring in insects which will then encourage insectivores like fantails.”

From June 24 to July 2, you too can take part in the 2023 New Zealand Garden Bird Survey.