Bring back birds

Fiona Eadie makes a case for plant­ing our na­tive flora… on be­half of our na­tive fauna!

NZ Gardener - - Contents -

Love na­tive birds? Then love the na­tive plants they need, says Fiona Eadie

We love our na­tive birds and want them in our gar­dens, but do we love with equal pas­sion the plants that pro­vide every­thing our en­demic feath­ered fauna needs to thrive?

ihave had so many peo­ple say to me, “if New Zealand’s na­tive plants were only more in­ter­est­ing, I’d plant more of them.” Which to me trans­lates as, “if our na­tive plants had bigger and more colour­ful flow­ers, I would plant more of them.”

But if you are fo­cus­ing on flashy flow­ers, you’re miss­ing out. If you take the time to learn about the in­cred­i­ble evo­lu­tion of our na­tive plants, I guar­an­tee you’ll re­alise that our na­tives are more amazing than any ex­otic you can name. Plus they pro­vide every­thing our na­tive birds need to thrive.

That’s be­cause our birds and plants evolved to­gether. In fact it is the fault of na­tive birds that our na­tive plants aren’t as florif­er­ous as we would like!

Peo­ple also have told me they plant ex­otics be­cause their flow­ers bring in birds. They seem to too eas­ily for­get that our birds and our plants pro­vided all that was needed for each other’s sur­vival be­fore hu­mankind set foot on this land.

We do not need to plant for­eign plant species to feed our birds. We sim­ply need to plant more – a lot more – of our own amazing na­tive flora. I am sad to say that there are now more weed species than na­tive plant species found in New Zealand.

The case for na­tive plants

New Zealand’s na­tive birds and the plants found a niche within the ecosys­tems that ex­isted. Over mil­len­nia, and be­fore hu­man set­tlers ar­rived here, they ex­isted to­gether and ex­erted a pro­found in­flu­ence on each other’s evo­lu­tion. Be­fore the first peo­ple ar­rived on the Land of the Long White Cloud, a quar­ter of our birds had evolved to be­come land or wa­ter dwellers (we have more species of flight­less birds – liv­ing and ex­tinct – than any other coun­try in the world). But no won­der they be­came lazy – their only preda­tor was the nowex­tinct Haast ea­gle… and who wouldn’t have been scared of that mag­nif­i­cent crea­ture! But the birds that lived here weren‘t all nec­tar feed­ers that “re­ward” flow­er­ing plants by pol­li­nat­ing them. In fact only 8 per cent of our na­tive plant species are pol­li­nated by birds – and some of those plants are happy for an in­sect to do it in­stead. Many of our na­tive birds – bell­birds, hihi, k¯ak¯a, sad­dle­backs, t¯u¯i and more – are un­usual in that they eat both the nec­tar and fruit of many plants (and in do­ing so pol­li­nate the flow­ers and help spread the seed). So lots of our na­tive plants pro­duce both bird-pol­li­nated flow­ers and bird-dis­persed fruits, rather than just fo­cus­ing on flow­ers!

Our na­tive birds do not just need flow­er­ing plants – we can get over that idea! They don’t need bread ei­ther – for­get throw­ing out the crusts if you want to en­cour­age na­tive birds (al­though su­gar feed­ers are OK as a sup­port for nec­tar­feed­ing birds in win­ter).

If you don’t plant na­tives be­cause you don’t like the way they look, I en­cour­age you to look at them again. Many gar­den­ers I meet are in­ex­pe­ri­enced with our na­tive plants, and have not seen what can be done with them. Oth­ers feel they are hard to grow, or sim­ply, do not know them so don’t buy them.

Yet, our na­tive plants have tex­ture, look good, are there in the win­ter… and yes, some of them of­fer flow­ers too!

I am not say­ing you can­not have your ex­otic flow­er­ing plants; nor that you should have only na­tive plants in your gar­den. But I am say­ing that na­tive plants pro­vide our birds with what they need – and sup­port all our other fauna too.

I would love to see gar­den­ers grow more na­tive plants. We are the ones who can bring our coun­try’s flora – and con­se­quently its fauna – back to life. Be sure to ask at your gar­den cen­tre for any species you can­not find so they can let the nurs­eries know there is a de­mand. If they do not know, they will not try to pro­duce them.

Na­tive plants, pol­li­na­tion & evo­lu­tion

In the evo­lu­tion­ary sense, New Zealand is a young coun­try. There has not re­ally been time for the close as­so­ci­a­tions that can form be­tween a plant and its pol­li­na­tor – and the of­ten-fancy flow­ers that fol­low else­where in the world.

Pol­li­na­tion is the first step in the sex­ual re­pro­duc­tive process in plants, it is the pollen (male part with sperm in­side) coming in con­tact with the stigma of the fe­male part.

Self-pol­li­na­tion is when the egg is fer­tilised by its own pollen or one from a flower on the same plant. This is great if you wanted to re­pro­duce quickly, like many of our short­lived weed species. But, there is no ge­netic di­ver­sity, so there is less like­li­hood that the species will have off­spring ca­pa­ble of be­ing able to adapt to changes in its en­vi­ron­ment and/or be re­sis­tant to cer­tain pests and dis­eases.

Cross-pol­li­na­tion on the other hand leads to ge­netic di­ver­sity, the pollen coming from a ge­net­i­cally dif­fer­ent plant of the same species. This is all about sur­vival. We think that all plants look iden­ti­cal but an in­di­vid­ual species is as vari­able as we are as

Homo sapi­ens. We are all so dif­fer­ent and so are our plants!

In­ter­est­ingly it has been shown with kˉakˉabeak that it de­sires cross-pol­li­na­tion but if it gets to the end of the sea­son and it thinks it has not pro­duced enough seed it will hap­pily self-pol­li­nate. Some weed species have also been shown to un­der­take self-pol­li­na­tion to colonise a new area and once es­tab­lished move to cross-pol­li­na­tion. How do they know? Ahh, we still know so lit­tle about plants!

To en­sure cross-pol­li­na­tion plants need a means of trans­fer­ring the pollen from one plant to an­other. Some, such as our na­tive beech trees, podocarps, all our grasses and even our co­pros­mas, are lazy and use the air­waves, let­ting loose vast quan­ti­ties. Such plants do not re­quire fancy flow­ers as there is noth­ing to at­tract.

All the other plants use an­i­mals. To get the an­i­mals to come, the plant needs to pro­vide an in­cen­tive, and like most an­i­mals food is of­ten the win­ner on the day. For most it is nec­tar but for some it will be pollen or even both. In gen­eral, the larger the flower the larger the an­i­mal un­der­tak­ing the pol­li­nat­ing. No mat­ter the size of the pol­li­na­tor it is cost­ing the plant en­ergy to make the prod­uct; the bigger the pol­li­na­tor the greater the de­mands on the plant. This en­ergy could be be­ing used to grow, de­fend them­selves from pests and dis­eases, take up nu­tri­ents from the soil and more. There is a cost to pro­duc­ing a fancy flower but they will do it for re­pro­duc­tion.

Here, very few na­tive plants pro­duce large flow­ers be­cause the nec­tar feed­ers we have are small. They in­clude our na­tive bees and wasps (both small when com­pared to rel­a­tives else­where in the world), moths and our few but­ter­flies. Their pro­boscises (great word for their straw-like tongues) were of equally small stature. Other nec­tar-feed­ing pol­li­na­tors here are flies, w¯et¯a, bats and of course birds. It used to be thought we had an ab­nor­mally high per­cent­age of plant species (about 12 per cent of all flow­er­ing species) that had sep­a­rate male and fe­male flow­ers; that is, that were dioe­cious. The the­ory was it en­sured cross-pol­li­na­tion, in turn as­sur­ing ge­netic di­ver­sity. But the­o­ries come and the­o­ries go. A very re­cent study de­ter­mined that we do not have a lot of dioe­cious plants here (in some trop­i­cal forests, dioe­cious plants make up 40 per cent of flow­er­ing species). Plus more re­cent science sug­gests that only a few plants de­vel­oped this char­ac­ter­is­tic once here – per­haps our clema­tis and rubus species. The rest are now thought to have ar­rived al­ready with the char­ac­ter­is­tic. It seems we are not as unique as we thought – but we can cope with that!

18

Rimu.

Pit­tospo­rum.

Kaka beak.

Miro.

Myr­sine di­var­i­cata.

Nothofa­gus.

Macropiper.

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