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Mast Years and Parakeets

Perhaps this seems an odd combination of subject matter when one realises what a “Mast Year” actually is. This Wikipedia item will give some background to my observations.  https://en.wikipedia.org/wiki/Mast_(botany)

Rimu & Coprosma species.

Rimu mast occasionally, the last was in autumn 2022, before that in 2019, and before that 2016. I have one tree on Ulva I take particular notice of, and have done a very unscientific assessment of the seed drop. 2016 & 2022 where what I would call average, with somewhere around 3 to 400 seeds per sq metre. 2019 was a cracker year, and this tree produced a bit under 4000 seed per sq metre. ….. a long slow job down on my knees counting tiny seeds !!. That year saw the forest floor scarlet with seed in places. The seeds are tiny, with the actual seed perched on top of a tiny extremely sweet “fruit”. So for seed eating birds these mast years are a cornucopia of high quality food, which appears in mid to late autumn. But the years between masting are barren.

Coprosma species generally fruit most years, but in the years Rimu mast they all appear to fruit significantly heavier than normal. This is especially obvious in some such as C ciliata which will normally have just a scattering of fruit, but in the mast year will be laden. And although unlike Rimu they will fruit in the following and intermediate years. The following year will be a VERY light fruiting. Coprosma sp fruit somewhat before Rimu, with the small sweetish berries starting to ripen in early to mid February.

So generally a Rimu mast is complimented by a Coprosma mast, thus lots and lots of food, followed by a year of relative famine.

On Ulva the Parakeets seem to be the species that take most advantage of this late summer/autumn food bonanza and we find them well into nesting by late January.




Rimu Fruit on the Tree, 2019

Rimu Fruit.
The actual seed is the small dark nodule at the tip

Rimu Fruit.
Around 400s seed per square metre

Coprosma ciliata in heavy fruit

Coprosma lucida in heavy fruit


Yellow Crowned Parakeet harvesting Rimu Fruit


Yellow Crowned Parakeet harvesting Rimu Fruit


Red Crowned Parakeet eating C foetidissma Fruit


Red Crowned Parakeet in our garden with Lancewood fruit


In our garden with Lancewood fruit under the tree


Courtship Feeding


At the nest


At the nest


Parent feeding  a fledgling


Mast Year 2019

That year was an exceptional year for both Rimu and the various Coprosma sp and the parakeets seemed to take full advantage of it. I doubt there was an egg hatched that didn’t fledge, and the young fledglings left the nest to a forest full of food.

So spring 2019 the forest was alive with parakeets. One of the things with parakeets is that they are generally the shyest of our forest birds on Ulva and you seldom get all that close to them, at least if they are paying attention. That spring and early summer I was seeing flocks of anything up to 20 birds, all feeding. Many of these were on the ground and they seemed so focussed on searching for food that on many occasions we got to within a couple of meters of a bird before it would fly off. Completely atypical behaviour. The flocks seemed to hold until mid January when, as mentioned earlier they found that the vast amount of Rimu & Coprosma fruit of the previous season didn’t eventuate in 2020.. What coprosma fruit there was got stripped off the branches almost before it ripened, and little or not getting to the ground.  And the flocks just melted away. The nest sites I was aware of were unoccupied, and by late autumn the population was significantly reduced.

Mast Year 2022.

Although it was a more  “normal” mast ….. not the extraordinary event of 2019, more or less the same pattern has eventuated. I had wondered what happened to the large numbers of Ulva birds post mast, and had surmised that they might perhaps have looked across Paterson Inlet and emigrated on the hope of finding more food across the water. Which perhaps they would have, as mainland Stewart Island generally has an observably lower population of parakeets than has Ulva which does not have the issues of predation that Stewart Island has. (well maybe that’s not entirely correct, as rats got back on Ulva 18 months ago, but won’t yet be near to potential population density)    So less population pressure on a food resource. And it’s noticeable around our own garden, which is well endowed with food, mainly Pseudopanax species which is fruiting heavily at the moment. We’ve been seeing anything up to 4 or 5 birds in the tree at any one time.