Rosellas - Pests?

[namunamu]

...just wandering what peoples thoughts are, is there any research about them competing with native birds for food, habitat, etc.
I've seen some pretty big flocks in the bush north of Whangarei,
feedback much appreciated, thanks namunamu

[Jamie Stewart]

We have a pair nesting in the garden in Wellington. They don't seem to have displaced the Tui...but yeah definitely interested.

[Leovb]

What is a pest?

Rosellas are indeed not NZ natives, at least thats what is the general opinion.

But what is a pest?
It would be very usefull if we consider the use of the word.
Do we mean that the species is competing/outcompeting with NZ birds? (as is suggested by the rosella question)
Do we mean the species is species is harmfull to any other floral or faunal resource? (like rats eating weta)
Do we mean the species is a pest for humans? (e.g. bringing diseases)
Do we mean it is an agricultural pest? (eating a percentage (how many?) of agricultural crops or bringing diseases to livestock like the possums are supposed to do with TB for cattle)
Do we mean it is a "monumental" pest (doves pooing old buildings thereby damaging it)

So "a pest" is a very broad formulation that doesn't give any more information than something general like; "the species is harmfull to at least one of the things one or a number of human(s) find important".

To give an answer to your question means there would have to be done research. I believe that several species considered a pest in NZ will prove not to be a real pest (depending on the definition you choose) once objective scientific research is concluded.

As long as there is no serious research being done in to that matter I would state that it is fair to say that rosellas are NOT a pest.

[namunamu]

Just bringing this up again, the block I've been trapping on must have had a good season for the Rosellas. Last year when there was a resident population of about 8 birds, yesterday I was shocked to find a flock of about 30 - 40 of them. Population-explosion? What could cause such a dramatic increase in numbers,  has anyone observed something similar around the country? What kind of home-range would they have?

[Dave Houston]

Someone was asking me the same question just the other day.  I've found an oldish DOC publication (2001) on rosellas that may answer some of your questions.  Haven't read it myself yet, but you can find it at http://www.doc.govt.nz/upload/documents/science-and-technical/DSIS18.pdf

[namunamu]

Thanks for that Dave, a bit of light reading there

[Steptoe]

But what is a pest?

Rosella for a start.
They go to nest earlier than our birds, nest in same/ similar  places as many pf our species including kakariki, and are rather an agressive bird, espec when they have gone to nest

With rosella around, not controled birds like kakariki that where once one of NZ most common birds will remain a stranger.

[John Dowding]

Yes, there has been some research recently. There was a talk on nesting ecology of rosellas given by an Auckland University student (Josie Galbraith) at the OSNZ conference in Lower Hutt over Queen's Birthday weekend. The study looked in some detail at nest-site selection by rosellas and at comparisons of nesting niches of native birds with those of rosellas. It found that overall cavity availability was low in the study areas, and that there was overlap in nest-site characteristics between natives and rosellas. It concluded (quote from abstract) "rosellas can be considered a genuine competitor for nest sites where they occur in sympatry with their native counterparts".

[Steptoe]

With all due respect, is it not funny how these 'studies' suddenly are great revelations of what has been common knowledge for decades....
And studies so often simply confirm studies decades before, as if the wheel has been reinvented.

A classic is brass door panels and taps etc are natuarally sterile because of the copper in them...which is why they where made of brass upto the late 50s and early 60s ...then some edcated designer thought stainless looks better....so now they are studing the major places wherehese super bugs are transmitted....gess where?
And a couple yrs ago a guy did a phd in stainles/brass in Aussie I think......gess what he found out.
And gardeners have known about copper for centuries, fish breeders and keepers have known about brass and copper pipes, storage for the same time.
But in spite of the super bug we still use stainless and hopefully rely on strong chemicals to do the job...most of the time.

Here is a study that should have taken place yrs ago.
What happens to an established flock of NZ birds with established social structure in captivity, and releaed into a park, urban enviroment?
Also as above, but a non established flock and no social structure in place.

And repeat in mainland  uncontrolled and controlled pest areas.

Such studies have/are sort of been done in part, in controlled areas.
That is constructive study with huge potentual to the future directions of successful and effective restoration policies.

But studies of things that we aleady know, and have very little or any power to do anything about....sorry too often studies tend to be no more than upgraded jnr high school run of the mill science projects.....like what sort of surfaces that come into common contct with our hands dont  grow and do kill bugs.

[Dave Houston]

Thanks John, good to have some hard data on this.  Has Josie published her findings anywhere?

[John Dowding]

Not published in a journal yet, as far as I know, Dave - part of her thesis work I gather, so will probably appear soon. I've got her email address if you want it - contact me off-forum.

I see one of the posts on this topic asks what the point of the study was when we've known the answer for years. But another further up says that rosellas shouldn't be considered a pest until there is serious research proving them to be. Hard to please everyone!

I also note a comment that this is something we have little or no power to do anything about. I would suggest that until studies like Josie's have been undertaken, and we understand the mechanisms behind the interactions better, we don't actually know whether we can do anything about it or not.