Problems caused by endemics

Any experienced NZ birder can tell you of at least one occurrence in which they have seen a tui chase away another bird for no apparent reason.

They are bona fide bullies when it comes to how aggressive they are to other birds, despite not usually having anything to protect.

Because some people are quick to come to the conclusion that the aggression that such birds as eastern rosellas, mynas, and starlings show towards other birds means that they are effecting their numbers, I'm wondering if anyone has ever thought about this for tui, and considered studying whether or not their aggression has a more serious impact on other birds than previously thought?

This is an example of how an endemic species can be a notable problem to the natural or cultural environment. Though conservationists are more lenient regarding the killing and control of natives, such as black-backed gulls, spur-winged plovers, and shovelers, the possibility of endemic species being a problem is more-or-less a taboo subject to them. The weka is the only endemic species I know of which has been widely accepted among conservationists as being a 'troublemaker'.

There are examples of endemic birds apart from the tui causing problems to the natural or cultural environment. There is some evidence that native robins can cause tomtits to die out easily via competition, kereru are occasionally considered a pest to fruit crops, just as eastern rosellas are, and South Island pied oystercatchers have been accused of taking too many shellfish and being a major nuisance in other ways.

I am not suggesting that any of these species should be culled for their apparent negative impacts. Neither of the complaints about the oystercatchers are reason enough to cull them, and they were most likely being used as scapegoats for why there seemed to be fewer shellfish around.

As for the impacts that kereru and robins have, however, perhaps further investigation should be made (especially in the case of the robins).

Perhaps there will come a time when the weka is not the only endemic bird species that has been killed in defence of something or someone else.

My point is that it's time for it to be more widely acknowledged that, in one way or another, endemic birds can be pests too. The fact that they are found nowhere else on earth has nothing to do with their environmental impacts.

Hybrid partridges?

The red-legged partridge is a bird species in New Zealand that has been liberated a number of times, but has yet to become genuinely established in the wild. Despite this, it is still featured in field guides to NZ's birds.

Its close relative, the chukor/chukar partridge, is an uncommon established species in the South Island. It is closely-related and very similar-looking to the red-legged partridge. Both species are commonly kept in captivity here.

I have reason to believe that the red-legged partridges kept in New Zealand, however, are not genetically 'pure', and carry some chukor blood, due to the fact that first-generation hybrids between the two, at least, have been bred in captivity.

As previously stated, the red-legged partridge is very similar-looking to the chukor (though not as similar to the chukor as the rock partridge). They are most easily distinguished from chukors by their streaked necks; an obvious feature of their phenotype. Still, I am sure that even this could be 'missed', meaning that unintentional hybrids between chukors and red-legs could be bred in captivity.

What I don't know, however, is whether or not chukors and red-legs are fully interfertile. My assumption is that they are, meaning that first-generation hybrids and all of the following generations are fertile, meaning that it is possible for pure-looking red-legs and chukors to carry the blood of both species. It is possible, however, for closely-related species not be fully interfertile; an example of this is the two Aix ducks.

Another important part of my assumption that I know nothing about is what the first-generation hybrids look like. If they can't be told apart from 'pure' specimens of one of the two species, then the captive population of one of the two partridge species becoming genetically 'swamped' by the blood of the other species is practically inevitable.

If DNA testing is done and NZ's red-legged partridges are found to carry chukor blood, perhaps some will decide that they should not be treated as an actual species in New Zealand.

But then, perhaps not. After all, the wild Lady Amherst's pheasants of the UK are/were considered to be fully acceptable as a species, but I have yet to see a photo of one that does not show obvious signs of golden pheasant hybridisation.

'Let's not go bulbul bashing'.

In Texas, a small red-vented bulbul population has existed for about a decade.

Red-vented bulbuls are infamous for being an economic burden to the horticultural industry. In Oahu, Hawaii, for example, they have an annual economic impact of $300,000, and they are being closely monitored in Hawaii so that they do not become established on any of its other islands. They are also suspected to displace some native birds where they have been introduced, but this apparently hasn't been well-studied.

Despite this, however, there have yet to be any efforts to do away with the Texas population. Instead, the population is being studied, and they apparently haven't been found to be a threat to native species. It seems that the possibility of them becoming an economic burden there is being ignored.

New Zealand is no exception when it comes to viewing red-vented bulbuls as being an unwelcome and unwanted species; several small populations have arisen in New Zealand, all probably derived from released or ship-assisted birds; the first arose in the early 1950s and was quickly eradicated, just as the other populations have been. The most recent population arose in 2013 and was eradicated before the following year ended. It is the MPI that deals with them.

Note how they say that kereru are particularly vulnerable to the aggression of the species, which I suspect is an allusion to the fact that they are regularly chased off by tui.

If the MPI found out about the fact that there has been no attempt to eradicate the population in Texas, I imagine that they would either think that the Texan authorities are utter morons, or would contact them and urge them to do something about it. Or both.

To me, any addition to NZ's avifauna is welcome, as long as it doesn't have a serious impact on any native species. Trying to convince the MPI to leave red-vented bulbuls alone, should they be seen here again, however, is out of the question.

The only 'respected' introduction

The status of introduced birds, no matter where they're from, where they're imported to, and what they do to the environment, tends to be controversial.

Birders in some countries, such as Singapore and the USA, don't usually care much about them.

In New Zealand and Australia, however, the predominant attitude towards them is that they aren't needed, and whenever possible, they should be done away with.

Obviously, some introduced birds are rarer than others in New Zealand, but that doesn't often change peoples' opinions of them. Kookaburras are rare and localised here, but because all it takes is a flight to Australia's east coast to see plenty of them, it seems that few birders would care if they died out. Cockatoos and (especially) galahs are rare and localised as well, but they aren't of much interest to birders, because they're seen as being public aviary and zoo fodder. Rooks have nearly been eradicated here, but the idea of 'NZ - rooks = no corvids in NZ' doesn't seem to bother any birders.

There is one rare introduced bird in NZ, however, that seems to be exempt from the dislike directed at the rest of NZ's introduced species, common and rare; this being the cirl bunting. This is mainly because it is rare and hard to find, but the fact that it is now rare and relict in the UK and is apparently declining throughout its native range might have something to do with the 'respect' it receives as well.

It's good that at least one of NZ's scarce introduced birds is having its presence enjoyed while this is still possible.

Still, it's a shame that most of those who like it don't think much of the rest of them.

Extralimitals

To me, the rainbow bee-eater is a species that is confounding in the way that, despite being an annual summer migrant to southeast Australia, there has not been even one record of the species in New Zealand.

Because of that, this species could be called an 'extralimital' species for New Zealand.

Extralimital species are birds that are considered likely to eventually occur in a particular area, but have never been recorded there in the past. Some field guides include extralimital species for the areas that they cover, but to my knowledge, there has yet to be a NZ field guide to include them. Given the fact that the New Zealand region is made up of fairly isolated islands, however, I consider this to be sensible.

My opinion on extralimital birds is that, unless an extralimital bird regularly occurs literally only a few tens of kilometres away from a region that it seems it could eventually reach, it shouldn't be included in a field guide for that region.

Yes, there have been species that have occurred in an area a very short time after being featured as an extralimital in a field guide for that area, but that doesn't mean that including extralimital species in serious bird guides should be encouraged.

Mynas are not a pest in NZ.

Common mynas don't get a lot of love outside of their native range, and New Zealand is no exception.

Them being called 'pests' is common, particularly in Australia, where they are completely unwelcome and their eradication in the near future is highly desired.

I don't know much about what mynas do in Australia. There, they are mainly accused of competition and aggression towards native birds, and are also called a human health risk (which I doubt). Given the fact that Australia's climate is in favour of the spread of mynas (unlike most of New Zealand), and the fact that Australia's avifauna is very different from NZ's, and the fact that the forests of Australia are different from NZ's, mynas very well could be an actual ecological pest in Australia.

In New Zealand, though? In regards to ecological impacts, at least, I'm afraid not.

The only evidence that I have found regarding a major impact that mynas have on other bird species in NZ is in Ell's Encouraging Birds in the New Zealand Garden (1981), in a part about starlings which reads, 'An aggressive bird held in check in the northern part of New Zealand by its cousin the myna'. Even this statement, however, seems to be based on anecdotes.

The only case in which I consider it reasonable to consider mynas a pest in NZ is when they have been seen near the nesting sites of New Zealand fairy terns; they have been shot because of this. Mynas destroy the eggs and chicks of other birds, and those of the fairy tern are unlikely to be exceptions. Given how small the NZFT population is, I can understand that having mynas in the vicinity of where they nest is not a risk worth taking.

As for other native birds, mynas don't usually breed or reside in NZ forests, which means that most native birds are safe from them. The natives that I imagine would be most vulnerable to having their eggs and chicks destroyed by mynas are banded, North Island NZ, and black-fronted dotterels, and pipits, as they are all small ground-nesters, but I haven't found anything regarding whether or not mynas have ever been seen destroying the eggs and chicks of these species. I imagine that native forest birds which would be effected on a small scale would be silvereyes and grey warblers that nest in gardens; these would be easy targets for mynas, but mynas destroying the eggs and chicks of either of these species in gardens has a negligible effect on the populations of both, as most of them nest in forests. I also imagine that if mynas tried to destroy the eggs or chicks of kingfishers that have their nesting sites in rural areas, the kingfishers would kill them, so they're in no danger.

In conclusion, there's no good reason to consider mynas a major ecological pest in New Zealand, and therefore, no good reason to eradicate them from the country.

It would be nice if facts such as these could be more widely known and understood, but given the fact that 'introduced = bad' comes naturally to most kiwis, I don't think that that will happen any time soon.

More regarding NZ's grey partridge

While I was writing the initial post about the grey partridge in New Zealand, I vaguely recalled reading somewhere that sightings of the species had taken place in the North Island long after they had been introduced there (mostly in the 19th century), apart from the one recorded during the 1969-1976 bird distribution survey, and it seems that I've found the source for that text. Uncommon Birds in New Zealand (1975), from the Mobil New Zealand Nature Series, reads:

only recent reports from North Canterbury, Southland, Bay of Plenty, Hawke's Bay and Taranaki.

The use of the vague term 'recent' is not helpful, but provided that the authors of the book were not misinformed, this brings up a few questions; were the sightings that took place in those three North Island locations of birds that had only been recently released, or of birds that had been persisting since being introduced there in the 19th and early 20th centuries? If they had been recently released, were the releases by people in the North Island who had been breeding them, or were they authorised releases that simply aren't covered in the 2010 OSNZ Checklist? If the releases were by North Island breeders, would them being released be a part of why no grey partridges currently exist in captivity in New Zealand?

None of those questions are ever likely to be answered with certainty. What I can say, though, is that if those 'recent' North Island sightings had been of birds derived from the introductions that took place there before 1940, then this would make Robertson & Heather's field guide stating that the species persisted in Southland into the 1980s reasonable.

That doesn't meant that any exist there now, though.