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Research Native bird foraging impacted by invasive parakeets

 
 

This page contains 24 reader comments. Click here to view (latest Thu 27/03/14 11:53).

A recent study, focussed on London, has demonstrated the significant impact of Ring-necked Parakeets on the foraging behaviour of native birds. The study, published in Behavioral Ecology, has found that presence of parakeets leads to increased vigilance and decreased feeding in our native birds. Furthermore, it was found that these behavioural changes are much more pronounced than in the presence of a dominant native species (namely Great Spotted Woodpecker).

The study concentrated on the effects in Great and Blue Tits — both common species in urban areas. Study of feeding stations suggested that the parakeets introduce a spatial shift in the tits' foraging behaviour which, if consistent, could feasibly cause reductions in population. If proven, this would represent the first case of such impact by non-native avian species in Britain, though a similar (and known) established British case concerns the Grey Squirrel.

Ring-necked Parakeet
Ring-necked Parakeets are a conspicuous species, found commonly right across Greater London. But is their vociferous nature having an impact on native species such as Blue Tit? (Photo: Bill Dykes)

The abstract can be read below:

"Resource competition is one potential behavioral mechanism by which invasive species can impact native species, but detecting this competition can be difficult due to the interactions that variable environmental conditions can have on species behavior. This is particularly the case in urban habitats where the disturbed environment can alter natural behavior from that in undisturbed habitats. The Rose-ringed Parakeet (Psittacula krameri), is an increasingly common invasive species, predominantly associated with large urban centers. Using an experimental approach, we tested the behavioral responses of native garden birds in response to the presence of a rose-ringed parakeet versus the presence of a similarly sized and dominant native bird, the Great Spotted Woodpecker (Dendrocopos major). Parakeet presence significantly reduced feeding rates and increased vigilance among native birds compared with our control treatments. Of visits made by native birds in the presence of a parakeet, feeding was more likely to occur in sites within the parakeet range compared with sites outside, suggesting some habituation of native birds has occurred following prior exposure to parakeets but overall foraging behavior is still disrupted. The results of our study suggest that nonnative species can have complex and subtle impacts on native fauna and show that a nonnative competitor can impact native species simply through their presence near resources."

The full paper is open access, and can be read and downloaded from the Behavioral Ecology website.

.

Peck HL, Pringle HE, Marshall HH, Owens IPF & AM Lord. 2014. Experimental evidence of impacts of an invasive parakeet on foraging behavior of native birds. Behavioral Ecology DOI: 10.1093/beheco/aru025

Link to external website here.

Related pages

Ring-necked Parakeet Ring-necked Parakeet


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The information in this article was believed correct at the time of writing. BirdGuides accepts no responsibility for errors, or for any consequences of acting on information in the article. The opinions expressed are those of the author(s) and are not necessarily shared by BirdGuides Ltd.

hide section Reader comments (24)

#1
Artificial numbers of Blue and Great Tit effected by artificial numbers of parakeets!! Get a life!
   John Miles, 20/03/14 09:38Report inappropriate post Report 
#2
You'd have thought we'd have learned by now - non-native species are bad news and often it's too late to deal with the problem by the time the effect on native wildlife is seen. They should have been controlled earlier, however it's not too late! It would be a lot easier and cheaper than the Ruddy Duck extermination. Why wait to assess the damage when you can stop it before hand.
   Dave, 20/03/14 09:45Report inappropriate post Report 
#3
There's been a desperate attempt to find something negative about RN Parakeets and now it turns out they have finally found some tentative evidence that they are dominating artificial feeders. Desperately clutching at straws comes to mind. No doubt, they will be demanding total extermination so that only native species can feed at feeding stations stuffed with peanuts and coconuts imported from abroad. How about a massive study on introduced Pheasants and the adverse effect they have on native species - or will that be bad for business?
   Duncan Fraser, 20/03/14 15:42Report inappropriate post Report 
#4
I would suggest that the breeding density of both Blue and Great Tits in the artificially maintained environment of urban gardens with extensive feeding and added nest sites is already abnormally high compared with the value for “natural” woodland environment. I would surmise that the introduction of Parakeets has only rapidly accelerated the change that would otherwise have happened. Nothing is achieved by comparing one artificial situation with another equally artificial. My general view...more more
   Jeff Clarke, 21/03/14 00:04Report inappropriate post Report 
#5
Should you have to look for 'anything negative'? Should'nt an introduction and presence of a totally non-native species be perceived as negative by default? The effect of invasive spp can be very subtle whether it is competition for nest sites, or food supply. The furore and polarisation of the Ruddy Duck cull could have been avoided if a zero-tolerance approach had been taken many decades ago. 4 million other reasons - Grey Squirrel?
   Laurie Allan, 21/03/14 07:43Report inappropriate post Report 
#6
This is stupid. Next we will have to eradicate Little Owls for destroying to many earth worms!
   Matthew Stainthorpe, 21/03/14 16:08Report inappropriate post Report 
#7
"Shouldn't an introduction and presence of a totally non-native species be perceived as negative by default?"

Errr, no. See Matthew's post.

Fallow deer are pretty benign too, come to think of it...

And Muntjac.

And Red-legged partridge.

And Ring-necked pheasant

Even rabbits.

And so on...

A species is a "problem" if it's a problem.
   Keith Reeder, 21/03/14 18:00Report inappropriate post Report 
#8
Surely they will only become a problem to the so called ecosystem (that is heavily influenced by our man made environments anyway) if they spread out from London into the countryside? I hope they do not have to be slaughtered, because of some outdated notion that we anything like a balanced natural system that is under threat from 'invasive aliens'. The real problem is human overpopulation (sorry controversial opinion). Phil
   Phil Rhodes, 22/03/14 00:49Report inappropriate post Report 
#9
Evidence is emerging from Belgium that RNPs are having a detrimental effect on breeding native species especially nuthatches. They are spreading from Inner London into suburban and semi rural park and woodland habitats. The latest population estimates suggest as many as 30,000 birds in the UK. My understanding is that they are now legally classified as pest and can be destroyed by famers if they can show that they are causing damage to crops. I don't accept the argument that because the tit population is artificially high we shouldn't try and protect it. Many bird populations are kept artificially high in the UK by nest protection and predator control. Non native birds should be monitored and were they are affecting native bird populations, they should be controlled.
   Ian Bradshaw, 22/03/14 07:17Report inappropriate post Report 
#10
We have Parakeets in our garden and Great Spots, sizes - parakeet is bigger, which maybe a factor why they might be more dominate that Woodpeckers. But, we do not see any aggression by either species towards Tits, the Tits simply avoid feeding on a feeder with a larger bird present. Also when the parakeets turn up there are more than one, but we only get one Woodpecker at a time. Also this study is at what can be best described as a man made environment that does not create a natural...more more
   Chris Lamsdell, 22/03/14 10:22Report inappropriate post Report 
#11
Are you serious Keith? Really, non-native deer are causing no problems? Come on fella do some research, I would suggest starting by looking at the recent studies on Nightingale declines. Or the effects of competition between Grey and Red-legged Partridge. Or the effects on other ground nesting birds caused by increased fox numbers which in turn is in part driven by the availability of the millions of Pheasants released annually (not to mention the collateral effects on native predators through human persecution). As others have pointed out this particular argument against RN Parakeet is much, much weaker. However with the current state of affairs garden feeding does provide a lifeline for several farmland species (see BTO data) so the argument in principle is not spurious. As Ian has pointed out though, the primary problem with RN Parakeet as an invasive species remains, at this point in time, its effect on agriculture.
   Jim Clarke, 22/03/14 19:11Report inappropriate post Report 
#12
I don't want to name any individual respondent, but it is clear that we have entered a new era of species control freakery in the UK. Some people (not all) seem to be operating under the guise of sorting out the illegal immigrant problem, oops sorry got confused there! In effect, a sort of xenophobia against non-native wildlife in general. Of course in many instances evidence is there that non-native species can impact on native species, but native species also impact on each other. It's...more more
   Iain Gibson, 23/03/14 05:04Report inappropriate post Report 
#13
Brilliant Iain. I will add the figures for Goshawk removing Collared Dove from Berlin. Down from 100,000 pairs to 1000 pairs!! What man did there was not to remove the Goshawk. Goshawks in Britain are massacred by the shooting industry. Two nests took 68% and 95% Grey Squirrel as food!! Parakeets are now food for the increasing Peregrine population in urban areas with the Peregrines potentially saving £millions on removal of feral pigeons which damage buildings as well as giving diseases to the human population.
   John Miles, 23/03/14 07:25Report inappropriate post Report 
#14
I do'nt agree with Matthews' post and as such i do'nt need to be referred to it..... On a brighter note for the 'let's have everything living here' brigade you no longer have to legally report the presence of Grey Squirrels to the Police as the 1937 law has now been repealed - this was technically punishable by a fine upto £5! The only people who could have possibly afford such a fine back in those days would be from the same background as the people who introduced the bloody...more more
   Laurie Allan, 23/03/14 08:28Report inappropriate post Report 
#15
Iain I find your attempted linking of scientific studies into the problems caused by invasive species with xenophobia and right wing politics utterly contemptible. Smearing a group of people who hold a different view to you on a particular subject by applying a completely unfounded set of attributes to them is pure fascism.
   Jim Clarke, 23/03/14 13:46Report inappropriate post Report 
#16
Thanks Jim, your hysterical response is precisely why many people are afraid to speak their mind and address the sociological and psychological factors contributing to this trend. I didn't 'smear' anyone, and made it clear that I don't disagree with all concerns about the impact of non-native species. I also made it clear that I was referring to some attitudes, not everyone who disagrees with my own views. If anyone feels smeared I'd say that's down to their individual conscience. You have a...more more
   Iain Gibson, 23/03/14 16:03Report inappropriate post Report 
#17
Iain I think your second reply is disingenuous to say the least. You've been peddling this xenophobic slur for a number of years now. You called me it when I advocated the destruction of grey squirrels. It was an infantile argument then, does nothing to advance your position and frankly undermines the other valid points you make.
   Ian Bradshaw, 23/03/14 22:03Report inappropriate post Report 
#18
This discussion needs to be driven by more evidence and less opinion. Unfortunately except for the known problem species science cannot predict if an introduction could become a problem. So as Laurie Allen states the effects can be very subtle. Additionally we are dealing with artificial (man-made) changes to an artificial (man-made) environment – where can we draw the line? When dealing with non-native rats, goats, pigs etc. on an island the evidence is usually clear but here we have no “natural” baseline to work from. This leaves us only with speculation, opinion, bias, prejudice and all of the rest. I may not be totally sure of my facts here but I believe that the number of Mandarin Ducks in Britain is now a significant proportion of the world population which has been substantially reduced both in China and Russia although the Japanese population appears stable. Is this an example that introductions are not necessarily bad?
   Jeff Clarke, 24/03/14 00:36Report inappropriate post Report 
#19
I note with interest that the principal opponents of my sincerely held views have resorted to mud slinging. I've now been called contemptible, disingenuous, infantile and accused of being a fascist. Why so sensitive? Perhaps I've touched a raw nerve. To accuse me of promoting 'pure fascism' is so wide of the mark it's particularly ridiculous, not to mention defamatory, and an insult to the brave people who fought to defend us from the real thing. This is what happens when someone tries to...more more
   Iain Gibson, 24/03/14 03:14Report inappropriate post Report 
#20
Agreed - the word fascist is not one that should really be appearing on a bird forum and imo should be reserved for.........fascists. Unfortunately anybody that dares to question our immigration policy and enforced multi-culturism and seemingly feral, alien birds has to run this gauntlet. Who could have foreseen the potential effect of Ruddy Ducks with White-Headed? Now i realise that RNP's do not appear to have anything native in which to practice coitus but are they not cavity nesters? We all know there is a shortage of suitable trees and that cavities are at a premium (do'nt quote me on that). I do'nt know the answer but previous experience shows that just because there 'does'nt appear' to be a problem does'nt mean there wo'nt be one. History shows that there is one eventually. There are obvious examples such as releases and retro's such as Great Bustard, Goshawk, Little Owl etc where a niche appears to be being filled. Pork sandwich anybody?
   Laurie Allan, 24/03/14 07:19Report inappropriate post Report 
#21
Iain, your argument is old hat and long since dismissed in the community of scientists who actually study biological invasions. You might start here: www.researchgate.net/publication/.../9c96052681c6263708.pdf and then follow up with some of the references cited. More generally, the issues are: do aliens have impacts? If they do, do we need to mitigate those impacts? If we do need to mitigate those impacts, can we? Some aliens undoubtedly have serious and significant impacts, some...more more
   Tim Blackburn, 26/03/14 20:21Report inappropriate post Report 
#22
I contacted the woman running this to offer my garden for the study but it quickly became clear that she was anti parakeet so, believing the study to be biased I decided not to get involved. In my grade the parakeets and tits feed at different times of the day. The parakeets don't feed in my garden all year round but when they do I don't see any drop in the number of small birds visiting my garden. I have had up to 18 parakeets in my garden at any one time. I also get a pair of blue tits or great tits nesting each year. Usually there will be a pair of blackbirds nesting in the bushes too. Robins nest just the other side of my fence and a pair of wrens also nests close by. Last year I even had a family of long tailed tits nesting in a jasmine browning up by my kitchen window. None of these birds were in the least bit concerned about the parakeets.
   Sally Turner, 26/03/14 21:40Report inappropriate post Report 
#23
I live in West London close to Bushey Park and Hampton Court Park, probably the centre of the highest RNP density. I have plenty visiting my garden and also plenty of blue and great tits; I have seen no decline in tit numbers at my feeders. What I have seen is a massive decline in Nuthatch numbers in the two parks. I am lucky to hear the odd bird or two now whne 20 years back there seemed to be a Nuthatch on almost every tree in the parks. I also wonder whether the RNPs have had any influence on the decline of the Lesser Spotted Woodpecker. Howevr, I would totally oppose any suggestion of a RNP cull; I felt the same way about the Ruddy Duck. Tony Leppard (Whitton)
   Tony Leppard, 27/03/14 11:12Report inappropriate post Report 
#24
I don't know about nuthatches as I've only ever seen one locally but I get greater spotted woodpeckers feeding in my garden, both adults and juveniles. I've even seen them chase off a parakeet. The woodpeckers have only been visiting regularly in the last decade, before that it was an odd sighting. I also, now occasionally get green woodpeckers too but that is just the odd sighting.
   Sally Turner, 27/03/14 11:53Report inappropriate post Report 

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