Atitlan grebe (1 Viewer)

During the debate on the ruuddy duck cull I mentioned the plight of the now extinct Atitlan grebe. It was pointed out that the pied-billed grebe invasion was possibly an natural expansion whereas I was under the impression that the invasion was human-assisted. I have since checked the details and it seems that both ideas may have an element of truth. The Atitlan initially declined asa result of reed cutting an introduction of bass for the game fishing industry when Pan Am promoted the lake as a tourist destination. An earthquake then reduced the volume of water and further removed their nesting habitat so that the population fell to a maximum of 80 birds. The population then recovered to around 200 birds before the pied-billed grebes became established. Pied-billed grebes are distributed through Central and South America as well as North America and it is thought that colonisation of the lake was partly helped by human habitation springing up around the shoreline. The precise way that this worked is not really known but an attempt was made in 1986 to round up what were thought to be the last birds but at least a dozen birds simply flew away and it was realised these were probably hybrids. The last presumed pure birds were seen in 1989 but it is now thought these may also have been hybrids and the species ceased to exist many years before.

In conclusion, I now retract this as a direct comparison to the ruddy duck/WHD situation except as an illustration of the dangers of inaction until it is too late.

A similar sorry tale can be told for the presumably now lost Alaotra Grebe of Madagascar; predatory fish introduced, habitat change and range expansion by the Little Grebe.

surely the PB Grebes shoud've been culled then?

Hi Tyke

conservation is very very low on the priority list of Guatemala - they have much more pressing issues

it is no suprise to see the hand of man involved again here.

It seems that one brave lady tried to save it:-
http://traveltolatinamerica.com/0393308006.html
Colin

Tim Allwood said:

surely the PB Grebes shoud've been culled then?

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I am afraid not, pied-billed grebes are/were distributed throughout Centraal and South America and it is not known why the Lake Atitlan population became isolated and evolved separately. All the same, there was always a possibility that pied-billed grebes would get back onto the lake without human interference apparently.

Tyke said:

Ian-what a dreadfully sad story .
Do you know whether the Guatemalan Government had given the area any conservation protection -or did the development of game fishing etc start illegally-or did no one foresee the consequences ?

On RD cull could you tell me what the current status is -Is the trial cull the end of it-or will it be resumed-or is it stalled on consultation etc .?
Thanks
Colin

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The Guatemalan government seems to have been extremely accomodating but the efforts largely seem to have been coordinated by people from the USA according to what I have read. I assume the game fishery was also sanctioned by the government but I imagine that no one could figure out what the impact would be. If there is one lesson to apply to the ruddy duck it is that we cannot afford to keep interfering and hope that we will get away with it. It is by sheer luck that Canada geese have not caused a conservation problem (although local councils will tell you there isa severe environmental problem) and we can shivver at the thought of the potential in ring-necked parakeets and black swans. I often think that the reason some people have such strong feelings about the ruddy duck isssue is because it is being over-promoted as a purely Spanish problem.

The cull is ongoing but it is at a relatively early stage and this reflects the main cull not the trial, which ended two years ago. There is no consultation because all the appropriate parties agreed things ages ago although one body has since changed tack. I do not wish to sound curt but I am not going to comment any further about this side of things because my wages are not paid by any other organisation and it would be wrong of me to make any other representation.

Thanks for that Ian-I agree with all you say-I hope the cull is a success . I hope someone wakes up to the parakeets before its too late .
I remember taking my young children to Canon Hill Park in Birmingham 25 years ago when the Canada Goose shit was a skating rink of a health hazard .
God knows how many of these pests we have now .
Colin

Yes Ian , I know the distribution of Pied billed Grebe.....

given the human interference detailed in your own post Ian, plus the efeects of the introduction of Large-mouthed Bass, a cull would be attempted today i would hope.

Tim Allwood said:

Yes Ian , I know the distribution of Pied billed Grebe.....

given the human interference detailed in your own post Ian, plus the efeects of the introduction of Large-mouthed Bass, a cull would be attempted today i would hope.

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I am not that certain, I think in this case (especially given the ID difficulties) it would have been prudent to advocate a rolling control. People have suggested this in the ruddy duck case but it does not help the "animal rights" case because it would inevitably involve a lot more than the 6,000 birds outright eradication (in the UK) would take. However, this underlines one aspect of the ruddy duck case perfectly, that a cull option is not an automatic choice and is not as ill-considered as some people would have us believe.

Tyke said:

Thanks for that Ian-I agree with all you say-I hope the cull is a success . I hope someone wakes up to the parakeets before its too late .
I remember taking my young children to Canon Hill Park in Birmingham 25 years ago when the Canada Goose shit was a skating rink of a health hazard .
God knows how many of these pests we have now .
Colin

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Ian Peters personal comment alert - I know, I wonder if some of the opponents of the ruddy duck cull (and I don't mean BF members) will be consistently vocal against the cormorant issue or the canada goose issue. In both cases, this is likely to involve many more than 6,000 birds over a number of years.

What I do agree with is that the Ruddy Duck cull is absolutely nessecary to preserve the Whiteheaded Duck, though I am not happy with it.

But what I do not like is the attitude that often goes with the introduced species. Many people here in Europe seem to think that generally introduced species can be considered as "vermin "; give them this and other equally "bad names" and want them to be exterminated.
In my view this can only be termed "ecological racism" .

People forget that the species themselves did not ask for being brought here, this is due again to human action. So, if an introduced species in a new habitat does not have much impact on native species, we should leave it at that, but keep the species under close observation (and do research on their biology in the new country). I don´t think we have the moral right to exterminate a no-problem species again, after we humans have brought it here.

We have problems enough with species like the American mink (that threatens the rare european mink and probably also the polecat), the grey squirrel, the ruddy duck and several plant species, where immediate action is nessecary. Therefore we should focus our main efforts in eradication programmes on those organisms, watch the other introduced species to see if some may cause problems in the future (scientific research needed, not some anecdotal evidence) and try to prevent the introduction of new species.

I think that every exotic species seen in the wild should be watched and follow "10 scenario" - if there are ten individuals and they are breeding, they should be eliminated. You can change number a little, but the rule remains.

Most exotic animals at the beginning can be caught alive or prevented from breeding. This would be good for animal welfare, too - many exotics suffer in new conditions, eg. parrots die in cold spells. A minority of species could not be caught humanely and need to be monitored and eventually shot - again, just a few animals at a time.

At some point there was only a few Ruddy Ducks or Mink breeding in Britain. Hiring two men with boat to catch first wild Ruddy Ducklings, or with live-traps to catch escaped mink would be cheap and wise compared to what is now. Additional gain would be that people would be more careful about keeping captive animals - because they might pay the bill.

There are now about fifteen House Crows flying free in Holland, some Bar-headed Geese and Black Swans in Britain - why to wait and wonder how many of them will be in ten years? We made mess with Ruddy Ducks and Mink. But we can at least prevent making mess with other species.

Hi Joern-you touch on a really difficult set of choices I think-& a really interesting & important debate . Our Government is apparently considering setting up an agency for the control of " alien " species ( I have presumed this doesn't include Conservative voters ! ) & if it ever happens I can foresee considerable controversy .
If a species-like grey squirrel over here- is introduced by the actions of man-deliberately or by default into an ecological niche which they would not "normally" have reached & which gives them an unfair competitive advantage over a native species-then the choice is clear :- You turn a blind eye & risk or encourage local extiction(s) and/or hybridisation ;or you seek to avoid this outcome by reversing the mistake made in facilitating the introduction . There is a report in our papers today of the successfull eradication of grey squirrels from the Isle of Anglesey-& the explosive growth in the population of native red squirrels . I feel this was a good thing to do . If such a species-say Canada Goose becomes a health hazard to humans -& this bird has in UK parks-then surely it is reasonable to remove this hazard-if neccessary by culling -you would do it if it were dogs or rats-what's different ?.
The areas I find more difficult are 1) Introduced species which appear to pose no competitive disadvantage on a native species & 2) New species to our country which have arrived of their own volition-perhaps as a result of climate change effect on range & feeding .
In the former case ,part of me says they should be removed -but like our moorland wallabies (!) where they seem to provide no disadvantage to a native-I could not support their elimination-perhaps a watching brief & light culling to limit expansion . In the latter case I believe that no action is justified -species come & go & change as the earth changes -this is evolution & we should just watch & wonder at it .
Colin

If they are non-native and pose ANY threat to native biodiversity they need removing. History is littered with examples of extinction, including birds, resulting from introductions.....knowingly or unknowingly made.

I would be very suprised if species colonising an area by 'natural' means leads to the extinction of a bird species.

Some interesting points and a subject that clearly needs debate. Unfortunately it is very difficult to define species colonising by ‘natural means’ on this increasing disturbed planet. Pied-billed Grebes and Little Grebes in Guatemala and Madagascar respectively colonised ‘naturally’ but taking advantage of habitat alterations caused both directly and indirectly man. As has, I believe, the Stilt which now threatens the endemic New Zealand one (can’t remember the names of the top of my head) it a situation very similar to Ruddy and WH Ducks. I whole-heartedly agree with Jurek that any exotic species which looks like establishing themselves should be eliminated as early as possible even where there is no scientific evidence that they may affect native species. All introduced species are likely to be damaging particular in insular habitats. In Mauritius I was involved in research (yet to be published) which showed that nest predation by the introduced Red-whiskered Bulbul, previously regarded as fairly benign species, is probably the underlying cause for poor nesting success in endemic passerines such as Mascarene Paradise Flycatcher.

And attempts to anthropogenise and inflame the argument with comments about ‘ecological racism’ are surely misguided. Introduced species are bad per se and need to eliminated as before they become established.

I personally am extremely uneasy with this public enemy no1 staus that seems recently to have become attached to any introduced species...as if the taint of human intervention puts them beyond the pale conservation wise...

How people feel about this with regards to -

The reintroduction of species such as Red Kite, White-tailed Eagles, Capercaillie (particularly as with these three - as range expansion into the areas they now inhabit looked to have been impossible from their existing population?)

Mandarin Ducks - potentially under threat in the far east, their UK population may become important in the great scheme of things if numbers continue to fall within their natural range (perhaps one day the same may be said about Golden Pheasants)

House Crows - their natural range expansion has been facillitated by ship-assistance (and who`s to say the same didn`t apply to the now sadly defunct Snowy Owl breeding population in the Shetlands - most UK Snowies these days look like candidates for Ship-assisted vagrancy rather than naturally dispersing birds)

Introduced species which seem to have been around and settled for so long we almost forget that they are not indigenous - like the Little Owl

Birds whose expansion into Britain have been natural but facilitate by human activity and would never have occured without human impact on the environment - such as Fulmar and Collared Dove?

Hi Tyke, the feral Canada goose in parks are a different thing in one way- at least in germany -they stay in the parks because they are feed by "wellmeaning" humans. But Feral Greylags do the same here and cause the same problems. This is more a problem like the pigeons problem in the cities...If feeding stops, the populations may sink again.

Another point is the question if Canada geese pose a threat to the native greylags by competition and hybridisation. If yes then they need to be removed.

Tim , I am tending to agree with you there, but the problem here is that there are people that say: If it is non-native let us eradicate it, regardless if a species poses a threat or not. I would prefer to have such things clarified by research projects monitoring the species before calling for the gun, and instead concentrateon those species that are already known to pose a threat to native species.

Another point: if an introduced species has a slight impact on a native species, lets say, reduces the population about 2-3%, should it be removed then, in your opinion?

Jasonbirder said:

I personally am extremely uneasy with this public enemy no1 staus that seems recently to have become attached to any introduced species...as if the taint of human intervention puts them beyond the pale conservation wise...

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Well, its not ANY introduced species that is Public Enemy no. 1, although personally I feel that there are very few that can really be justified if they are complete aliens i.e. from a different zoogeographic region.

To answer each question

Red Kite etc. - all have to sanctioned scientifically now before they can be done (admittedly Capercaillie was before this), only reintroductions of species belived to have been extirpated by man are usually sanctioned and none have expanded their ranges to cover their historical ranges. No problem.

Mandarin Duck - as they are well-established and occupy a completely vacant ecological niche I would leave them BUT the conservation importance of the UK pop has been massively overstated - there are a lot more in the Far East than previously thought. Single flocks have been recorded in Korea with several times the UK pop in them.

Hooded CRow - dangerous species, should be controlled, would not spread without man's help. Get rid.

Snowy Owl - there was a clear influx of birds into Shetland in the 1960s. There was absolutely no evidence for them being ship-assisted.

Little Owl - vacant niche/well-established/no obvious competitors argument again. There is also evidence of prehistoric (as in before written records) occupation of UK.

Fulmar/Collared Dove - okay, yes, there are no cases now of completely natural expansion as all species will occupy habitats altered by man. In both cases, the cause of the original expansion is still unknown but evidence suggests that it was not caused by man, although it may have been facilitated by human activity.

There are so many introduced species it is impossible to control them all - but I would welcome any control of species having a clear detrimental effect on the 'natural' ecology, given that the word natural needs a lot of qualification in the modern world.

As a counter-argument - I believe that it is almost impossible to catch native fish in Florida as there are so many aliens and that common graden birds in NZ are nearly all introduced alien species. Personally, I think it would be a very sad day if we allowed that to happen anywhere else.