So it sounds like in all likelihood the chickens there ARE established?
Interesting/Little Known introduced populations
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Haliaeetus
Well-Known Member
The situation seems unique in Europe.
In France I can't see any situation like this, even around biggest cities like Paris, where there's plenty of crows, rats, and even foxes that can threaten quickly the life of the chickens and of their clutches.
In France I can't see any situation like this, even around biggest cities like Paris, where there's plenty of crows, rats, and even foxes that can threaten quickly the life of the chickens and of their clutches.
Onychorhynchus coronatus
Well-Known Member
Arapaima are now being found in rivers in Florida it would appear:
An Amazonian arapaima washed up in a Florida river. It didn’t swim there
Honestly, what the hell is wrong with the people living in that particular state with their proclivity to buy exotic pets and then release them into local ecosystems ?
Sometimes it just seems like it is an extension of a hyperconsumerism mentality, purchasing something on a banal whim and then ignorantly throwing it away without any consideration of the consequence.
It really irritates me when I read about this kind of thing...
An Amazonian arapaima washed up in a Florida river. It didn’t swim there
Honestly, what the hell is wrong with the people living in that particular state with their proclivity to buy exotic pets and then release them into local ecosystems ?
Sometimes it just seems like it is an extension of a hyperconsumerism mentality, purchasing something on a banal whim and then ignorantly throwing it away without any consideration of the consequence.
It really irritates me when I read about this kind of thing...
Honestly this is unfortunately fairly true. People buy turtles, pythons, iguanas, cichlids, catfish, etc as little babies, often not realizing the eventual size of the animal nor the commitment. Many places won't take those animals and they end up dumped into the wild. The places that do take them get inundated with the creatures. It's really a serious problem at this point.
Onychorhynchus coronatus
Well-Known Member
When I look at the amount of invasive species in Florida it really truly makes me despair.
It is a total ecological mess because of this problem and it seems that once there is a push to erradication one species then before too long there is another exotic species that is found to be establishing there and having an adverse impact on native biodiversity.
I mean it is really a sort of illustrative case / cautionary tale of the dangers of invasive species for conservation biologists all around the world.
I think ultimately at least some of the solution is that this whole phenomenon probably has to be tackled at its root cause which are social and is the exotic pet trade and legislation regarding ownership of these exotic animals.
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Feral chickens are far from established in the Netherlands. SOVON, the Dutch centre for field ornithology, estimates at most a few dozen pairs across the country. Some chickens are known to be able to keep themselves alive for years in "the wild", and some even breed, but calling it an established population is a huge exaggeration.
The main distribution of chickens in the Netherlands according to SOVON in on the eastern part of the province of Zuid-Holland (east of Rotterdam) and the western part of Utrecht. That area lies comfortably within the distribution of Northern Goshawk, Common Buzzard, Tawny Owl, Carrion Crow, Rook, Eurasian Magpie, Herring Gull, Lesser Black-backed Gull, Grey Heron, Great Egret, Norwegian Rat, Stoat, Weasel, Polecat, Red Fox and Beech Marten, all of which are potential predators for chickens or their eggs and young (based on SOVON and the Zoogdiervereniging - the Dutch mammal association). The maps are often not detailed enough to exclude small pockets within the 5 x 5 km grid to be "predator free" (although I guess there will always be corvids, rats, cats or dogs), but the situation for chickens is far less favourable than described by @Jurek7.
EBBA2 furthermore notes that the main hubs for chicken distribution in the Netherlands are areas with large numbers of illegal released. Given the frankly enormous number of chickens kept both by farmers and hobbyists, and especially the latter category regularly keeps them behind inadequate fencing or even free-ranging, there's a huge and constant influx of releases and escapees. And yet the best estimates we have for the populations talk about a few dozen breeding pairs at most. So no, chickens are far from established and I doubt many "populations" would keep going for more than a few generations without influx of new individuals or human support. In contrast, Egyptian Goose, Canada Goose, Rose-Ringed Parakeet, Vinous-throated Parrotbill, Common Pheasant and a number of other exotics are known to reproduce steadily over multiple generations here, often surviving with minimal human help and sometimes (e.g. for the geese) despite eradication effort, something I've not seen reported for chickens.
It is highly complicated, and ever-changing which makes it even worse. Some of the long-established parrot species are actually declining, being caught and sent into the pet trade again. Budgerigars once had a sizable population in Florida, yet they are now all but gone, outcompeted for nest sites by other invasives like starlings. Pythons and alligators go back and forth eating each other, and nobody can really say who has the upper hand. Vagrant birds from the Caribbean confound population statuses such as with White-cheeked Pintails. It's become an absolute mess, and I doubt it will ever be fully solved at this point.
Florida has started banning importation and ownership of many invasive species, mostly with reptiles and fish. As far as I've heard most of the birds are generally coexisting with natives without much problem, barring a few like starlings and the Purple Swamphen. The latter faced eradication attempts by shooting, but after the birds kept appearing and the native Purple Gallinule suffered from misidentification, attempts to eradicate them ceased. They are controlled as best as possible, but they are here to stay.
It doesn't even have to be the exotic pet trade either. Red-eared Slider and American Bullfrog are both natives that were introduced to much of the country outside their core range. Pet trade and eating respectively were the reason they arrived, and they essentially have cemented themselves everywhere. Or look at goldfish. There's numerous populations formed from released individuals, and yet they still are sold all over. (Additionally Goldfish suffer from an ethics issue, most people do not keep them properly at all, and the fish live a stunted, short life.)
There's also hunting, which has seen the introduction of various gamebirds and hoofstock. Interestingly most of the successful gamebirds have assimilated themselves into our ecosystem without much conflict. Ring-necked Pheasant, Gray Partridge, Chukar, and Himalayan Snowcock have really only minimally impacted our ecosystems. The hoofstock on the other hand, such as Nilgai in Texas and Gemsbok in New Mexico are having a significant impact on the environment and eradication is the target.
All together a very difficult situation indeed.
Onychorhynchus coronatus
Well-Known Member
Yes , I agree, it is very much an evolving situation and it is often hard to see through all the static as it is with all situations with biological invasion.
True, some of the vagrant birds from the Caribbean that you mentioned may be natural colonization events rather than invasives as such.
It is natural that populations will wax and wane even if there is an initial rapid reproduction and dispersal rate but even if some of these species that you mention have not eventually established I think there will be some which invariably do and those are to be worried about.
I agree it is such a difficult situation in Florida and actually when I look at it and what a total mess it is it makes me feel somewhat less overwhelmed with the situation of invasive marmosets that we are dealing with here in Brazil.
Hi, concerning feral chicken in the Netherlands, you can check the map yourself:
Kip (gedomesticeerd) - Gallus gallus forma domestica
It shows that they are much more widespread than Sovon estimates. Only last year, 167 1x1 km squares were reported. While fewer are wild, this suggests much more than 'at most few dozen pairs'. It is typical that non-native birds are overlooked by the ornithologists. They go after long-established native birds going extinct.
I agree that it is difficult to know how self-sustaining are feral chicken. Probably the question is wrong: in the Netherlands, domestic and potentially self-sustaining wild groups are one mixing population, like feral cats.
Just remark on predators: 5x5km grid is meaningless from the point of view of mammal predation on ground birds. Multiple canals and motorways create plenty of much smaller pockets of land like individual parks, and green spaces, where chicken live but predatory mammals practically don't visit.
Kip (gedomesticeerd) - Gallus gallus forma domestica
It shows that they are much more widespread than Sovon estimates. Only last year, 167 1x1 km squares were reported. While fewer are wild, this suggests much more than 'at most few dozen pairs'. It is typical that non-native birds are overlooked by the ornithologists. They go after long-established native birds going extinct.
I agree that it is difficult to know how self-sustaining are feral chicken. Probably the question is wrong: in the Netherlands, domestic and potentially self-sustaining wild groups are one mixing population, like feral cats.
Just remark on predators: 5x5km grid is meaningless from the point of view of mammal predation on ground birds. Multiple canals and motorways create plenty of much smaller pockets of land like individual parks, and green spaces, where chicken live but predatory mammals practically don't visit.
I don't think exotic pets are significantly more common in Florida than anywhere else, but that it is simply much easier for most released pets to survive in Floridian weather than other states.
Waarneming.nl is not a trustworthy reference to know actual breeding populations. Everyone can upload everything and the moderators don't really show a lot of interest in exotics. Furthermore, I suspect many sightings to be escapees or releases. SOVON, while also in part depending on citizen science, at least has standardized counting protocols, and several of their projects specifically request also counting feral and exotic species (in particular MUS for urban bird census counts).
The 5x5 km grid is not meaningless. It very clearly rebuts your claim that the Netherlands has an 8000 km2 area with "almost no predators". Furthermore, avian predators can easily reach most of the isolated pockets you cite, and the barriers for mammalian predators often also limit chicken dispersal.
I'm not saying there are no feral chickens in the Netherlands. My point was that the actual situation is far less favourable for feral chicken populations than you claim it is, and that long-term establishment of the species in the wild in the Netherlands is rather questionable.
Onychorhynchus coronatus
Well-Known Member
Yes, I agree, but the fact remains that they seem to end up within the local ecosystem as invasives more in Florida than in most places and that is just a very depressing situation.
I have just seen this interesting bit of recent research that I think is worth sharing here.
A study of the genetic diversity of Chinese water deer introduced to Britain has shown that they could be valuable to restoring native populations in Asia. While the study found, as expected, that genetic diversity was higher in China, the deer introduced to Britain are of a genetic type that is now probably extinct in China. They are therefore excellent candidates for repatriation to China for reintroduction.
Britain is currently home to approximately forty percent of the global Chinese water deer population.
An article about the study is included here:
Chinese water deer introduced to UK may be valuable to restoring numbers in Asia | Imperial News | Imperial College London
The abstract for the scientific paper is included below:
Conservation genetics of native and European-introduced Chinese water deer (Hydropotes inermis)
A study of the genetic diversity of Chinese water deer introduced to Britain has shown that they could be valuable to restoring native populations in Asia. While the study found, as expected, that genetic diversity was higher in China, the deer introduced to Britain are of a genetic type that is now probably extinct in China. They are therefore excellent candidates for repatriation to China for reintroduction.
Britain is currently home to approximately forty percent of the global Chinese water deer population.
An article about the study is included here:
Chinese water deer introduced to UK may be valuable to restoring numbers in Asia | Imperial News | Imperial College London
The abstract for the scientific paper is included below:
Conservation genetics of native and European-introduced Chinese water deer (Hydropotes inermis)
Andrew Swales
Well-Known Member
Maybe the EU should add the chicken to their invasive species lists and ban farmers from keeping them?
Be careful what you joke about. I’d really like some Egyptian Geese
Andrew Swales
Well-Known Member
They could add the domestic cat too, along with the chicken.Be careful what you joke about. I’d really like some Egyptian Geese
Banning the populations favourite pet and protein source at the same time, must be a great vote winner!
Haliaeetus
Well-Known Member
It makes me think about subspecies of the Tammar and Parma Wallabies, extinct for decades in their native range, but both surviving as introduced animals on a small New Zealander island (Kawau island), and then reintroduced in Australia.
There may be other examples like this one ; it confirms that at least in some cases, the introduced species shouldn't be considered as aliens or pests, but they have got a real genetic and biological value.
Beavers in Patagonia :
https://phys.org/news/2021-04-broug...-ivddNw_F5MiLoiJZg5fdjLfHaMUE7wkcaLFAMla-W0tI
https://phys.org/news/2021-04-broug...-ivddNw_F5MiLoiJZg5fdjLfHaMUE7wkcaLFAMla-W0tI
Arabian sand gazelle have allegedly been introduced to Nushki, Balochistan in Pakistan by the same Arab royalty who have decimated the local goitered gazelle population. I don't know for certain if this claim is true yet though.
Also, blackbucks, which don't occur west of the Indus have been introduced, and are living wild, in Kirthar National Park in Sindh, and at least 3 female Ladakh urials have been released on Kharpocho hill, in Gilgit-Baltistan, nestled between the town of Skardu on one side and the Indus river on the other.
Also, blackbucks, which don't occur west of the Indus have been introduced, and are living wild, in Kirthar National Park in Sindh, and at least 3 female Ladakh urials have been released on Kharpocho hill, in Gilgit-Baltistan, nestled between the town of Skardu on one side and the Indus river on the other.
Be careful what you joke about. I’d really like some Egyptian Geese
I do like Egyptians, with the piratical eye patch, the bright colours and that steam-engine huffing noise the males make. They may be coming to you shortly anyway. They are already colonising East Dorset now so West Dorset may be next. A pair were photographed perched on the battlements of Corfe Castle recently...