This thread started by Stuart Bowie raised a good thought in my head. Having come from a diving and somewhat amateur ichthyology background I was wondering what would happen to the Seagull if it were to ingest a poisonous species of fish.
FYI - Pufferfishes (fam. Tetraodontidae) are known to be poisonous for human consumption so it is natural to think that the poisons may have a similar effect of a bird's digestive system. Could you shed some light perhaps? I'll also ask some local experts on this subject.
Stuart, your image will get quite some views, as I will link it to a local birding resource.
Good question Ákos. I don't know the specific answer but I can speculate. It would be good if others would too.
There are examples of smaller, fruit/seed eating birds which happily ingest poisonous berries that would make us very sick or even result in death. I imagine gulls, being scavengers to some degree, have "cast-iron stomachs" and can eat all sorts of foods contaminated with E. coli, Salmonella etc. Botulism toxin is another thing, and wild birds do die of avian botulism.
Pufferfish tissues contain an extremely powerful toxin called Tetrodotoxin, as you know Ákos. I doubt very much if gulls could withstand this super-potent poison in their system as it works at a very basic level of nerve transmission.
Another natural and potent toxin in the environment is the one that causes Paralytic Shellfish Poisoning. Invertebrates and lower vertebrates like fish seem to be able to deal with this toxin but higher vertebrates like birds and mammals are affected and will die if sufficient toxin is ingested.
From what you are saying I understand that Paralytic Shellfish Poisoning is contained in invertebrates and the higher up the foodchain the animal containing the toxin is when it is eaten by a predator, the more likely it is going to harm the predator due to the posions having cumulated in the victim's system over time? Hence why we are not meant to eat things like shark or tuna or generally fish liver as they contain much high concentrations of toxins.
I think it's partly bio-accumulation up the food chain but I think there is also something going on with lower verts like fish, which makes them tolerant of the toxin.
Please note while many people will say "Seagulls" there is no such "thing" or group of birds. They are in fact just Gulls. I understand it's the common thing to say and many people know all Gulls as Seagulls. As some what of a "hard core" birder it's just a minor point but thought I would bring it up.:)
Also most gulls do not spend their time at sea but near shore and many are found inland and near lakes and rivers.
It's somewhat like people saying Canadian Geese...no such thing they are Canada Geese (Goose).
Having said all this it's an interesting topic about poison fish and gulls or any seabird that might eat such a fish.
All of which is making me hungry so now I'm off to lunch and a nice tomato salad....or is that "tomoto"?
You are of course correct Shawn; "seagull" is a colloquial, collective term and is not strictly correct. Maybe we should ban the word, like Artie Morris has banned "nit" on BPN! I know one of my supervisors would come down hard on you if you said "seagull". When people say seagull to my face, I normally, gently remind them that there are only a very few true seagulls and one of them is my favourite bird, the kittiwake. The rest are just gulls and mainly live nearshore or inland.
Ákos- you got off lightly!
It's good to have a pedant or two on BPN. Well done Shawn!
Thanks so much for the great feedback and info on the subject. Whilst posting the image, my only thoughts were of the gull with an unusual catch. I was aware puffer fishes were poisonous, but didnt realise the danger to marine birds as well.
Akos, I now understand your interest, being a diver.
I am happy to be corrected on my colloqialism and personally also prefer the correct common name usage without any doubt. The species I know locally is technically called Silver Gull (Larus novaehollandiae) but we all call them Seagulls. :o We also refer to people who are pests as Seagulls. I will only retain the word in that case, and the Lord be my witness.