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Gulls acting strangely on flying ant day?

Posted by on July 30, 2014

Black-headed gull on flying ant dayGulls and other birds are often seen behaving strangely during flying ant season. Rebecca Nesbit (co-ordinator of the flying ant survey) discusses whether this could have anything to do with formic acid.

Following the latest article in the Telegraph on gulls getting drunk on flying ants, it seemed time to share some of my research which never made it into the article. There are many reasons why gulls behaviour can be noticeable and, as I explained last year, they range from formic acid to botulism.

There seem to be conflicting reports of gulls being ‘dozy’ and gulls being ‘boisterous’, which is a flaw in the drunk analogy: alcohol can induce both these behaviours in people, but it’s very unlikely that formic acid would be inducing both in gulls. There are lots of possible explanations for both behaviours. 

Boisterous is a common mind-set for gulls, and the feast that flying ant day provides often leads to loud cries from circling birds. Dozy is also very common, and can be a sign of illness or of over-heating. A common illness for gulls and ducks is botulism, which may have contributed to herring gull decline.

Most botulism outbreaks happen during the summer and autumn when temperatures are high. It affects the peripheral nerves in birds and results in paralysis of certain muscles. Inability to fly is an early sign, followed by the inability to walk.

What about the effect of formic acid on gulls? We know that it’s not a good thing for humans to drink (“ingestion  of formic acid  at  high  concentrations  can  be  fatal;  there  are  local effects  on  the stomach,  derangement  of blood  clotting mechanisms,  and  in  acute  cases  renal  and  respiratory failure  leading to  death”). I wasn’t able to find much about the effect on birds from the scientific literature. I found that it can be corrosive, but this is specifically on birds’ skin rather than having consumed it.

There is evidence that ‘anting‘ (when birds intentionally cover themselves in ants) could be to rid the ants of formic acid before they are consumed. The negative effect of consuming formic acid may not be intoxicating though.

However, formic acid is found in higher concentrations in Formica ants than in the species we’re seeing most commonly on flying ant day.

In summary, I don’t have enough evidence to rule it out, but my money would be that the answer to the question ‘can gulls get drunk on flying ants’ would be a no. And I would like to put in a word for the gulls. I say gulls, not ‘seagulls’ in recognition of the fact that there are many different types of gulls with different life-styles and behaviours. They can be both beautiful and fascinating.

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