World Rat Day 2026 (or: How Rats Sank a Ship)

Today (4th of April) is World Rat Day! On this auspicious day, we want to take the opportunity to tell two stories: a story of RATTUS and a story of rats.

A RATTUS story  

This weekend marks the end of Dr Michelle Feider’s time on the RATTUS project. She was the first postdoc to join us back in 2023. Over the last 3 years she has criss-crossed her way across Europe in 36 journeys, searching through collections large and small to find rat bones for the project to collect, catalogue, and analyse. When she wasn’t finding traces of rats in the past all over the continent, she was in the RATTUS office, the earliest one in each morning, weighing, measuring, and creating data for these thousands of bones.

Over these years, she’s been the backbone of our research project, helping the rest of us with advice, jokes, stories and, as one of the few car-owners on the project, many trips!

We’re very grateful for the countless hours and tireless work, her inventive solutions and her artistic talents. The project would have been impossible without her, and it won’t be the same after her leaving.

While we will miss Michelle a lot, she’s not going far! After a well-deserved few weeks’ leave, she will stay on at the University of York, using her many talents in her new role in student support just across the road from the RATTUS office! And you can never really leave the RATTUS project!

 Decorations celebrating Michelle's last day in the office

A rat story

As RATTUS is losing a member of its mischief (= a group of rats), it seems fitting to talk about perhaps one of the most bizarre examples of ratty mischief (= trouble caused by rats) our project historian, Daan Jansen, has found!

Let’s travel back in time almost exactly 141 years ago, to 1885. An average British barque, the Acorn, was on an average journey. It had just left the Indian Ocean island of Mauritius (of dodo fame) and was bound for Mumbai with a hold full of sugar. On the 18th of March, the Acorn started taking on an alarming amount of water. The water level in the hold was 2 feet and 2 inches (66 cm) that morning. After a full day of pumping water out of the hold, and taking shifts during the night, the water was still rising, up to 3 feet (91 cm) the next morning. 

 

Although no images of the Acorn could be found, this is a Barque from the same era that might 
serve as an example, the American ship Salmon P Chase. Via Wikimedia.

Pressure was mounting. This leak could spell disaster. The shipmaster, carpenter and first mate all sought desperately for the leak that might explain the huge amount of water coming in. They couldn’t find anything in the dark, wet hold. It’s unclear how large the Acorn was, but as a barque, she was at least 30 meters long – 3 feet of water would be at least 200,000 litres that had to be pumped out of the hold!

Realising the ship was sinking and stuck in the middle of the Indian Ocean, the shipmaster ordered the crew to start signalling for help and prepare for a possible evacuation. By the time a ship appeared and responded to their signalling, the Acorn had taken on 8 feet (244 cm) of water. The sugar in the hold was by now mostly dissolved into the seawater, which must have made a strange salty-sweet concoction! All agreed that the cargo was beyond saving and the ship would soon be doomed as well. The crew, exhausted from their constant work pumping water out of the hold, was evacuated and the Acorn was scuttled and allowed to sink into the Indian Ocean.

The ship that rescued the crew carried on its journey to Aden, Yemen, and a standard trial was held to determine what had happened. The trial record is the main source we have for this event. What’s remarkable about these records is that the crew could only come up with one explanation: Rats.

The shipmaster claimed that the Acorn “was full of rats”. The boatswain went further, stating “she [the Acorn] was full of rats. I think it must have been them.” The carpenter agreed, saying “I do not know how she came to leak so badly unless the rats had eaten a hole in her, she was full of rats.” Ultimately, the court ruled that rats were indeed to blame, and none of the (human) crew was found to be at fault or punished.

Were rats really to blame? Without some extreme underwater archaeology, it’s unlikely we’ll ever really know. Sailors were known to regularly blame rats for loss of cargo, and they were probably right to do so. A ship getting sunk by rats was definitely unusual. Several people have written comments on the court documents indicating surprise and speculating how rats might have sunk the Acorn. One suggested that the rats might have gnawed through one or more of the ship’s lead pipes responsible for regulating plumbing and water on board. It is certainly possible the ship was sunk by their handiwork – or toothiwork, in this case.  

Ship rats depicted in a children's magazine in 1870, T.W. Higginson, ‘Our Menagerie. IV.–Rats.', 
Our Young Folks: an Illustrated Magazine for Boys and Girls, Vol 6, No 8, p 488.  

Considering this was so rare, what might have happened? Was this simply an accident? A rat unthinkingly gnawing on some delicious lead piping that happened to cause disaster? That’s definitely possible.

I wonder, however, if we might consider the ship’s cargo: Sugar. Rats were known and indeed expected to nibble a bit off any ship’s cargo, and a hold of sugar is a proverbial jackpot to a rat. Research conducted a century ago, when biologists were less concerned with matters of ethics, established that rats could live quite well on diets consisting of up to 80% sugar – perhaps even more. Rats, it seems, could have easily survived on the cargo of the Acorn and probably thrived. So much food available meant that the population exploded. The constraining factor to the rat population onboard was likely either space or water, not food availability. In other words, when the crew said the Acorn was full of rats, they might not have been speaking metaphorically.

On a more depressing note, more recent studies have sugar that sugar has similar effects on rats as it has on us, causing addiction, stress, anxiety. With so much food available and little water or space, rats would end up in unusual places hoping to find something to drink. Dominant rats might bully smaller siblings away from the hold and into the piping, where fresh water would condensate. These stressed rodents, prone to gnawing to find comfort, might have a nibble at this wonderful water-forming pipework, inadvertently tearing through it, causing a leak, and ultimately sinking their home.

While the human crew was saved, it is unlikely any rats were allowed off the sinking Acorn. All hands survived, but she was lost with all paws.

This French ship in the Indian Ocean was sunk not by rats but by German raiders 
in the First World War. Nevertheless, the crew of the Acorn probably had a similar 
view after they left the ship to sink. Via the Australian War Museum. 

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If you’d like to read more about rats on board ships, I highly recommend: 

Kaori Nagai ‘Vermin Writing’ in Journal for Maritime Research 22:1 (2020) 59-74

Jules Skotnes-Brown 'Scurrying seafarers: shipboard rats, plague, and the land/sea border' in Journal of Global History. 18:1 (2023) 108-130