ANIMAL SMARTS
Crows collect discarded cigarette butts, goldfish learn to drive a mobile fish tank and orcas demonstrate some unusual behaviour
CORVID CLEANING
A startup in Södertälje, Sweden, has developed a machine that trains crows to collect discarded cigarette butts from local streets. When crows deposit the fag ends in the machine it rewards them with food. “They are wild birds taking part on a voluntary basis,” said Christian Günther-Hanssen, the founder of Corvid Cleaning, who believes his method could reduce the cost of picking up cigarette butts in the city by 75 per cent. theguardian.com, 1 Feb 2022.
FISH ON WHEELS
There is an old joke that goes: “Two fish are in a tank; one says to the other, ‘How do we drive this thing?!’” Now, Israeli researchers have made the joke a reality. To test fish navigation skills Shachar Givon and colleagues from Ben-Gurion University of the Negev have created a robotic vehicle and taught six goldfish, named after characters from Pride and Prejudice, to navigate it on land. They have mounted a fish tank on wheels and allowed it to be steered by the orientation and movements of the fish. They were then given a pink target in a room and were rewarded with food every time the vehicle touched it. When trained, fish managed to navigate the vehicle to the target from different starting positions in the room – even successfully navigating obstacles like false targets or after hitting a wall. Some did particularly well. “Mr Darcy and Mr Bingley… were total rock stars,” Givon says. While many studies have shown that fish can navigate in aquatic situations, the researchers say that this shows that the ability to navigate – essential to animal survival wherever they live – is universal to all species and does not depend on their environment. theguardian.com, 8 Jan 2022.
HELPFUL ORCAS
Whale watchers in Bremer Bay, Australia, caught a unique interaction between orcas and a humpback whale on camera, using a drone. Humpback whales usually spend the southern hemisphere summer near Antarctica, feeding on krill, so it was unusual to see one in the bay at the same time as the orcas, but this one appeared to be in bad shape, scrawny and covered in parasites; it also had some fishing gear tangled round its tail flukes. Initially two males from the orca pod investigated the humpback and were driven off by the whale lashing out with its pectoral fins and tail flukes, but then the pod matriarch approached in a great flurry of splashing and after she withdrew and the water settled, it could be seen that the rope binding the fishing gear to the humpback’s tail was floating away. Then, rather than attacking, the orcas swam away and apparently spent the rest of their day socialising and “harassing sunfish”.
Writing in the description of their video, the whale watching crew asked: “Did the Orca deliberately rescue this Humpback or was the decision made that due to his ill health the effort of the hunt was not worth the energy reward at the end?” livescience.com, 21 Jan 2022.
“JERKS OF THE SEA”
Orcas are certainly capable of taking down whales much larger than themselves because they hunt in co-ordinated packs, and at other times they have very much maintained their reputation as “jerks of the sea”. While there have been reports of orcas chasing blue whales, which can be 33m (108ft) long, actual authenticated attacks have been rare. Now, a paper published in the journal Marine Mammal Science has documented three co-ordinated, brutal killings of blue whales by orcas since 2019, also observed by whale watching boats off Bremer Bay. The attacks seem to have been
predominantly carried out by female orcas – surprising to scientists, as they had believed that for orcas to tackle large whales, the bigger males would need to take the lead.
In the first attack they observed at least 12 orcas, led by eight adult females and one male, with younger ones watching, kill a healthy adult male blue whale. Their onslaught on the whale continued for more than an hour, leaving it with large chunks of skin and blubber stripped off and most of the dorsal fin missing. Then, three female orcas lined up and rammed the whale in the side, pushing it underwater to prevent it breathing, while two others attacked its head, and another swam into its mouth and started eating its nutrient rich tongue. After that, more than 50 orcas joined in, feeding on the dying blue whale for several hours, along with a large flock of seabirds feasting on the scraps. The other attacks targeted a calf between 10m and 12m (33 to 39ft) long and a yearling up to 14m (46ft) long. In each case they followed the same pattern of an extended, systematic assault by a co-ordinated female-led group, forcing the whale under the surface with attackers targeting the mouth and tongue, followed by a larger group coming in to finish the dying whale off.
However, one of the study’s authors, Robert Pitman from Oregon State University, says that this might not be anomalous behaviour: “Maybe what we’re starting to see now is how the ocean used to be before we took out most of the large whales… As some of these populations continue to recover, we have a better chance to see how normal marine ecosystems function.” theguardian.com, 27 Jan 2022.