Most of the news to emerge through 2021 was mainly associated with pandemic-led traumatic experiences for the human race and the changing climate’s impact on the environment.
It wasn’t all bad, however—amid the serious findings, some studies designed to reveal some previously unknown quirks and behavioural antics from the animal kingdom brought in some light-hearted news for us to reminisce.
From enraged female octopuses throwing stuff at harassing males, to squirrels performing acrobats, here are the top quirky animal behaviours that were discovered by scientists in the year 2021:
The creative ways used by females to steer clear of untoward advances from male counterparts.
Within the avian community, it is commonly known that males have a bright coloured plumage to attract females. But what may come as a surprise is that, in hummingbirds, a quarter of the females have been observed to have the same shimmering plumage as their male counterparts.
A 2021 study conducted by Cornell Lab of Ornithology and Smithsonian Tropical Research Institute revealed that some female hummingbirds have developed this unique strategy, wherein they pretend to be males by looking like them, specifically to dodge harassment from the males. Such harassment behaviour includes pecking and body-slamming from males, especially when the females are feeding.
It is important to note that females show this kind of ornamentation only outside of their reproductive period, when they are not looking for mates. This further supports the theory that they pull such tricks only to steer clear of unwanted attention when it isn’t needed.
An interesting study led by Peter Godfrey-Smith found that female octopuses have a lot in common with human females, in that they retaliate against sexually harassing males by throwing objects at them!
While this behaviour was noticed back in 2015, its intention had remained unclear. After studying several such instances, it became evident that females were, in fact, engaged in several types of object-throwing behaviour.
They mostly tossed materials like silt, shells and rocks to simply remove obstacles along their way or to build nests. However, these objects were sometimes also thrown at nearby male octopuses—especially those attempting to mate with them.
The material was hurled and placed over a siphon that octopuses use to push out a jet of water very quickly and subsequently propelled at their desired target. One female was even seen throwing a shell like a frisbee using one of her tentacles!
Whether it is offence or defence, the animal kingdom surely knows how to keep their enemies away.
Although as tiny as the size of a rice granule, baby mantis shrimps are known to pack a pretty intense punch to protect themselves from predators, and that too with great speed.
Researcher Jacob Harrison as part of his PhD research found out that in one of the species of mantis shrimp, named Gonodactylaceus falcatus, the punching began as early as in the fourth larval stage—when the mantis shrimp larvae float up and become plankton—at an average of about 1.5 kmph!
And in natural conditions, in case the larval mantis shrimp use the punches to attack a predator, they might even move at even higher speeds as compared to the defensive ones.
During a research study conducted on wild putty-nosed monkeys, a type of forest guenon in Mbeli Bai, it was found that the females of the monkey clan use their male counterparts as shields when assessing a threatening situation.
The females are also known to recruit other males to ensure group defence, while the males themselves give "pyow" calls to the clan, to signal their commitment to serve as hired guns.
Researchers even identified a new call type named "kek", which was used by males when they were exposed to a moving leopard model created by researchers for field experiments. These calls appeared to be population-specific or exclusively for moving threats. If so, this would be a strong indicator for vocal production learning, which is otherwise debated to exist in the animal kingdom.
Screaming honey bees
New research led by researcher Heather Mattila found that honey bees create noisy and fierce sounds to alert their mates and get them to defend their hive against their most dreaded predator, the giant hornet.
Hornets are capable of destroying entire bee colonies at once. A single hornet, which uses its large mandibles to strike and decapitate prey, can kill as many as 40 bees per minute!
However, when alerted by the screams of a patrolling bee, the shrill warning sounds function as a signal to get all the brave bees to gather at the hive’s entrance to set up defences—similar to soldiers defending a fort. They even form bee balls to collectively kill the deadly hornets or spread animal dung around the entrances to repel the attackers.
The real detectives within the animal kingdom
While cats are often perceived as aloof and uncaring pets, cat owners know that this is a myth, and a new research helped them bust just that. It turns out that cats do care about their owners' whereabouts and, in fact, keep track of their movements even when they are out of their sight using their socio-spatial cognition!
According to scientists from the University of Kyoto, when domestic cats cannot see their humans, they use their preternatural ability to generate "mental maps" using acoustic cues to identify the location of their humans.
While it is universally acknowledged that the little furballs are fiercely intelligent, this study opened a new dimension to their cognitive abilities.
Dolphins are known to communicate directly with one another, and to echo-locate their prey before striking.
But several years ago, researcher Charlotte Curé, a bioacoustics expert, wondered whether they could also pick up messages that were not intended for them from other dolphins.
After four years of field studies, Curé’s team reported the first evidence of cetaceans eavesdropping on each other, and then using that information to decide where to swim next.
For example, when social recordings of male dolphins—which are known to harass females and antagonise other males—were played in front of other dolphins, most of them swam away to avoid interaction with the males.
The true artists of the animal kingdom
While musical notes are almost always associated with songbirds within the animal kingdom, and least of all, primates, a new study found that Indri Lemurs of the Madagascar forest produced sounds that consisted of musical notes with a categorical rhythm.
Indris are highly social, family-loving animals, and they sing together in harmony with voices varying according to their age and gender. Male and female songs have different tempos, but similar rhythms. While adult voices seem deep and sorrowful, the young, bubbly offsprings sing in a cacophonous high-pitched chorus.
On comparing the interval lengths between each sound, a research team led by senior investigators Marco Gamba from the University of Turin and MPI's Andrea Ravignani found that the songs broke down into typical textbook rhythmic ratios of 1:1 metronome, or 1:2, with the first interval being half as long as the second.
This is the first-known primate music band that showed the skills of a 'ritardando'—a decreasing musical tempo—similar to classical music.
While it is a common sight to see squirrels navigate through narrow branches that bend and sway with the wind, research conducted by N. Hunt and team showed that these rodents make split-second calculations to assess the stakes of making tricky jumps on bendy branches.
Now, it would be obvious to wonder how they make such accurate decisions. Jump too early, and the squirrel will fall short; too late, and the squirrel will find itself on a branch too flimsy to take off.
But by comparing statistical models that simulated optimal jumping decisions, the researchers found that the flexibility of branches had a major influence on their decision to jump rather than the length of the gap. If squirrels had cared more about distance, they’d have jumped from the same spot each time.
In fact, for longer jumps, or those that had a risky landing, many squirrels rotated mid-air, using their legs to “jump” off an adjacent vertical wall in a parkour-style manoeuvre.
While these fascinating behaviours definitely added a fun element to a grim year, here’s hoping that animal behaviour research continues to shed light on more interesting quirks from different species, while helping scientists conserve more species and heal the planet.