Dark fur provides great nighttime camouflage, but may impair visual communication between melanistic cats, a new study says.
Black cats have long intrigued us, from comic book heroes to symbols of superstition. They’re also more common that you might think: At least 14 of the 35-plus species of wildcat—including jaguars, leopards, and bobcats—can carry a gene that causes melanism, or a surplus of melanin, or pigment, in the cat’s fur. The term “black panther,” in fact, is a catch-all term that refers to any wildcat with a black coat.
The persistence of melanism among wild felids suggests it offers some advantage, such as camouflage or regulating body temperature.
Now, new research published December 18 in the journal has unearthed a potential downside: Hindering communication. Many wildcat species possess white marks on the backs of their ears and tail tips that allow them to signal crucial information to other individuals—markings that don’t exist in melanistic cats.
For the study, ecologist Maurício Graipel of the Universidade Federal de Santa Catarina and colleagues modeled the connection between black coats and communication. Their results suggest that though better nighttime camouflage is a boon of being a black cat, the absence of white markings is their Achilles’ heel, resulting in an evolutionary dilemma—is it better to be melanistic or not? (See our exclusive picture of a rare black wildcat seen in Africa.)
, a house cat-size feline, in southern Brazil, when his camera traps captured evidence of both melanistic and non-melanistic animals.
To his surprise, the data showed that melanistic tigrinas were more active during moonlit nights than the regularly spotted tigrinas. Graipel and his colleagues attributed this pattern to the black cats’ more effective camouflage, which renders them less visible to both predators and prey.
However, Graipel noticed something else: While non-melanistic tigrinas have white spots behind their ears, their melanistic cousins are missing these bright spots of fur.
White is conspicuous at night, and all cat species are at least partially active in the dark, Graipel wondered about the role of these white marks in visual communication—and what it would mean for the melanistic cats that lack them.
So Graipel and his team collected records of all the scientifically confirmed occurrences of melanism in the cat family that they could find. Then they scoured books, articles, and the internet for images of cats with white marks on the backs of their ears. To this data, they factored in ecological characteristics of the species, such as their activity levels during day and night, and used statistical modeling to investigate the association between black coats and communication.
“Considering that positioning of the ears can signify many things, especially to other individuals of the same species, and that felines are able to see very well even in low light, such white marks can serve as a silent warning signal to those following them at night,” Graipel said in an email.
In addition, mother cats can warn their kittens of danger ahead by raising their heads and stretching their ears, flashing their white spots, he says.
Lucky black cats?
The vital role that white markings play in cat communication may limit the number of melanistic individuals in most cat species. However, if a species is active during the day, then having a dark coat may not be so bad.
Take South America’s jaguarundi, for example. It’s the most day-dwelling wildcat, so nocturnal communication by white marks is less important for survival. Supporting that theory, about 80 per cent of jaguarundis are melanistic, the highest frequency of melanism among all cat species, Graipel says.
February 12, 2019 – San Diego Zoo Global researchers have confirmed the presence of rare black leopards living in Laikipia County, Kenya.
Sourse: www.nationalgeographic.com.au
