A video of a crow and a rat appearing to fight or chase each other in a local park raises questions about how two of Vancouver's most populous animals interact.
A Â鶹´«Ã½Ó³»resident recorded the video on April 27, just after 8 a.m., while she was walking her dog in Douglas Park. It shows the two animals interacting in the sun by a sidewalk before the crow chases the rat into the field.
But the footage doesn't show a typical predator hunting prey scenario. Instead, the crow hops after the galumphing rat without diving or wildly attacking it. It fluffs its head feathers, hunches its back while cawing, and nips the rodent's tail once or twice, but never completes a full-on ambush.
Chris Stinson is the Lead Curatorial Assistant of Mammals, Reptiles, and Amphibians and Cross Collections at the UBC Beaty Biodiversity Museum and says crows and rats are both highly intelligent animals. While they can both stand their ground, he says crows can kill rats.
"I've seen crows kill a squirrel," he recalls. "It was several crows that were probably being territorial."
Rats are nocturnal, and scurrying around in the daylight isn't the animal's modus operandi. But it isn't unheard of for the animals to run around during the day if they are chased. Cats, dogs, wildlife, and other birds of prey hunt the rodents.
Crows will more often go after rats that are "wounded, diseased, or young," he adds.
The crow may not have been hunting the rat
Still, the crow wasn't necessarily trying to make a meal of the rat. Stinson says it was most likely defending its territory, particularly if it was roosting. Crows know that rats are omnivorous. Rats will eat crow eggs or young, although the rat featured in the video - a brown Norway rat - doesn't typically climb trees. Vancouver's other resident rat, the black rat, can be found in trees (they are agile climbers).
"The crow is doing a territorial display. It has fluffed up feathers on its head, and it has tilted its beak down," he explains, adding that it is also making a "medium caw."
Crows and ravens mate for life, although they will "remarry" if their partner dies. When paired up, crows tend to mate and raise their young and fiercely defend their territories (something most locals have likely heard in the springtime).
During this time, crows are known for enacting their famous "swoops" - a defensive behaviour used to ward off would-be predators from their nests. While they can harm humans, they aren't trying to "attack" them. Instead, they hope to deter folks from the area where fledglings are falling as they struggle with early flying attempts.
But the animal expert hesitates to hang his hat on the explanation.
"You're always assuming with animal calls, but you're never 100 per cent. They have a complicated repertoire of things; our hearing isn't as good, and there are visual cues that we can't see," he explains.
Stinson likens understanding animal interactions or calls to understanding an alien language. Without knowing their thoughts, humans can only ascertain motives from studying them; they never get a complete translation.
"You should never make an assumption"
The rat's behaviour appears defensive, and they are known to charge at attacking animals by baring their fearsome incisors. They have strong jaw muscles, sharp claws, and can stand their ground. However, the rodent may also be playing a bit with the rat.
"You should never make an assumption," he underscores. "I hate to anthropomorphize it, and they could be playing it, but it seems more defensive."
In some cases, rats infected with a blood parasite have exhibited bizarre behaviour. They lose fear of cats and get attracted to feline urine, making them an easy meal. The parasite prolongs its lifespan when the rat gets devoured by the cat, Stinson explains.
Crows also interact with animals on a more sophisticated level than other birds. They understand other bird alarm calls, including stellar jays (another corvid) and chickadees. When these other birds call out an alarm, such as for an owl, the crows will mob the predator.
"They are aware and adaptable," he comments.
