This beaver trivia quiz has 60 free questions with answers and covers the animal from every angle: the biology (why the teeth are orange, how long a beaver can stay under, what the tail is really for), the engineering (the record dam in Alberta you can see from space, how fast a family rebuilds a broken one), the history (the felt-hat trade that nearly wiped out both species, the Hudson's Bay Company's 'made beaver' currency) and the culture, from Canada's nickel and first stamp to MIT's mascot, Oregon's two-sided flag and the beavers Idaho dropped from aeroplanes in 1948. The first questions are easy enough for a classroom or a family car ride; the back half will test a wildlife biologist. Every answer comes with a short explanation, so you leave knowing something you did not before. Every question has been checked against a primary source, mostly Wikipedia's beaver, castoreum and fur-trade articles, and shows its citation once you have answered.
30 of 60 questions with answers and explanations. Play the quiz
Q 01Beavers are the second-largest living rodents. Which animal is the largest?
Capybara
The capybara of South America can top 60 kg; a big beaver reaches about half that.
Q 02What gives a beaver's front teeth their distinctive orange colour?
Iron compounds
The iron-hardened enamel sits on the front of the incisor, so the softer back wears faster and keeps the edge chisel-sharp.
Q 03When a beaver slaps its tail hard on the water, what is it doing?
Warning other beavers of danger
The crack carries a long way over water and usually sends the whole family diving.
Q 04What kind of eater is a beaver?
Herbivore
Bark, twigs, aquatic plants and sedges are the menu; the fish are just neighbours in the pond.
Q 05What are baby beavers called?
Kits
Up to four are born each spring or summer after a three-to-four-month gestation.
Q 06The beaver sits on a rock on the reverse of which Canadian coin?
The nickel
The G. E. Kruger Gray design has been on the nickel since 1937.
Q 07Which US state is nicknamed the Beaver State?
Oregon
The beaver is also Oregon's official state mammal and the mascot of Oregon State University.
Q 08Beavers' dome-shaped homes of sticks and mud are known as what?
Lodges
The entrances are underwater, which is why beavers need a pond deep enough not to freeze solid.
Q 09The beaver genus name Castor comes from a word in which ancient language?
Greek
The English word beaver, by contrast, descends from Old English beofor.
Q 10At most, roughly how long can a beaver hold its breath underwater?
15 minutes
Typical dives are far shorter, five or six minutes, and its heart rate halves while it is under.
Q 11How fast can a beaver swim?
About 5 mph (8 km/h)
Webbed hind feet do the work; the tail acts as a rudder rather than a paddle.
Q 12While diving, a beaver's heart rate drops to about how many beats per minute?
60
That is half its normal rate, and on surfacing it can swap out three-quarters of the air in its lungs in a single breath.
Q 13The largest known beaver dam in the world is in which protected area?
Wood Buffalo National Park
It sits in a remote corner of northern Alberta and was spotted on satellite imagery before anyone had walked to it.
Q 21In the wild, beavers usually live up to about how many years?
10
Wolves, coyotes, big cats and bears are the main predators of adults.
Q 22The second toe on a beaver's hind foot carries a split 'double nail'. What is it for?
Grooming the fur
Combing keeps the dense coat waterproof; a beaver's pelt packs up to 23,000 hairs per square centimetre.
Q 23A beaver's lips can close behind its front teeth. What does this let it do?
Gnaw underwater without swallowing water
The back of the tongue rises to make a second waterproof seal.
Q 14Roughly how long is that record beaver dam in Alberta?
775 m (2,540 ft)
NASA imagery shows it did not exist in 1975; generations of beavers have been adding to it since.
Q 15A 652-metre beaver dam, 4.3 m high, was found near Three Forks in which US state?
Montana
At the base it measured seven metres thick, sturdier than many human levees.
Q 16A study in Poland found beavers could rebuild a destroyed dam and restore water levels in about how long?
8 hours
Which is why simply tearing out a dam rarely solves a landowner's flooding problem.
Q 17How quickly can a beaver fell a tree about 15 cm (6 in) thick?
In under 50 minutes
Thicker trunks of 25 cm or more can keep a beaver busy for hours.
Q 18A beaver lodge sturdy enough to survive the coming winter can be finished in as little as how long?
Two nights
Experienced families build much bigger ones, up to two metres high and six metres across above the waterline.
Q 19Where do beavers store their winter food supply of cut branches?
In the deepest part of the pond
Submerged wood stays fresh and reachable under the ice when the family cannot leave the water.
Q 20Beavers live in monogamous family groups. At what age do young beavers become independent?
Two years
Yearlings often stay on to help raise the next litter before dispersing to find territory of their own.
Q 24Besides steering and propping the animal upright, what does a beaver's flat tail store?
Fat
A countercurrent blood system in the tail also dumps excess heat on hot days.
Q 25What protects a beaver's eyes while it swims underwater?
Nictitating membranes
Valves in the nostrils and ears close at the same time, sealing the head like a submarine hatch.
Q 26What did more than 27 Russian attempts to hybridise North American and Eurasian beavers produce?
A single stillborn kit
North American beavers carry 40 chromosomes, the Eurasian species 48.
Q 27By the early 20th century, roughly how many Eurasian beavers survived across the whole of Eurasia?
About 1,200
They clung on in just eight scattered populations between France and Mongolia.
Q 28By 2020, the Eurasian beaver population in Europe had recovered to what level?
More than one million
Reintroductions across the continent turned one of Europe's rarest mammals into a common one within a century.
Q 29The beavers released into Scotland's Knapdale forest in 2009 came from which country?
Norway
Norway had kept one of the few beaver populations that never died out in Europe.
Q 30How many North American beavers were released in Finland in 1937, a group that grew to 12,000 within 64 years?
7
The imported species now outnumbers the native Eurasian beaver in much of Finland.