There are two species of beavers: the North American Beaver and the Eurasian Beaver. Eurasian beavers are sightly the larger of the two species, and have narrower muzzles and tails. North American Beavers tend to build larger dams on bigger rivers.
By
1900, Eurasian beavers had been hunted near to extinction, with just
1,200 individuals left. Now, they are widespread from the UK to
China and Mongolia.1
The Eurasian beaver is the world's
second largest rodent after the capybara. Unusually for mammals,
female beavers are (slightly) larger than males.2
 |
| Eurasian Beaver [Source: Per Harald Olsen] |
Beavers
live in freshwater lakes and slow-moving rivers. They're crepuscular
(active dawn and dusk) and don't hibernate.
In summer they mostly eat vegetation like grasses;
in winter tree bark, leaves and twigs.3
Beavers
are highly territorial, live in family groups, and are thought to be
monogamous. They mate in Jan-Feb. Two to four kits (baby beavers) are
born in spring. They stay with parents until 2 yrs old then find
their own territory.4
Beavers in the UK
Eurasian
Beavers are native to the UK but were wiped out sometime around the
12th
- 16th
centuries by hunting.
Recently,
however, two new wild beaver populations have been introduced to the
UK, both of them in Scotland. The
first population is centred in Tayside and has recently been
estimated to number 146 individuals.5
They orginated from escaped captive beavers, and for a time the
Scottish Government had asked for them to be rounded up. The
second is the official Scottish
Beaver Trial in Knapdale, Argyll & Bute. This is a five year
project that began in 2009. The aim of the trial is to explore how
beavers can enhance the local environment and to assess any impact
they have.6
The results will inform the future of beavers in Scotland.
 |
| Beaver and Kit [Source: Ray Scott] |
Beaver Adaptations
Beavers,
as semi-aquatic mammals, have developed an amazing array of adaptations to their
environment.
The
ears, eyes and nose of a beaver are high up on its head so it can
remain observant & inconspicuous while swimming. They have dense underfur & long (60-65 mm) stiff dark guard hairs that
help trap air for warmth and repel water.7
Beavers can remain underwater for up to 15 minutes at a time. In
winter they will even swim under the ice!
Beaver
teeth have a hard enamel layer (coloured orange) at the the front and
a softer dentine at the back. As they gnaw, this naturally creates a
chisel-like shape. Here is a
video of beaver teeth in action! Beavers
eat birch, oak, rowan, alder and willow, and they are especially
partial to aspen and poplar.8
Beavers
sometimes store food under the water near the entrance of their
lodge. That stops it getting frozen in the winter. They have a
special tissue that seals their mouth behind their teeth so they can
gnaw at bark even while under water.
The tail has to be the beaver's most incredible adaptation. It is flat and
scaly. It is used to steer through the water and for balancing the
weight of heavy logs.10
The fat in the tail helps the beaver to thermo-regulate. Most
famously of all, beavers use their tails as an alarm signal, slapping
it loudly on the water and then diving underneath!
 |
| Beavers' Tails [Source: Groucho M] |
Nature's Engineers
Beavers
feel safe surrounded by water, so they sometimes build dams to
create deeper ponds for their lodges. Beaver
dams alter water flow however they can create biodiversity hotspots
by introducing new wetland microsystems.
 |
| Beaver Dam [Source: Juliux] |
Beavers
build lodges when the banks of the river are not large enough for
them to build a burrow the size they would like. The living chamber
of a burrow is above water, but the entrance is under water. Dams
help submerge the entrance.
As
well as dams and lodges, beavers even construct canals so they can
travel further and float materials along for building and food.11
Beavers
stimulate new tree growth by gnawing on tree stems and, effectively,
coppicing. There's a strong argument that by felling established
trees and stimulating new tree growth, beavers keep woodland areas
renewing.
Beavers in Culture
'Beaver'
comes from Old English 'beofor.' Similar Germanic roots are evident in Old Norse 'biōrr' and Old High German 'bibar.'12
Beaver was originally slang for 'a bearded man,' but by 1927 was
being used as vulgar slang for female genitals.13
In
the twelth century, Gerald of Wales wrote a passage on the beaver.
This includes a famous quote that is sometimes used to illustrate how
rare beavers had become in the UK: “Teivi is...the only river in
Wales, or even in England, which has beavers; in Scotland
they're...found in one river.”
Lewis
Carroll included a beaver in his famous nonsense poem 'The
Hunting of the Snark':
There
was also a Beaver, that paced on the deck,
Or
would sit making lace in the bow
And
had often (the Bellman said) saved them from wreck,
Though
none of the sailors knew how.
The most famous beavers in literature are Mr and Mrs Beaver
from The
Lion, The Witch & The Wardrobe
by C S Lewis. The Beavers in Narnia are examplars of people with
absolute faith in Aslan's prophecies.14
Beavers
are such a unique animal they have become iconic for some countries
and institutions. Canada adopted the beaver as its national symbol
in 1975. The oldest corporation in America the Hudson's Bay Co. has
had beavers on its crest since 1678. Even the London School of
Economics has a beaver emblem! It was selected for its "foresight,
constructiveness and industrious behaviour"
Beaver Products
Beavers
were hunted close to extinction because they were used for a number of
products.
They were hunted
first and foremost for their meat and fur. The fur was valued
for its inner soft layer. This was used for 'beaver' hats or coats
like this worn by Oscar Wilde:
 |
| Oscar Wilde in Beaver Coat [Source: Library of Congress] |
Beaver
teeth were used by the Anglo-Saxons to make pendants, such as this
one at the British Museum or this
in Sheffield.
Beaver
testicles have been used in some
cultures for traditional medicine.15
Beavers
produce a secretion called castoreum. Once this was used to treat
ailments such as aches and pains. Even now, it is used in perfume and
as food additive.16
Salicylic acid, which is present in castoreum, remains an ingredient
of aspirin drugs today!
Strange but True...
Remains
of a now extinct giant beaver have been excavated, including one in
the UK.
At the time of writing, one of its teeth was actually up for sale,
here!
1http://www.bbc.co.uk/nature/life/Eurasian_Beaver
2http://www.scottishbeavers.org.uk/beaver-facts/beaver-trial-faqs/how-big-are-european-beavers/
3http://beaversinengland.com/beaver-biology/diet-and-feeding-activity/
4http://www.scottishbeavers.org.uk/beaver-facts/beaver-trial-faqs/when-do-beavers-start-breeding-and-are-they-around-all-year/
5http://www.bbc.co.uk/news/uk-scotland-tayside-central-20781407
6http://www.scottishbeavers.org.uk/about-the-trial/
7http://beaversinengland.com/beaver-biology/beaver-biology-2/
8http://www.welshbeaverproject.org/beaver-basics/
9http://beaversinengland.com/beaver-biology/beaver-biology-2/
10http://www.k12.nf.ca/stannesacademy/AnimalAdaptations/BEAVER.htm
11http://www.snh.gov.uk/protecting-scotlands-nature/species-action-framework/species-action-list/euro-beaver/
12http://www.thefreedictionary.com/_/dict.aspx?word=beaver
13http://m.dictionary.com/etymology/beaver?linkId=8uxrdf
14http://wiki.narniaweb.com/index.php/Mr._and_Mrs._Beaver
15http://bestiary.ca/beasts/beast152.htm
16https://en.wikipedia.org/wiki/Castoreum
No comments:
Post a Comment