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What the sources say

North American BeaverCastor canadensis

Every figure, record and mechanism on the North American Beaver profile was written from a source, and this is the working table behind it: 59 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

Smithsonian's National Zoo and Conservation Biology Institute

Beaver. Smithsonian's National Zoo and Conservation Biology Institute.

The page saysSelf-sharpening orange teeth strengthened with iron
The source saysTheir large, orange incisors grow continuously throughout their lifetime ... These teeth are self-sharpening ... The iron strengthens the enamel
The page saysdams streams into ponds
The source saysDams reduce stream erosion by forming slow-moving ponds.
The page saysthe largest rodent in North America and the second largest in the world, behind the capybara
The source saysNorth American beavers are the largest rodents in North America and the second largest in the world (South America's capybaras being the heaviest).
The page saysIt weighs 35 to 65 pounds (16 to 30 kilograms)
The source saysThey weigh between 35 and 65 pounds (16 to 30 kilograms)
The page saysthe heaviest beaver on record weighed 110 pounds (50 kilograms)
The source sayswith the heaviest beaver on record weighing 110 pounds (50 kilograms)
The page saysruns 3 to 4 feet (1 to 1.2 meters) long
The source saysThey are 3 to 4 feet (1 to 1.2 meters) long
The page saysBeavers typically live 10 to 12 years
The source saysNorth American beavers typically live 10 to 12 years.Note: Smithsonian gives no wild/captive qualifier; ADW's older 'average lifespan of a beaver in the wild is 10 to 20 years' disagrees, and the current Smithsonian page wins
The page saysthe oldest one on record reached 30 in human care
The source saysThe oldest on record lived 30 years in human care.
The page saysA beaver's incisors keep growing throughout its life, and daily use wears them down
The source saysThese teeth grow continuously throughout its life and are worn down through daily use.
The page saysSelf-sharpening, iron-strengthened incisors that keep growing throughout its life and can cut through a finger-thick sapling in one bite
The source saysThese teeth grow continuously throughout its life ... These teeth are self-sharpening and can cut a tree the size of a person's finger in a single bite! ... The iron strengthens the enamelNote: 'sapling' (a young tree) stands in for the source's 'a tree the size of a person's finger'
The page saysTheir incisors keep growing throughout their life
The source saysThese teeth grow continuously throughout its life
The page saysthe outer enamel is loaded with iron
The source saysthe high amount of iron contained in the enamel, which is the hard outer layer of the teeth
The page sayswhich makes the teeth look dark orange and strengthens them, helping stop them cracking or breaking as the beaver gnaws
The source saysBeavers' incisors appear dark orange due to the high amount of iron contained in the enamel, which is the hard outer layer of the teeth. The iron strengthens the enamel, helping prevent the teeth from breaking or cracking while the beaver gnaws.Note: 'look' is the source's 'appear', a description of colour rather than a hedge
The page saysThe iron makes the teeth look dark orange and strengthens the enamel, helping keep them from cracking or breaking while the beaver gnaws
The source saysBeavers' incisors appear dark orange due to the high amount of iron contained in the enamel, which is the hard outer layer of the teeth. The iron strengthens the enamel, helping prevent the teeth from breaking or cracking while the beaver gnaws.Note: 'look' is the source's 'appear', a description of colour rather than a hedge
The page saysBeaver teeth are self-sharpening
The source saysThese teeth are self-sharpening
The page saysa single bite can cut through a sapling as thick as a finger
The source sayscan cut a tree the size of a person's finger in a single bite!Note: 'sapling' (a young tree) stands in for the source's 'a tree the size of a person's finger'
The page saysincisors that grow too long to let the back molars meet can lead to starvation
The source saysIf the incisors become too long, they can prevent the beaver's mouth from closing enough for its grinding molars to meet, which could lead to starvation.
The page saysIf the incisors grow too long to let the back molars meet, though, a beaver can starve
The source saysIf the incisors become too long, they can prevent the beaver's mouth from closing enough for its grinding molars to meet, which could lead to starvation.
The page saysUnderwater, a see-through nictitating membrane, a kind of built-in swim goggle, slides over each eye
The source saysThe beaver's eyes have a thin, transparent membrane, called a nictitating membrane, which is pulled over the eyeball for underwater work.Note: 'a kind of built-in swim goggle' is a plain-language gloss for the term, not a claim about eyesight
The page saysslides over each eye for underwater work
The source sayswhich is pulled over the eyeball for underwater work
The page saysvalves close its ears
The source saysIts ears are external, small and rounded, with valves that also close while submerged
The page saysvalves close a beaver's ears while it is submerged
The source saysIts ears are external, small and rounded, with valves that also close while submerged
The page saysIt can swim at up to 6 mph (10 km/h) on webbed hind feet
The source saysTheir larger hind feet are webbed for swimming ... beavers can swim up to 6 mph (10 kilometers per hour)
The page saysit can swim at up to 6 mph (10 km/h)
The source saysbeavers can swim up to 6 mph (10 kilometers per hour)
The page saysoversized lungs let it stay submerged for up to 15 minutes while traveling over half a mile
The source saysTheir oversized lungs allow them to stay submerged for up to 15 minutes while traveling over half a mile.
The page saysOversized lungs let it stay underwater for up to 15 minutes while traveling over half a mile
The source saysTheir oversized lungs allow them to stay submerged for up to 15 minutes while traveling over half a mile.
The page saysA Tail With Four Jobs
The source saysThe tail is used as a rudder in swimming, as a balance prop while working on land and to signal danger when slapped on the water. Beavers will also store fat in their tailsNote: the lead-in counts the four uses the page gives: rudder, balance prop, alarm signal, fat store
The page saysA beaver's broad, flat, scaly tail
The source saysa broad, flat, scaly tail
The page sayssteers it through the water, props it up while it works on land, and slaps the water as an alarm
The source saysThe tail is used as a rudder in swimming, as a balance prop while working on land and to signal danger when slapped on the water.
The page saysan alarm that tells nearby beavers to head for deep water
The source saysthis alarm signal alerts others in the area to seek refuge in deep water
The page saysIt also stores fat: beavers eat more in the fall so they can live off that fat through winter if food runs out
The source saysBeavers will also store fat in their tails, eating more in the fall so they can survive off the fat stored in their tails through winter if food is not available.
The page saysalong with leaves, woody stems, roots and aquatic plants
The source saysBeavers are herbivores, eating leaves, woody stems and aquatic plants.Note: roots come from ADW, claimed separately
The page saysTheir favorite trees for both food and building are poplar, aspen, willow, birch and maple
The source saysTheir chief building materials are also their preferred foods: poplar, aspen, willow, birch and maple.
The page saysThey build watertight dams of sticks woven with reeds, branches and saplings, caulked with mud
The source saysthey build watertight dams of sticks woven with reeds, branches and saplings, which are caulked with mud
The page sayswhich turn streams into slow-moving ponds
The source saysDams reduce stream erosion by forming slow-moving ponds.
The page saysBeavers also build dome-like lodges that rise 6.5 feet (2 meters) or more and can reach 39 feet (12 meters) wide
The source saysBeavers also build dome-like lodges that rise 6.5 feet (2 meters) or more and can reach widths of 39 feet (12 meters).
The page saysOften built away from the shore, a lodge forms an island that can only be entered from underwater
The source saysOften built away from the shore, these lodges form islands that can only be entered from underwater.
The page sayswalls a third of a meter thick can insulate the chamber inside
The source saysThe lodge chamber may be 4 feet (1.2 meters) wide and 2 feet (0.6 meters) high, insulated by walls one-third of a meter thickNote: 'can' carries the source's 'may'
The page saysBeaver fur was once in constant demand for robes, coats and top hats
The source saysBeaver fur was in constant demand for robes, coats, clothing trim and top hats (called beavers).
The page saysWars, including the French and Indian War, were even fought over access to beaver trapping areas
The source saysWars, including the French and Indian War, were even fought over access to beaver trapping areas.
The page saysIn the early 1800s, beaver pelts were the single most valuable commodity in most of North America
The source saysDuring the early 19th Century, beaver pelts were the single most valuable commodity in most of North America.Note: early 1800s = early 19th century
The page saysWith trapping totally unregulated well into the 20th century, beavers all but disappeared from most of their original range
The source saysWith trapping totally unregulated well into the 20th Century, beavers all but disappeared from most of their original range.
The page saysNow protected from overexploitation, they have reestablished themselves over most of the continent and have even become an agricultural pest in some regions
The source saysNow protected from over exploitation, beavers have reestablished themselves over most of the continent and have even become an agricultural pest in some regions.
The page saysPonds, lakes, rivers, marshes, streams and wetlands across North America, except the California and Nevada deserts and parts of Utah and Arizona
The source saysBeavers are found throughout North America with the exception of the California and Nevada deserts and parts of Utah and Arizona. They live in ponds, lakes, rivers, marshes, streams and adjacent wetland areas.
The page saysleaves, woody stems
The source saysBeavers are herbivores, eating leaves, woody stems and aquatic plants.
The page sayspreferring poplar, aspen, willow, birch and maple
The source saysTheir chief building materials are also their preferred foods: poplar, aspen, willow, birch and maple.
The page saysBeavers live in ponds, lakes, rivers, marshes and streams across most of North America
The source saysBeavers are found throughout North America with the exception of the California and Nevada deserts and parts of Utah and Arizona. They live in ponds, lakes, rivers, marshes, streams and adjacent wetland areas.Note: 'most of' carries the source's exceptions: the California and Nevada deserts and parts of Utah and Arizona
The page saysa builder that weaves sticks, reeds and saplings into watertight dams
The source saysthey build watertight dams of sticks woven with reeds, branches and saplings, which are caulked with mud

Source
02

Animal Diversity Web, University of Michigan

Castor canadensis (American beaver). Animal Diversity Web, University of Michigan.

The page saysits nostrils close too
The source saysthe animal's closable nostrils, closable ears, and transparent eye membranes are for aquatic existence
The page saysThey eat bark and cambium, the soft growing layer just under a tree's bark
The source saysBeavers eat bark and cambium (the softer growing tissue under the bark of trees).
The page saysroots and aquatic plants
The source saysThey also eat water vegetation, as well as buds, and roots.
The page saysBark and cambium
The source saysBeavers eat bark and cambium (the softer growing tissue under the bark of trees).
The page saysroots and aquatic plants
The source saysThey also eat water vegetation, as well as buds, and roots.

Source
03

Cassola 2016

Cassola (2016). Castor canadensis. The IUCN Red List of Threatened Species 2016: e.T4003A22187946.

The page saysThe IUCN lists the species as Least Concern
The source saysLeast Concern

Source
04

Wright, Jones & Flecker 2002

Wright, Jones & Flecker (2002). An ecosystem engineer, the beaver, increases species richness at the landscape scale. Oecologia.

The page saysan ecosystem engineer
The source saysecosystem engineering by beaver leads to the formation of extensive wetland habitat
The page saysIn New York's Adirondack Mountains, beavers create wetlands that can support herbaceous (non-woody) plants found nowhere else along the river
The source saysIn the central Adirondacks, New York, USA, ecosystem engineering by beaver leads to the formation of extensive wetland habitat capable of supporting herbaceous plant species not found elsewhere in the riparian zone.Note: 'non-woody' defines herbaceous; 'along the river' is a plain-language stand-in for 'the riparian zone'
The page saysIn New York's Adirondack Mountains, beavers create wetlands that can support herbaceous plants found nowhere else along the river
The source saysIn the central Adirondacks, New York, USA, ecosystem engineering by beaver leads to the formation of extensive wetland habitat capable of supporting herbaceous plant species not found elsewhere in the riparian zone.
The page saysCounting stretches beavers had changed and stretches they had never occupied, a 2002 study found that beavers raised the number of herbaceous plant species in the riverside zone by more than 33%
The source saysbeaver increase the number of species of herbaceous plants in the riparian zone by over 33% at a scale that encompasses both beaver-modified patches and patches with no history of beaver occupationNote: 'riverside zone' is a plain-language stand-in for 'riparian zone'; 'stretches they had never occupied' paraphrases 'patches with no history of beaver occupation'; 2002 is the reference's publication year
The page saysThe researchers call the beaver an ecosystem engineer: an animal that physically reshapes its habitat
The source saysEcosystem engineering - the physical modification of habitats by organisms ... ecosystem engineering by beaver

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.