Editing Beaver (section)

===Infrastructure===
{{redirect|Beaver lodge|the town in Alberta, Canada|Beaverlodge}}
{{further|Beaver dam}}
[[File:American Beaver, tree cutting.jpg|thumb|alt=Beaver chewing through a tree trunk|North American beaver chewing down a tree.]]

Beavers need trees and shrubs to use as building material for [[Beaver dam|dams]], which restrict flowing water to create a pond for them to live in, and for lodges, which act as shelters and refuges from predators and the elements. Without such material, beavers dig [[burrow]]s into a [[Bank (geography)|bank]] to live. Dam construction begins in late summer or early fall, and they repair them whenever needed. Beavers can [[felling|cut down]] trees up to {{cvt|15|cm|0}} wide in less than 50 minutes. Thicker trees, at {{cvt|25|cm|0}} wide or more, may not fall for hours.{{sfn|Müller-Schwarze|Sun|2003|pp=54, 56–57, 68, 108}} When chewing down a tree, beavers switch between biting with the left and right side of the mouth. Tree branches are then cut and carried to their destination with the powerful jaw and neck muscles. Other building materials, like mud and rocks, are held by the forelimbs and tucked between the chin and chest.{{sfn|Runtz|2015|pp=84, 103}}

Beavers start building dams when they hear running water, and the sound of a leak in a dam triggers them to repair it.{{sfn|Runtz|2015|p=104}} To build a dam, beavers stack up relatively long and thick logs between banks and in opposite directions. Heavy rocks keep them stable, and grass is packed between them. Beavers continue to pile on more material until the dam slopes in a direction facing upstream. Dams can range in height from {{cvt|20|cm|0}} to {{cvt|3|m|0}} and can stretch from {{cvt|0.3|m|ft}} to several hundred meters long. Beaver dams are more effective in trapping and slowly leaking water than man-made concrete dams. Lake-dwelling beavers do not need to build dams.{{sfn|Müller-Schwarze|Sun|2003|pp=54–56, 109}}

[[File:Beaverlodge.JPG|thumb|alt=see caption|Open-water beaver lodge in Canada.]]

Beavers make two types of lodges: bank lodges and open-water lodges. Bank lodges are burrows dug along the shore and covered in sticks while the more complex freestanding, open-water lodges are built over a platform of piled-up sticks. The lodge is mostly sealed with mud, except for a hole at the top which acts as an air vent. Both types are accessed by underwater entrances.<ref name=JohnHopkins/>{{sfn|Müller-Schwarze|Sun|2003|pp=56–57}} The above-water space inside the lodge is known as the "living chamber", and a "dining area" may exist close to the water entrance.<ref name="MacDonald"/> Families routinely clean out old plant material and bring in new material.{{sfn|Müller-Schwarze|Sun|2003|p=32}}

North American beavers build more open-water lodges than Eurasian beavers. Beaver lodges built by new settlers are typically small and sloppy. More experienced families can build structures with a height of {{cvt|2|m}} and an above-water diameter of {{cvt|6|m}}. A lodge sturdy enough to withstand the coming winter can be finished in just two nights. Both lodge types can be present at a beaver site. During the summer, beavers tend to use bank lodges to keep cool and use open-water lodges during the winter. The air vent provides ventilation, and newly added carbon dioxide can be cleared in an hour. The lodge remains consistent in oxygen and carbon dioxide levels from season to season.{{sfn|Müller-Schwarze|Sun|2003|pp=6, 57–58}}

Beavers in some areas will dig canals connected to their ponds. The canals fill with groundwater and give beavers access and easier transport of resources, as well as allow them to escape predators. These canals can stretch up to {{cvt|1|m}} wide, {{cvt|0.5|m}} deep, and over {{cvt|0.5|km|1}} long. It has been hypothesized that beavers' canals are not only transportation routes but an extension of their "[[Central place foraging|central place]]" around the lodge and/or food cache.<ref name="canal">{{Cite journal |last1=Abbott|first1=Matthew |last2=Fultz|first2=Brandon|last3=Wilson|first3=Jon|last4=Nicholson|first4=Jody |last5=Black |first5=Matt |last6=Thomas|first6=Adam|last7=Kot|first7=Amanda|last8=Burrows|first8=Mallory |last9=Schaffer |first9=Benton |last10=Benson|first10=David|year=2013|title=Beaver-Dredged Canals and their Spatial Relationship to Beaver-Cut Stumps|volume=121|issue=2|pages=91–96 |journal=Proceedings of the Indiana Academy of Science |url=https://www.researchgate.net/publication/275098832}}</ref><ref>{{Cite journal |last1=Grudzinski |first1=Bartosz P. |last2=Cummins |first2=Hays |last3=Vang|first3=Teng Keng |year=2019|title=Beaver canals and their environmental effects|journal=Progress in Physical Geography: Earth and Environment |pages=189–211 |doi=10.1177/0309133319873116 |volume=44 |issue=2 |s2cid=204257682 |url=https://www.researchgate.net/publication/335838343}}</ref> As they drag wood across the land, beavers leave behind trails or "slides", which they reuse when moving new material.<ref name=JohnHopkins/>