Thread by @je_light

NEXT UP: #5 seed Beaver (Rodentia: Castor canadensis) vs #12 seed Mink (Carnivora: Neovison vison) #2019MMM

Rodents continue to impress with their adaptations. North American Beavers are the largest rodents in North America, with an average size of ~20 kg (90 stoats #stoatsasmeasurement). The only rodents larger than beavers, on average, are capybaras. Why are beavers so big? #2019MMM

Beavers may be big because of living in aquatic environments. Water is typically colder than mammalian body temperature & saps the heat from the body of a warm-blooded mammal. Larger size=more favorable surface area to volume ratio=less heat lost to the environment #2019MMM

Beaver fur is thick & has superb insulatory value; prefect for cold temperatures. Although when wet, some of this insulatory value is lost (note the red boxes) #2019MMM

In addition to size & fur, Beavers have several other aquatic adaptations: webbed feet & a paddle-like tail, & adaptations to keep water out of their ears, nose, eyes, & mouth (valvular ears & nostrils, nictitating eye membranes, & lips that close behind the incisors) #2019MMM

Mink also have key adaptations for water- thick, longish, oily, water-resistent fur perfect for insulation in water ecosystems in colder climates. And Mink are pretty good swimmers () (Dunstone 1979, Lowery 1974)

Indeed, Mink often live in ecosystems with Beavers! #NoHomeCourtAdvantage But unlike the herbivorous ecosystem engineers, Mink are CARNIVORES! And water systems are their hunting grounds for fish, amphibians, crustaceans, birds, & small aquatic mammals (Lariviere 1999) #2019MMM

Tonight, our battle takes place at the John Prince Research Forest in British Columbia, Canada. At 13,000 hectares, JPRF is one of the largest research forests in North America (unbc.ca/about-unbc/tou…) #2019MMM

John Prince Research Forest is unique in that it is the only research forest in North America that is jointly managed by a university (University of Northern British Columbia @UNBC) & a First Nation community. Current conditions: COLD #2019MMM

Our Mink is exploring the edge of a pond, sniffing the area & detecting the enticing scent of castoreum. Beavers produce this substance from castor glands near their rear & spread the scent to mark its territory link.springer.com/article/10.100… #2019MMM

FYI, castoreum does not smell bad #BeaverButt bit.ly/2Bl9RtB #2019MMM

Mink are substantially smaller than Beavers, averaging around 1kg (~4.5 stoats #stoatsasmeasurement). Mink are not Beaver predators & can only scavenge on beaver carrion after a larger predator has successfully killed a Beaver #2019MMM

This wafting castoreum DOES tell the Mink dinner is probably nearby... #2019MMM

Beaver ponds are prime habitat for Mink's preferred meal... MUSKRAT #LoveMuskrat #ForDinner #2019MMM link.springer.com/article/10.100…

Beaver brings all the Mink to the yard, because their Muskrat, it's better than yours. Dam right, it's better than yours #BeaverDamPond #2019MMM

Beaver forages on water plants near a muskrat. Even though they are eating the same plants there is plenty to go around with little conflict #2019MMM

Mink slinks into the water swimming toward his intended muskrat prey #2019MMM

Beaver looks up thinking Mink needs to respect Beaver's personal space & whacks his tail against the water in a "back off" signal #2019MMM

Mink circles away from Beaver to approach muskrat from a different angle #2019MMM

BEAVER DISMISSES MINK!!!!! #2019MMM