Rare but potentially fatal causes of mortality in rodents

[Diggie's Friend]

This thread is devoted to those rare potential unconfirmed causes of mortality in rodents including squirrels.

Listed amongst the deadliest mammals on earth, the bite of the Southern short-tailed shrew is lethal to other small mammals like squirrels. In the wild, short-tailed shrews and tree squirrels wouldn't commonly cross paths; yet with squirrels housed where there is access to their cage, they may. At least one member has reported this winter that a shrew had made its way into the bottom tray of their squirrels cage.

Southern short-tailed shrew https://thetarpan.com/poisonous-veno...rttailed-shrew

"With its grooved incisors, the seemingly calm shrew can deliver a killing bite, with venom that is potent enough to kill 200 mice.

While that may not be enough to kill a human, it causes pain, swelling, and muscle problems. The shrew’s toxins would cause pains and are not worth vexing a shrew to find out."

It was just the other day that I learned about the N.A. shrews being venomous to small mammals. Here is more info should you want to learn more on the shrews. Like the Southern short tailed shrew, the Northern short tailed shrew, that inhabits north central and northeastern US into Canada, is also venomous to small mammals. These shrews are active both in the daytime and at night. It is noted that 90 percent of their population doesn't survive the cold of winters. This appears why N.A. shrews may seek shelter in and around warmer human dwellings, perhaps attracted by left out dog or cat food. For this reason, please be aware that if you see a shrew trap and relocate it far enough away from your home.

https://animalcorner.org/animals/nor...-tailed-shrew/

"Among mammals, the short-tailed shrew B. brevicauda (Say, 1923) is well known to produce a potent venom in its saliva, which is toxic to mammals, such as mice, voles, rabbits, and cats (1, 3). Human accounts of bites from Blarina describe a local burning sensation around the tooth puncture marks and subsequent swelling (10). In general, soricine shrews consume large amounts of food to meet their high metabolic demands (11). Although they belong to the order Insectivora, B. brevicauda do not eat insects and invertebrates exclusively but also vertebrates, even larger than themselves, such as murid rodents and frogs (1, 11–13). Therefore, this shrew species may use its venom to paralyze and catch larger preys."

"With a very high metabolic rate that requires shrews to consume animal sourced protein, also requires that they digest it with the support of specific protease compound to digest. This source is located in glands located in their upper and lower jaws that mixes with their saliva. This particular protease source unlike others, is neurotoxic to small animals. And though cats due to their larger size survive shrew bites, the bad bacteria in the shrews mouth, much like that of cats, can result in bite wounds becoming infected."

[island rehabber]

Another good reason to make sure our cages, indoor and outdoor, have at least double-ply hardware cloth bottoms. Keeping out snakes, insects and short-tailed shrews is a VERY big deal! Raccoons, badgers and larger predators can actually rip hardware cloth enclosures apart if they are not made securely with edges wrapping around the wood or metal frames at least once.

[Diggie's Friend]

NORTHERN SHORT-TAILED SHREW VENOM
Glands in the Northern Short-tailed Shrews mouth contain a neurotoxin (a toxin that acts specifically on nerve cells) which allows it to immobilize larger animals such as snakes and birds. Cannibalism is not uncommon between these Shrews – If not able to find food within about a two-hour period, these small mammals will attack and eat each other.

https://mlbs.virginia.edu/organism/n...orttailedshrew

These shrews do not hibernate; rather, they curl up in a deeply lined nest in the wintertime and forage more during the day when it is warmer, rather than at night as they mostly do in the summer. They also cache food in their burrows in case of a prey shortage, decrease their activity levels during cold periods, and use nonshivering thermogenesis, a biochemical method of creating body heat. In spite of all this, the mortality rate over the winter sometimes exceeds 90%.

B. brevicauda inhabits disturbed and undisturbed areas: forests, marshy areas, fields, gardens, fencerows; anywhere with sufficient vegetation and groundcover to for them to tunnel in. These shrews generally tunnel belowground, through leaf litter, or between the snow and the ground. Elaborate tunnel systems may be constructed, with deep nests for the wintertime, as well as latrines, storehouses for food, and mating nests for raising their young.

Southern Short Tailed Shrew

Prefers moist, well-drained hardwood forests for easier excavation of their underground tunnels, but also occurs in a variety of other wet and dry habitats such as fields and marshy areas.

They are primarily carnivorous; eats spiders, centipedes, earthworms, insects, and occasionally snakes, birds and rodents. Some vegetation is eaten as well.

[Diggie's Friend]

US range of Northern short tailed Shrew