These storms were part of an "Atmospheric River" that covered mostly northern California. The following is NOAA's simple description of an atmospheric river.
"Atmospheric rivers are relatively narrow regions in the atmosphere that are responsible for most of the transport of water vapor from the tropics. Atmospheric rivers come in all shapes and sizes but those that contain the largest amounts of water vapor and strongest winds are responsible for extreme rainfall events and floods. This type of hydrologic event can affect the entire west coast of North America. These extreme events can disrupt travel, induce mudslides, and cause damage to life and property. Not all atmospheric rivers are disruptive. Many are weak and provide beneficial rain or high elevation snow that is crucial to the water supply."
North Yuba River - 11/26/24
The North Yuba River widened, and was running fast and full! Last Saturday, the volume of water peaked at 3,000 cfs (cubic feet per second). On Thursday it was down to 373 cfs. The river rose to almost 8' last Saturday, by Thursday it was down to 2.95'.
North Yuba River - 11/17/24
Columbian Black-tailed Deer (doe & fawn) - Odocoileus hemionus columbianus
Mammals in the Rain
Surviving day after day of drenching rain can become difficult for some wildlife. Mule Deer, however, don't appear to be that affected by rain. Their thick winter coat sheds rain, and has hollow guard hairs that trap air and insulate them against the cold. A very fine hair under their guard hairs insulates them even further. Winter coats can range from 0.2 to 1.1 inches deep; this is 5 to 6 times deeper than summer coats! Hair depth is critical for survival because deeper coats trap more insulating air. The dark color of Mule Deer's winter fur helps absorb the suns heat, keeping them warmer.
Columbian Black-tailed Deer (buck) - Odocoileus hemionus columbianus
If the rain is very heavy, Mule Deer may temporarily seek shelter in dense brush or forests. During periods of moderate rain, they carry on with their normal foraging and traveling.
The swift high water of the river can be difficult for River Otters. The turbidity of the water can make it difficult for them to find prey. The fast current also makes it more difficult to maneuver underwater.
"When a river is in flood stage, river otters will typically move to higher ground within their territory, seeking out areas with calmer water, less current, and potential food sources, often utilizing existing burrows or finding new sheltered locations to ride out the flood event; they may also temporarily reduce their foraging activity due to the disruption to their usual prey availability."
(This quote is from AI on Google, and I couldn't find it's exact source.)
In our area, that means they might frequent local ponds, or small streams in the forest. They are quite capable of traveling on land, at a speed of up to 15mph!
Chickaree or Douglas Squirrel - Tamiasciurus douglasii
Small mammals, such as squirrels and mice take to their dens during periods of heavy rain. Their dens can be in a tree trunk, rotten log, or underground. I have often seen them out during periods of moderate rain, and they appear to be holding their tails over their backs for protection!
Western Gray Squirrel - Sciurus griseus
These mammals also store food for the winter. They can rely on these caches of food during inclement weather.
Gray Fox - Urocyon cinereoargenteus
Gray Foxes inhabit our neighborhood, but I don't often see them. Their multi-colored coat helps camouflage them, especially in the winter when shrubs are leafless. Like deer, their thick coat insulates them against the cold and wet weather. The following information from https://www.berrypatchfarms.net/do-foxes-come-out-in-the-rain/ explains this thoroughly.
"Outer Guard Hairs Repel Moisture: Foxes have a thick, fluffy coat made up of two layers that help them stay dry in the rain or snow. The top layer consists of long, coarse “guard” hairs that are water-repellent. These guard hairs are coated with oils that cause water to bead up and run off the fur without penetrating to the skin underneath. The texture and structure of the guard hairs also help repel moisture. They are straight, thick, and hollow which allows air to become trapped and create insulation.
In addition, foxes frequently groom themselves by licking and nibbling their fur. This helps distribute oils across the guard hairs to maintain their water-resistant properties. When it starts to rain, foxes will fluff up their fur which causes the hairs to become more tightly packed. This makes it even harder for moisture to penetrate down to the skin. So from their fur structure to their grooming habits, foxes have adaptations that allow them to stay dry in wet weather.
Underfur Keeps Skin Dry: Underneath the longer guard hairs is a thick underfur layer. While the guard hairs repel external moisture, the underfur works to retain body heat and keep the skin dry. The underfur consists of short, fine, and very dense hairs that trap air close to the skin. This creates an insulating barrier to retain the fox’s body heat. Even if rain is wetting the outer guard hairs, the thick underfur prevents it from reaching the skin. The trapped air helps absorb and evaporate any moisture that gets through the outer layer. And the fox’s skin gives off oils that waterproof the underfur to prevent internal moisture from wetting the fur. So between body heat evaporating external moisture and their skin oils waterproofing internal moisture, a fox’s underfur keeps their skin nice and dry.
Can’t Afford to Stay in Dens During Short Rain Showers: Foxes have high metabolisms and can’t go more than a day or two without eating before they become weak from hunger. Their digestive systems are adapted for frequent small meals, not infrequent large feasts. So while heavy downpours may keep foxes sheltered a bit longer, light rain showers of an hour or less won’t typically deter them.
Gray Fox - Urocyon cinereoargenteus
Rain Makes Scenting Prey More Difficult: A fox’s exceptional sense of smell is key for finding prey in tall grasses, bushes, and other ground cover. But rain can interfere with their ability to detect critters by scent. So foxes may have to rely more on their hearing to listen for small animal sounds on rainy days.
Their excellent night vision helps them spot motion during gloomy weather too."
Steller's Jay - Cyanocitta stelleri
Birds in the Rain
Birds have a harder time than mammals keeping dry and warm in heavy rain. They also have to deal with the lower atmospheric pressure during rainstorms! The following information from https://www.audubon.org/ explains this phenomenon.
"During a rainstorm, you’re more likely to see birds perched and hunkered down than flying around. Most birds are mostly waterproof. Their feathers, combined with oil from preen glands, keep them pretty watertight. So why do birds avoid flying during rainstorms? It’s not just about getting wet. It may have more to do with the air than with the water.
Storms alter the medium in which flight takes place: the air itself. Rainstorms tend to occur when atmospheric pressure is low. Air in a low-pressure system is less dense. But it’s dense air that gives birds the aerodynamic lift they need to take wing. Falling rain and high humidity also add lots of water molecules to the air. That water takes up space in the air, making it even less dense.
So rather than fly, many birds perch and conserve energy during a storm. They sit it out under the cover of a tree. Or perch on a fence wire facing into the wind, reducing their air resistance — and limiting the loss of precious body heat. But when the storm passes, birds once again take to the skies."
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Red-shouldered Hawk in the Rain! - Buteo lineatus
This additional information is from birdwatchingpro.com.
"If the rain does not cease, then the birds will eventually run out of energy. So, they will have to venture out and find food to fuel their energy. Birds that feed on insects may have a tough time finding grubs while it is raining, but they tend to be spoilt for choice after the rain.
Raptors may also suffer during prolonged periods of rain. Birds that feed on seeds and worms will be okay for food, especially since heavy rains tend to unearth worms. If a storm rages on for a prolonged period of time, then raptors and insect-eating birds will suffer greatly and face hypothermia and even death."
Red-tailed Hawk in the Rain! - Buteo jamaicensis
The following is from https://raptor.umn.edu/.
"Raptors are usually comfortable in rain, although like any animal they can be faced with certain risks that come along with big storms. Raptors are good at finding shelter during these occurrences. Feathers have a certain level of waterproofing that allows birds to fly even when they are somewhat wet. When they get fully soaked, however, the structure of their feathers become more compact and heavy, making it much harder to fly. If this happens, raptors would find shelter and wait for their feathers to dry before taking to the sky."
What about those mushrooms???
What's happening in the foothills?
Check back in two weeks to find the answers to these questions and more!
After 8 years of posting my blog, I've decided that I'm only going to post my blog twice monthly from now on. My next post will be on the weekend of December 14th. See you then!
Also, check out my latest post on my newly re-opened Damp Earth Blog at dampearthart.blogspot.com
Your questions and comments are always appreciated. Please email me at northyubanaturalist@gmail.com. Thanks!
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