The North Yuba River Critters

Due to heavy rain and warmer temperatures, the 
North Yuba River was bookin' this week!  
In seven days we got  13" of rain, plus LOTS of snowmelt, 
which made for a very swollen river!  At one point, the river was moving at a rate of 16.76 cubic ft. of water per second!!! 

               Rock Creek on Thursday & Rock Creek on Saturday 

How were all the river critters affected 
by this sudden change?

Today, I walked down to an area on the river, that typically gets flooded 
when the river is high.  It's been 2 days since the river crested so the water has receded somewhat.  Just as I hoped, there were Dobsonfly Nymphs 
(or Helgrammites) in some of the newly created landlocked ponds!    

Dobsonfly Nymph - subfamily Corydalinae

I found this one in a silted pond, and watched him climb out of the water!  
They need lots of oxygen, and my guess is that he was looking for the river!  
He has only 6 legs, all the other appendages are gills, through which oxygen is 
absorbed from the river water!  Normally these nymphs live on the rocks in the 
super oxygenated white water of a river.  They live underwater for up to 2 years, 
feeding on other aquatic insects, before they molt and fly away as an adult.   

Great Blue Heron - Ardea herodias  & Helgrammite & Weasel -Mustela erminea

I found these large bird tracks in the bottom of the same silty pond!  
They might be Great Blue Heron tracks!  Perhaps the heron was feeding on 
landlocked fish and aquatic insects!  In times of high water, fish will try to 
stay on the bottom of the river, behind rocks.  Sometimes this works, 
but sometimes they get swept away by the force of the water.  
Some of them may have ended up in this pond!

The unusual tracks, on the right, I found in a moist depression that had 
been a pond.  I think the long thin ones, with lots of tiny foot prints, might 
be helgrammite tracks!  Perhaps they were heading for the river after their 
pond diminished!  There are also some bigger footprints in the mud.  
They might be weasel tracks!  Maybe the weasel ate the nymphs!

River Otter - Lustra canadensis

The absolutely most exciting tracks I found were these River Otter tracks!!!  
I've never seen one in person, so these tracks were super cool to find!  
They traversed along the edge of a pond and then onto a field of boulders, where I lost the track.  When the river is a raging torrent, River Otters have trouble catching fish in the swift, murky water, so they come on shore.  

Their main food is fish, but will also eat crayfish, molting ducks, frogs, newts, aquatic insects, and garter snakes.  They are not proficient predators on land, but they occasionally eat voles, hares, and beaver kits. They do not normally chase after fish, but use surprise attack to catch them!  

Underwater they can, hold their breath for 4 minutes, dive down to 60+ feet, swim at 6-8 mph, and travel up to 440 yds. in distance!  They usually travel from 
1.5 to 3 miles in a normal day,but have been known to travel as much as 26 miles!
They can handle the cold river water, because they have a layer of 
insulating fat and a thick undercoat of dense fur.

Usually male River Otters lead the life of a bachelor, except when they are 
looking for a mate.  The females raise the kits on their own, usually in an underground burrow, that has an underwater entrance.  Males will den in a 
hollow log, under a rock or driftwood pile, or in abandoned animal burrows.

River Otters can be 33-52 in. long, and weigh up to 6 lbs.

I wonder how all the underground 
mammals fared during this past rainy week.  
Did their burrows get flooded?  
How far down do they dig their burrows?
Do earthworms drown in the rain?
Check back next week for the answers.