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Monday, March 20, 2017

Methow Mammal Course - Class #5 Rodentia & Lagomorphs

Our 2017 "Conservation Course" started February 6th.  Below are notes taken by Susan Ernsdorff & Jan Sodt.  Photos by Mary Kiesau (except beaver images).  See notes and videos from the previous classes here:
Class #1
Class #2
Class #3
Class #4
Learn more about the Mammal Course here

Class #5 - Rodents & Lagomorphs with Kris Ernest, March 6 2017
plus a mini presentation by Torre Stockard on the Methow Beaver Projec
(Watch and listen to the entire class on this video)

Red Squirrels are common in the Methow!

Themes of the talk
    1.    Small body size has advantages and disadvantages
    2.    Adaptions to herbivorous diet and “life in the fast lane”
    3.    Amazing diversity – physiology, behaviors, survival strategies.  Why diversity?  Being small bodied allows for different ways to make a living in a given niche; and evolution can take place more quickly because they are shorter-lived and breed more quickly than larger species.

We think of mice when we think of Rodents but this order also includes voles, squirrels, chipmunks, ground squirrels, marmots, porcupine, muskrat and beaver!

If you have a skull in the hand, you can ID rodents and lagomorphs by teeth type and amount (dental formulas)

Rodents have 1/1 Incisors - 1 on the top, one of the 1 bottom, per side.
Muskrats eat lots of vegetation, and build small lodges too.
They have 0 Canines, the gap where the canine teeth would have been is called the diastema.
Premolars + Molars = 5 or less on top, 4 or less on the bottom, per side
Total teeth = 16 to 22
So: I 1/1, C 0/0, P + M  S5/S4 = 16-22 teeth=  most rodents have total of 16 teeth

Lagomorphs have 2/1 Incisors - 2 on top and one on the 1 bottom, per side
They also have no canines. 
Premolars + Molars = 5 or 6 on top, 5 on the bottom, per side
Total teeth = 26 to 28 (significantly more than rodents)
So: I 2/1, C 0/0, P + M 5-6/5 = 26-28 teeth
Lagomorphs also have a funny little second incisor on the top behind the incisor called the peg tooth.
Other characteristics of Rodents & Lagomorphs
Rodents and lagomorphs are each others' closest relatives taxonomically.  Both are found worldwide.
A chipmunk or a golden-mantled ground squirrel??

Rodents are very small, 20-100 grams.
Their feet are bare on the soles.
There are 36 families, totaling 2300 species (more than 40% of total mammal species)
They are mostly herbivorous or omnivorous but they can be carnivorous

Lagomorphs are mostly smallish, less than 5 kilograms
Feel are fully furred.
There are only 2 families totaling 94 species.
Lagos are only herbivorous.

Advantages to being small:
~ Easy to hide and to find shelter
~ Need small amount of food
~ Live in a small territory so there are bigger populations in an area, better genetic diversity
~ Higher reproductive rates

Disadvantages to being small:
~ Easy to be eaten, especially when snowpack is low
~ Can't carry much or move very fast
~ Have more surface area per mass – harder to stay warm, have to eat more per unit weight
~ Limited ability to see far
A Hoary Marmot basking (a warming strategy)

Surface area/volume ratio for smaller mammals is 60 times greater than larger mammals.  And smaller animals have to eat far more:  Elephants are 200,000 times larger than a mouse; but their mass-specific metabolic rate 1/12 as large.
For example: here are some mass-specific metabolic rates (energy needed per unit of mass):
Shrew = 7    Flying squirrel = 1    Elephant = .2

Strategies to stay warm when it's cold
~ Live in warmer micro-habitats (most do this - like burrows under snow or in soil)
~ Insulated nests (most do this)
~ Communal huddling (many do this, like deer mice and marmots, but pika are solitary)
~ Hibernation (some do this, like marmots)

So cute, but fierce protectors of their territories!
Pikas (because they really are the cutest species)
Have a super-high metabolism and thick fur, so they overheat easily.  They live in high alpine talus fields and nest under big rocks where it's cooler and there's good cool air flow.  Across their range, they are threatened by a warming climate - there's been quite a research done on them.  They just can't go higher up, they are already at high elevations.
They eat plants year-round, with no hibernation or torpor phase.  They dry plants in the summer for winter consumption (their stacks of dried plants are called hay piles and can be quite large!  This drying also leaches out the toxicity in certain plants).
Therefore they have to digest cellulose, which is difficult.  Their strategy? Coprophagy.  They re-eat their first round of "poop" pellets for more digestion and absorption of nutrients the second time around.  The pellets we humans see are the second round.

All rodents have teeth that never stop growing (the word rodent comes from Latin rodere, "to gnaw"). Beavers are a great example of that.  They have special skulls and very strong jaws for constantly chewing.  Their teeth are also strong, containing iron, which is why they have an orange tinge to them.  

We've talked about being an herbivore, omnivore or carnivore, but many rodents are also "Granivores" (grain eaters) or "Fungivores" (fungus-eaters aka Mycophagy).  The Great Basin pocket mouse has external fur-lined cheek pouches for hauling grain.  They literally have a flap of skin on the outside of their cheeks (not like a chipmunk with internal pockets.  They don't have to drink water because they can get all they need as a byproduct of metabolizing food.  Northern flying squirrels, red-backed vole and Pacific jumping mouse are fungivores - they eat fungi and spread spores and nutrients around the forest.

Conservation concerns     
Western Gray Squirrel – State Threatened
American Pika – no conservation status, but petitioned for listing, specifically because of global climate change
Northern Bog Lemming - State Monitored species (a few are known to be in the Methow Cascades)
The Snoqualmie Pass East Project is attempting to increase wildlife connectivity and safe passage, and decrease mortality across I-90.  The project includes 30 new crossing structures under and over the freeway, plus habitat enhancements such as logs and plantings, adding microhabitat features, innoculating with local fungal spores, using local soils, etc.  Monitoring of use of crossing structures by small animals is done using live traps and pit fall arrays.  The project is also monitoring pika patch occupancy.  They can live right next to the interstate if there's enough cover, food and other habitat requirements.

THE METHOW BEAVER PROJECT with Speaker Torre Stockard
Our watershed is 1800 square miles.
Goals of project: Restore beavers where they used to be; improve the watershed health and restore complexity to the stream systems of the watershed.
Measurable outcomes: Improve water quality; delay runoff and increase storage of water; expand riparian habitat; increase stream complexity; reconnect floodplains.

Key innovations in the first 10 years: 
~ GIS analysis of watershed to identify good beaver locations
~ Live capture and handling and processing of beavers - they created a special "beaver bag" so beavers don't have to be anesthetized
~ Determined how to distinguish sexes (via anal glands), which was not known anywhere prior to the Methow Beaver Project.

Beavers being housed at the Fish Hatchery until relocation
About 325 "nuisance" beavers have been captured and relocated since 2008.    These are beavers that landowners have requested be removed and the project deemed necessary as well (clogging culverts; chewing orchards, etc). 

PIT (passive integrative responder) Tagging allows tracking of their movement – they can move far!  One went down the Methow River to the Columbia, up the Columbia and then up the Okanogan river, last monitored at Canadian border.  142 miles.

A temporary lodge made by humans for released beavers.
Captured beavers are temporarily housed at the fish hatchery pens on Twin Lakes Road.  Lots of  volunteers help with feeding.  Monitoring is done to see if a male and female pair seems to get along, before relocating.  Before beavers are released at a chosen site, a temporary lodge is built for the beavers to use while they build their own.  Site monitoring shows remarkably fast work!  One picture showed that in the first week the beavers had already built a dam and created a pond.   Water storage and changes in stream temp are monitored too.

So far, there's about a 50% success rate of the relocated beavers staying put.  Approx 45 pairs have been established in 9 years.  The project is now working on ways to improve success such as more preliminary work to help beavers get established in very compromised landscapes (such as highly-incised stream cuts), as well as more education to local landowners on how to live with beavers instead of relocating them, including the creation of structures to block them from culverts. 

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