Saturday, May 26, 2018

Mouse in a Bluebird House

 
We have a bluebird trail of 14 boxes at Bull Mills, all wired 4' up on metal fence posts. When I was cleaning them out this year I found one chock full of grass with a little hollow on top, not unlike a bird nest.  When I opened the side door fully I found the back end of a small mammal with a very long skinny tail.  It scurried under the grass nest and I was able to close the box up.  I came back later with a 5 gallon bucket and managed to scrape the mammal and the nest into it.  It immediately made several incredible 12-14" leaps straight up toward the rim before I could get a lid on it.  I transferred it to an aquarium where I could now see and photograph a small and timid mouse.

The mouse in this house was not a house mouse!  Our so called house mouse, Mus musculus, aka "fancy mouse" came across the big pond from Europe with early explorers, probably originating in India, before having reached Europe around 100 B.C and North America with the British in the later 1600s.  They are more adapted to living with humans than almost any animal with the exception of college graduates moving back in with their parents.  Their greatest importance is in our research laboratories and to the exterminator industry.


The tremendous jumps of my new friend led me into a rabbit hole of researching like Alice in Wonderland  (actually more of a mouse hole).  There are 12 species of mice in Missouri in addition to the common house mouse. The dramatic leaps of my mouse immediately brought to mind the jumping meadow mouse (JMM), Zapus hudsonius pallidus, which has been reported scattered throughout Missouri although Christian County has never had a confirmed sighting.  They are noted for their extremely long tail, 150% of their body length, and their long hind feet measuring 28 to 35 mm long.

A whale of a tail
Click to enlarge - Photo Debbie Fantz MDC

I contacted Debbie Fantz, Heritage Mammalogist with the Missouri Department of Conservation.  My photographs of our mouse were in less than perfect light but appeared a little lighter than the typical JMM, leading her to suggest that it might be a juvenile before molting into darker colors.  The colors also matched the fulvous harvest mouse (FHM), Rreithrodontomys fulvescens, a southern species that has been reported in southwest Missouri.  The upper body is a mixture of reddish brown (fulvous means reddish yellow, tawny) and black.  It too has a tail longer than its body, but not usually quite as long as a JJM.

I have finally decided that this was a particularly athletic specimen of a fulvous harvest mouse based on a single trait.  My mouse was housed in the bottom of a bluebird nest box wired 4' up on a metal fence T-post.  The box had two small triangular openings in the wooden floor.
"Perhaps the most fascinating habit of the fulvous harvest mouse is its ability to build large, above-ground "penthouses" in grasses, low shrubs, or small trees (Davis and Schmidly 1994). These may be constructed of the materials in the animal's habitat or may be converted bird's nests. The solid, globe-shaped nest has one or two exits near the bottom end which can be clogged up."  AnimalDiversity.org
The hair on the upper body is a mixture of reddish brown and black, creating a salt and pepper effect (Hall and Kelson 1959). R. fulvescens has a tail that is much longer than its body and its under parts are white to buff. The adult plumage is brighter than that of the juvenile and adults molt once a year.The hair on the upper body is a mixture of reddish brown and black, creating a salt and pepper effect (Hall and Kelson 1959). R. fulvescens has a tail that is much longer than its body and its under parts are white to buff. The adult plumage is brighter than that of the juvenile and adults molt once a year.
The hair on the upper body is a mixture of reddish brown and black, creating a salt and pepper effect (Hall and Kelson 1959). R. fulvescens has a tail that is much longer than its body and its under parts are white to buff. The adult plumage is brighter than that of the juvenile and adults molt once a year.
The hair on the upper body is a mixture of reddish brown and black, creating a salt and pepper effect (Hall and Kelson 1959). R. fulvescens has a tail that is much longer than its body and its under parts are white to buff. The adult plumage is brighter than that of the juvenile and adults molt once a year."
Reithrodontomys fulvescens
Reithrodontomys fulvescens
The lengths that plants and animals go to for survival, however humble they be, are incredible.  As Bill Bryson says in A Short History of Nearly Everything, “Life just wants to be; but it doesn't want to be much.”

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Thanks to Debbie Fantz and Ashley Schnake of MDC
Wild Mammals of Missouri lists 13 mouse species.

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