Small mammals

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Small mammals
Relative abundance and Habitat preference
Jenna King Field Research 101 2001-2002
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Relative abundance
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The comparison of small mammal numbers between
habitats
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Small mammals of the Field Research Station
(In order of abundance)
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White-footed mouse
Peromyscus leucopus

• Common
• Has many behavior and feeding habits similar to
  that of the deer mouse- eats mainly seeds but
  will also feed on green vegetation, fungi and
  insects
• Extremely hard to distinguish from the deer
  mouse one difference is that the White-footed
  mouse lacks a sharply bicolored tail
• Very similar to deer mouse in appearance, but
  generally smaller

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Peromyscus maniculatus
Deer mouse

• A generalist in terms of habitat and food
  sources- can be found both in wooded areas and in
  open areas like prairies
• Feeds mainly on the seeds of trees, but also
  eats small plants and grasses, invertebrates like
  beetles moths and grasshoppers, insect larvae,
  fungi and any fruits when available
• Probably the most prolific mammal in North
  America

• Most abundant small mammal in the study area.
• A generalist in terms of habitats and food
  sources.

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Northern short-tailed shrew
Blarina brevicauda

• A large shrew- almost the size of a deer mouse
• Probably the most common shrew in the area
• Feeds mainly on on insects and other
  invertebrates, but they are capable of killing
  mice and voles also. Some plant matter is also
  included in their diet
• Capable of living in a number of different
  habitats

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Clethrionomys gapperi
Southern red-backed vole

• Very habitat specific prefers plenty of cover
• Feeds on young leaves and tender shoots, fungi,
  fruit, seeds and will occasionally partake in an
  insect or two
• Does not cache food during winter like mice and
  squirrels- continues foraging under snow during
  the winter

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Microtus pennsylvanicus
Meadow vole

• Prefers wet and grassy habitats (the Field
  station pasture is perfect)
• Feeds exclusively on shoots from long grasses,
  but would probably take the occasional insect
• Along with the construction of a nest, these
  animals also make obvious tunnels through their
  habitats

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Masked shrew
Sorex cinereus

• A tiny shrew and most likely the smallest in the
  area, second only to the pygmy shrew (a specimen
  I obtained from the Field station had a total
  length of only 9 cm) .
• An invertebrate specialist - feeding almost
  entirely on slugs, spiders, insect larvae,
  beetles and crickets- almost never attacking
  vertebrates
• Prefers to live in rotting logs or anywhere that
  has a lot of moisture

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Microtus ochrogaster
Prairie vole

• Extremely habitat specific, and is rare for this
  reason (listed as Special concern by Wisconsin
  DNR)
• Feeds on prairie grasses like bluegrass and other
  prairie plants
• Distinguishable from other voles in the area by
  its buff or yellow underside (most voles have
  gray or silver bellies)

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Habitat preference
Animals live where they have everything they need
to survive. Plenty of food and cover are
important to small mammals. Because human
development has altered the environment so
dramatically, an effective way to learn about how
ecosystems should work is to look at populations
of mice, voles and shrews. Where these animals
are present or absent gives a good comparison of
a healthy ecosystem and one that has been damaged.
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The
Predators
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Live trapping
Some General information...

• Weather should be warm, (50-60 degrees) and with
  low humidity
• Traps should be checked as often as possible to
  reduce trap death
• Traps are placed in areas of likely animal
  activity near tunnels or runways, nests, or near
  potential microhabitats like stumps and rotting
  logs
• Animals should be handled carefully and with the
  animals well-being in mind, but also with proper
  safety precautions to prevent spread of disease.

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Small mammals
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Live trapping in the pasture
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Trap placement is critical. Most animals will not
enter the trap if they are not placed well and
reasonably camouflaged. I Usually place
branches and leaves around the entrance to the
traps so animals feel they have enough cover, and
that it is safe to enter the trap.
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1. Traps are opened and animals are shaken gently
from the traps into a bag 2. The animals are
identified to species and recorded 3. Animals are
removed from bag for any final observations (the
least amount of handling, the better) 4. Release!
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juvenile red-back vole
Trapped in the Oak Savannah on Oct. 30, 2001
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Sometimes trapped animals can get a little wet.
Their warm breath condenses on the side of the
traps and forms water droplets. This little vole
was obviously wet and a little cold, but I
released him right back into the log I caught him
from.
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My ears are back and my eyes are wide- the sign
of a very stressed Deer mouse. Sometimes it can
be hard to get a good look at these animals
before their release.
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Trapping can occur year-round, however small
mammal populations are at their peak during the
fall. Continuing into the winter will result in
trap death. I had a very small window of time to
successfully trap animals. Live-trapping is a
very involved and time consuming task.
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Winter work at the Field station
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Winter small mammal tracking
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Sometimes clear tracks are visible
Here you can even see a tunnel underneath the
snow
Sometimes youll find a spot where the animal has
walked and then tunneled through the snow
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Small mammal tracking during the winter months is
especially helpful in learning about their
locations and movements, as well as the potential
for finding nests or feeding areas. Here we can
see a location I dubbed The Small mammal highway
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Some aerial predators leave their mark... here we
can see where
birds of prey have hit the snow in pursuit of a
small mammal
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Here we can see a path underneath a branch that
small mammals have used to go from tunnel to
tunnel under the snow.
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The tunnels made by small mammals during the
winter can be seen when the snow begins to melt
in spring
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This is a shrews winter hide-out. There there is
most likely a nest within this clump of trees,
and is probably one of many areas belonging to
the individual where food is cached
You can see the paths and tunnels made by the
shrew as it traveled through and under the snow
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Track tubes
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When weather became too cold to successfully
live-trap animals, I began another leg of my
research the relative abundance of all small
mammals (mice, voles and shrews) between
habitats. I did this with the track tubes. They
can be made with a wide array of materials, but
the ones I used were made from square plastic
piping. They include a removable plastic plate
that contact paper can be attached to (the sticky
surface picks up the tracks well). There is a
small dish in the center where bait is placed.
Pigment is placed at each entrance for the animal
to walk through. Inks can work for this, but may
dry out. A generously applied charcoal type
substance is probably best. Track tubes are not
commercially made, nor are there any solid
protocols for using them. This made
track-tubing very exciting.
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Small mammal tooth marks from the track tubes...
Who was eating the peanut butter?
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Analyzing Track Tube Data

• Contact paper is removed from the track tubes.
  Each is mounted on paper and covered by a
  transparency to preserve them.
• Contact paper from each habitat is labeled and
  dated. Some notes on the vegetative cover within
  the habitat are also recorded on the sheets
• A computer image program (Scion Image) allows me
  to manipulate the image of the contact paper
  after being scanned into the computer
• The raw data is in percents- Each percent is how
  much of the contact paper is taken up by tracks.
• This method gave me a solid and consistent way to
  measure and compare levels of activity from one
  habitat to the next.

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The following is the percents from each track
tube within each habitat added up this creates a
visual comparison of activity within these
habitats during the fall and winter months.
I put out five track tubes at a time- they are
out for one night, and within one habitat only.
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This is my Track tube data on an Archview layout.
No activity appears as a yellow check. The levels
of activity are shown by size of the red markers.
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ANATOMY OF A TRACK
All small mammals tracks are basically the same
the tracks seen here are made by a White-footed
mouse

• Four toes will register on a front paw print,
  while five will register in the hind print.
• A hind paw print is shown here in red
• A front paw print is shown here in green
• The other registering parts of the print are made
  by small structures on the feet called plantar
  tubercles- small, projecting wart-like growths.
• Each species has a different number and pattern
  of tubercles on the feet, and not all will
  register in a print

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Predator
and
Prey?
In this section of contact paper taken from the
track tubes in December, there are not only
prints belonging to mice and shrews, but there
are also tracks from a much larger animal (The
clearest print can be seen in the lower
right-hand corner). Because the track tubes are
much too small and narrow to accommodate a
squirrel or any other animal, I believe these
tracks may belong to a least weasel- which preys
on small mammals like mice, voles and shrews.
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Species-track connections
By having live caught specimens run through track
tubes, I was able to match track with species.
This will be valuable information that can be
used in the future during track tube surveys.
Unfortunately, time constraints prevented me from
getting positive tracks from each species. This
is one thing that I hope will be done in the
future.
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These tracks were made by a
White-footed mouse
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These tracks were made by a Deer mouse
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When I saw this section of a track tube from a
deciduous forest, initially I thought these
little specks were just dirt and debris upon
closer inspection I realized they were actually
tiny tracks. This size of this image had to be
increased to even pick out an individual track.
Although I never saw the animal that entered the
track tube, I believe it was a Masked shrew- the
smallest mammal I have found in the area.
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I believe these tracks are mainly those of the
Northern Short-tailed shrew. The plantar
tubercles do not typically register in these
tracks- mainly because of the way they place
their feet. Shrews are what I would call toe
walkers. Notice also that these tracks are
slightly smaller than those made by the Deer
mouse or White-footed mouse.
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Areas with highest amount of small mammal
activity
Dry, deciduous forests dominated by red oaks and
with brushy ground cover on the forest floor
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Oak Savannah
and
Pasture
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Mixed coniferous and deciduous forests can be
homes for a wider variety of small mammals
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Even the open fields are home to small mammals.
Their tunnels that were made through the snow can
be found in spring, and burrows can be found
year-round
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Prairies
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Coniferous Red pine plantations
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The home of a deer mouse
in a mixed forest
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This layout from Archview shows where each
species was caught
(October 2001-May 2002)
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I would like to thank the following people...
Mr. Tweed for everything, but mainly your advice,
encouragement and helping to take pictures Mr.
Thiel for your time, advice and enthusiasm (and
letting me use your classroom sometimes) Mr.
Kampa for your time and support with my Archview
data. Thanks also for letting me use your
computer) Darb (a.k.a. Brad Dotson) for driving
me around, for the entertainment, and for helping
with my Archview data. I hope I was of help to
you somewhere My family (especially my parents)
for putting up with me and for their support
And to all the staff at Beaver Creek Reserve and
everyone attending the symposium...
Thanks for coming!