Field Guide to Red Tree Vole Nests Damon B. Lesmeister and James K. Swingle
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Field Guide to Red Tree Vole Nests
Damon B. Lesmeister and James K. Swingle
Cove
r art
: Adu
lt re
d tr
ee v
ole
on a
nes
t, dr
awn
by C
arol
Clo
thie
r
Fiel
d Gu
ide
to
Red
Tree
Vol
e N
ests
Dam
on B
. Les
mei
ster
and
Jam
es K
. Sw
ingl
e
2
Dam
on B
. Les
mei
ster
and
Jam
es K
. Sw
ingl
eUS
DA F
ores
t Ser
vice
, Pac
ific N
orth
wes
t Res
earc
h St
atio
n, C
orva
llis,
OR 9
7331
Surv
eys f
or re
d tr
ee v
ole
(Arb
orim
us lo
ngic
audu
s) n
ests
requ
ire
tree
clim
bing
bec
ause
the
spec
ies
is a
hig
hly
spec
ializ
ed a
rbor
eal r
oden
t tha
t liv
es in
the
tree
cano
py o
f con
ifero
us fo
rest
s in
wes
tern
Or
egon
and
nor
thw
este
rn C
alifo
rnia
. Tre
e vo
les a
re a
ssoc
iate
d w
ith o
ld co
nife
rous
fore
sts (
≥80
year
s old
) tha
t are
stru
ctur
ally
com
plex
, but
are
ofte
n fo
und
in y
oung
fore
sts (
<80
year
s old
), es
peci
ally
in u
nthi
nned
you
ng fo
rest
s adj
acen
t to
old
fore
st. T
hrou
ghou
t muc
h of
thei
r ran
ge,
tree
vol
es p
rim
arily
fora
ge a
nd n
est i
n Do
ugla
s-fir
(Pse
udot
suga
men
zies
ii) a
nd o
ccas
iona
lly in
gr
and
fir (A
bies
gra
ndis)
. The
exc
eptio
n is
in th
e Si
tka
spru
ce (P
icea
sitc
hens
is) z
one
alon
g co
ast o
f Or
egon
, whe
re tr
ee v
oles
pri
mar
ily n
est i
n an
d fe
ed o
n Si
tka
spru
ce a
nd w
este
rn h
emlo
ck (T
suga
he
tero
phyl
la).
This
pho
togr
aphi
c nes
t gui
de is
inte
nded
to a
id id
entif
icat
ion
and
clas
sific
atio
n of
tr
ee v
ole
sign
with
min
imal
impa
ct o
n ne
sts.
The
prim
ary
user
s of t
his g
uide
will
be
tree
clim
bers
w
ho se
arch
for d
istin
ctiv
e tr
ee v
ole
nest
mat
eria
l tha
t ind
icat
es p
rese
nce.
The
tree
vol
e su
rvey
pr
otoc
ol (h
ttp:
//w
ww
.blm
.gov
/or/
plan
s/su
rvey
andm
anag
e/ fi
les/
sp-R
edTr
eeVo
le-v
3-0-
2012
-11.
pdf)
is th
e pr
imar
y do
cum
ent f
or su
rvey
s of t
ree
vole
nes
ts o
n la
nds m
anag
ed b
y th
e US
DA F
ores
t
3
Serv
ice
and
USDI
Bur
eau
of L
and
Man
agem
ent.
The
tree
vol
e su
rvey
pro
toco
l cla
ssifi
es tr
ee v
ole
nest
s as “
activ
e” if
ther
e ar
e gr
een
cutt
ings
, res
in
duct
s, or
feca
l pel
lets
pre
sent
, or “
inac
tive”
if th
e ne
st m
ater
ial i
s old
. In
this
gui
de, w
e w
ill u
se th
e bi
olog
ical
term
s occ
upie
d, li
kely
occ
upie
d, o
r rec
ently
occ
upie
d to
def
ine
“act
ive”
tree
vol
e ne
sts
and
old
vole
nes
t to
defin
e “in
activ
e” n
ests
. Clim
bers
shou
ld b
e aw
are
that
was
ps, h
orne
ts, a
nd
othe
r stin
ging
inse
cts a
re li
kely
to b
e en
coun
tere
d du
ring
tree
vol
e su
rvey
s.
Fund
ing
for t
his fi
eld
guid
e w
as p
rovi
ded
by:
Inte
rage
ncy
Spec
ial S
tatu
s and
Sen
sitiv
e Sp
ecie
s Pro
gram
USD
A F
ores
t Ser
vice
, Pac
ific N
orth
wes
t Reg
ion
USD
I Bur
eau
of L
and
Man
agem
ent,
Ore
gon/
Was
hing
ton
Port
land
, Ore
gon
4
5
Tree
vol
es h
arve
st co
nife
r bra
nch-
tips a
t nig
ht a
nd st
ore
thes
e cu
ttin
gs o
n to
p of
or i
nsid
e th
eir
nest
s as t
heir
food
sour
ce. T
his p
hoto
show
s a D
ougl
as-fi
r bra
nch
afte
r a tr
ee v
ole
harv
este
d th
e tip
(arr
ow).
The
resu
lt is
a ch
isel
-cut
at a
45°
ang
le fr
om th
e to
p of
the
stem
to th
e bo
ttom
. Di
scov
erin
g a
harv
este
d br
anch
tip
may
sugg
est t
ree
vole
pre
senc
e, b
ut p
rovi
des n
o ev
iden
ce o
f ne
stin
g, b
ecau
se tr
ee v
oles
ofte
n co
llect
cutt
ings
from
adj
acen
t tre
es th
at h
ave
inte
rcon
nect
ing
bran
ch p
athw
ays w
ith th
e ne
st tr
ee. F
urth
erm
ore,
oth
er a
rbor
eal r
oden
t spe
cies
such
as t
he d
usky
-fo
oted
woo
drat
(Neo
tom
a fu
scip
es),
bush
y-ta
iled
woo
drat
(N. c
iner
ea),
nort
hern
flyi
ng sq
uirr
el
(Gla
ucom
ys sa
brin
us),
Doug
las’
squi
rrel
(Tam
iasc
iuru
s dou
glas
ii), a
nd w
este
rn g
ray
squi
rrel
(S
ciur
us g
rise
us) a
lso
harv
est l
ive
coni
fer b
ranc
hes a
nd in
corp
orat
e th
ese
cutt
ings
into
thei
r nes
ts.
Eric
For
sman
pho
to.
6
WR
TV
TV
TV
15 c
m
7
Thro
ugho
ut th
eir r
ange
, tre
e vo
les f
eed
prim
arily
on
Doug
las-
fir, b
ut o
ccas
iona
lly so
me
will
feed
on
gran
d fir
. Tre
e vo
les t
hat f
eed
on D
ougl
as-fi
r will
har
vest
bra
nch
tips t
hat a
vera
ge 1
4 cm
in le
ngth
(r
ange
= 1
–35
cm) a
nd st
ore
thes
e cu
ttin
gs o
n th
e to
p or
insi
de o
f the
nes
t. Th
is p
hoto
com
pare
s 3
tree
vol
e (T
V) cu
ttin
gs to
the
larg
er w
oodr
at (W
R) cu
ttin
g. C
ompa
red
to tr
ee v
ole
cutt
ings
, w
oodr
at cu
ttin
gs a
re ty
pica
lly lo
nger
, thi
cker
, and
hav
e m
ore
axill
ary
bran
chle
ts e
mer
ging
from
the
mai
n st
em. E
ric F
orsm
an p
hoto
.
8
2 cm
9
The
left-
hand
pho
to is
a cr
oss-
sect
ion
of a
Dou
glas
-fir n
eedl
e th
at il
lust
rate
s the
loca
tion
of th
e 2
late
ral r
esin
duc
ts (a
rrow
s). D
ougl
as-fi
r res
in d
ucts
are
tubu
les a
long
the
oute
r edg
e of
the
entir
e le
ngth
of t
he n
eedl
e. T
hey
are
the
coni
fer’s
def
ense
aga
inst
her
bivo
res,
as th
ey co
ntai
n te
rpen
es
and
othe
r unp
alat
able
chem
ical
s. Tr
ee v
oles
mec
hani
cally
rem
ove
the
2 re
sin
duct
s in
each
nee
dle
by ch
ewin
g al
ong
the
oute
r edg
es o
f the
nee
dle.
Res
in d
ucts
are
def
initi
ve e
vide
nce
of tr
ee v
ole
pres
ence
bec
ause
no
othe
r spe
cies
rem
ove
resi
n du
cts f
rom
nee
dles
and
inco
rpor
ate
the
duct
s int
o th
eir n
ests
. Ore
gon
Stat
e Un
iver
sity
phot
o.
Doug
las-
fir re
sin
duct
s are
line
ar o
r slig
htly
curv
ed, a
nd v
ery
thin
(rig
ht-h
and
phot
o). U
nder
m
agni
ficat
ion,
toot
h m
arks
that
app
ear a
s jag
ged
edge
s on
resi
n du
cts c
an b
e ea
sily
seen
. Afte
r re
mov
ing
the
resi
n du
cts,
tree
vol
es co
nsum
e th
e re
mai
ning
nee
dle
tissu
e. M
ost r
esin
duc
ts h
ave
a re
ddis
h-br
own
enla
rged
tip
at o
ne e
nd w
here
the
resi
n du
ct jo
ins t
he p
etio
le a
t the
bas
e of
the
need
le, a
nd a
tape
red
tip a
t the
oth
er e
nd. A
noth
er n
est m
ater
ial s
imila
r in
appe
aran
ce to
resi
n du
cts i
s fila
men
tous
lich
en. U
nder
mag
nific
atio
n, fi
lam
ento
us li
chen
app
ear s
moo
th a
nd d
o no
t ha
ve a
pet
iole
. Jim
Sw
ingl
e ph
oto.
10
5 cm
11
Resi
n du
cts a
re u
sed
as n
est m
ater
ial,
and
a de
finiti
ve si
gn th
at a
tree
vol
e us
ed th
e ne
st. T
he
surv
ey p
roto
col c
lass
ifies
tree
vol
e ne
sts a
s “ac
tive”
if re
sin
duct
s are
bri
ght g
reen
(lik
ely
occu
pied
or
ver
y re
cent
ly o
ccup
ied
vole
nes
t) o
r ove
r tim
e fa
de to
a p
ale
gree
n (r
ecen
tly o
ccup
ied
vole
nes
t).
Old
resi
n du
cts a
re re
ddis
h-br
own,
and
resu
lt in
clas
sify
ing
the
nest
as “
inac
tive”
(old
vol
e ne
st).
Deba
rked
twig
s tha
t are
≤6
cm lo
ng w
ith ch
isel
-cut
s at b
oth
ends
foun
d in
a n
est a
re fu
rthe
r ev
iden
ce o
f tre
e vo
le p
rese
nce.
Tre
e vo
les r
emov
e ba
rk a
nd e
at th
e te
nder
bar
k, o
r rem
ove
the
bark
to e
at th
e ca
mbi
um la
yer b
elow
. Deb
arke
d tw
igs p
ersi
st lo
nger
than
oth
er tr
ee v
ole
sign
such
as
resi
n du
cts,
feca
l pel
lets
, and
cutt
ings
, whi
ch ra
pidl
y de
com
pose
to a
soil-
like
mat
eria
l. Er
ic
Fors
man
pho
to.
12
5 m
m
13
Tree
vol
e fe
cal p
elle
ts a
re sm
all a
nd o
val-s
hape
d (5
mm
x 1
.0–1
.5 m
m),
and
are
anot
her
dist
inct
ive
sign
of t
he sp
ecie
s’ pr
esen
ce. W
ith th
e ai
d of
mag
nific
atio
n, th
e fib
rous
and
bri
ght-
gree
n in
teri
or co
mpa
red
to th
e da
rk-g
reen
ext
erio
r can
be
seen
in d
isse
cted
tree
vol
e pe
llets
. Tre
e vo
le fe
cal p
elle
ts ca
n be
use
d to
est
imat
e th
e ac
tivity
stat
us o
f a tr
ee v
ole
nest
. An
occu
pied
or
rece
ntly
occ
upie
d ne
st w
ill h
ave
moi
st o
r dri
ed d
ark-
gree
n fe
cal p
elle
ts, a
nd th
e ne
st sh
ould
be
char
acte
rize
d as
act
ive.
Bro
wn
to b
lack
feca
l pel
lets
iden
tify
an o
ld v
ole
nest
(i.e
., ina
ctiv
e). W
hite
-fo
oted
vol
es (A
rbor
imus
alb
ipes
) are
the
only
oth
er a
rbor
eal r
oden
t tha
t has
nes
ts w
ith g
reen
fe
cal p
elle
ts th
at a
re n
early
iden
tical
to tr
ee v
ole
feca
l pel
lets
. The
refo
re, o
ther
evi
denc
e m
ust b
e us
ed to
det
erm
ine
whi
ch sp
ecie
s use
d th
e ne
st. S
easo
nally
, whi
te-fo
oted
vol
es u
se a
rbor
eal n
ests
in
coni
fers
if th
e br
anch
es a
re in
terc
onne
cted
with
red
alde
r (Al
nus r
ubra
) or C
alifo
rnia
haz
el
(Cor
ylus
corn
uta)
tree
s. Fe
cal p
elle
ts fr
om o
ther
arb
orea
l rod
ents
are
usu
ally
bla
ck, r
ound
, and
la
rger
than
tree
vol
e pe
llets
. Dee
r mou
se (P
erom
yscu
s man
icul
atus
) fec
al p
elle
ts a
re th
e ex
cept
ion,
as
they
are
ova
l-sha
ped,
but
diff
er fr
om tr
ee v
ole
pelle
ts b
ecau
se th
ey a
re sm
alle
r, bl
ack,
and
us
ually
hav
e on
e en
d th
at ta
pers
to a
poi
nt. J
im S
win
gle
phot
o.
14
15 c
m
15
Man
y tr
ee v
ole
nest
s are
bui
lt on
bro
ken
tree
tops
, for
ked
trun
ks, e
pico
rmic
bra
nche
s, or
clos
ely
spac
ed li
mb-
who
rls.
Thi
s nes
t con
tain
s fre
sh tr
ee v
ole
nest
mat
eria
l and
is p
ossi
bly
unde
r co
nstr
uctio
n, b
ecau
se th
ere
is n
o co
veri
ng fo
r the
nes
t cha
mbe
r. Th
e cu
p de
pres
sion
is a
goo
d ex
ampl
e of
how
an
inne
r cha
mbe
r of a
tree
vol
e ne
st w
ould
look
with
out a
roof
. The
dep
ress
ion
was
mad
e by
a tr
ee v
ole
spin
ning
in ci
rcle
s and
com
pact
ing
the
resi
n du
cts w
ith th
e fr
ont f
eet,
caus
ing
the
cup-
shap
ed d
epre
ssio
n in
the
resi
n du
cts.
Jim S
win
gle
phot
o.
16
15 c
m
17
This
nes
t was
occ
upie
d by
a m
ale
tree
vol
e. If
the
tree
vol
e w
as n
ot o
bser
ved,
the
nest
wou
ld st
ill
be cl
assi
fied
as a
ctiv
e ba
sed
on th
e gr
een
resi
n du
cts a
nd fr
esh
Doug
las-
fir cu
ttin
gs. T
he n
est c
ould
no
t be
seen
from
any
poi
nt o
n th
e gr
ound
, eve
n th
ough
the
nest
was
qui
te lo
w (8
m).
Mal
e tr
ee v
ole
nest
s are
typi
cally
smal
ler t
han
fem
ale
nest
s, es
peci
ally
if th
e fe
mal
e is
rais
ing
youn
g. T
his n
est
was
bui
lt in
a cr
otch
of a
bro
ken
top
with
2 le
ader
s. Fr
esh
resi
n du
cts w
ere
foun
d on
the
outs
ide
of
the
nest
. The
re w
as a
sing
le e
ntry
that
was
plu
gged
with
cutt
ings
on
the
top
of th
e ne
st a
gain
st th
e bi
gger
mor
e ve
rtic
al le
ader
. On
the
oppo
site
side
, the
re w
as a
n es
cape
tunn
el a
t the
bot
tom
of t
he
nest
at t
he ju
nctio
n of
the
crot
ch a
nd sm
alle
r lea
der.
Esca
pe tu
nnel
s are
loca
ted
on th
e bo
ttom
of
tree
vol
e ne
sts a
nd o
ften
are
plac
ed b
etw
een
gaps
in th
e bo
le o
r bra
nche
s. Jim
Sw
ingl
e ph
oto.
18
19
This
is th
e sa
me
tree
vol
e ne
st fr
om 2
diff
eren
t van
tage
poi
nts.
It w
as m
onito
red
with
cont
inuo
us
vide
o fo
r 15
wee
ks to
doc
umen
t the
beh
avio
r of a
fem
ale
tree
vol
e. T
he fe
mal
e at
this
nes
t pr
oduc
ed 3
litt
ers o
f you
ng w
hile
the
nest
was
mon
itore
d. C
ompa
red
to m
ale
nest
s, fe
mal
e tr
ee
vole
nes
ts a
re u
sual
ly e
asie
r to
see
from
the
grou
nd b
ecau
se o
f the
ir la
rger
size
, esp
ecia
lly n
ests
of
fem
ales
that
are
rais
ing
youn
g.
This
nes
t wou
ld b
e cl
assi
fied
as a
ctiv
e ba
sed
on fr
esh
Doug
las-
fir cu
ttin
gs a
t 3 e
ntra
nces
(arr
ows)
sh
own
on to
p ph
oto.
The
bot
tom
pho
to sh
ows 2
esc
ape
tunn
els e
xitin
g th
e bo
ttom
of t
he n
est a
t th
e br
anch
junc
tions
(arr
ows)
. The
re m
ay h
ave
been
mor
e es
cape
tunn
els t
hat w
ere
hidd
en fr
om
view
. Ofte
n tr
ee v
ole
sign
can
be se
en a
t the
bot
tom
of a
nes
t. In
freq
uent
ly, c
lum
ps o
f nes
t mat
eria
l (b
ox) c
an b
e fo
und
on th
e gr
ound
, whi
ch m
ay b
e a
resu
lt of
the
mat
eria
l cal
ving
off
or th
e ne
st
bein
g to
rn a
part
by
a pr
edat
or. E
ric F
orsm
an to
p ph
oto,
Jim
Sw
ingl
e bo
ttom
pho
to.
20
21
This
is li
kely
an
occu
pied
tree
vol
e ne
st, g
iven
the
pres
ence
of b
righ
t-gr
een
resi
n du
cts,
dark
-gre
en
feca
l pel
lets
(arr
ows)
that
are
moi
st, a
nd fr
esh
Doug
las-
fir cu
ttin
gs. A
bove
the
feca
l pel
lets
is a
side
en
tran
ce tu
nnel
that
was
bui
lt ag
ains
t the
tree
bol
e. M
any
tree
vol
e tu
nnel
s are
loca
ted
agai
nst
the
bole
of t
he tr
ee o
n de
nse
bran
ch w
horl
s tha
t pro
vide
firm
foun
datio
ns fo
r the
nes
ts. T
he st
icks
(>
30 cm
long
) aga
inst
the
bole
are
thic
ker t
han
tree
vol
e cu
ttin
gs o
r tw
igs a
nd su
gges
t tha
t the
tr
ee v
ole
built
its n
est i
n an
aba
ndon
ed sq
uirr
el n
est.
Thes
e st
icks
crea
ted
an id
eal s
ubst
ruct
ure
on
whi
ch th
e tr
ee v
ole
built
its n
est,
as th
e st
icks
wer
e tig
htly
wov
en to
geth
er a
nd se
cure
d fir
mly
to
the
bole
and
bra
nch
who
rls.
Mik
e M
cDon
ald
phot
o.
22
This
tree
vol
e ne
st w
ould
be
clas
sifie
d as
act
ive,
bas
ed o
n th
e gr
een
Doug
las-
fir cu
ttin
g, b
righ
t-gr
een
resi
n du
cts,
and
dark
-gre
en
feca
l pel
lets
that
are
inte
rmix
ed
with
bro
wn
and
blac
k pe
llets
. Thi
s w
as p
roba
bly
a fe
edin
g pl
atfo
rm
rath
er th
an a
nes
t bec
ause
of t
he
lack
of a
dditi
onal
nes
t mat
eria
l. Th
e lic
hens
in th
e to
p le
ft of
the
phot
o (b
ox) w
ere
appr
oxim
atel
y th
e sa
me
diam
eter
as t
he re
sin
duct
s (bo
ttom
ce
nter
of p
hoto
). Li
chen
fila
men
ts
are
kink
ed a
nd tw
iste
d co
mpa
red
to th
e lin
ear o
r slig
htly
curv
ed re
sin
duct
s. N
icho
las S
obb
phot
o.
23
Nor
ther
n fly
ing
squi
rrel
nes
ts
ofte
n co
nsis
t of f
resh
mos
s with
a
cham
ber a
bout
the
size
of a
gr
apef
ruit
(app
roxi
mat
ely
10
cm in
dia
met
er) b
uilt
on a
bas
e of
stic
ks. F
rom
the
grou
nd, t
his
appe
ared
to b
e a
nort
hern
flyi
ng
squi
rrel
nes
t, bu
t a ju
veni
le tr
ee
vole
was
foun
d on
top
of n
est.
The
pela
ge o
n th
e ba
ck a
nd h
ead
of th
e ju
veni
le w
as tr
ansi
tioni
ng
from
gra
y to
the
adul
t red
, in
dica
ting
that
the
juve
nile
was
at
the
age
whe
n it
wou
ld d
ispe
rse
from
the
mat
erna
l nes
t. M
ike
McD
onal
d ph
oto.
24
1 m
25
This
is a
n ex
ampl
e of
why
tree
s sho
uld
be cl
imbe
d to
det
erm
ine
if a
tree
vol
e us
ed a
nes
t. Fr
om th
e gr
ound
this
nes
t loo
ked
to b
e an
old
woo
drat
nes
t, bu
t clo
se in
spec
tion
reve
aled
that
the
nest
als
o co
ntai
ned
tree
vol
e si
gn. T
he w
oodr
at n
est w
as co
nstr
ucte
d of
stic
ks, m
oss,
and
liche
ns, a
nd b
uilt
on b
ranc
h w
horl
s tha
t com
plet
ely
circ
led
the
bole
of a
seco
ndar
y le
ader
that
was
gro
win
g fr
om th
e br
oken
top.
Mos
t woo
drat
nes
ts co
ntai
n a
vari
ety
of v
eget
atio
n, in
clud
ing
deci
duou
s lea
ves a
nd
coni
fer c
uttin
gs, b
ut w
oodr
at co
nife
r cut
tings
are
typi
cally
long
er a
nd th
icke
r tha
n th
ose
foun
d in
squi
rrel
or t
ree
vole
nes
ts. A
dis
tinct
ive
char
acte
rist
ic o
f an
occu
pied
woo
drat
nes
t is a
stro
ng
urin
e od
or.
Tree
vol
e si
gn a
t thi
s nes
t con
sist
ed o
f bro
wn
feca
l pel
lets
, bro
wn
resi
n du
cts,
and
deba
rked
twig
s on
the
insi
de o
f the
nes
t. An
esc
ape
tunn
el (a
rrow
) lin
ed w
ith re
sin
duct
s exi
ted
at th
e ba
se o
f 2
bran
ches
. Thi
s wou
ld b
e cl
assi
fied
as a
n ol
d vo
le n
est.
Nic
k H
atch
pho
to.
26
20 c
m
27
This
is a
n ex
ampl
e of
an
unus
ual t
ree
vole
nes
t. In
side
this
squi
rrel
nes
t, co
nstr
ucte
d of
lich
en,
was
a sm
all t
ree
vole
nes
t con
stru
cted
of r
esin
duc
ts, w
ith a
few
cutt
ings
that
coul
d be
seen
w
hen
the
liche
n w
as ca
refu
lly o
pene
d. W
e re
com
men
d th
at cl
imbe
rs ca
refu
lly o
pen
nest
s tha
t do
not h
ave
tree
vol
e si
gn o
r for
whi
ch a
ctiv
ity st
atus
cann
ot b
e de
term
ined
by
exam
inat
ion
of th
e ex
teri
or. I
nter
iors
of m
ost n
ests
can
be se
arch
ed fo
r tre
e vo
le si
gn w
ithou
t dam
agin
g th
e in
tegr
ity
of th
e ne
st. J
im S
win
gle
phot
o.
28
We
susp
ect t
hat t
ree
cavi
ties
are
an id
eal p
lace
for t
ree
vole
ne
sts.
Cavi
ties h
ave
stur
dy
foun
datio
ns fo
r nes
ts a
nd
prov
ide
prot
ectio
n fr
om st
orm
s an
d pr
edat
ors.
Man
y ty
pes o
f ca
vitie
s are
use
d by
tree
vol
es,
incl
udin
g br
oken
tops
, bol
es,
and
limbs
. Sea
rchi
ng fo
r a n
est
in a
cavi
ty o
f a li
ve tr
ee is
ofte
n di
fficu
lt be
caus
e en
tran
ces a
re
typi
cally
smal
l and
the
cavi
ty
can
exte
nd b
eyon
d th
e re
ach
of
the
tree
clim
ber.
Eric
For
sman
ph
oto.
29
Occa
sion
ally
tree
vol
es w
ill
nest
in tr
ee sp
ecie
s oth
er
than
Dou
glas
-fir.
This
nes
t is
in a
big
leaf
map
le (A
cer
mac
roph
yllu
m) c
avity
that
had
br
anch
pat
hway
s int
erco
nnec
ting
with
Dou
glas
-firs
, fro
m w
hich
th
e tr
ee v
ole
colle
cted
cutt
ings
. Ca
vity
nes
ts a
re ra
rely
seen
from
th
e gr
ound
, but
can
ofte
n be
seen
w
hile
clim
bing
adj
acen
t tre
es.
Ther
efor
e, w
hen
cond
uctin
g su
rvey
s clim
bers
shou
ld se
arch
fo
r nes
ts in
adj
acen
t tre
es in
ad
ditio
n to
the
tree
they
are
cl
imbi
ng. J
im S
win
gle
phot
o.
5 cm
30
Tree
vol
es a
nd o
ther
ar
bore
al ro
dent
s ofte
n ne
st in
dw
arf m
istle
toe
(Arc
euth
obiu
m sp
p.)
broo
ms i
n Do
ugla
s-fir
and
w
este
rn h
emlo
ck b
ecau
se
thes
e st
ruct
ures
are
idea
l fo
unda
tions
for n
ests
. N
icho
las S
obb
phot
o.
3 m
31
Occa
sion
ally
, gra
nd fi
r cu
ttin
gs m
ay b
e fo
und
in tr
ee v
ole
nest
s. Gr
and
fir re
sin
duct
s ar
e si
mila
r to
Doug
las-
fir b
ut m
uch
shor
ter
(app
roxi
mat
ely
1.0
cm v
s. 2.
0 cm
, res
pect
ivel
y). E
ric
Fors
man
pho
to.
40 c
m
32
1.5 cm
33
In th
is se
ctio
n, w
e di
scus
s tre
e vo
les i
n th
e co
asta
l for
ests
of O
rego
n in
the
Sitk
a sp
ruce
zon
e,
whe
re tr
ee v
oles
feed
on
wes
tern
hem
lock
or S
itka
spru
ce. T
he le
ft-ha
nd p
hoto
show
s the
sing
le
resi
n du
ct in
the
cent
er o
f a w
este
rn h
emlo
ck n
eedl
e (a
rrow
). In
stea
d of
chew
ing
alon
g th
e ed
ge
of th
e ne
edle
to m
echa
nica
lly re
mov
e th
e re
sin
duct
s as i
n Do
ugla
s-fir
and
gra
nd fi
r, tr
ee v
oles
eat
w
este
rn h
emlo
ck n
eedl
es b
y ch
ewin
g al
ong
the
leng
th o
f one
side
of t
he n
eedl
e an
d co
nsum
ing
this
mat
eria
l bef
ore
flipp
ing
the
need
le o
ver a
nd re
peat
ing
the
proc
ess a
nd d
isca
rdin
g th
e ce
ntra
lly lo
cate
d re
sin
duct
. Hem
lock
resi
n du
cts h
ave
a di
stin
ctiv
e do
uble
-ser
rate
d pa
tter
n w
here
th
e in
ciso
rs o
f the
tree
vol
e re
mov
ed th
e pa
lata
ble
tissu
e of
the
need
le. O
rego
n St
ate
Univ
ersit
y ph
oto.
The
righ
t-ha
nd p
hoto
show
s wes
tern
hem
lock
resi
n du
cts w
ith a
com
plet
e ne
edle
in th
e m
iddl
e fo
r com
pari
son.
Wes
tern
hem
lock
resi
n du
cts a
re cu
rved
, and
like
Dou
glas
-fir d
ucts
, one
end
has
th
e pe
tiole
that
att
ache
s to
the
twig
stem
. With
the
aid
of m
agni
ficat
ion,
wes
tern
hem
lock
resi
n du
cts h
ave
2 si
des t
hat a
re se
rrat
ed w
here
a tr
ee v
ole
nipp
ed o
ff an
d co
nsum
ed th
e ou
ter p
ortio
ns
of th
e ne
edle
. Jim
Sw
ingl
e ph
oto.
34
The
nest
was
like
ly
occu
pied
by
a tr
ee v
ole
beca
use
the
top
of th
e ne
st w
as co
mpl
etel
y co
vere
d w
ith w
este
rn
hem
lock
cutt
ings
that
w
ere
quite
fres
h. F
rom
the
grou
nd it
was
impo
ssib
le
to d
eter
min
e if
thes
e w
ere
the
tips o
f hem
lock
br
anch
es o
r cut
tings
. Eri
c Fo
rsm
an p
hoto
.
20 c
m
35
Her
e is
a tr
ee v
ole
nest
bui
lt in
a d
war
f mis
tleto
e br
oom
in
a w
este
rn h
emlo
ck. S
hort
, 2-
to 5
-cm
wes
tern
hem
lock
cu
ttin
gs la
y on
top
of th
e ne
st, b
ut a
few
add
ition
al
cutt
ings
can
be se
en o
n th
e si
de o
f the
nes
t. Se
arch
ing
for t
ree
vole
sign
in d
war
f m
istle
toe
broo
ms i
n w
este
rn
hem
lock
is d
iffic
ult b
ecau
se
the
broo
ms a
re v
ery
dens
e,
with
num
erou
s bra
nche
s cl
osel
y sp
aced
and
twis
ted
arou
nd e
ach
othe
r. Er
ic
Fors
man
pho
to.
36
DF
SS
37
The
left-
hand
pho
to sh
ows a
cros
s sec
tion
of a
Sitk
a sp
ruce
nee
dle
with
a si
ngle
resi
n du
ct in
the
low
er p
ortio
n of
the
need
le o
n th
e ri
ght (
arro
w).
The
dist
ribu
tion
of re
sin
in S
itka
spru
ce n
eedl
es
is u
niqu
e in
that
it d
oes n
ot o
ccur
cont
inuo
usly
like
resi
n du
cts i
n Do
ugla
s-fir
, wes
tern
hem
lock
, an
d gr
and
fir. I
nste
ad, r
esin
may
occ
ur in
sacs
that
are
irre
gula
rly o
r lin
early
dis
trib
uted
, or r
esin
sa
cs m
ay n
ot b
e pr
esen
t at a
ll in
Sitk
a sp
ruce
nee
dles
. The
resi
n sa
cs a
re fo
und
prim
arily
in th
e ba
sal h
alf o
f the
nee
dle.
Nes
ts o
f tre
e vo
les f
eedi
ng o
n Si
tka
spru
ce m
ay co
ntai
n on
ly fe
cal p
elle
ts,
deba
rked
twig
s, an
d Si
tka
spru
ce cu
ttin
gs. O
rego
n St
ate
Univ
ersit
y ph
oto.
The
righ
t-ha
nd p
hoto
com
pare
s 2 S
itka
spru
ce (S
S) re
sin
duct
s (ab
ove)
on
top
and
2 Do
ugla
s-fir
(DF)
resi
n du
cts (
belo
w).
The
Sitk
a sp
ruce
resi
n du
cts w
ere
colle
cted
in a
Son
oma
tree
vol
e (A
. pom
o) n
est i
n Ca
lifor
nia.
Com
pare
d to
Dou
glas
-fir r
esin
duc
ts, S
itka
spru
ce re
sin
duct
s are
sh
orte
r (2.
0 cm
vs.
1.5
cm, r
espe
ctiv
ely)
and
mor
e se
rrat
ed. W
e su
spec
t tha
t the
Son
oma
tree
vol
e re
mov
ed a
seri
es o
f lin
ear r
esin
sacs
, res
ultin
g in
wha
t app
ears
to b
e a
sing
le, l
ong
spru
ce re
sin
duct
. Jim
Sw
ingl
e ph
oto.
38
In th
is se
ctio
n, w
e de
scri
be n
ests
of o
ther
arb
orea
l mam
mal
s tha
t may
be
mis
take
n fo
r tre
e vo
le
nest
s. In
fact
, whe
n ab
ando
ned
thes
e ne
sts a
re o
ften
used
by
tree
vol
es.
This
pho
to il
lust
rate
s the
top
port
ion
of a
nor
ther
n fly
ing
squi
rrel
nes
t. Th
ese
nest
s are
usu
ally
cons
truc
ted
of m
oss,
with
a g
rape
frui
t-si
zed
cham
ber o
n to
p of
a b
ed o
f stic
ks.
Flyi
ng sq
uirr
els w
ill in
corp
orat
e st
ripp
ed b
ark
into
thei
r nes
ts, b
ut
not a
s ofte
n or
to th
e ex
tent
that
Do
ugla
s’ sq
uirr
els d
o. A
n en
tran
ce
is lo
cate
d at
the
base
of t
he m
oss
in th
is p
hoto
, but
usu
ally
flyi
ng
squi
rrel
nes
ts d
o no
t hav
e su
ch a
n ob
viou
s ent
ranc
e le
adin
g to
the
nest
ch
ambe
r. Jim
Sw
ingl
e ph
oto.
39
This
was
an
occu
pied
whi
te-
foot
ed v
ole
nest
, with
red
alde
r cu
ttin
gs th
at h
ad ch
isel
-cut
bas
al
tips.
The
nest
als
o co
ntai
ned
feca
l pe
llets
that
wer
e ve
ry si
mila
r to
red
tree
vol
e pe
llets
, but
no
resi
n du
cts o
r deb
arke
d tw
igs w
ere
foun
d. B
ecau
se w
hite
-foot
ed v
oles
fe
ed o
n no
n-co
nife
r veg
etat
ion,
th
eir n
ests
do
not c
onta
in re
sin
duct
s, de
bark
ed tw
igs,
or co
nife
r cu
ttin
gs. W
hite
-foot
ed v
ole
nest
s of
ten
cont
ain
deci
duou
s lea
ves,
but t
he sp
ecie
s pri
mar
ily e
ats
forb
s and
fern
s. Er
ic F
orsm
an
phot
o.
40
41
Wes
tern
gra
y sq
uirr
el n
ests
are
ver
y di
ffere
nt fr
om tr
ee v
ole
nest
s bec
ause
they
are
cons
truc
ted
of la
rge
stic
ks th
at a
re lo
osel
y w
oven
, and
typi
cally
cont
ain
deci
duou
s lea
ves.
Dist
inct
ive
char
acte
rist
ics o
f gra
y sq
uirr
el n
ests
can
easi
ly b
e se
en fr
om th
e gr
ound
with
the
aid
of b
inoc
ular
s. W
e ha
ve fo
und
tree
vol
e si
gn in
side
gra
y sq
uirr
el n
ests
that
app
eare
d to
be
cons
truc
ted
only
of
stic
ks a
nd d
ecid
uous
leav
es w
hen
view
ed fr
om th
e gr
ound
. How
ever
, if t
he n
est i
s in
a de
cidu
ous
tree
that
doe
s not
hav
e in
terc
onne
ctin
g br
anch
es w
ith co
nife
rs fr
om w
hich
tree
vol
es ca
n ob
tain
cu
ttin
gs, i
t is u
nlik
ely
to b
e oc
cupi
ed b
y a
tree
vol
e. E
ric F
orsm
an p
hoto
s.
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