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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.