Lau ie
Wunde
and
And ew B. Ca ey, USDA
Fo es
Se
ce Pac c No hwes Resea ch S a on.
3625 93 d
A enL e
SW. Oly .p
a Washing on 98512
Use
o he Fo es Canopy
by Ba s
Abs ac
O ihe l5 species o ba s in hc Paciljc N*o ih$es . I I e known o nxkc cgl la use
o he o es canop] b oosling. lo ,lging.
and ep oduc ion. This papc c ic$s oos ing equi emen s, lb aging. and he impo ance o landscape scale luc(o s 1() canopy
using species in hc Noih$es . N4ani no ih es ba s use sclclal di ie en pes o ee oos s. Comm|)l c'os ing silcs a e in
c. i ies. c e!ices. and oliage. Fac o ha m l be impo anl in oos si e selec ion include nic oclina c. oo sl uc u.c. c own
chi ec u e. c anop) | cc agc and
sl)ec ie . ba k c h c e is ic s. ibliagc den si , ,
and s and nd laDdscape conposilion. Some
ep e
sen a i e
P ci ic o hwes c, !i ) and c e ice/ha k- oos ing
species includc lhe ll lle b own b {M ol/ u.il ,q l. sil c hai cd
ba il.a'id ..ie s oc ingans). xndlong lcgged h^ li ,1.
ol(ol). Only l$o Paci ic
No h$e i species a e known o ooslin
lbliagc. Se e al
pecies i)mge in lb cs gaps.
along o es edges. o in ipa ian a cas.
I-ong ea ed
(M. . l l . nd Keen's M
l.., iil ba s
n ay o xge $ i hin he lb es canopy. al hough
o ging beha io
()1
iesc spccics
in lhe Paci ic No h$es is no $ell
documen ed.
S and- nd landsc pc sc lc complexi ! m y he nnpo ianl in p o!iding ba s i h he abundance and di e sily oi'
..,J ^ , L
p.
- J ibe n:, n
.i (.
lhL]
- ,
L e
ln oduc ion
Li Lle wo k has been done on o cs canopy use
by ba s in he empe a e egion. pa icula ly in
he
Paci ic Nonhwes . Mo eo e , he unde s anding
o he signi icance o he o es canopy
o ba s is
complica ed
by he ac ha 1ew empe a e
spc-
cies a e
es ic ed o any one habi a ype
b o -
aging and
oos ing. Mos species nee only some
o hei equi emen s
wi hin he o es canopy and
musi
go ou side he canopy o sa is y he emain
de o hei needs. The e m canopy
is uscd he e
in he
b oadcs sense o encompass all compo-
nen s
( unks,
as well as b anches and
i liage) o
he uppe pa s
o c o ,l]s o ees ha makc up
lb es s ands.
A de alled lis o canopy a ibu cs
o
po en ial
signi icancc
1o ba s and o he canopy
spccies may be bund
in Ca ey
( his
issue).
Abou I I spccies o Pacilic No hwes ba s
appea
o egula ly use he
b es canopy. An ad
di ional wo species a e
occasional canopy use s
( he inged ba , M. h sanodes and he es e n
small- bo ed ba ,
M. llio u Dnl ) (Table
l ). Fo -
es ba communi ics
in he Paci ic No hwes
a c
made up o somc
six o eigh M dis species
and
bu -
non-M}o i. species. The mos equen ly
encoun c cd
species include he
li le b own ba
(M. l i ug s). he Yun a ba (M. lwnunen is).
he Cali b niab
(M.
zldb i lo ). he longJegged
ba
(M ola . ).
he long ea cd ba
(M ?l/.
e ,. l. J.
he big b own
b (Ep esi us
scusl, he
sil e -
hai ed ba (.Ld. io 1)-c e is
oL i|ugon ) a]nd he
hoaly ba (Las u as
cll?" c l J
(Chds y and Wes
1993). To nsend's big-ea ed ba (Pleco us
l,, n' ilii
also lb aFe.
in L' el ed cn i on ncnl .
Ba s use he canopy b a a ie y o pu poses,
including
oos ing. o aging, and ep oduc ion.
ln his
pape .
we will examine
he usc o he o
es canopy
by No hwes ba s o oos ing and
o aging. The inpu anL
e,' l n lsci pe
(on po:i
ion o ba s,
will lso be discussed.
Roos ing
The oos ing ecology o ba s
has bccn e iewed
by Kunz
(1982a).
Species di e si y and
popula-
ion size o colonial ba s appea
o inc ease wi h
inc eased oos a ailabili y and di e si y
(Humph ey
1975. Findley 1993).
A eas ha o -
e a a ie y
o lee, cli . and
ca c oosls. o en
suppo he
la ges numbe o ba species and in-
di iduals
(Humph ey
l975,
Findley 1993).
The specilic oos si es
selec cd by aious ba
specics may be de e mined il pa l by such ac-
o s as mo phology, ligh and ccholoca ion ca
pabili ies, p o x i m i y o o he esou ces
( ood,
wa e .
hibema ion si es). clima ic ac o s. and oos a ail-
abili l'. among o he s.
Vaughan
(
I 970) has c iewed
he ela ion be wccn no phology (skull shape,
pel ic gi dle,
and
li nb p opo ions)
and oos
selec ion in ba s. Shunp and Shump
( 1980) ound
ha hoa y and ed ba s.
which oos in exposed
loca io s,
ha e
g ea c pelage
insula ion han Ii le
h ,'u n and big b ou n ba s.
u hich oo.l in m,, e
No hwes Science,
V l.70, Special lssue, 1996 19
TABL i L Fo cs
cunop u e b) Paci lc
No lh les b spe-
cics. Species ma ked $ilh ! e isk {") a e
nl equen c. nopl
u c : all o he s li ed a e
cgula
anop usen.
he
signi icance o p oximi )' o malc ni y oos s
o Ii) aging
a eas and hibe na ion
si es in g ay
ba s
(M o is
g isescensl.
Thomas
(1988)
and Ba clay
(
1991
)
ha e
sugges ed ha clima e
and elc a ion
may play a olc in he choice oI oos loca ion
and dis ibu ion
o he sexes in some
ba specics.
Choice
o oos si e ma
di e
wi h sex, age.
eploduc i c
condi ion. and mig a o y
s a us o
an indi idual.
Cons an ine
(1966)
obse ed
ha
young
ed b s oos
highe in ees
han do adul s.
Fen o
(1970)
ound h ep oduc i e
cmale
li le
b own ba s selec
dille eD oos si es
han domales,
based
upon hei he mal equi emenls.
Mos
Paci ic No hwes
species oos in
a a
del) o si ua ions. a he han in only onc pa -
lcula oos pe
( an
Zyll dc Jong 1985). Thc
oos ing
ecology o Paci lc No ihwcs ba s has
been e icwed
b Ch is and Wes
(
1993).
The majo ypcs o ee oos s uscd
by em
pe alc
ba s include ca i ics,
c e ices behind
ex-
blia ing ba k. c e ices olmed in ugose
ba k,
c acks
in wood. and in lbliage. Ra ely.
ba s ha e
been epo ied
oos ing in nes s
o o he man mals
(squinels)
and in epiphy es
(Spanish
moss) on
cu.
l eill 1q52.
Con. n ine lq58).
T ee
Ca es
T ee ca i ics
used by ba s may be in hollows
b med
in he unks
o b anches o snags
o dam-
agcd li e ees. They
gene ally
p o idc
a ela-
i ely s ablc mic oclima e
and o e
p o ec ion
ion
p cda o s (Kunz 1982a. Tidemann
and Fla el
1987).
Fac o s
in selec ing
ee ca i ies include
ni
c oclima e,
s uc u e. ee
age. size. and heigh .
Mic oclind (. Mic oclima e
o a ca i y
can be
a ec ed by llspec .
en ance heigh ,
canopy co e ,
densi y
o sunounding
ege a ion. ce s a us
(ali e
o[ dead). hickness
and insula ing p ope lics
o
he
ca i y walls, cc diame e ,
ca i y size.
and
numbe o b s occup ing he ca i y.
Maeda
(
1974)
b ud ha la gc noc ule
ba s
(N_ c ala.i
/asioplen s)
in
Japan
p .e elen ially
oos in ca i ies in li e
ees.
which p o ides
no e cons an
enpem u cs han
ca i ies in snags. Tideman
and Fla el
(
1987)
sug-
ges cd
ha
he highe wa e con en
o li c ees
inc eases
hei insula i e
alue and ca i y hu nidi y.
Femalc b s in ep oduc i e
condi ion genc ally
hu
e dil[< en h . c,]in!-.e .on
oos ng
equi e-
men s
han nales and may
oos sepa a ely
iom
CJ o )] .!
Roos ing l_o.aging
M|o i uD uk i :
V o is c llilbnins:
Lul,on L1e k no. h u!un '
Pl? I) ' c dii
.Vl i ,, ' d o/. * l
M o isIilijlah u,i:'
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Ba bou
nd D !i 1969. l-a al
c l. 1977. Fen on
c a].
1980. en()n a d Ba cla) 1980.
Blllch] and Cash 1985.
Fenlon
e al.
1980 l llZ)lldeJong
1985.
'K u sch
195,1 Fen on and Bcll 197q. Fen on e al. 1980.
'B ke Lnd Philljps 1965. Vhxake
e al. 1977. Fcn on
and
Bcll 1979
'N,l. nning
nd.lol cs
1989. Ba cl. ) 1991.
"Co$an
and Cuigue 1965.
len on e . 1. 1980. B lgh n 1991.
'Con inlinc 1966. Shump. nd
Shun p 19E2. Blucl 198.1.
Ba clay l9E5.
'Cons an i e
1966. Fu longc
cl aL. 1987.
Kunz l98lb, Ba cli,,-
1985.
Kunz and ,laiin 1981.
' Ba bo
nd Dl lis 1969. hiFkc c al. 1q77.
'Fen()n
eI al. 1980. !l1n
Z)ll de JonS 1985.
p o ec ed
si es. Thesc au ho s ela ed pelagc
di -
e ences o di le ences
in oos condi ion
and
g e
ga iousness
in hese specics. Hoa y
ba s ha e a
ela i ,el)' high aspec a io
and wing-loading
and
a e no well adap cd i highly
maneu e ablc ligh ,
uhich m y in luence hci choice
o oos si cs
(Cons an ine
1966.
Ba clay 1985).
Cons an ine
(
1966)
bund ha hoaD'
and cd ba s
gcnc ally
oosl whc c hey could d op down h -ough an
unobs uc ed
dis ance o a ain ligh
speed.
No be g
and Rayne
(
1987.)
discuss he ela-
lon be wccn mo phology.
ligh . and echoloca
ion capabili ies in ba s. Tu le
(1976J
cxam neq
lJO Wundc ancl
Ca e
hcm. P egnan o lac a ing lcmales o el oos
colonially a mo e
p olec ed
oos si es ha p o-
ide hc high empe a u es
necessa y o maxi-
mizing g ow h
and de elopmen o he young
(Ba clay
l99l). Males
and non ep oduc i e e-
males commonly
oos soli adly o -in
small
-q oups.
in less
p o ec ed
and he ma ly
s able en i on-
men s
(Ba clay
1991
).
S LlLlu e
Maeda (197,1)
cpo ed ha la ge
noc ule ba s
selcc oos s based on he
bllowing
s ucluml cha ac e is ics
o hc oos ca i )': shape,
posi ion. cn ance heigh , size, and
cleg cc o eD
ance
p o ec ion. The
posi ion
o he en ance has
o pe mi easy
ligh om he ca j y. Tiden an
and
Fla cl
(
1987) s udied ca i )- q)s ing
ba s in
Aus alia and lbund ha ba s
sclec ca i ies
u,i h
en a ce
holes
ha
a c
jus la ge han he
size o
he bal hesumably, smallen anccs
p o ide
![ea e
p o ec ion om p cda o s
and may educe conl-
pc i ion
om bi ds and o he b: s.
Roos en lances
a e also o ien ed
o p e en
he en y o in in o
he cl l y.
Tn, ' l a a,
i.' i,
': The JFi, l .'i il)
l cc'
is impo an o ba s o he
ex cn ha i is a lac o
in iequency
o ca i y o ma ion, ca i y sizc. and
ca i y cha ac e is ics
(Tideman
and Fla el 1987).
Tide nan
and Fla el
(1987)
ailed
o lnd any e
la ion be wee oos si e
selec ion and ce heigh ,
o he Aus alian ba s hey s udied. Lunney e
al.
(
1988).
ound ha heAus alian big-ea cd
ba
(N : ophil s go uli
)
ca i y-
and c e ice oos ing
species. selec
la ge diame e ees, o mo e han
1J0 cm d.b.h. o oos ing.
Some examples
o Paci ic No ihwes
ba s
k own o usc
ee ca i ies a e he
li le b own ba
(Fen on
and Ba clay l9E0),
hc big b o "n ba
(Bigham 1991), he C li o nia
ba (K u zsch
195'1). and
he sil e hai ed ba
(Kunz 1982b).
Somc
o hese species
(pa icula ly
he li le b own
ba . he big b own ba . and he Cali innia
bal)
commonly use buildings
as oos si es as
well.
Ba bou and
Da is
(1969)
lis buildings
as he
p ele eLl oi'.1 si e. lb he.e
h ee.pccie..
T ee
C e lces
Many ec- oos ing ba s oos behind
cx olia ing
ba k on nks o b anches o dead o li e ees.
Ba k oos s
p o ide
a much less
pcnnanen ,
less
secu e and
less hc mally s able cos ing en i on-
men han
ca i ics. Ba s ha oos unde ba k
mus
ih ngc oosl. mo e l equen ll
h ho.e oo. inp
in ca i ies because
o he n o e ansien na u e o
hei oos si es
(Kunz 1982a). They a e
p obably
also mole ulne able
o p cda ion
and wea he .
O he ypes o c e ice oos s include c acks
in ee unks and in lugc b anches, and c e -
ices clea ed by ba k ugosi y. Pe kins and C oss
(
1988) epo ied ha sil e -hai cd
ba s
p e e
oos
ing in old (> 150
yeu-s)
Dix glas- i
(PseLldo sugu
nenz.iesii)
o es s in O egon.
p obably
bccause
o he
ba k cha ac e is ics o dd ees.
Thc ba k
ol old Douglas i end o
p o ide
mo c c e! ces
by sepiua ing no e widely iom hc unk. Old
ees also de elop
mo e p onounced
idges and
c e ices in he ba k i sel .
Ba s wc e lound o
p e e
Douglas-n o ponde osa pine (Pl is
2o,, de os i)
and ue
i (ADies
spp.).
p obably
because
o di -
le ences
in ba k cha ac eds ics. The ba k o hese
la e
species cnded o be less ugose and
gene -
ally did no o m as deeply c e iced
u ows.
Ba clay e al. 1988 obse ed
sil e -hai ed ba s
ix s ing in spaces behind i ds o ba k. in spli
ee unks.
andin dep essions on ee unks. O he
No hwes ba s
ha oos undel ba k o in o he
ee c e ices
include Lhe long legged ba and he
long-ea ed ba
( an
Zyll de Jong 1985).
Foliage Roos s
Foliage
oos s
p o idc
he mos exposed ype dis-
cussed hus a .
They a c used mos equeo ly in
l opical egions. Po en ial
oliage oos si es a e
m e JbUnd n hun c il]- nJ c|c ice- oosl..
bu hei
g ea e
exposu e
makes hcm mo e haz
a dous. Thei abundance.
howc c , makes hem
easy o ind nea
li aging a cas, and migh help
o educe commu ing
dis ance. The abundance
o oliage oos s also acili ales he wide dis li
bu ion o some bliage
oos ing spccies. P eda
ion isks a e
p obably
highe
i oliagc oos -
ing ba s, and many empe a e and opical
i)liagc
oos c s a e c yp ically colo ed and
oos soli a ily
o in small amily g oups (Kunz 1982a). One
No hwes oliage oos ing
specics, lhe hoa y ba .
has a cha ac eds ic
g izzled
appea ance
ha may
con ibu c
o i s concealmen . Ten pe a e
i liagc
cos ing
specics a e
geDe ally
wellinsula ed agains
cold empe a u (]s
(Shump
and Shump 1980) and
i l
mule l,'n3 Ji. . nce la i udinal n il l i,,n
in
esponse o dininished wil e ood supplies
(Shump
and Shump 19821.
Foliage
oos ing ba s end o change oos s
n o e
uequen ly han o he species in esponse o he
ansicnl
na u e o hei oos si es.
Wi hin he
Ba Canopy Use 8l
same
season! hcy may show some ideli y o a
gene al
a ea, howe c
(Kunz 1982a, Lunney
e
al. 1988.1.
Ba s
ha oos in bliage
may oos high
in
he canopy. in subcanopy ees.
o in unde s o y
lb1iage.
Roos si es may be in densc b iage.
in
ela i ely
exposed loca ions.
among lea cs,
o on
b anches.
Si es may be concealed
iom abo e,
bu conspicuous ' om
below
(Cons an ine
l966,
Kunz 1982a).
Hoa y ba s
and ed ba s
(Za. l(/- s
Do ealis) o cxample,
ha e been bund o selec
oos si cs co e ed
by dcnse bliage
abo c and
a ound
he sides. bu open below. This a ange
men
p esumably
educes
hei isibili y and
ac-
cessibili y k) p eda o s.
bu
pe mi s
hem o ake
ligh
leadily
(Cons an ine
I 966).
Loca ion
o he oos
ee elad c o sunounding
ege a ion may also be o impo iance
o Son e
species.
Ce ain species
may p el ees
wi hin
he o es in e io .
and olhc species p e e
o oos
along a o es cdge.
Cons an ine
(
1966)
epo ed
h hoa y and ed ba oos si es we e usually
loca eci along
a lb es edge.
Pe kins and
C oss
(1988)
i)und
ha hoa y ba s
e e p ima ily associa ed
wi h old Douglas- i
b es s in O egon and hypo hesized
ha his is
duc o ba s' oos ing
cqui emen s.
The la ge
ees
al]d la gc nd he e ogeneous
canopies ound in
such lb es s may u nish mo c oos
si es a ail-
able b lbliage oos ing
ba s han
young
o es s.
Old coni 'e ous
lb es s a c no e ljkely o p o ide
he
canopy s uc u e, including
dense bliage
ad
iacen o unclu e ed
ligh space.
equi ed i '
oos ing
by hese ba s. In con as o younge ees.
olde l ccs
end o ha e c owns
ha begin l ighe
o T he g ound and ha e he necdles
mo e con-
cen a ed
owa d he
edge o he canop
(Pe kins
and C oss 1988).
Fo aging
Fo aging
ends o bc oppe unis ic
a he
han
es lc ed o a
pa icula
o aging s a egy
o habi a
lb os No h Ame ican ba spccies
(Vaughan
1980. Ba clay
l99l.bu seeFen on
1982. Fu longe
e al. 1987). Fu longe
e al. (1987)
ound ha
ba s in
eas em Canada
exploi concen a ed
pa ches
o p ey. Thcy sugges ed
ha his ype o o aging
sl a cgy may supe sedc
p e e elce
o a pa icu-
liu ype o o aging
habi a . Some
au ho s
(Black
197,1.
C ome and Richa ds
1988. Findley
1993)
main ain
ha species o ba s ma pa li ion
o aging
habi a
by cge i ion
s uuc u e, e lec ing
di e -
cnces in hei mo phology.
echoloca ion
call s uc-
u e. and ligh capabili ics. Findley
(1993)
e-
icws he ela ion be u'een
no phology and
c()mmuni y s uc u e
in ba s.
Fo ag ng Hab a
Ald idgc
and Rau enbach
(1987)
di ided
Al i
c n il cc i .' u hl . in o i,'u
n ajo
e ,'up.
acco ding
o o aging-habi a p el'e ence: ( J
) clu e
b age s,
maneu e able
specics wi h echoloca ion
calls sui ed
o a clu e ed
gn i onmen
and ca
pable o o aging wi hin he i es
canopy; (2)
inlc media e
clu e o age s.
mode a ely
naneu-
e able ba s capable o o aging in open a eas
and open woodland.
bu no wi hin
dense eg-
c a ion:
(3)
woodland-edge
o age s; and
(4)
open-
ai lb age s ha lack naneu e abili y.
O ic au-
ho s h e used sinila classi ica ion schemes
o
desc ibe No h Ame ican ba species.
La al e
al.( 1977)
s udied ba
popula ions
in Missou i
and
lbund ha
hoiuy and ed
ba s ended o b age
in
open a eas away
om o es clu e ,
including high
o e
he lb es canopy
and o e opcn ields.
G ay
ba s o aged in ipa ian
a eas and
o e wa e Li le
b own
ba s o aged along
b es edgcs
and wi hin
he b es .
The nonhen my o s
(.M.
sep e idnlis)
a close ela i e
o $e Keen's
myo is. a Paci ic
No hwes
species, was a clu e
lb age
and b
aged in o es ed
a eas. The Indiana
myo is
(M
sodcll. ),
ano he clu e b age , o aged p ima-
ily in Lhc
canopy, bu he no hem myo is b
aged
below he can )py
bu abo e he
unde s o y
sh ub layc . which sugges s
ha sone e ical
s ll i ica ion
na occu u'i hin ba co nmuni ies.
C ome and Richa ds
(1988) in es iga ed
hc
di e cn ial
use by ba s o gaps
(c ea ed
by logging)
iu d closed canopy
a eas in an Aus alian
ain b -
es . They
di ided ba species in o canopy
special-
is s
(clu le
o age s). gap
inco po a o s (in e me-
dia e
clu e olage s.).
and
gap
specialis s
(open-ai
b age s).
Habi a p e e encc
o he ba s was ound
o be ela ed o wing mo phology
and ligh ma-
neu e abili y
Canopy-specialis s
wc e highly ma-
neu emble,
and
gap
specialis s
we c capable o as e
bu less
maneu e able
ligh . Gap inco po a o s.
which o aged
in bo h ypes
o habi a s. had
wing
cha ac e is ics
and ligh capabili ies in e nedia e
be ween he
o he wo ypcs.
C ome and Richa ds
(1988)
concluded
ha ege a ion s uc u e
ai d wing
mo phology
de e mine
alloca ion o di e en
habi a
ypes among
species.
82 Wundc and
Ca ey
Many Paci ic No hwes
spccies lo age n n-
pa ian
a eas
(li le
bn)wn
ba s and Yuma ba s
(Ku a
1982. Hc d and Fen o 1983,
Lundc and Ha cs ad
l986, B igham
e al. 1992), in clea ings and
oads
wi hin lb es s
(Cali b nia
ba .
Yuma ba . and long-
Iegged ba
(Ba bou
and Da is 1969.
Fen on and
Bell 1979. Bdgham e al. 1992)
o in open a eas
o along o es edges (hoa y ba , ed ba )
Cons n ine
195i. B el lqR5'. Clelnin .lc-
cies,
such as he long ea ed ba and
possibly
he
Keen's ba . may
b age wi hin he canopy
(Cou'an
and Guigue
1965, Manning and Jones 1989.
Ba clay l99l ).
Nonc o hese species a e
kno$'n
o es ic i s o aging o ius one
habi a ype,
howe e . Ripadan a eas and
o es edges a e ex-
ploi ed
by many ba
spccies o some ex en ,
pe -
haps because
hese a eas suppo
highe densi-
ies o lying insec s
(Fu longe
e al. 1987. C oss
1988,
Thomas 1988. Ba cla-
1991).
Landscape Con ex
AlLhough se e al canopy al ibu es nay be o
consequence o ba s
(Ca ey,
his issue). he com-
posi ion
o he sunounding
landscape may also
plaS
a ole
in le e min ng he el i e
imp,'nancc
o spccilic a ibu es, and
n ay inlluence ba dis-
ibu ion. Somc
landscape scale conside a ions
ue
discussed
belo .
Dis ibu ion o Ba s
Sc e al au hon ha e lookcd a he diYe si y o
ba communi ics
iD di e en b oad
habi a ypes.
ln gene al,
opog aphically
complex egions end
o
suppo he mos ba species. Jones
(1965)
s ud
icdba s in he Mogollon
MounL ins o NewMexico
and A izona. He cco ded he g ea es
pe cen -
age o cap u cs
in highe ele a ion,
mixed-coni-
e . o es : an in emedia e pe ccn age
in mid-el-
e a ion.
pine-oak
woodlandi and he Iowes
numb,c
o cap u es in lowland,
xe ic-sh ub.
g assland.
These di 'e ences
we e
p esumably ela ed o di -
e ences in a ailabili y o q)s si es. ood e-
sou ces. and wa e . Jones
(1965)
ound ha di -
elen species don ina e
he ba conxnuni y
in each
o hesc habi a s. Big b own ba s
p cdonina e
in
highe ele a ion coni e ous
o es , and hoa y ba s
a e mos common in be pine-oak
$'oodland.
Tholna.
l bb'
l,'un.l .L J l opo ion e u.e
o old-g ow h Douglas li s ands by ba s in he
Cascacle
Range o hshing on and O cgon and
Coas Ranges o O egon.
compa ed o. oung and
ma u e s ands. Inc eased
oos
a ailabili y in old
g o , h
s ands
p obably accoun ed o his di e -
ence
because ba s did no appea o be concen-
a ing lb aging ac i i y wi hin he o es s ands.
Besou ce
P oximi y
Al hough o es ba s may ha e oos s ha nee
hei p ima y equi emen s
wi hin a pa iiculal b es
s and, he composi ion
o he sulTounding
land-
scape is impo ian in de e mining
whe he oos
si es can be
used success ully. P oxini y o good
quali .
oos si es o i) aging and d inking a eas.
as weli as
o hibe na ion si es, can
gduce hc
ene gc ic
cos s o co nmu i g
(Tu lc
1976). Be
(cusc
m n) bl . cunLenl c
Ihei lo agi g in i-
pa ian
a eas,
p oximi y o oos si es o ipa ian
a eas
assumes
pa iicula
impo ance.
whc e oos
si es a e a ' o n b aging a eas,
iu enile mo -
ali y may be highe Tu le
(1976)
lbund ha
g ow h
and su i al
o ju enile
g ay
ba s
in he
sou heas em Uni ed S a es is impai ed when he
dis ance om he ma e ni y
oos si e o o aging
a eas is oo g ea .
Op imal na emi y oos con-
di ions,
highly
p oduc i e
lb aging si es,
and nca by
hibema ion si es can
compensa e o g ea e oos -
o- i) aging
si e dis a ces, howe e
(Tu lc 1976).
Bill 50 ne ime.
ma) equ c connecling co -
ido s o sui able
habi a be ween c i ical e sou ces.
Tu le
(1976)
obse ed ha
gmy ba s.
which oos
in ca es and o age o e
wa e .
genc ally
ly be
ween hese si es
wi hin he o es canopy.
The abun,lunec.
Ji e l). and elali e
p .,po -
ion o c i icll e ou ce
mJy l.o bc i npo :ln
o ba s.
Many ba s change oos s liequen ly and
equi e se e al di e en oos s o di e se cha
ile lo co npen Jle
lo change. in li empe a-
we, wea he ,
p eda o s, p ey pa ches,
and o he
ac o s. Humph ey e al.
(1977)
obse ed
a ma-
emi y colony o Indiana ba s ha used wo oos
si es abou 30 m apa . Each
oos si e had di e -
en he mal p epe ics.
and he colony shilied
be $,ecn
hem depending on empe a u c
and
wea he condi ions. Ba s may hc c o e need a
selec ion o di e en oos si es
(and
pe haps
di -
e en ee species), wi h a a ie y o he mal and
o he
p ope ies.
dis ibu ed
ac oss he landscape
and
loca ed wi hin a ai ly cons ained
a ea.
R
pa ian
Zones
As is ue lb many o he
e eb a es. ipa ian zones
assume disp oponiona e
impo ance o many ba s.
Ba
Canopy
Use 83
'hich m do mos o hei o ging
in hese in-
secl- ich a eas
(B igham
e al. 1992).
Ba s e-
quen ly
use ipa ian zones
as a cl co ido s
as
uLll.
Th,,n . alql)
l,'unLl hi
lb ging c.
o se c al P ci ic No hwes M- 'o l.i species
ale
si-uni ican ly
highc o e wa e
han in he i) es
whc e
hey oos . Roos si es ma
be no e abun-
dan in ipa ian
a eas bccause
o an inc eascd
numbc o snags and olde ces,
as
u'ell
as ock
c eYices in e oded
s ean banks
(C oss
1988).
Fo species such as he hoa J ba , known o oos
in dcciduous
ees. ipa iln a eas n ay
be
p e e cd
because o a p eponde ance
o such ees in he
ipa ian
zone
(C oss
19118).
Ripa ian a cas also
p o ide
he open ligh space
and lb es edgc con-
di ions lequi ed
by son c species.
Role
in Fo es Ecosys ems
T ee oos ing ba s.
which deposi la ge
amoun s
ol ni ocen
dch
guano
a he loos si e, may help
10
p o ide
nu den s in i es
ecosys ems wi h
nul icn -pool-
soils. Gi en hci
g ea
nobili )'. ba|s
ni y bc impo an
in aDspo ing nu iel s om
ipa ian a cas o loca ions
ou sidc he b es
eco
sys en in o o cs communi ies
(C oss
19E8,
Rainc e
al. 1992).
Con inuous
occupa ion o ca i y oos s
by ba s
l nodiil Ih ' l uh5l cle
nLl cn i nlnenl
in ways l' a a lcc
o hel ca i y dwellc s. These
e ec s may inciude
e osion o ca i y sides. in-
c eased hunidi y. inc cased
an monia. inc casecl
[en]pc u e.
and an enhuced a e
o de e io a-
ion o hc oos ee
by he accumula ion
o 1e
ces
and u ine
(Kunz 19li2a).
Ba s
co sune lnany insec s.
such as e mi cs.
ha a e conside ed o bc o es
pes s
(Whi akc
e a]. 1977). Thei
ole in con olling o es pes s
em ins
o be de c n inecl.
ho e ,e .
Li e a u e
Ci ed
Ald ldge. H. D.
J N.. and L L. l au enbach.
1987. Io phol-
^e].
..'h ".:' ..' : i J e.
.
( -.,
I,, ' i i ' '
.(.
li o ous b. s. J. Anim. F-col.56:761
778.
U.ilc .
R. H.. lnld C. J. Phillip . 1965.
Nlu n ls lioln El Ne a.lo
dc Colim . Me ico.
J. Nl nnn. l..16('1):691
693.
B bou .
R W. nd . II. D, is 1969. B s oi An c ca.
Unile si P ess
d Kc Uck -. Le ing on.
Ba cll ).
R. I. R. 198.1.
Oh !' !a ions on he mig a ion.
ccol
og) . nd beh !ioul olba i . l Dcl a N1a h. Nlani ohi.
C.Ln. I-ield N 98(l):lll 316.
s cla). R. NL R. lql s. LonS c su lho . nge o . gjng
l lLcg es ol ho
(1-( l| k,"lJ] nd,iil e hai cd
(L1sio, i nodi I !( .
)b. s
nd he conscqucnccs
lb p e) elec ion.
Cl n. J. Zoo1.63:1501 2515.
Conclusion
Ba s
a e a highly di e si ied axonomic g oup
whosc small
size. low cp oduc i e
a e. high
cne g
demand. and con plex
needs ha e
made
hem,
pe haps,
mo e ulne able
hi n many o he
e eb a e g oups.
These
complex nccds equi e
a complex
en i onnen . Tall canopies and di e se
lo es sl uc u e,
such as hosc bund in la e sc al
s ages
o coni c ous b es s
may
p o ide
some o
he complexi y
needed by ba s
(Pe kins
and
C oss
1988).
Fo many ba species.
a mosaic
o habi a
ypes in close
p oximi y o one ano he , includ-
ing
u n i ol i,, . :. ,nenil)g:.
un.l ip: i n
l
eas. m y p o ide op in al habi a .
A e nendou:
c n, unl
,'l e ca ch c n ins
lo
be donc o assess he olc o b es canopics in
Paci ic
No hwcs ba
communi ics. The ela i e
impo ance o he canopy a ibu es
descdbcd in
Ca ey
( his
issue), including
such lac o s
as
lay
e ing, dcg ee
o canopy closu e,
gaps,
canopy ol-
ume, i d ee species
cha ac e is ics. need
o be
in es iga ed.
Much o he inlb lna ion cu en ly
a ailable is
anecdo al. o en
based on unp o en
assump ions. o ep esen s genemliza ions
de i ed
om knowledge
o ba communi ies
elsewhe e.
Addi ional
da a a e needed
on oos a ailabili y
s. use. insec
densi ies. and
p ey
selec ion by
ba s iD he canopy
and il lb es
gaps,
and el ec s
o landscape
composi i{)n
on ba beha io E ec i e
nanagcmen b ba s in hc Pacilic
No hwes will
equi e
basic csea ch
ol o es canopy
and land-
scapc use. This
ype o in i ma ion
should
p o e
aluable
o making managemen
dec slons
on
ca ,i y ce e en ion.
c e ion
o mul ilayc ed
c nopies. and ipa ian
zone
p olcc ion.
Bx cl. ,,-.
R. lU. R. l99l. Popul. xm
s uc u e
o lcnpem e
zone
j$ec i Iyous ba s in el ion o o aging
b.hu!iou
al1d ene g! demand.
J. Anin. Ecol. 60:165
178.
Ba clay.
R. I{. R... nd K. J. C. sh. 1985. A non
co nnensal
ma e ni ) oos
o l c liule b o! 'n ba
(Ml i /ll.i|, q, ).
J. IamJnal.
66(1):782,7i11.
Ba cl
l. R. 4. R..
F u e. PA. . nd I). R.
F l9l 8. Roos
inq beha ,io
and oos elec io by nig a ing sil 'e
hai ed
ba s
(L./ i n./. iuo i ..l8. , ). J. Nl. nmal.
69(.1):821
815.
B .l' H. T. n 1.
{ - (
npi ., e
h]|
.
u e dp e, popl la ions
J. ,l. m'nal.55(I
):138-157.
B igham.
R. . 199i. Flcibili )- in aging
and oos ing
beh. iou b] hc big b o$,n ha ( p. i.llJ l lj.!J).
Can.
.1.
Zool.
69:117- l2l.
lJ,l Wundc and
Ca cy
B ighan. R. M.. Ald idgc.
H. D. J. N. . nd R. L. Niackc,"-.
1992. V ia ion in habi a usc and p e] seleclion b
Yuina ha . ,lh o i / d {, i !. J. N4amn .1l.
73(l):6.10
6'15.
Ch is ] l . 8.,
and S. D.
s l993.Biolo!, o ba sinDou
gl ll lb es s. USDA Fo Sen'.
Ccn. Tcch Rep P 1 '-
GTR-108 Piciiic No lh$. Res. S n.. Podland.
O cgoi.
28
P.
Con(!an inc. D. G. 195iJ. Ecological obsc !
alions on lasiu ine
ba s in
Cco gia. J. Nlalnnlal. 39(l):6.1 70.
Cons . n i e. D. G. 1966. F-cologicll
obse ! ions on lasiu inc
hal i. Io$. . J. Nl lmm l.
.11(
|
):-11
,l
l
Cow. D. L 1 . and C..1. Cuiguc .
I 965. The ln Lnlmals o B i
lsh
Colu bia H. Ddb. I L B iiish Col nnbiaP o!. NIus.
Viclo i . B i ish Columbia.
Cmme, F. H. J.. id c. C. Rich. ds. 19E8. Ba s
and
g. ps:
nlic ochl op e an
cL n) 11uDi s [lc u e in .l Queen land
| | n ..i,. c, l.,p]
6a' i lu( u
1
,0".
C oss.
S. P 1988. Ripa iL n s ems and small
nanmals and
ba s ? K. J.
Racdckc
(ed.)
S eamside managcmcnl:
ipl i. n iildlile nd o c y n e ac ions.
Uni!e si y
o . shing on. Insl.
Fo . Resou . Con ib.59.
Sca lc.
U!hing on.
len m. l B. ]970. Popula ion
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Con .
R.
Ol1 . {us.7l:1-3,1.
len on. ,1. B. 1981. Iicholoca{ion.
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NI. B. nd R.lU. R. Ba cla) 1980.
M i. /l.l/4/g i.
Nlam al. Spccics. l,l2: I
-8.
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M. B.. and G. P Bell. lc)79. Echdoc, ion
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Can. J. Zool.57 ll71 1177.
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Cam
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Can..l. Zool.
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55.
BaL Canopy
Use 85
