TrevorA. Kinley and Nancy J. Newhouse,Sy van Consut ng Box 249, nvermere,
BritishColumbia,VOA1K0 Canada
Relationshipof RiparianReserveZoneWidthto Bird Densityand
Diversityin SoutheasternBritishColumbia
Abstract
Britjsh Columbia forestry guidelinesrequirc riparian managementareasof20 to 50 m wid$ betwccn small streamsand cutblocks.
composed of reserve zones (no timber hanest) and/or managementzones (limited timber harves0. Cuidelines in Kootenai
Nari,,rnalForest,Montana. limit fbrest huvesting for 30 m adjacent1(lpermanenlstfeams. As one slep in providing a basis lo
assesssuch guidclines. we compared(1) habitat strucrurebetwccn spruce-dominareddparian forest and pine-dominatedupland
f'rrest, (2) breeding bird characterisitics(density of detections.spccicsrichnesr, lpecies diversity and speciesequitability) be
tween riparian and upland tbrest. and (3) breedingbird characterisilicsbctween riparian resen'ezonesofvrrious widths (aveng
ing 70. 37. or 14 m wide). The study occurredin the Montane Spruccbiogeoclimalic zone of southeasternBritish Colunbia. ln
felation to upland forest. nparian forest had greatertall shrub and canopy covet but felver live trees. Snag densily, low shrub
cover.and coarsewoody debris did not difter at P<0.05. The two habitat typesdid not difTerin meanbird speciesrichncss per site.
bul riparian forest had greater speciesdiversity and spcciesequirabilit]'. greater density of all speciescombincd. atd greater
density of thrcc indivjdual species. The density of all birds combined. all riparian-associatedbirds combined. and t})Jccof the
four riperian associatcdspeciesincreasedwith increasingreserle zonc widlh. Speciesdiversity and speciesequilability did no1
differ significantly anong treatments.
Thc widths ofriparian managemenrareasrequircd under cunent British Colunbia and Kootenai National Forestgujdelines
nanower than the widest caregoryofreservesinlestigated in this study (70 nl). Our dala indicate that prescribed
are considerabl_v
dparian managementareasunder cunent guidclineswill have loner densitiesof total birds and ofripatlan associaledbirds than
ifreserres \\'ere reouired to arerase 70 m in width.
lntroduction
Riparianhabitatsareconsideredessentialfor many
wildlife speciesbecauseof high plant and anrmal productivity,complexhabitatstlrcturc. proximity to water, and role as movementcorridors
(Thomaset al. 1979b,MorganandWetmore1986,
Bunnell et al. l992, Bunnell and Dupuis 1993,
Naimanet al. 1993,Stevenset al. 1995). In the
Montane Spruce biogeoclimatic zone of British
Columbia, where this study occurred, approximately 65cloof vertebratespeciesare associated
with riparian areas(Bunnell and Dupuis 1993).
The Forest PracticesCode of British Columbia rcquiresthat forest managen maintain riparian managementareas(RMAs) betweencutblocks
and streams,consistingofriparian reservezones
(RRZs) with no forest harvestand dparian managementzones(RMZS)with limited harvest.The
width of thesezonesis variable.dependingon a
stream'schannelwidth and its valuefbr fisheries
or as a domestic water supply. For strcamsless
than 20 m wide. reservezonesvary from 0 to 30
m and managementzonesvary from 20 to 30 m,
for a toral of 20 to 50 m (BC Minisry ofForests
and BC Environment 1995). The national lbrest
nearestto the study areais Kootenai,in northem
Montana.Guidelineslbr KootenaiNationalForest
require that permanentstreamsbe buffered by
streamsidemanagementzones (SMZs) that are
generally 30 m wide and in which only limited
timberharvestingis permitted(KootenaiNational
Forest 199,1).
I n w e s r e mN o r t hA m e r i c r .I i t t l er i p u r i r nr e searchhasbeenspecificto conifer-dominatedriparian habitatsof dry to mesic inland montane
regions. However,it is well establishedthat the
creationof edgeand the ratio of edgeto interior
forest habitat have significant effects on faunal
characteristics(Thomaset al. 1979a,Strelkeand
Dickson 1980,Kroodsma1982,Hansson1983,
Kroodsma1984,Wilcove 1985,Thompsonet al.
.[992.Faaborget al. 1993).Recently,severalstudies have specifically addressedthe effectsof the
width of riparian reservezonesor management
zones on bird community characteristics. Narrow reservesgenerallytail to provide habitat for
the complete range of naturally-occurringbird
species(Staufferand Best 1980,Croonquistand
Brooks 1993, Spackman and Hughes 199,1,
Darr'eauet al. l995.Gyug 1995),but resultsdiffer
NorthwestScience,Vo]. 71, No. 2, 1997
o l99l br-Lh€Nonhscn s.icnrilicA$o.iarionAll ilhrs Fsened.
15
betweenlandscapes.In somesituations,
no major difl'erencesare apparenteven over a broad
rangeofriparian rcservezonewidths (Snith rnd
Schael'er1992). Furthermore.McGarigal and
VcContbI lQa2r rcp.n rrr'.rscu hereriparianurrnes
exhibitlower speciesdiversityand densitythan
upland sitcs. Theretbre, it is not clear to what
extentcurrentforestryguidelineswill maintain
lhc ecologicalvaluesof riparianhabitatsof Lhc
inlandNorthwcst.
As one stepin providing an empirical basisto
:ls.es:!:uidcline\.$ e comparedI l) hahitatstrucrure
betweenriparian and upland tbrest, (2) brceding
bird characterisiticsbetweenriparianand upland
forest, and (3) breeding bird characteristicsbet$'eeniparian reservezonesofvarious widths in
the MontaneSprucebiogeoclimaticzoneofsoutheastemBdtish Columbia.
Methods
This study occurred in the "Dry, Cool Montane
Spmce" (MSdk) biogeoclimatic subzoneof the
lnvermereForestDistrictin southeastem
British
Columbia(Figurel) at elevations
of I 100to 1300
m. Mean annual precipitation fbr the MSdk is
590nur. with a meansummertemperature
of about
8.5'C and a mean winter temperatureof about
3.0'C (Braunandland Curran 1992). Fifteen
study sitcs were establishedadjacentto streams
with channelsI to 10 m wide. parallelingone
sideofthe streamlbr 300m andextendingupslope
fbr 100m. Siteswcrea minimumof 500mapart
at the closcst points. The forestedarea in each
siteincludeddparianfbreston historicfloodplains
and upJandfbrest farther upslope,and was 80 to
1,10years oJd. Sites exhibited complex vegetational pattems,but basedon the MSdk classifi
cation (Braumandl and Curran I992), riparian
fbrest correspondedmost closely to the "hybdd
white spruce- dogwood ho$etail" (Pice.rglarca
s engelmanni- Contus stolonifera - Equisetum
an'eirse)series.anduplandfbrestwasmost sinilar
to thc 'lodgepolepine - Oregongrape pinegrass"
(Pinus t:ontorta- Mahonia uquifoliun Calanogrtstis rubescens)sedes.Control sitescontained
only riparian and uplandforest,while treatments
included recent clearcuts(<l to 5 years old) at
the upslopeend. The threeteatmentswereclassed
asnarrow,mediumor wide resen'ezones.according to the width of forest remaining betweenthe
cutblock and the stream(Table I and Figure 2).
These strips of forest correspondedto RRZs of
ForestPracticesCodenomenclature,andincluded
both riparian and upland vegetation. Forest on
the oppositesideofthe streamfrom eachsite was
in a mature, uncut state and was vegetationally
similar to the study site. Habitat typesin all sites
weremappedat l: 1000scale,basedon fansects
run perpendicularto the strcamat 25-m intervals.
The forestedareaofeachsitewasdeterminedusing
a digital planimeter,then divided by 300 m to
yield the mean width of each reservezone.
Coarse woody debris (CWD) volumes were
assessed
using the methodofLofroth ( 1992).and
included all pieces210 cm diameteron one 200m tnnsect per habitattype at 15 sites. Sampling
methodsfor vegetativecharacteristics
were modified from provincial standards(HabitatMonitoring Committee 1990) becausethe linear nature
of our ripaLriansitesand the habitat units within
TABLE 1. Chatacteristic! of 15 riparian \tLidy sites in the Moniane Spruce7onc. ln\ermefe ForesrDislrict. B.C., 19939 199,1
ao|ltrnl
Charr!tcri,tic
S . r m p l eS i z e
Width ol Riparian Forest (m)
\lean (Range)
Width of LrplandFore\l (n)
Mern (Rarge)
TdalWidth of RRZ (m)
Mean (Range)
Width of Curblock 0n)
Mcan (Range)
Tolal Sitc \lidth 0r)
Length Parallel to Strean 0n)
S l o p e( L = < 1 0 ' l . :H = > 1 0 %)
'76
lJ(r ren.
Wide
ReservcZone
Kinley and Newhouse
5
27 (9 :15)
73 (55-91)
t00
:r00
2N.2S.1W
lL.:lH
3
25(r r 4.1)
,15(29 54)
10 t61-73)
30 (27-36)
100
300
1N.2E
3H
Mcdium
Resene Zone
)
2 l (1 3 , 3 1 )
r 6 ( 1 02 3 )
37 (33-.13)
-67)
63 (5',7
N-arrow
ReserveZone
2
l,l ( l3- 1,1)
100
t)
l,l (13-l:1)
86 (86-87)
100
300
3N.2S
300
]N,IE
2L.3H
2L
't;a-
''
",j":1
-''r':'
. \ - .C r ee z
Lr l_--.'
*',,j,
Temn4|;{*n*
J
rll
5
etl
Dqyck4
o
l @
t('r
.':,'
qt C2
tta / J \\)
',,:;. ',"r';,
s.!i.
-;
,ti:,
(D
k
'.:
3
(\
.t
|
o
o
.1.
'nPek
FronceS-7
N
British
Columbia
l/\
1 0k m
o
Controls
@ WideReserves
@ MediumReserves
NarrowReserves
o
Figure L Srudl area and study sile bcations.
RipilriirnReser\eZone Birds
qy'
i : ; '
f
t
,
siteboundary
.
1100m'.
I
I
;
::
:,.r:.
: ,:.
,.
..
I
,
,
stream
i
E
:l
meanwidthof
reservezone
unharvested
forest
ControlSites
cutblock
.,,i
cutblock
.: ,. ., ,: ,; ",'
WideReserveZones
it-t-''*:===4
MediumReserveZones
cutblock
I-'---;g.'*
NarrowReserveZones
Figure 2 Control and rreatmenttypes.
78
Kinley andNewhouse
them precludedthe use of randomly-oriented
transects.and madeit necessaryto samplefrom
smallerplots (4 m mdius) than recommendedfor
forestedhabitats. For each habitat type at each
site,fbul circularplotsweredrawnon habitatmaps
using random X and Y coordinates,then trans
fered to the field. Within eachplot, the following data were recorded:number of snags,number of trees (>10 m tall), percent canopy cover
(using a spierical densiometer),percentcover of
the tall snrub stratum (2 to 10 m), and percent
cover of the low shrub stratum (<2 m). Twotailedt-testswereusedto detenninewhethervalues
diff:red among habitats. Becausethe study was
iD:endedto be exploratory rather than comprehensive,samplesizeswere low andP valueswere
not adjustedfbr multiple comparisons.
Each site was divided into a bird survey grid
of twelve 50 m x 50 m plots, anangedin an array
of six squaresaligned parallel to the streamby
tuo squaresdeep. The grid covered the entire
300 m x 100 m site. Thus, in all but contols ir
included both the cutblock and the rcscrvezone.
Plot boundarieswere marked on l:1000 habitat
maps. Each site was visited three times during
May andJune,oncein eachofearly, mid and late
moming. On each occasion,an obseryerspent
tive minutes at the centerof each plot, marking
locationson habitatmapsofall birds seenor heard
within the plot.
Speciesrichness(numberofbird species)was
tallied lbr eachsite,and alsofor eachhabitattype
in contlols. Bird density (number of detections/
ha) was calculatedfor each speciesand for all
speciescombined. In control sites,dersity was
calculatedseparatelylbr riparian forest and upl u n d l b r e s t . R i p a r i a n - r s w r c i a tsepde c i e sw e r e
definedby determiningwhich species'popula
tions were significantly more abundantin dpalian forestthan uplandforcst in control sites.This
wasaccomplishedusingone-tailedt-testsfor species which general referencesor other studies
indicatedwereriparian-associated
in similar ecosystems(Farand 1983a,1983b,1983c,Godfrey
1986,Cyug 1995,Scon 1987,Campbellet al.
l990a,1990b,Peterson1990,Semenchuk1992),
a n d u r i n g t u o - t a i l e dt - l e \ l \ l o r ( , l h e r{ p e c i e . .
Densitiesof eachriparian-associated
species.all
riparian-associated
speciescombined,and all
speciescombinedwere eachcompared(ANOVA)
among treatments(narrow. medium or wide reservezone). Contols were usedto define dpar-
ian-associatedspecies.as describedabove. but
were not compared to reserve-zonetreatments
becausebird useofstreamsideareasmay be qualitatively dift'erentin reservezonesthan in intact
forest, as a result of temporary "packing" into
reservezonesof birds that formerly occurredin
adjacentioggedland (Lehmkuhlet al. 199l, Gyug
l 9 q 5 ) . T h u . . t h ep r e s e n coef a b i r d i n r r e . e r r e
zonemay not reflect the samelevel of useor habitat
value that it would in a forest standwidely separated fiom cutting. A regressionequation was
calculated
for resenezonewidth (m) versusdensiq,
of ripadan-associated
birds. Riparian-associated
specieswere determinedbasedon two years of
data but other comparisonswere based on one
yea.r.asthe tull rungeoftreatmentswasonly studied
in one year. Speciesdiversity and speciesequitability were also comparedamong habitat types
fbr controls and amongtreatmentsusing the fbllowing equations(Krebs1989):
H = -I (p)(tog,op,)
j-t
where:
H = Shannon-Wienerindex of speciesdiversity
s = numberof speciesat site
pi = propoftion of samplebelongingto i'h species
| - Llllnn
a
where:
I = speciesequitability
S = number of speciesin all sites(as an approximation of the numberin the community)
Results
In comparisonto uplandforest,riparianforcsthad
greatercanopycover,a lower densityoflive trees,
and greatertall shrubcover (Table2). CWD volume, snag density and low shrub cover did not
difter significantlybetweenthe two habitattypes,
althoughthe calculatedP value for CWD (0.19)
suggeststhe possibility that CWD values were
greaterin dpadan forest.
Within controls.speciesrichnesswas similar
betweenriparian forest and upland forest: mean
richnessper site was 7.3 for both riparian and
upland, while total richnesstbr all five siteswas
22 for riparian and 19 for upland. Bird density
washigher in riparianforestthanin uplandforest
Riparian ReserveZone Birds
79
TABLE I
Ripafirn linest anduplandforcsl habitarathibutes
in 15 nalure st nds ofthe N{ontaneSpruccrolte.
I n v e r m e . eF o r c n D i s t r i c t ,B . C . . 1 9 9 3 - 1 9 9 . 1 .
Habilat Arribulcs
Ripdian Forest Upland Forest r Ten
mean
SE
lnean
CwD (n'Aa)
l0l
Canopycolcr (q )
Lile trees(\tems/ha)
11
ll
2
56
.10
79
61
82
116
t0
2t
666
Snagslctems,ha)
Tall shrubs(tZ.co\'ef)
169
Low,ihrubc(9: covcr)
23
l5
2
3
SE
13 0.19
3 <0.01
85 0.04
11 0.91
I
0.05
2
0.59
tbr all speciescombined( 12.2versus6.5 detections/ha,p=0.03)andfor threeindividual species:
golden-crownedkinglets (Regrllls sutrapd: 3.8
versus 2.3. p=0.04), Hammond's flycatcher
(Enpidonttx lnmmoirdill 1.7 versus0.5, p=0.03)
and w i nter w r et (Trog ktth t es t rog I ocl2-t e.;; 0.5
versus0.0, p=0.01). Speciesdiversityand species equitability were also higher in rhe riparian
(H^,"=0.96,H.".=0.86; Jo,u=0.62,Jr".=0.55).
Speciesdensitiesby habitattype arc summarized
in Table3.
Riparian-associated
birds were consideredk)
be the thrce having greaterdensitiesin the dparian than upland, plus the Townsend'swarbler
(.Dendrcicatownsendl)r. Densitiesof thesetbur
speciescombined differed bet*een treatments
(ANOVA, P<0.01;Table4). This was alsotrue
fbr each of the dparian-associatedspeciesindividually (P<0.01). exceptHammond'sfl ycatcher
(P=0.26). The regressionof reservezone width
versusdensity of riparian-associatedbirds (Fig
ure 3) had a correlationcoefficient (R2)of 0.803
and the regressionequation:
y = 0.093x- 0.303,where
y = densityofriparian-associated
birds (detectionsfta)
x = reservezone width (m)
ln addition,the densityof all speciescombineddifferedsignificantlyamongfteatments.
with
higherdensitiesin wider sites(Table4). How
ever,speciesdiversityand speciesequitabilityper
sitedid not dilfer significantlybetweentreatments
(P=0.15), with mean values of Hnoo=0.8,1.
Hn,uo=O.7
l, H*o=0.89 andJ\iR=0.54,JMED=0.46,
J*u,=0.58. Densitiesby treatmentfor each species are summarizedin Table 3.
80
Kinley and Newhouse
Discussion
The diflerencesbetweenriparian fbrest and upland forest for several of the habitat aftributes
indicate that these forest types provided different environments. For example.riparian fbrest
provided greatercanopy cover with fewer trees,
greatertall shrubcover and possiblyrnoreCWD
than uplandfbrest. Thesedifferencesemphasize
the impofianceof maintainingthe rip.rrianforest's
structural attributes to provide landscape-scale
hrhitutrariabiliry.particularllhecru.e.pccie.cln
be strongly associatedwith particular structural
patterns(Marzluff and Lyon 1983,Sharpe1996),
and riparian forest composesa relatively snrall
parl of the landscape.
We found bird density. speciesdiversity and
speciesequitability to be higher and speciesrichnessto be similar in riparian forest comparedto
adjacentupland forest. This was true despitethe
riparianfbrestpofiion ofcontrol sitesbeing considerablysmallerthan the upland ponion (recall
Table l). These results suggestthat, at least at
the stand level, riparian areashave a disproportionately high value in maintaining diverse avifaunasin conif'er-dominatedlbrcsts of the Mon
taneSpmcezone. Therefore.guidelinesintended
to maintainripadan forest arejustifiable trom an
avianperspective.Ow resultsareconsistentwith
the findings of many other authorswho reported
greaterabundanceor diversity of birds in riparian areascomparedto upland areas(Thomas et
al. 1979a.Staufferand Best 1980,Emmedch and
V o h s l 9 8 2 , K n o p f 1 9 8 5 ,B u n n e l le t a l . 1 9 9 1 ,
CroonquistandBrooks 1993.LeungandSimpson
1994). However, the results of several studies
indicated patternsopposite to this. Mccarigal
andMcComb (l992) foundthatuplandforestin
the wet coastal region of Oregon had more di
verse avifaunasand higher populationsthan adjacent riparianforest. The authorsofthe Oregon
study suggestedthat their study area.relative to
more arid regions,showedlesscontrastbetween
dpadan and upland habitats in terms ot water
availability,microclimate,andsttuctumlcomp]exity. In fact,overstorycover,low shrubcover,snag
density and conifer basalareawere all greaterin
upland than riparian areasin their study. Habitat
useby someindividualspeciesalsodifferedgreatly
betweenour study andthe Oregonstudy. We found
golden-crowned
knglets andHammond'sflycatchers to be more abundantin riparian forest. and
TABLE 3. Mean densit) (detections,4ra)
ofbird\ iD 3-ha sites.rdiaceniio streamsin ihe luontane Sprucezone,InvermereFbrest
Distric!. B.C. Comparisonsof lbrcsr rlpc arc poolcd lbr 1993 and 199,1.and lhose of reservezone width are from
199'1.
Specics
ForeslTypc
Riparian
Upland
(n=51
(n=5)
r!ra!
tTutdt6 tnisraturius)
Black cappid Chickadee
\Pdtu\ dtticttpi11usJ
Bro\tn Creeper
(C. rthiu dt|eri(and)
Bro',r'n hcadcdCowbird
lM0lothru\eter)
Calliopc Hunmjngbird
(Stellula cullioF)
Cedar \\'axwing
in)
lBonb\itia &tn
Chippillg Sparrow
lSt)i.elh putserinu)
D a r k - e l e dJ u n c o
\Junco hrenlalit)
Golden-crownedKinglet
(ReRulLts
sdtrapa)
Gray Jay
lPerisorcus candde sis)
Grert Cr:lv O$l
Hairy-Woodpcckcr
(PiL0ifus rillosu!)
H a m m o n ds F l ) ' . c a r c h e r
I L nt id o ntLthdnnntftr i i)
NfacGillivray s \4'arbler
(Oporcnt\ tolniei)
Mountain Chickadee
(t'utut ga,theli)
Oli!e-sided Flycatcher
\Co topus borcalis)
Pileated\\bodpecker
lDtlcopus pileatus)
5L
!!q!
! Tes!
5L
0.09 0.06
0.02 0.02
0.35
0.03 0.03
0.05 0.05
0.80
0.00 0.00
0.02 0.02
0.3-l
0.03 0.03
0.02 0.02
0.i17
0 .t 4
0 . 1I
3.76 0.66
0.'19 0.11
0.06
2 . 3 1 0 . 3 5 +0.0,1
0 . l 5 0 . 1 5 0.00 0.00
0.33
0.06 0.06
0.33
0.00 0.00
1.73 0.56
0.11 0.11
*0.03
0.06 0.06
0.00 0.00
0.33
0.00 0.00
0.02 0.02
0.33
0.04 0.0.1 0.00 0.00
Widc
(n=3)
ReserveZone Tlpe
Nlcdium
Narrow
(n=5)
(n=2)
ANOVA
I!]c!! 5L
0.0'1 0.04
I]]ca! SL loeaa SL
0.03 0.03 0.00 0.00
-L
0.7E
0.05 0.0s
u.00 0.00 0.00 0.00
0.35
0.0,1 0.04
0.00 0.00 0.06 0.06
0.35
0.00 0.00
0.00 0.00 0.06 0.06
0.13
0.09 0.09
0.09 0.09 0.06 0.06
0.96
0.84 0.25
0.71 0..r5 0.r8 0.r8
0.80
2.9',70.22
t.44 0.22 0.62 0.39
0.01
0.r8 0.04
0.00 0.00 0.00 0.00
0.01
0.04 0.0.1 0.00 0.00 0.00 0.00
0.3s
).02 0.11
1 . 1 90 . 3 0 0 . 6 2 0 . 5 t
0.26
0.00 0.00
0.00 0.00 0.06 0.06
0.r3
0.09 0.09
0.00 0.00 0.00 0.00
0.35
0.0,1 0.011 0.00 0.00 0.00 0.00
0.35
0.54 0.20 0.76 0.38
0.67
0.0,1 0.0,1 0.00 0.0 0.00 0.00
0.35
0.33
(Pinicold enucleatoa
Pine Siskin
(Carduelis pinus)
Purple Finch
(Carp)daus purputeu')
Red Crolsbill
(Ln\ir.t cutrirosrra)
Red breastedNuthatch
(Sitta tanadensit)
Red-napedSapsucker
(Sfi ,"rdp i c us nut hat i s)
Ruby-cfowned Kinglet
lRegul s calendula)
0.59 0.38
0.68 0.27
0.8,1
1.08 0.76
0.91 0.9r
0.62 0.50
0.78
2 . 3 0 2 . 1 1 0.09 0.09 0.06 0.06
0.3,r
0.03 0.03
0.09 0.06
0.19
0.tr4 0.0:l
0.03 0.03 0.13 0.13
0.50
0.54 0.5'+ 0.00 0.00
0.33
0.00 0.00
0 . 0 00 . 0 0 0 . r 7 0 . 1 7
0.r3
0.03 0.03
0.58
0.0'1 0.104 0.31 0.28 0106 0.06
0.70
0.06 0.05
conllnucd. ncxl page
Riparian ReserveZone Birds
8l
TABLE 3. condnued
Species
Forcsl Type
Ripaian
Upland
(n=51
!rE!!r
R u f o u sH u l n m i n g b i r d
0.00
6cLasphorus n[L )
Solitar! Virco
0.00
\Virco \olituriIs)
SpruceGrouse
0.1I
\De, rasapus candulen'i5J
Swrinson s Thrush
0.30
(Cutharus ustuLan6)
Townsends Warbler
1.26
(Denlnxn touse/..lii)
Varied Thrush
0.20
llxortusId.t,ius)
\\'arbling Virco
\\Ireo giltus)
SL
Eelrn -SL
0.0
0.02 0.02
0.00
| Test
Wide
(n=3)
RcserveZone Type
Mediun
Narrow
(n=5)
(n=2)
ANovA
!]c4! lL
lscdn,sl
0.33
0.09 0.05
0.03 0.03 0.00 0.00
0.25
0.l5 0.09
0.l2
0.:14 0.37
0.00 0.00 0.00 0.00
0.24
0.07
0.00 0.00
0.r5
0.11
0.36 0.16
0.16
0.98 0.55
0.20 0.08 0.11 0.ll
0.14)
0.17
0.67 0.33
*0.16
l.r-J 0.27
0.17 0.12 0.06 0.06
0.01
0.r2
0.05 0.05
*0.13
0.09 0.05
0.00 0.00 0.00 0.00
0.05
o.23 0.22
0.00 0.00 0.00 0.00
0.07
0.25 0.25
0.00 0.00 0.00 0.00
0.35
ae!!
_g
L
0.00 0.00
0.08 0.08
0.33
0.l7 0.12
0.00 0.00
0.1/
0.,19 0.17
0.00 0.00
*0.01
0.,130.15
0.00 0.00 0.06 0.06
0.01
0.25 0.13
0.30 0.11
0.19
0.21 0.lr
0.:180.35 0.2:1 0.01
0./9
(P rntaga I ullari( iTta)
White winged Crossbill
(l.orid le copten)
(Tn g I otl) t eI trc s lot^ t es)
Ycllo$ rumped \Varbler
(Dendrcica connata)
" P v a l u e s a r e b a s e do n o n c l a i l e d t - t e s t \ f o r
s p c c i e sw h i c h o t h e r L i l c r u t u r ei n d i c a t e dw c r e r i p a r i a n - a s s o c i a t eidn s i m i l a r
e c o s y s l e m sa. n d o n t w o t a i l c d I l e s t s f o r o l h e r s p e c i e s( s e e m e t h o d s ) . S p e c i e sf o r v h i c h o n e - r a i l e dt e s t sw e r e d o n e a r e
i n d i c a t e dw i r h a n * .
TABLE '1. Mean dcnsily (detections,fta*)of all bird speciescombined and of riparian associatedbirds in ten 3-ha sires that
iDcludedripanan reservezone\ in the Montane Sprucezone.lnvermere Forest Disfict, B.C., 199:1.
Wide Res. Zone
Species
All riparian-associatedspp.
Golden-cfowDed Kinglel
Hammond s Flycatcher
Townsend s Warbler
mean
SE
13.7
0.9
0.',7
0.2
6.5
3.0
2.0
Ll
0.,1
0.7
0.3
0.1
Medium Re!. Zonc
Narro{'Res. Zone
ANOVA
SE
5.3
2.8
1.4
t.2
0.2
0.0
0.1
0.3
0.2
0.3
0.1
0.0
,t.3
1.,1
0.6
0.6
0.1
0.1
0.1
04
0.5
0.1
0.1
<0.01
<0.01
<0.01
0.26
<0.01
0.01
* basedon rotal area in each site. which included riparian and upland forest plus
cutblock
winter wrens to occur only in riparian fbrest,
whereasin coastalOregon,Hammond's flycatchers
occuned only in upland sites, golden-crowned
kinglets were more abundantin uplandsites,and
winter wrens were less abundantbut presentin
upland sites. InVetrnonl. Spackmanand Hughes
(1994) found the greatestbird abundanceon
82
Kinley and Newhouse
transectsthat were the greatestdistanceftom the
high water mark of streams(>150 m). Murray
and Stauffer (1995) found in Virginia that some
specreswere positivelyand somewere negatively
associatedwith the riparian, with no significant
o v e r a l l r e n d si n r e l a t i \ ea b u n d a n coer s p e c i e .
nchness. The resultsof theselatter threestudies
p
@
r
6 6
(t
o
E 4
_c
o
E
2
o
o
0
0
2
0
4
0
6
0
8
0
Reservezone Width (m)
Figure 3. Density ofriparian associatedbirds ir 10100 m wide silesthat included riparianreserve
zoner in the Montane Sprucezone. lnve lcre ForestDistrict. B.C., 199'1.
indicatethatthe valueof riparianhabitatto agiven
species,guild or community may dift'er widely
betweenregions. Simi)arly, Knopf (1985) tbund
that the relative significanceofriparian nreasvaried
along an elevationalgradient. Our researchand
much ofthe literaturegenerallysuppofithetheory
that riparian areasare disproporionatelyimportant in maintaining diverse,abundantavilaunas,
but their value cannot be generalizedbetween
regions or elevations. Managementmust theretbre be basedupon a local understandingof the
distinctivenessof dparian habitat relatlve to upland habitat.
birds
We found densitiesof riparian-associated
and ofall bird speciescombinedto increasewlth
width for riparianreservezonesaveraging1,1,37
and 70 m. It is not kno$n how f'ar this trend
would continue fbr even wider reserve zones.
Controlswere not comparcdto this trendbecause
they had no definable width (therewas no adjacent cutblock) and becausehabitat use by birds
was probably qualitatively different in the contiguous forest of the controls, comparcd to the
stdps of fbrest and edge that made up the treatments. The observedpattem of increasingbird
density with increasingrese e zone width occurred despiteour cgnsusareasbeing the same
width (100 m) for all reservezone widths, the
true riparian vegetationbeing intact in all sites.
andtheoppositebankprovidinga continuousblock
of intact tbrest. Given these facts, our results
suggestthat for nanower reserves1) bird popu
lations did not fully compensatefor lost habitat
"packing" into a smallerfbrestedarea,as ocby
curs in somefragmentedtbrests(Lehmkuhl et al.
1991),or by making useofthe adjacentcutblock,
2) riparian habitat value may be allected when
adjacentupland forest is cut, even if the riparian
i t s c l Ii s n o tc u t .r n d J ) n a r o u e r r i p r r i a nr e . e r r e
zonesare of lessvalue than wider reservezones,
even if fbrest on the oppositeside of the stream
is intact. The 1ow habitat value of narrow and
medium reservezones rclative to wide reserye
zonesis consistentwith most otherstudies.Three
of the four speciesthat we consideredto be ripadan associatesand were sensitlveto reserve
zonewidth (Townsend'swarbler,winter wren and
golden crowned kinglet) were also found to be
sensitiveto fbrestedriparian corridor width by
Gyug (1995) in habitatsvery similar to those we
studied.Gyug found far fewer individualsof these
speciesin reservezoneslessthan 50 m compared
to those greaterthan 100 m, basedon siteshaving reservezonesand cutblockson both sidesof
thesfeam. InQuebec,Darveauet al. (1995)found
that dpadan reservestrips 60 m wide supported
forest dwelling birds in a pattern similar to controls. but that strips 20 or 40 m wide did not. In
Iowa, Stauffer and Best (1980) found a positive
correlationbetweenreservewidth and bird speciesrichnessfor sitesrangingfrom l0 to 250 m
Riparian ReserveZone Birds
83
wide. Croonquistand Brooks(1993)notedthat
sensitive specieswere absgnt from riparian resen es<25 m wide, andthatreserves>125 mwidc
were neededto suppofia nearnaturalavifaunain
Pennsylvania.
SpacknanandHughes(1994)found
thatripariancorridorsofabout 175m were needed
to maintain95'l. of the bird speciesfound in control sitesinVemont. In contrast.
SmithandSchaeler
(1992)tbund very little differencein bird commu
nity chancteristicsbetweenriparianreserves20 to
60 m wide and those75 to 150 m wide on urban
steams in Flodda, but felt this may havercflected
an inadequaterangeof widths studied.
Differencesin habitat characteristicsand bird
communitiesbetweenriparianand uplandforests
\ u p p o r lI h e p r a c t r c o
e I I n i ] l n t r i n i n rge \ e r v e :i n
streamsideforest. There are undoubtedlysome
speciesthat are less abundantor less active in
spruce dominated riparian forest than in lodgepole pine-dominated upland forest. However,
given the rarity of riparian fbrest relative to upland forest, differencesin habitat attributesbetween riparian and upland, and the high species
d i r e r s i r ;r n d r b u n d r n c ei n r h er i p a r i i l ni r. i s p r u d e n t o p r e f e r e n t i a lpl ;r r r ri d ep r o r e c r i rm
e anuge
ment to riparian habitatsin the Montane Spruce
z o n e . W h e r ep f f t i a l c u t r i n go c c u r si n r i p a r i a n
forest,thedifferencesin forestattdbutesthatmake
nparianhabitaruniquefrom uplandhabitatshould
be maintained. Riparian wildlife might benetit
ifprescribed volumesoftimber were removedin
patchesrather than unifbrmly. to ensurethat at
least part of the riparian habitat maintains its
uniquenessand high habiratsuitabiliry. This hypothesisrequiresinvestigation,
as it might also
result in greater habitat fragmentationper volume of timberremoved.
Dependingon channelwidth, British Colum
bia guidelinesrequireRMAs of 20 to 50 m on
small streams,with only a portion of this being
an RRZ and thereby being free from forest har
yesting(BC Ministry of Foresrsand BC Environment1995).Basedon thoseguidelines,RMAs
in the Montane Sprucezone may have considerably lower bird densities,includingthoseof dparian associates.than they would if they wer.e
70 m wide. A similarsituationis likely ro occur
in Kootenai National Forest, where timber harvestingis restrictedonly in SMZs 30 m wide
(Kootenai National Forest 1994). Fudhermore,
even the widest reservezonesstudied,if isolated
from contiguousmature forest, would probably
be severalordersofmagnitude too small to main8,1
Kinley and Newhouse
tain all speciesof neotropicalmigrants because
of the small anount of habitatarrdexpectedhigh
rates of nest predation and brood parasitism
(Faaborget al. 1993).Thus,ifone goalof riparlan managementtSto Supportneir,rnaturaldenSi
ties of riparian-associated
birds a nd maintain diverseavitaunasat the standlevel, ,it appearsthat
RMAs or SMZs shouldbe wider th an currently
required under British Columbia o,. Kootenai
NationalForestguidelines.and shouldr rot be isolated from larger standsof maturefbresL..
Currentriparianmanagement
guidelines.in B.C.
are not basedon vegetationalcharacteristics. A
"riparian"
managementarea will consist al_most
entircly of upland fbrest when the blnd of ril rar
ian vegetation is narrow, or altgrnatively, $
maintainonly a poftion of the riparianforestwhe
that vegetationtype extendsa greatdistancefron
the stream.This is likely becauseguidelineswerr
developedto maintainrecreational,aesthetic,tisheries and hydrological values, nor just wildlife
values. However.wildlife valuesand many other
values could more adequatelybe maintained if
prescribedwidths of reservezones.management
z o n e sl n d R M A s a : a u h o l ew e r e\ e e na 5m i n i mums,with provisionsto enlargethemwhereriparianhabitatextendedgreaterdistancesfrom the
stream,regardless
of chamelwidth,fisheriesva1ue,
or use of a streamas a domesticwater supply.
Acknowledgements
This project was completedunder conrracrro
British ColumbiaEnvironment,with funding provided by the Silvicultural SystemsFund. Rob
Neil andTrudy ChatwinofBC Environmentacted
ascontractmonito$. Marion Pofier and Clayton
Apps provided excellent field assistance.Jesse
D'E1ia,lrs Gyug.Eric Lofroth, KenMorgan,John
Richardson and Gerry Wright provided usef'ul
c' 'mmenl\on progre!\repon\or earlier\ er\itln\
of this manuscript.
Notes
1. The 1 lest for whether rhe Townsend,swarbier occurs at
greaterdensity in rhe dparian ihan the upland yietded a
P v a l u eo f 0 . 1 6 , u h i c h i s g e n e r a l l yb e y o n da c c e p r a b l e
significance. However. a morc ertensivc study in !ery
similarhabitat (Cyug 1995)found rhis speciesro be )re
c o m m o nl n l h e r i p a . i a n( P = 0 . 0 1 ) .s o i r i s i n c l u d e dw i | h
o l h e fr i D c t i J n
t r . . o c t . r r i(r, . r n r . ) . e ." t , h < . rf e . n o n . ( t , ,
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