An Inexpensive Elevated Mist Net Apparatus Gene Albanese
and Victoria
D. Piaskowski
Zoological Society of Milwaukee County 1421 North Water
Street
Milwaukee, Wl 53202
[email protected] ABSTRACT
We describe the design and use of a mist net apparatus capable of samplingvegetation strata from groundlevel to an 8.5 m height. The device is inexpensiveto produce (about US $35, not includingthe mist net) and, once erected, safe to capturedbirds,simpleto use, and versatile.
Some disadvantagesof existingmethodsinclude the following: 1) Componentsof the designare expensiveand not readilyavailable.
2) Designis complicatedand difficultto construct. 3) Design requiresmore than one personto operate.
4) Designrequiresskilledtree climbers,tall trees nearby, and can damage trees.
5) Designis difficultto use and requirestoo much
INTRODUCTION
time to operate.
Mist netting is one of the most efficient means used to sample small birds (Austin 1947, Berthold 1976, Karr 1981). The placementof a mist net in a habitatis also importantfor the determinationof which species are present (Stamm et al. 1960, Jenni et at. 1996). In habitats that possess multipleverticalvegetationstrata, mistnets set in the standard manner sample effectively only those species that move commonly near the ground (Slud 1960, Munn 1991, Remsen and Good 1996). To sample birds that spend all or part of their life cycle in the higher vegetation strata of these habitats,it is necessaryto elevate mist nets (Jenni et al. 1996, Greenlaw and
We developeda simple,elevatedmistnet system of inexpensivematerials (an 8.5 m device costs about US $35 withoutthe mist net) that requires little heavy constructionand no tree climbingto assemble. Once erected,our systemis quickand simpleto operate for a singleindividual. The net has also proved safe to captured birds and adequateto capturethe samesize speciesas with a standard mist net placement. METHODS
1991, Whitaker 1972). Many designscapableof elevating mist nets and successfullycapturing birds have been introduced (Dejonghe and
During spring 1999, a single elevated mist net systemwas testedon the northsideof Pewaukee Lake in Waukesha Co., Wisconsin,at an existing bandingstationrun by the ZoologicalSocietyof Milwaukee County as part of the Birds Without Borders-AvesSin Fronterasproject. The success
Cornuet 1983, Greenlaw and Swinebroad 1967,
of this initial test led to the construction of three
Heselton 1990, Humphrey et al. 1968, Chapin
more devices all placed at the same station in differenthabitattypes duringfall 1999.
Swinebroad1967, Humphreyet al. 1968, Meyers and Pardieck 1993, Munn 1991, Paton et al.
1988, Karr 1979, Mease
and Mease
1980,
Meyers and Pardieck 1993, Munn 1991, Nixon 1972, Sheldon1960). These methods,however, have disadvantagesand remain mostly unused by banders. Oct. - Dec. 1999
The design describedhere is for a system that elevates a single net to a height of 8.5 m. More materials
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can be added
or subtracted
if other Page 129
heights are desired. (We use two elevated net systemsmeasuring7 m and findthem adequatein locationswith lower canopy vegetation or when the desired
results facilitate
use of nets at lower
levels). We recommenda maximum height of 10 m with the pole material described. Metal stress may resulton the lowerelectricalmetallictube of a pole erected above this height.
Materials - The followingmaterials needed to constructthe elevated mist net system can be obtainedin any goodhardwarestore: - Six 2.5 cm (1 in) by 3 m (10 ft) electricalmetallic tubes (EMT). - Four 2 cm (3/4 in) by 10 cm (4 in) blackpipe
nipples. - 85 m (280 ft) of 0.5 cm (3/16 in) diameter "clothesline cord" (148 kg [325 lb] breaking
strengthand 1% stretchwith 16 kg [35 lb] load recommended).
- Twosingle pulleys designed fora 0.5cm(3/16in) diameter rope size. - One doublepulleydesignedfor a 0.5 cm (3/16 in) diameter rope size.
- One mid size rope cleat. - Ten metal shower curtain pins. - Correctsize nuts,bolts,and washersnecessary to attach pulleysand rope cleat. Assembly of the Poles - Three attached 3 m lengthsof EMT constitutethe polesfor each side of the elevated net system (see Fig.l). First, drill holes for the hardware and guy. lines to fit dimensionsshownon Fig.1 and Fig. 3. Poles are then attached to one another :using black •pipe nipples as dowels. To join poles, drive a pipe nippleintoeach end of the two center sectionsof EMT that compriseeach pole. To insertthe nipple intothe EMT, use a lubricant(WD-40, WD-40 Co. San Diego, CA) on the pipe nipple and mallet to drivethe nippleintoplace. When insertingthe pipe nipple, brace the opposingside of the EMT on a hard surfaceand drivethe nipplehalf way intothe central EMT section. Pipe nipplesare made of a
heavy duty steel, but care shouldbe taken when hammeringnotto hitthem unevenlycausingthem tO dent.
Pole
Single Pulley
Single Fig.
Mist Net
t.
7-10.I
Guy Line/
II1
• GuyLine
/
.,
t
':
,.
,
: ;
ß Pulley
•
Rop. i-'T---
\
\
.6m
........................... .i...: ....1..... ............................................................................ ?...... 1.......... .•............................... -.-. T"
m ,,"
\
!
Ground
/
\
J'",,../
1 /
"'..,..
Figure 1. Diagram of elevated mist net apparatus. Diagram is not to scale Page 130
North American Bird Bander
Vol. 24 No. 4
• Single Pulley SinglePulley
Stopper
Knot
Knot
Shower i• Pin Iqetal
Iqetal Curtain '-•-•e
Curtain
Shower
• Rope
•ouble Pulley • Ends
Figure2. Diagram of ropelayoutandassemblage. After nipplesare in place on both sides of the
thereforebe usedwithinthe pulleysystem. If additional swaths ofropeareneeded to lengthen can then be attacl•ed(Fig. 1). We recommend the ropeassemblage withinthe pulleysystem, construction of polesbe doneat the locationwhere attachthe added rope at the positionof the the net is to be erected. This allows for easier stopperknotslocatedat the top of the rope
centersection of EMT,endsections of eachpole
manipulation andtransport of poles.Lubricate the schematic(Fig.2). Moreropemaybe addedto exposedhalvesof the pipenipplesand position areasclearof the pulleysystem. the end sectionsof EMT overthe top of the exposed nipple.Drilled holesforpulleys andrope cleatmustbe oriented so thepartsarepositioned as in Fig. 1 beforeconnecting end sectionsof EMT. Again,braceopposing endsof the EMT 12cm
sectionsyou are connecting on a hard surface. Hammer the end sections of EMT over the
Ilcm ø
exposed pipenippleuntilthe EMTsections join, creatinga smoothcoupling.The EMT is madeof
muchsoftermetalthanthe blackpipenipples.
Whenhammered, the EMTmaydentbefore sections joinoverthenipple.Thedenting willbe minimal andwillnotaffectthesystemitself,asthe sectionsof pole betweenthe pulleysremain
.'•uy//* •
"Lines.' ,'
/*
Metallic
Pulley
Knot
Tubing Metal
Shower Curtain
in
Mist Net
/ Loops
•o•e i
smooth and undented.
Assembly oftheRopeSchematic-Assembly of
Knot
a correctropeschematic is essential to operation
ofthiselevated netsystem (Fig.2). Thepremise of thesystemis fortheropeto glideuninterruptedFigure3. Detailof singlepulleyandguyline through thepulleys.Longsections ofropemust dimensions.Notecorrectmetalshowercurtainpin Oct.- Dec. 1999
and rope assemblage attachment.
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I
A separate length of rope with correctlyattached shower curtain pins is required for each pole. Length of rope needed for each pole is different (Fig. 2). We recommend a length of rope measuring28 m (90 ft) f6r the polewiththe single and double pulleyattachments(Fig. 1). A shorter length of rope measuring 22 m (70 ft) is
attached single pulleys (Fig. 3). Attach the double pulley and rope cleat onto the poles. String and fasten lengthsof ropethroughholesdrilledfor guy line. (To save on the cost of rope, we used a very inexpensiveclotheslinecord for the guy lines and
knottogetherany scrapsOf ropefromthe pulley rope assemblage.)
recommended forthe pølewiththepulleyandrope
cleatattachments (Fig.1). Showercurtainpinstied intothe ropecarrythe net up and down. When purchased, shower curtain pins are circular with an elongated extension on which the pin clasp is found. The elongated extensionmustbe eliminatedin orderfor pinsto move on poles. Use a pair of pliersto straighten the bend of the pin• that forms the elongated extension. When the manipulationof the pin is complete,its shape will resemblea teardrop(Fig.
3), andit willslidesmoothly up anddownthe verticalpole. Tying shower curtain pins into the ropes requires precision.Use the mistnet intendedforthe system as a guide when spacing shower curtain pins. Spacing of these pins on the rope is essential to maintainingthe correctpocketdepth in each tier. Spacepinson the ropeat exactlythe same length that separateseach tier of the net when the vertical trammel line is fully extendedand tie them tightly into the rope. When all of the pins are tied intothe rope, they mimic the spacing of the net loop to which they will eventually be attached. The resulting pocket depth •in the mist net is approximately10 cm (4 in) to 15 cm (6 in). Deeper pocketdepth improvesthe capturerate of larger bird species (Merseyside RingingGroup, 1971). To make pocket depth deeper, shorten the distancebetweenshowercurtainpins. Erection of Elevated Mist Net ApparatusAttachmentof rope assemblage and hardware to
polesisdonebeforeerecti'on oftheapparatus. To complete poleassembly,',,attach singlepulleys positionedat the top of each pole (Fig. 1). Use
enoughwashersto insure • that whenthe single pulleysare fixed in their.final positionsthey rest level and parallel to the,pole (Fig. 3). Slide the
shower curtain pins of' the completed rope assemblages onto the poles to which they correspond,and feed the end of the rope into the Page 132
To erectthe apparatus,dig •:small0.7 m (2 ft) hole in the locationwhere the first pole is to be placed. To secure the pole in the ground,gather enough rock or any heavy refuse materialto refillthe hole. (In areas with wet or soft soil, holes and refill material are not necessary if the poles can be pushed into the ground to the desired depth.) Raise the first pole and place it in the hole. Make sure the pole is orientated in manner shown in Fig. 1. Fill,the holewith rocksand then piledirt removed from the hole aroundthe base of the pole. Be sure to stompdown dirt and rocks,as they will settle in a few days. Tie.the guy lines so that the pole is straightand secured. Use
the
mist
net
intended
for
use
with
the
apparatus as a guide to establish the distance of the next pole location. (Mist nets can vary slightly in length.) Attach the loopsof the mist net to the shower curtain pins on the rope assemblage (Fig. 3) of the erected pole, and walk the mist net out in the direction that you want the mist net placed. Stretchthe top trammel line untilit is tightand mark the groundunder the spot of its maximumstretch. We have determined
that this is the best method
for establishingthe location of the second pole. Duringuse and exposureto weather, mist nets will stretch (G. AIbanese, pers. obs.). We strongly recommendthe use of this methodfor establishing the distance to the second pole location, as it ensures that the net maintains the correct tension
necessaryto capture birdssafely while in use with this apparatus. At this mark, dig another hole and repeatthe instructionsdescribedfor raisingthe first pole. Attachthe mist net to the shower curtainpins on the rope assemblageof the secondpole. String the rope through the double pulley using the correct rope schematic(Fig. 2). Operation-This system requiresonlyone person to operate. Locatethe four ropeends near the rope cleat. By pullingon the two correctropeends, the operator can raise and lower the mist net. Opposing lines on the poles, when pulled
North American Bird Bander
Vol. 24 No. 4
simultaneously, will raiseor lowerthe net evenly
DISCUSSION
(whenbirdsarecaptured inthenet,careshould be takento keepthe net levelwhenlowering).When the mistnet is open, ropesare fastenedto the rope
cleatt,oprevent thenetfrommoving onthepolesif a largenumberof birdsare.captured.Alwaysfree the ropesfromthe ropecleatbeforeattemptingto
The elevatedmist net apparatusdescribedhere
has provencapableof capturing varioussized birdssuccessfully inmultiple vegetation strata.Of the 371 birds captured during 1999 with the
lowering thenet,wecolor-coded theropeendstwo differentcolorsso the operatorcan readilyidentify
device,no injuriesor fatalitieswere incurred. Whileourdataispreliminary atthistime,useofthe elevatedmistnetapparatus at ourWisconsin and Belizestudysiteswillallowus to determine the
whichtworopeendsto pullto raiseor lowerthe net.
effectivenessof this apparatus in capturinga
(Weusegreenontheropeendsthattakedownthe
representative sampleof the aviancommunity
netwhenbirdsare presentand redonthe endsthat returnthe emptiednetto the elevatedposition.)If, after loweringthe mistnet, birdscapturedin a top
utilizinghighervegetationstrata.
Theelevatedmistnetapparatus described inthis
tier cannot be reached for removal by the operator,
paperisinexpensive toproduce (about $35USin
pullingdowntheshowercurtainringsonthepoleto the desired level will lower the tiers of the net.
1999). It isuncomplicated to assemble anderect. Once materials•re acquired,it takes'two
Under certain conditions, such as in damp
individualsabout 3 to 4 hours to assemble and erect. In addition,opce constructed,it is easily
move the net. To avoid confusion when raising or
weather, mist nets may become loose. Rather than movingthe poles of the system,we have
operatedby onlyone individual.
found that rubber bands can be utilized to eliminate
Jenniet al. (1996)suggested thatmistnetsshould
sag in the nets. Locate the saggingvertical
coverthe entireve9etatior•heightof a habitatto allowadequatesampling of birdspreferring higher
trammel lines of the net. At the end of the'.•(};ines
locate the net loops used to attach the mis[ net to
theapparatus. Stretch •d f,'•sten a rubber'•nd at or beforethe midpoii•tof thenetloop. Ti',•½ result is a smaller r•etloop. Reattachthe stoalie.? ;•(;•loop to the shower curtainring. Repeat [his pror?.sson
any net loopsattachedto saggingtrammellines. Duringwet conditions this methodwill eliminate sag in the attachedmist nets, so thst safe
operation oftheelevated mistnetapparatus m.aY
vegetationstrata. '?heyalso suggestedthat samplln 9 all vsgot,3t•o;' strata might aid in determiningvertic;,Idistr•butio•patterns. The uncomplicated des,gr•and affordability of our elevatedmistnetapparatusmakestheseoptions possiblefor researcr•ers. ACKNOWLEDGMENTS
continue.
We thankStephanieAlbanesefor her helpin the conception and implementation of the design;
To samplea heightlessthan8.5 m, keepthe mist net level on the poles and choosethe desired' height. Whenthe net is elevatedto the desired height,tiethe ropeendsoffonthe ropecleat. The
Brian Francoisfor his help and advice; Marsha
Sinnerfor her help with the figures;and Dr. Anthonyand Donna Meyer and the Lake
mist net will remain secured at this height.
conduct research on their land.
To remove the mist net, unlatch it from the shower
LITERATURE
curtainringsandstore. If the locationwarrantsthe mistnet be leftoutforan extendedperiod,the mist net can be furledby loweringthe showercurtain
Austin,(3. L., Jr. 1947. Mistnettingfor birdsin Japan. Nat. Res.Section,Rep.No. 88,
ringsand furlingand tyingthe net.
Pewaukee Sanitary District for allowing us to
CITED
GHQ SCAP, Tokyo, Japan.
Berthold,P. 1976.Methodende Bestandserfassunginder(3rnithologie: Ubersicht undkritischeBetrachtung.J.OrnithoL 117:1-69. Oct.- Dec.1999
NorthAmerican BirdBander
Page133
Chapin,R. E. 1988. Constructionof polesfor double-tiered Bander
mist nets.
N. Am. Bird
13:108-109.
Dejonghe,J. F. and J. F. Cornuet. 1983. A system of easily manipulated,elevated mistsnets. J. Field OrnithoL
54: 84-88.
Greenlaw,J. S. and J. Swinebroad.1967. A methodfor constructing and erecting
Meyers, J. M., and K. Pardieck. 1993. Evaluation of three elevated mist-netsystemsfor samplingbirds. J. Field Omithol. 64:270277.
Munn,C.A. 1991. Tropicalcanopynettingand shootinglines over tall trees. J. Field Omithol.
Nixon, G.A.
62:454-463.
1972. A use of external marine sail
aerial-netsin a forest. Bird-Banding
trackingon mistnet poles. W. BirdBander
38:114-119.
47: 53-55.
Heselton, K. E. 1990. The AFMO Hi-Lo: double
height mist net utilizinga pivoted parallelogramsupportsystem. N. Am. Bird Bander
15:13-16.
on their role in the assessment
of passerinehabitatuse. J. Field Ornithol. 67: 263-274.
Karr, J. R. 1979. On the use of mist nets in the
studyof bird communities. Inland Bird Banding51:1- 10. Karr, J. R. 1981. Surveyingbirdswith mist nets. Stud. Avian BioL 6:62-67.
Mease, D. and E. Mease.
relets.
N. Am. Bird Bander 16:123-126.
Remsen, J. V. and D. A. Good. 1996. Misuse of
Humphrey,P.S., D. Bridge,and T. E. Lovejoy. 1968. A techniquefor mist-nettingin the forest canopy. Bird-Banding39:43-50. Jenni,L., M. Leuenberger,and F. Ramazzi. 1996. Captureefficiencyof mist nets with comments
Paton,P. W. C., C. J. Ralph,and J. Seay. 1991. A mist net designfor capturingMarbled Mur-
1980. Aerial net
assembly. N. Am. Bird Bander5:138-139.
data from mist-netcapturesto assess relativeabundancein bird populations. Auk 113:381-398.
Sheldon,W. G. 1960. A methodof mist netting woodcocksin summer. Bird-Banding31: 130-135.
Slud, P. 1960. The birds of Finca "LaSelva",Costa Rica: a tropicalwet forest locality.Bull. Amer.
Mus.
Nat.
Hist. 121:49-148.
Stamm, D. D., D. E. Davis and C. S. Robbins.
1960. A method of studyingwild bird populationsby mist-nettingand banding. Bird-Banding31:115-130. Whitaker,A. H. 1972. An improvedmistnet rigfor use in forests. Bird-Banding43:1-8.
MerseysideRinging Group. 1971. Catching CollaredDoves. Ringers'Bull. 3(10):9-10.
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