J. Field Ornithol., 62(4):486-491 RETENTION OF TRANSMITTERS ATTACHED TO PASSERINES USING A GLUE-ON TECHNIQUE GREGORYD. JOHNSON,1 JEFFREY L. PEBWORTH, AND HENRY O. KRUEGER Wildlife International,Ltd. 305 Commerce Drive Easton,Maryland 27607 USA Abstract.--Retentionof transmittersattached to the interscapularregion of four speciesof passerinesusing an adhesivecontaining cyanoacrylate was evaluated.Mean retentiontime was 20 d for Blue Jay (Cyanocittacristata), 19 d for AmericanRobin (Turdusmigratorius), 16 d for Brown Thrasher (Toxostomarufum) and 5 d for Northern Cardinal (Cardinalis cardinalis).Mean retentiontime for the Northern Cardinal was significantlyshorter (P < 0.05) than that of the otherthree species, presumably because cardinals were ableto remove transmitterswith their strongbills. No evidencewas foundthat cyanoacrylateincreased mortalityor impairedbehavior in radiomarkedbirds, and this adhesiveis believedto be safe for attaching transmitters to passerines. RETENCI•)N DE TRANSMISORES EN PASSERIFORMES UTILIZANDO LA T•CNICA DE PEGAMENTOS Sinopsis.--Sccvalu6 cn cuatrocspccics dc Passcriformcs,la rctcnci6ndc transmisorcs pegadosa la regionintcrcscapular utilizando un adhcsivoquc conticnccianoacrilato. El ticmpopromcdio dc rctcnci6nresult6 scr dc 20 d para Cyanocittacristata, 19 d para Turdus migratorius,16 d para Toxostomarufum y 5 d paraCardinalis cardinalis. E1 tiempo promedio de retenci6nresult6 ser significativamentemenor (P (0.05) en C. cardinalis,queen las otrasespecies. Es posible,que estas61timas hayan podidoremoverse el transmisorcon su picotan fuerte. No se encontr6evidencia que indicaraque el uso de cianoacrilatoscomo adhesivosde radiotransmisoresincrementaran la mortalidad o impidieran patronesparti- cularesde conductaen las aves.Se cree que la t6cnicano debacausarle dafio a Passeriformes. Radiotelemetryis a usefultechnique for monitoringmovements, habitat use, behavior,mortality and other parametersof wildlife populations (Mech 1983). Numeroustelemetry investigations have been conducted on upland game birds, waterfowl, and raptors. Comparativelyfewer telemetrystudies have been conducted on passerines,presumably because of early difficultieswith transmitterattachment and a lack of suitable transmitters(Godfrey 1970, Martin and Bider 1978). Advancesin trans- mitter designand developmentof transmitterattachment methods for small birds now make it possibleto radiomarkmost birds (Cochranet al. 1967, Godfrey1970, Martin and Bider 1978, Perry et al. 1981, Raim 1978, Sykeset al. 1990). We neededto radiomarkpasserines as part of a studyto evaluateeffects of insecticideson wildlife associatedwith corn fields.Perry et al. (1981) comparedseveral transmitter attachment techniques and adhesivesand concludedthat gluing transmittersto the interscapularregion using cy- anoacrylateis the bestattachment technique for Mourning Doves(Ze- naidamacroura). Our objectivewas to evaluatethis attachmenttechnique I Currentaddress: Western EcoSystems Technology, Inc., 7d06S. GreeleyHighway, Cheyenne, Wyoming82007 USA. 486 Vol.62, No. 4 Retentionof TransmittersAttached toPasserines [487 on BlueJays (Cyanocittacristata), American Robins (Turdus migratorius), Brown Thrashers(Toxostoma rufum), and Northern Cardinals(Cardinalis cardinalis)by determiningmean transmitter retention times, causesof transmitter loss and survival of radiomarked birds, and to determine if differencesin transmitter retention occurredbetween species. With the exceptionof an early study conductedwith an American Robin (Graber and Wunderle 1966), we know of no previouspublished telemetry studies conductedwith thesefour species. STUDY AREA AND METHODS We conductedthe study during the spring and summerof 1989 in Wayne, Lucas, and Warren countiesin south-centralIowa. The study area was composedof croplands,pasture and recentlyseeded grasslands interspersedwith deciduouswoodlands, wooded drainages and shelter belts.Topography varied from flat to hilly. Birdswere capturedin wooded areasadjacent to cornfields using mist nets (all four species)and modified Stoddardtraps (Wilbur 1967) baited with chickenscratch (Blue Jays, BrownThrashers, Northern Cardinals).Mist netswere setin the morning and evening, and were checkedat least once an hour, whereas funnel traps were set continuouslyand checkedlate in the morning and again late in the evening.Trapping sessionsoccurred 5 April-10 May and 10- 22 June 1989. Birds were bandedwith U.S. Fish and Wildlife Service and coloredleg bands. We used lithium battery-poweredtransmitters in the 217 and 218 MHz range manufacturedby Holohil Systems,Inc. (Ontario, Canada). The expectedbattery life was 6-8 wk. Transmitters had a 13.5-cm an- tennaand averaged 1.4 g (generally<3% of the bodyweight of individuals captured). Mean transmitter dimensionswere 22 x 10 x 6 mm. Trans- mitters were potted using epoxy and were slightly concavealong the longestaxis. Our transmitter attachmentprocedure generally followed that usedby Raim (1978) on Brown-headedCowbirds (Molothrusater) and Sykeset al. (1990) on captive Common Yellowthroats(Geothlypis trichas)and wild Kirtland's Warblers (Dendroicakirtlandii), exceptthat we usedcyanoacrylate (Super Glue ©) rather than a latex-baseadhesive. Transmitterswere gluedonto a pieceof cottonmending fabric slightly larger than, and similar in shapeto, the transmitter.Spinal tract feathers on eachbird's interscapularregion were clippedto within approximately 2 mm of the skin. A film of Super Glue © was applied to the cloth and the cloth was attached to the feather stubble and skin. Birds were released as soonas the transmitterwas in place and the glue was dry, generally within 15 min of capture. Birds were trackedoff road using directionalthree-element hand-held antennasand from roadsusing seven-elementantennas on fixed towers. Attemptswere made to locateall birds oncea day from time of capture until 14 d after conclusionof pesticideapplications on the cornfield where the bird was first captured.Attempts were madeto locateall birdsfor a minimum of 21 d, but somebirds were locatedfor up to 49 d depending 488] G. D. Johnsonetal. J.Field Ornithol. Autumn 1991 upon when each bird was caught prior to pesticideapplication. Intact radiomarkedbirds found dead were examinedfor possiblecause of death and analyzedfor pesticideresidues. Mean transmitter retentiontime, number of droppedtransmitters and lost signals,and number of mortalitieswere determinedfor each species over the 21-d period that all birds were monitored. Differences in trans- mitter retentiontime betweenspecies were comparedusing one-way AN- OVA. Individual birds that were never locatedafter attachingthe radio (one Blue Jay, three American Robins, eight Brown Thrashers, two Northern Cardinals), presumablybecause of emigrationor radio failure, were excludedfrom analysis. RESULTS One-hundredtwenty-eight passerineswere capturedand radiomarked during the study(Table 1). Mean transmitterretention time rangedfrom 5 +__0.2 d (SE) for Northern Cardinal to 20 ___0.5 d for Blue Jay. Differences in mean transmitter retention times between specieswere significant(F = 7.66• P = 0.0001) (Table 1). For all speciesexcept the Northern Cardinal, the mean would likely have been severaldays longer if we had continuedto track them, as 38% of the Blue Jays, 39% of the American Robins, and 20% of the Brown Thrasherswere still carrying functional transmitterswhen tracking was terminated. The longesta transmitter remained attached and functioningranged from 14 d for Northern Cardinal to 49 d for AmericanRobin (Table 1). All exceptthe Northern Cardinal were still being monitored upon study termination; thus we were not able to determinethe maximum length of time these individuals carried transmitters. After 7 d, 19% of the Northern Cardinals, 75% of the Blue Jays, 80% of the American Robins and 67% of the Brown Thrashers retained func- tional transmitters(Table 1). After 21 d, thesepercentages were 0% for Northern Cardinal, 50% for Blue Jay, 44% for AmericanRobin and 47% for Brown Thrasher (Table 1). Lossdue to droppedtransmitters ranged from 13% for Brown Thrasher to 38% for Northern Cardinal (Table 2). Dropped transmittersand transmittersrecovered from deadcardinals were all damaged;many were lacking antennasor had antennasthat had been coiledto only 1-2 cm in length.Antennas on transmittersrecovered from Blue Jayswere generally broken off to a length of 1-2 cm, whereas none of the transmitters recoveredfrom AmericanRobins or Brown Thrashersshowed any dam- age.We lostsignals for 21% of Blue Jays, 31% of AmericanRobins, 33% of Brown Thrashers and 31% of Northern Cardinals (Table 2). Mortality was similar for all speciesexcept the Northern Cardinal; 8% of Blue Jays, 5% of AmericanRobins and 7% of Brown Thrashers died during the study. In contrast,31% of radiomarkedNorthern Car- dinals died, all within 3 d of transmitter attachment. Although birds were not monitored intensivelyenough to quantify effectsof transmitterson behavior or breeding success,we noticedno Vol.62, No. 4 Retentionof TransmittersAttached toPasserines [489 TABI•I•1. Frequencyand duration of transmitterretention for radiomarkedBlue Jays, American Robins, Brown Thrashers and Northern Cardinals in south-central Iowa, April-July 1989. # birds Rangeof transmittersretaining after Retention time (d) dates Species(n) a trapped 7 d 14 d 21 d Range • SE Blue Jay (24) 6/10-6/20 18 17 12 1-36 20 0.5 American Robin (59) 4/06-6/19 47 35 26 2-49 19 0.2 Brown Thrasher (15) 4/19-6/22 10 8 7 5-32 16 0.6 Northern Cardinal (16) 4/05-4/13 3