Retention of Transmitters Attached to Passerines Using a Glue-On Technique Gregoryd

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 transmitter 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 cyanoacrylateis 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 transmitter 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 functional 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 durationof 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 1 0 2-14 5b 0.2

a Does not include one Blue Jay, three American Robins, eight Brown Thrashers and two Northern Cardinalsthat were neverlocated after attachingthe radioand were excluded from further analysis. bMean is significantly(P • 0.05) different from other species(Tukey's Multiple Com- parison Test). abnormal behavior in the birds we located. American Robins seemed especiallyadaptable to the transmitters,as two radiomarkedindividuals were observednesting during the study. DISCUSSION We were ableto track Blue Jays,American Robins and Brown Thrash- ers for as long as or longer than other radiomarkedpasserines (e.g., Brigham 1989, Martin and Bider 1978, Raim 1978, Sykeset al. 1990) and believeour attachmenttechnique is suitable for thesethree species, providedretention time is consideredwhen determiningstudy objectives. The short transmitter retention time for the Northern Cardinal suggests that this speciesmay not be a suitable candidatefor telemetry investigations using our technique. We believe our lack of successwith this specieswas due to its behavior.Apparently, this specieshas little tolerance for attachedforeign objects, and, becauseof its strongbill, it hasthe ability to removeor destroytransmitters. In addition to removingtransmitters, most cardinalsrecovered had removedcolored leg bands attachedat the time of capture. Signal loss was a major cause of attrition for all four species.We

TABLE2. Number of transmitterfailures, dropped transmitters and mortalitiesfor radiomarked Blue Jays, American Robins, Brown Thrashers and Northern Cardinals in south-centralIowa, April-July 1989.

# transmitters # signals dropped # mortalities Species(n) lost first 21 d first 21 d first 21 d Blue Jay (24) 5 5 2 American Robin (59) 18 12 3 Brown Thrasher (15) 5 2 1 Northern Cardinal (16) 5 6 5 490] G. D. Johnsonetat. J.Field Ornithol. Autumn 1991 attributedloss of signalsto a variety of factors.Transmitter failure cer- tainly causedsome loss; many signalsbecame erratic shortlybefore they were lost, which generally indicatesfailure is imminent. The condition of transmittersrecovered from Blue Jays and Northern Cardinalssuggests that transmitter and/or antenna damagecaused by the birds may have resultedin someradio failure. A significantproportion of the signalslost for American Robins and Brown Thrashers marked during the first interval (5 April-10 May) were probablydue to emigrationor migration becausethese species were marked prior to the time of territory estab- lishment. Droppedtransmitters also resulted in significantlosses of markedbirds. Due to the damagedcondition of transmittersthat droppedoff Blue Jays and Northern Cardinals,it is likely that mostwere removedby the birds. None of the transmitters recovered from American Robins or Brown Thrasherswere damaged,suggesting the birds did not try to removethem or did not have strongenough bills to removethem. Weather may also affectglue bonds(Sykes et al. 1990). We encounteredtemperatures rang- ing from -8.3 to 37.2øC during the period we monitoredbirds. Rainfall, rangingfrom a trace to 3.4 cm, occurredon 34 of the 98 d radiomarked birds were monitored.These temperatureextremes and periodsof rainy weather may have weakenedglue bondsand causedsome of the transmitters to fall off. Basedon presenceof pesticideresidues in the gastrointestinaltract, we attributedone American Robin death to pesticideexposure. One radiomarked Blue Jay was recapturedin a funnel trap and was killed by a predatorwhile in the trap. The one Brown Thrasher that died was found buried, and was probably killed by a predator. We did not determine causeof death for the other mortalities. Carcassesof two American Robins, oneBlue Jay and oneNorthern Cardinal were scavengedand only feather spotswere recovered.Four Northern Cardinal carcasseswere foundintact and did not show any evidenceof trauma or contain pesticideresidues. As cyanoacrylatesmay irritate skin and block skin pores,use of this adhesivemay potentially injure birds and result in mortality. This ad- hesivewas usedto attach transmittersto Mourning Doves (Perry et al. 1981) and to Least Terns (Sternaantillarum) and SnowyPlovers (Cha- radriusalexandrinus) (Hill and Talent 1990) without any apparent det- rimental effects,however. If cyanoacrylatedid contributeto the mortality observedin this study,we believesimilar ratesof mortality shouldhave occurredfor all four species,as it seemsunlikely that Northern Cardinals would be more susceptiblethan the other three species.Based on this evidence,and the fact that no apparentabnormal behavior was notedin radiomarkedbirds, we believe cyanoacrylateis a safe adhesivefor attaching transmittersto passerines.

ACKNOWLEDGMENTS

This research was supported by the Agricultural Division, Ciba-Geigy Corporation, Greensboro,North Carolina. The Iowa Department of Natural Resourcescooperated Vol.62, No. 4 RetentionofTransmitters Attached toPasserines [491 throughoutthe study and providedsome of the traps usedto capture birds. The following peoplewere instrumentalin capturing, marking and/or radiotrackingbirds: D. E. Black, T. S. Howard, D. K. Kavanaugh, T. J. Lee, C. D. Meyer, J. E. Perritt, D. L. Temple and D. L. Thompson.

LITERATURE CITED

BRIGHAM,R. M. 1989. Effects of radio transmitters on the foraging behavior of Barn Swallows. Wilson Bull. 101:505-506. COCHRAN,W. W., G. G. MONTGOMERY,AND R. R. GRABER.1967. Migratory flightsof Hylocichlathrushes in spring:a radiotelemetrystudy. Living Bird 6:213-225. GODFREY,G.A. 1970. A transmitter harnessfor small birds. Inland Bird Banding News 42:3-5. GRABER,R. R., AND S. L. WUNDERLE. 1966. Telemetric observationsof a robin (Turdus migratorius).Auk 83:674-677. HILL, L. A., AND L. G. TALENT. 1990. Effects of capture, handling, banding, and radio- marking on breedingLeast Terns and Snowy Plovers.J. Field Ornithol. 61:310-319. MARTIN, M. L., AND J. R. BIDER. 1978. A transmitter attachment for blackbirds. J. Wildl. Manage. 42:683-685. MECH, L. D. 1983. Handbook of animal radio-tracking.Univ. Minnesota Press,Min- neapolis,Minnesota. 107 pp. PERRY,M. C., G. H. Ht•s, ANDJ. W. CARPENTER.1981. Radio transmittersfor Mourning Doves:a comparisonof attachmenttechniques. J. Wildl. Manage. 45:524-527. RAIM, A. 1978. A radio transmitter attachmentfor small passerinebirds. Bird-Banding 49:326-331. SYKES,P. W., JR., J. W. CARPENTER,S. HOLZMAN,AND P. H. GEISSLER.1990. Evaluation of three miniature radio transmitter attachmentmethods for small passetines.Wildl. Soc. Bull. 18:41-48. WILBUR,S.R. 1967. Live trapping North Americanupland gamebirds. U.S. Bur. Sport Fish. Wildl. Rep. Wildl. 106. 37 pp. Received29 Oct. 1990; accepted2 Apr. 1991.