Capture and radio-transmitterattachment techniquesfor Roadrunners SandraL. Vehrencampand Liza Halpenny walksand jumpson the trap to peckat it, and eventual- sbreedingpart ofphysiologya two-year ofstudy Roadrunnersonthe behavior(Geococcyx and ly gets its feet caughtin the nooses.It usually takes californianus),a variety of techniqueswere employed several minutesof active lungingat the bait before a to capturethe birds and to attachradio transmitters.In bird becomessnared. Occasionally birds will work at a this paper we describethese techniquesand evaluate trap for 15 minuteswithout being caught,then lose their relative success.The studywas conductedat the interestin it. It is esse•,•t '.•,monitor the trap continu- Gamp PendletonMarine GorpsBase Reserve, about 10 ously.If the bird is not caughtsecurely, it can work its milesnorth of Oceanside,San Diego Gounty, Galifornia. way out of the noose in a few seconds,and if it is The Roadrunnersin thisarea were very shyand wary, securelycaught, it can injure its legsif left in the trap presumablydue to theoccasional appearance of Marine longerthan a few minutes.The trap is light enoughto troops and heaw vehicles.The birds preferentially be draggeda short distanceby the bird, but doesnot nestedin the largestclumps of prickly pear (Opuntia} need to be staked. cactus.Opuntia was typicallylocated in denseaggrega- This trap is inexpensiveand easyto construct.Many can tions on south-facingslopes. Seven active nestswere be set out simultaneously,and one personcan monitor found during one breedingseason by systematically 3 to 4 traps if they are carefully placed.However, the searchingthese areas. trap has 2 major disadvantages.The first is the low encounterrate of birds with traps, resultingin poor efficiencyof trappingeffort. We spentapproximately 12 Traps man-hoursmonitoring traps per capturedRoadrunner. Secondly,the trap selectivelycaught small males in our Raptor trap studyarea. None of thesebirds were seen again,and the few that were radio-trackeddisappeared from the Thistrap is a modifiedversion of theBal-chatri or studyarea within a few daysof capture.We surmised live-baitedfootnoose trap {Bergerand Mueller, 1959}. that thesewere youngdispersing or itinerantbirds, and We use an 18"square piece of 1/2"meshhardware cloth that their interestand persistenceat the trapsreflected as a base and attacha 12"x 8"x 11/2"cage of 1/4" their inexperience,unfamiliarity with the area, and re- hardwarecloth to it. The finer meshof the bait cageis ducedforaging success. Known breeding birds, especial- necessaryto preventthe bait fromescaping and to pre- ly females,actively avoided the trap or made a single vent the Roadrunnerfrom injuringthe bait. The trap is lunge at the mouse,then continuedon their foraging thenspray-painted a flat blackto improvevisibility of route.Traps placednear nestswere never successful. the bait. Noosesof medium-gauge{40 lb. test}monofila- ment fishingline are tied to the top of the base and cage.Noose loops of 2"to 3" in diameterplaced about Treadle trap 3"apart work best.The trapsare relativelylight, and severalcan be stackedtogether for transport,but they Thistrap employs a treadle-activated, spring-loaded tend to become entangled.White laboratorymice are door to captureforaging Roadrunners. It consistsof an the mosteffective type of bait; brown or blackmice are 18"-highband-shell-shaped body of 1/4"or 1/8"hardware less conspicuous,wild mice are much less active, and clothattached to a fiat 12" x 18"wooden base (Fig.1). lizardsare generallycryptic and inactive.The micedid The fine meshis necessaryto preventthe capturedbird notperish when left in the trapswithout food and water from injuringits bill. A smallmouse cage is attachedto and in full sunlightfor the entire morning. the insideback wall of the shell.A rat trap is attached to the base to supplythe closingmechanism. A wire This trap is placed either along trails and roadsfre- shapedthe sameas, but a bit largerthan, the mouthof quented by Roadrunners or near nests. A bird that the shell is connectedto the closingspring of the rat encountersa trap is usually attractedby the mouse, trap. Restraining"L's" are put on the rat trap springto Page 128 North American Bird Bander Vol. 6, No. 4 keep the wire framefrom closingpast the mouthof the Mist net shell. Heavy black nettingis sewn looselyto the wire frame to completethe door.A "T" of woodattached to A standardheavy gauge 4"mesh mist net was used to the triggerof the rat trap forms a large treadle.The net nestingRoadrunners. The net was either mounted wire that holds down the springand attachesto the on poles in the standardmanner in the vicinity of triggermust be reshapedto sustainthe addedweight of knownnests, or gentlydraped around the cactusclump the treadle. The entire trap is spray-paintedblack. containinga nest.(The latter proceduredid not destroy When the'trap is set,the wire hoopdoor lies flat on the the net.) In generalthe net wasplaced on the downhill groundand the treadle is elevatedinside the shell. A side of the nest. The bird was then flushed off the nest white laboratory mouseis used as bait. from the uphill side, whereuponit glided or ran into the net. This methodsuccessfully captured all birds at This trap was placed alongRoadrunner foraging trails active nests,and failed only at nests that were later where birds leaving their nestswere known to pass. Birds attracted to the mouse hit the treadle at the first discoveredto be abandoned.The disadvantagesof the method are: 1) the large amount of time involved in lunge,thereby quickly snapping the doorshut. The trap searchingfor nests,and 2) a high probabilitythat the was developedtoward the end of our study and was adults will abandon their nest as a result of the distur- thereforeemployed only a few times,but it successfully bance. capturedall birds that encounteredit. It worked espe- ciallywell on breedingfemales. The primarydisadvan- Rock net tagesare its large size and heavy weight, making it difficult to store and carry. Roadrunnershave been knownto enterthe commerciallyavailable, collapsible, Thistrap was designed tocapture birds that habitually squirrel-sizedtreadle traps, but we believe that the perchon rockoutcroppings for displayingor sunning.It higher and shorterhome-made trap with the flexible consistsof a 3'-squarepiece of heavy black netting, door is more effective for tall birds. weighted on four corners, and covered with monofila- ment noosessimilar to thoseused in the raptortrap. It was drapedover a rockwhere a male was seengiving courtshipcalls severaltimes. His feet were caughtin the noosesthe next time he returned to the rock, but he slippedout before we couldreach him. This trap seems to work aboutas well as the raptortraps, but sinceit containsno bait, it mustbe placedin a commonlyused site. Foot noose on a stick Thistrap consists ofa monofilament nooseattached to the endof a 6' stick.The nooseis openedand placed in a nest over the eggs,with the stick directedtowards the outsideof the nest clump. After the bird has settled onto the nest,the stickis pulled by a hidden person, closingthe noosearound the incubatingbird's feet. A similartrap is describedby Gartshore(1978). The noosestick was successfulthe one time we usedit, but it causeda great deal of trauma to both the bird and the investigator.The bird dove into the surround- ing cactusand becameentangled there. The investiga- tor was therefore forced to wade into the cactus as well. The nestsite was damaged,and the extremedis- turbance caused abandonment of the nest. Summaryof trappingmethods Forstudies requiring thecapture ofbreeding Road- runners,it is muchmore productiveto searchfor nests, Figure 1: A home-madetreadle trap employinga rat- observethe movementsof thebreeders, then trap the sizedsnap trap for the closingmechanism. birdsaway from thenest in a treadletrap or footnoose Oct.- Dec.1981 NorthAmerican Bird Bander Page129 trap. As discussed,trapping birds directlyat the nest were tiedaround the radioafter the wax-sealingstep, risks abandonment,and randomlytrapping foraging and potted in with the dental acrylic so that they birds and hopingto follow themto their nestsvia radio- emergedfrom the 4 cornersof theradio package. A soft trackingis inefficientbecause of thelarge proportion of vinyl pad wasglued to the backof theradio to prevent non-breedingbirds captured. chafingof the skin.The radio restedon the bird's back betweenthe scapulartracts with the antennapointing posteriorly.The top strapswere placedover the bird's Radio-trackingand attachmenttechniques shouldersand the bottomstraps went aroundthe rib cageunder the wings.Several methods of tying the Types of radios strapsover the chestwere attemptedwith varying success.Following Dunstan (1972) and Godfrey(1970) Threetypes of radio-transmitters wereused on the we tied the 2 shoulderstraps straight across the upper Roadrunners:1) a standardexternally mountedradio chestand the 2 underwingstraps straight across the rib for monitoringmovements and home ranges,2} an ex- cage,with a shortperpendicular piece connectingthe ternally,mounted radio with an internally implanted strapsat the midline. A secondmethod was to criss- thermistorlead for monitoringboth movementsand in- crossthe shoulderand under-wingstraps to form an ternal body temperature,and 3] an internally implant- "x" on the chest.With both of these methods,the birds ed thermistor radio. All transmitters were constructed managedto get their lower mandiblepermanently following the designof Bradbury et al [1979).Each caughtunder