© H.P. Smith, Jr. VIREO

Map credit: USGS Breeding Bird Survey Band-tailed Pigeon (Patagioenas fasciata) breeding range in US and Canada

Population Declines “This species is most numerous near the mouth “This species is most numerous near the mouth of the Columbia River, where immense flocks… … fairly rivaled those of the passenger pigeon” … fairly rivaled those of the passenger pigeon” William Carpenter (Bendire 1892) Coastal subspecies (P. f. monolis): population decline in recent decadesCoastal subspecies (P. f. monolis): population decline in recent decades Interior subspecies (P. f. fasciata): suspected population decline in recent decadesInterior subspecies (P. f. fasciata): suspected population decline in recent decades

Figure adapted from Pacific and central flyways management plan for the four-corners population of band-tailed pigeons (2001) Harvest Returns in Arizona

Research/Conservation Needs Development of reliableDevelopment of reliable population monitoring method considered a top management priority (Braun 1994, Casazza et al. 2000, Keppie and Braun 2000)

Study Objectives Evaluate two potentialEvaluate two potential survey methods: 1) auditory surveys 2) call-broadcast surveys Estimate and compareEstimate and compare detection probabilities associated with each survey method

Tucson Tucson Tucson Phoenix Phoenix Flagstaff Flagstaff Pinaleno Mts. Chiricahua Mts. Santa Catalina Mts. Huachuca Mts Santa Rita Mts. Study Area

Survey Methods Total of 101 survey routesTotal of 101 survey routes 40 routes stratified by forest type: mixed-conifer,40 routes stratified by forest type: mixed-conifer, pine-oak, pine, oak-juniper-pinyon Survey route: 2.4 km in length with 6 pointsSurvey route: 2.4 km in length with 6 points Total of 345 replicate surveys (May-August)Total of 345 replicate surveys (May-August)

Survey Methods Survey period: 135 min (beginning 15 min. < sunrise)Survey period: 135 min (beginning 15 min. < sunrise) Paired design: 6-minute auditory survey followed byPaired design: 6-minute auditory survey followed by 6-minute call-broadcast survey at each survey point For each calling pigeon, created a detection historyFor each calling pigeon, created a detection history by recording when pigeon first called during: 1) six 1-min intervals in auditory period 2) four 1.5-min intervals during call-broadcast period

Detection Probability P detect = P sings x P heard For both auditory and call-broadcast surveys: Used detection histories and removal models to estimate P sings (sensu Farnsworth et al. 2002)Used detection histories and removal models to estimate P sings (sensu Farnsworth et al. 2002) Used double-observer trials (n = 12) to estimate P heard (sensu Conway et al. 2004)Used double-observer trials (n = 12) to estimate P heard (sensu Conway et al. 2004)

Analyses For call-broadcast and auditory surveys: Compared average number of calling pigeonsCompared average number of calling pigeons detected using paired t-tests Estimated P sings in Program CaptureEstimated P sings in Program Capture Compared temporal variances in average number ofCompared temporal variances in average number of pigeons detected and P sings using %CV Χ 2 to compare frequency of pigeon detections at survey points in different forest types

Call-broadcast vs. Auditory Surveys Call-broadcast increased number of pigeons detected per survey route by 29% (0.68 vs. 0.53; t = 2.8; df = 100; P = 0.003)Call-broadcast increased number of pigeons detected per survey route by 29% (0.68 vs. 0.53; t = 2.8; df = 100; P = 0.003) Call-broadcast increased percentage of surveys with ≥1 pigeon by 16% (36% vs. 31%; t = 2.4; df = 344; P = 0.007)Call-broadcast increased percentage of surveys with ≥1 pigeon by 16% (36% vs. 31%; t = 2.4; df = 344; P = 0.007)

Temporal variance (%CV) in number of pigeonsTemporal variance (%CV) in number of pigeons detected similar for auditory and call-broadcast surveys (169% vs. 161%; t = 0.70; df = 25; P = 0.492) Pigeons detected more frequently at survey points in mixed-conifer forest (76%) compared to otherPigeons detected more frequently at survey points in mixed-conifer forest (76%) compared to other forest types (χ2 = 12.3, df = 3, P < 0.01) Call-broadcast vs. Auditory Surveys

Pigeons Detected During Call-broadcast (Black) vs. Auditory (White) Surveys

68% difference (P = 0.003)

Pigeons Detected During Call-broadcast (Black) vs. Auditory (White) Surveys 89% difference (P = 0.012)

Detection Probability P heard : similar for auditory (0.85) and call-broadcastP heard : similar for auditory (0.85) and call-broadcast (0.89) survey methods P sings : 21% greater for call-broadcast (0.90; 95% CIP sings : 21% greater for call-broadcast (0.90; 95% CI = ) compared to auditory (0.74;95% CI = ) surveys

P sings during Call-broadcast (Black) vs. Auditory (White) Surveys

Detection Probability Variance in P sings 32% less for call-broadcast (CV = 134%) versus auditory surveys (CV = 198%)Variance in P sings 32% less for call-broadcast (CV = 134%) versus auditory surveys (CV = 198%) P detect (= P sings x P heard ): 27% greater for call-broadcastP detect (= P sings x P heard ): 27% greater for call-broadcast (0.80) versus auditory (0.63) surveys during a 6- minute survey period

Discussion Both methods shared the following characteristics: Few (<1) pigeonsFew (<1) pigeons detected per survey Few (<50%) replicateFew (<50%) replicate surveys with ≥1 pigeon © H.P. Smith, Jr. VIREO

Discussion Call-broadcast improves accuracy of surveys by increasing # of pigeons detected, especially in early AMCall-broadcast improves accuracy of surveys by increasing # of pigeons detected, especially in early AM Call-broadcast appeared to improve precision of surveys by reducing variance in P singsCall-broadcast appeared to improve precision of surveys by reducing variance in P sings First time call-broadcast shown to increase detection probability for band-tailed pigeons (or any species of Columbidae)First time call-broadcast shown to increase detection probability for band-tailed pigeons (or any species of Columbidae)

Which Birds are Responding to Call-broadcast? Mated males absent from nests or present but quiet during early AM (Kirkpatrick et al. 2004)Mated males absent from nests or present but quiet during early AM (Kirkpatrick et al. 2004) Unmated males call 8x more than mated males (Sisson 1968)Unmated males call 8x more than mated males (Sisson 1968) Unmated males may be responding to call-broadcastsUnmated males may be responding to call-broadcasts © A. Morris VIREO

Conclusions Call-broadcast surveys provide useful methodCall-broadcast surveys provide useful method for monitoring interior subspecies in some areas In SE Arizona, early morning surveys in mixed-In SE Arizona, early morning surveys in mixed- conifer forest will yield most detections Call-broadcast surveys potential method forCall-broadcast surveys potential method for monitoring other pigeon species

Acknowledgments Surveyors: Moez Ali, Kelly Bergstrand, Bryon Cariss, Dave Fox, Greg Gryniewicz, Johanna Havelaar, Kristin Hemmelgarn, Dylan Holstein-Radin, Dominic LaRoche, Eduardo Martinez-Leyva, Eric Nolte, Chris Murray, Chuck Seal, and Julie Warr. Project Support: Susan Bennett, Susan Bensen, Clait Braun, Mike Casazza, Mike Cooper, Thomas Deecken, David Dolton, Debbie Fagan, Arthur and Mary Faul, Lee Fitzhugh, Jim Heffelfinger, Gary Helbing, Larry Jones, Sandy Lanham, Jerome Leonard, Bob Peterson, Mickey Reed, Todd Sanders, Mike Stanley, Bonnie Stolp, Josh Taiz. Funding: Arizona Game and Fish Department Heritage Fund Webless Migratory Game Bird Research Program Webless Migratory Game Bird Research Program U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service U.S. Geological Survey U.S. Geological Survey University of Arizona University of Arizona