March 1996 Short Communications 31 techniques: a radio-controlled bownet and power snare Prevost, Y.A. AND J.M. Baker. 1984. A perch snare for bald and golden eagles. J. Raptor Res. 28:268-273. for catching ospreys. J. Wildl. Manage. 48:991-993 O’Gara, B.W. and D.C. Getz. 1986. Capturing golden eagles using a helicopter and net gun. Wildl. Soc. Bull. Received 15 July 1994; accepted 15 July 1995 14:400-402. Raptor Res. 30(l):31-32 J. © 1996 The Raptor Research Foundation, Inc. A Mechanical Owl as a Trapping Lure for Raptors Eugene A. Jacobs Linwood Springs Research Station, 1601 Brown Deer Lane, Stevens Point. WI 54481 U.S.A. Key Words: Bubo virginianus; capture technique, great styrofoam head of the mechanical owl. Servo A supported horned owl', lure', mechanical owl', mist net. and provided movement to the mechanical owl’s head Servo B was placed in a holding bracket constructed of mm A live great horned owl {Bubo virginianus) used as a sheet metal and attached to an aluminum rod (7 dia. decoy is an effective method for capturing several species X 1 m) used to support the mechanical owl’s perch. In the underside of the mechanical owl’s perch, I inserted a ofbreeding raptors (Hamerstrom 1963, Bloom et al. 1992, copper sleeve (9 mm dia. x 12 cm) into the center and a Steenhof et al. 1994). Similar techniques were practiced pin (4 mm dia. x 11 cm) at one end with approximately by Arab and Persian falconers (Meredith 1943). Taxi- halfofthe pin exposed. To provide movement to the entire dermy mounts of great horned owls have also been used mount, servo B’s control arm was modified with a piece mm successfully to capture breeding raptors, but are not as of tempered wire (3 dia. x 30 cm) bent in half and effective as a live owl (Bloom 1987). Gard et al. (1989) attached at both ends to the control arm. The mechanical reported breeding American kestrels {Falco sparverius) re- owl and perch assembly were positioned on top of the m sponded less aggressively to a mounted great horned owl aluminum rod, elevating the owl 1 above the ground and allowing rotation of the mount. Servo B provided than to a live owl, suggesting that the lack of movement movement to the entire mount, allowing the observer to or some other subtle cue by the mounted owl may account control movement of the entire mount and the mechanical forthe lower responserate. However, logistics (e.g., weath- owl’s head independently. er conditions, remote nest sites, maintenance of owl, legal Method of Use. From 1989 through 1995, the me- constraints) sometimes warrant the use of a mounted owl chanical owl was tested on breeding sharp-shinned hawks as a substitute for a live great horned owl. Here, I describe {Accipiter striatus), red-shouldered hawks {Buteo lineatus), the materials used to construct a moving mechanical owl and Cooper’s hawks {Accipiter cooperii). A response was and compared the results of my trapping efforts with this considered to have occurred when the target species stooped m lure to other studies using a live and mounted (taxidermic) at least once within 1.5 of the mechanical owl’s head. During the nestling stage the mechanical owl was centered great horned owl. <1 m from the net, in view of and <50 m from the nest. Methods An observer concealed <25 m from the net activated the owl (via transmitter) when at least one of the adults was Materials and Assembly. A two-channel remote con- detected near its nest. trol unit (transmitter, receiver, battery pack, and two servo mechanisms) designed for a model car was slightly mod- Results and Discussion ified to provide movement to a mounted great horned owl. The owl’s head and body were separated and mounted Overall, the mechanical owl was successful in eliciting independently using standard taxidermy procedures. The a stoop from 79% (75/95) of the nesting adults. This mechanical owl’s body was attached to a horizontal wood- response was slightly lower than the 93% Gard et al. en perch (9 cm dia. x 20 cm). A piece of styrofoam was (1989) reported when using a live great horned owl on excised from the body of the mechanical owl at the top American kestrels, but considerably higher than the 33% center and fitted with servo A (Fig. 1). Two vertical pins they found with a mounted great horned owl. Fifteen of mm (3 dia. x 10 cm) were glued into the control arm of the 20 adults that did not attack the mechanical owl vo- servo A and two corresponding sleeves were glued into the calized for >15 min before leaving the area. The remain- — 32 Short Communications VoL. 30, No. 1 Resumen. Un biiho preparado taxidermicamente fue equipada con mecanismos radio-controlados en la cabeza y percha que permitian movimientos al buho. Este ingenio mecanico y una red de niebla fue usada como tecnica de captura durante siete estaciones reproductivas de tres es- pecies de rapaces. Este metodo fue exitoso atrayendo a un 79% de adultos reproductivos. Setenta y siete por ciento de Accipiter striatus, 60% de A. cooperii y 54% de Buteo lineatus, fueron capturados por este metodo. El movimiento del buho mecanico parecio ayudar a las especies bianco a localizarlo y verlo como una amenaza hacia susjuveniles. [Traduccion de Ivan Lazo] Acknowledgments I am grateful to L. Semo, L. Ayers, T. Hoppa, P. Hnilicka, R. Jacobs, G. Wolf, D. Grosshuesch, S. Braun, G. Proudfoot, and S. Lind for their field assistance. J. Runke supplied the drawing in Fig. 1. J. Jacobs, L. Semo, R. Rosenfield, D. Evans, P. Bloom and P. Schempf pro- vided helpful comments and suggestions on the manu- script. ing five individuals did not show any aggressive behavior toward the mechanical owl and left the area after a few Literature Cited minutes. While trapping red-shouldered hawks in California, Bloom, P.H. 1987. Capturing and handling raptors. Bloom et al. (1992) reported a higher capture rate using Pages 99-123 in B.G. Pendleton, B.A. Millsap, K.W. a live great horned owl than I experienced using a me- Cline and D.A. Bird [Eds.], Raptor management tech- chanical owl in Wisconsin (Table 1). Ofthe 13 red-shoul- DC dered hawks not captured with my technique, three stooped niques manual. Natl. Wildl. Fed., Washington, U.S.A. at the mechanical owl but escaped after hitting the net. In general, Bloom et al. (1992) found larger raptors , J.L. Hengkel, E.H. Henckel, J.K. Schmutz, were more difficult to capture than smaller ones. I expe- B. WooDBRiDGE, J.R. Bryan, R.L. Anderson, P.J. rienced similar results with the mechanical owl on the Detrich, T.L. Maechtle, J.O. McKinley, M.D. three species I tested. The sharp-shinned hawk was the McCrary, K. Titus and P.F. Schempf. 1992. The most aggressive, occasionally hitting the net and escaping dho-gaza with great horned owl lure: an analysis of its <4 times in <10 min. On six occasions the adult(s) ap- effectiveness in capturing raptors. Raptor Res. 26. parently saw the net and avoided it on each stoop. The J. 167-178. mechanical owl and net were then moved a short distance Gard, N.W., D.M. Bird, R. Densmore and M. Hamel. (<15 m), resulting in four captures. Themechanical owl was an effective decoy forcapturing 1989. Responses ofbreeding American kestrels to live these three raptors. Even though attack and capture rates and mounted great horned owls. /. Raptor Res. 23:99- were slightly lower using the mechanical owl than in stud- 102 . ies using a live great horned owl, I recommend its use Hamerstrom, F. 1963. The use of great horned owls when logistics render the use of a live owl difficult. in catching marsh hawks. Proc. Int. Ornithol. Congr. 13:866-869. Meredith, R.L. 1943. Methods, ancient, medieval, and Table 1. Comparison of capture rates of a mechanical modern, for the capture of falcons and other birds of owl to a live owl as a trapping lure. prey. Pages 433-449 in C.A. Wood and F.M. Fyfe [Eds.], The art offalconry. Stanford Univ. Press, Stan- Mechanical Live Owl ford, CA U.S.A. Owl (Bloom et al. Steenhof, K., G.P. Carpenter and J.C. Bednarz. (This Study) 1992) 1994. Use of mist nets and a live great horned owl to capture breeding American kestrels. Raptor Res. 28: Red-shouldered hawk 54% (15 of 28) 75% (199 of264) J. 194-196. Cooper’s hawk 60% (3 of 5) 52% (32 of 62) Sharp-skinned hawk 77% (48 of 62) a ® Not given. Received 14 April 1995; accepted 1 September 1995