64 Short Communications VoL. No. 37, 1 isten observaciones de movimientos migratorios de la es- science and conservation of migrating raptors in the pecie en Bolivia. Entre el 17 y el 24 de noviembre del western hemisphere. Torgos 28:97-108. 2000, se contaron un total de 477 individuos, volando Davis, S.E. 1989. Migration of Mississippi Kite Ictinia mis- solos o en bandadas en el Aeropuerto Internacional de sissippiensis in Bolivia, with comments on 7. plumbea Viru-Viru, en Bolivia. Todas las aves exhibieron un vuelo Bull. Br. Ornithol. Club 109:149-152- de planeo o aleteo unidireccional hacia el sur. La tasa de . 1994. Seasonal status, relative abundance, and paso fue de 8.5 halcones por bora. La mayoria de las behavior of the birds of Concepcion, Departamento rapaces 91% fueron registrados entre las 11 de la manana Santa Cruz, Bolivia. Fieldiana Zool. 71:1-33. y la 1 de la tarde. , E. Guzman, and E. Penaranda. 1995. Inventario de las aves de la pampa de Viru-Viru, Aeropuerto In- [Traduccion del autor] ternacional de Viru-Viru, Santa Cruz, Bolivia. Museo Acknowledgments de Historia Natural Noel Kempff Mercado, Universi- dad Autonoma Gabriel Rene Moreno. Many thanks to the Hawk Migration Association of Euller, M.R., W.S. Seegar, and L.S. Schueck. 1998. North America, Hawk Watch International, and the Hol- Routes and travel rates of migrating Peregrine Fal- iday Beach Migration Observatory for funding and sup- cons Falco peregtinus and Swainson’s Hawks Buteo porting the present study and making it possible; to Keith swaimoni in the Western Hemisphere. Avian Biol Bildstein for his support and for reviewing the manu- J. 29:433-440. script; to SABSA for allowing the performance of the present study at the Airport and for all of their support Hudson, W.H. 1920. Birds of La Plata. Vol. 2. J.M. Dent during field work; to AASANA for their help with envi- and Sons, New York, NYU.S.A. ronmental data; to the Museo de Historia Natural Noel Olivo, C. 2001. Conservation status and knowledge of WWGBP Kempff Mercado for their support; to Edilberto Guzman raptor migration in Bolivia. newsletter29-S2. for his help at the Museum; and especially many thanks Sick, H. 1993. Birds in Brazil, a natural history. Princeton to Rosa Strem for her assistance in the field; and to Ol- Univ. Press. Princeton, NJ U.S.A. iver Krone for reading the manuscript. Wetmore, a. 1943. The birds of southern Veracruz, Mex- ico. Proc. U.S. Natl. Mus. 93:215-340. Literature Cited Zah.es, J.l. and K.L. Bildstein. [Eds.], 2000. Raptor watch: a global directory of raptor migration sites Arribas, M.A., L. Jammes, and F. Sagot. 1995. Lista de BirdLife Conserv. Ser. No. 9. las aves de Bolivia. Asociacion Armonia, Santa Cruz de la Sierra, Bolivia. Received 16June 2001; accepted 10 December 2002 Bildstein, K.I.. andJ.l. Zalles. 1998. Moving targets: the Associate Editor: Juan Negro J Raptor Res. 37(l):64-67 © 2003 The Raptor Research Foundation, Inc. Nocturnal Arrival, at a Roost by Migrating Levant Sparrowhawks Reuven Yosef^ International Binding and Research Centre in Eilat, Department ofLife Sciences, Ben-Gurion University ofthe Negev, RO. Box 774, Eilat 88000, Israel Ki.yWords: Levant Sparrowhawk; Accipiterbrevipes; Eilat; species with a heavy wing loading to regions (i.e., land nocturnal migration. masses vs. bodies of water) where thermals and updrafts occur and dictates diurnal flight (Spaar 1997). This soar- Most soaring birds (i.e., raptors, Acdpiteridae, pelicans, ing strategy is used almost exclusively by the large raptor Pelicanus spp., storks, Ciconia spp., and cranes, Grus spp.) species (eagles, buteos) because they are mostly incapable require rising air currents, thermals, over and slope-up- ofgenerating sufficient power for sustained flapping flight drafts to accomplish their long distance movements (e.g.. (Pennycuick 1972). Smaller raptors (harriers, Cffim spp., Porter and Willis 1968, Safriel 1968). On migration, or falcons, Falco spp., sparrowhawks, Accipiter spp.) however, other long-distance movements, this requirement restricts can resort to flapping (powered)-gliding flight (Spaar 1997) during inclement weather conditions, or at night ’ E-mail address: [email protected] (Stark and Liechti 1993, Spaar and Stark 1996). March 2003 Short Communications 65 Table 1. Number of Levant Sparrowhawks observed ar- Table 2. Number of Levant Sparrowhawks observed ar- riving after dark at palm plantations at Eilat, Israel. Time riving after dark at palm plantations at Eilat, Israel, and IS presented as minutes after sunset (0). Data are pre- the numbers counted lifting off the next morning. Num- sented Mean ± SD for the seven nights observationswere ber in parentheses represents the percentage of birds undertaken. counted arriving at roost in the dark, or trapped the next morning, in comparison to those counted at lift offfrom the same area the following morning. Min AFTER N Sunset Mean SD Total Percent N N Detected 0-30 20 9 136 <1 AT Roost Counted at Trapped 30-60 309 28 2164 10 Date (Percent) Lift Off (Percent) 60-90 612 174 4286 19 90-120 1049 151 7341 33 18 April 1136 (31) 19 April 3111 22 (0.7) 120-150 1158 99 8104 37 19 April 1201 (24) 20 April 4432 36 (0.8) 150-180 13 7 90 <1 20 April 3752 (53) 21 April 7018 31 (0.4) >180 0 21 April 6726 (70) 22 April 9652 36 (0.4) Total 22121 22 April 6040 (71) 23 April 8422 44 (0.5) 23 April 90 (16) 24 April 546 19 (3.5) 24 April 3176 (59) 25 April 5344 53 (1.0) Israel, the only land bridge between three continents, TOTAL 22121 (57) 7 38 525 241 (0.6) IS at ajunction for birds migrating south from Eurasia to Africa in autumn and north to their breeding grounds m spring (Safriel 1968). In spring the Red Sea and the the number of birds I observed at the palm groves after Gulf of Aqaba/Eilat act as a long deflection barrier di- sunset, I could predict the volume ofthe flocks thatwould verting many northbound raptors to Eilat (Shirihai and take off early the next morning, and thereby increase our Christie 1992, Yosef 1995, Grieve 1996). Eilat is at the trapping success the next morning. northern edge of almost 2000 km of continuous desert regions of the Sinai and the Sahara. Hence many birds Methods and Materials land here to rest after crossing deserts to the south (Saf- I conducted seven night watches during the peak migra- riel 1968, Yosef 1998a). tion period of the Levant Sparrowhawk (18 April-24April) Recent studies document that during the northbound in the spring 1998 season. Observations were initiated at migration Levant Sparrowhawks {Accipiter brevipes) concen- sunset and continued until no flocks or individual birds trate in the Eilat region in great numbers (e.g., 45 000- were seen for at least 30 min. I used a Swarovski NC2 night scope (X4 magnification) to time the arrival of the flocks 50000; Safriel 1968, Shirihai 1987, Yosef 1995, Clark and and to estimate their numbers. For convenience of calcu- Yosef 1997, Shirihai et al. 2000, Yosef and Fornasari 2000) lation I split the observation period into 30 min blocks 1 and migrate north along the Great RiftValley towards Syria opted to observe the northern of the two palm plantations and Lebanon (Frumkin et al. 1995). Levant Sparrowhawks owing to logistic constraints along the Israeli-Jordan border are considered scarce, and Cramp and Simmons (1980) Data were recorded on appropriate observation sheets and state that information on their distribution, populations, are presented as mean values ±SD (Table 1). and status is limited. Recoveries of birds banded at Eilat Results and Discussion during northbound migrations are from Romania, Ukraine, Russia, and Syria (Yosef 1998b). I observed after-dark arrival by I,evant Sparrowhawk on During the trapping and banding operations of spring all seven nights of observation. For the first 60 min after 1996, 1997, and 1998, we noted that although we re- sunset very few arrivals were noted. An increase in the mained in the vicinityofthe palm {Phoenixdactylifera) plan- number of arrivals was noted between 90-150 min post- tations until dark we seldom saw Levant Sparrowhawks ar- sunset (Table 1). No Levant Sparrowhawks were observed rive, and yet on the next morning we observed large arriving after 180 min post-sunset. Numbers estimated numbers departing from the palmeries on their migration with the night scope were consistently lower than the north along the Syrio-African Rift Valley. Stark and Liechti numbers observed at lift-off at dawn the next morning — (1993) suggested that Levant Sparrowhawks might resort (Table 2). I attribute this to two major factors my visi- m to flapping flight to reduce time spent on migration (i.e., bility being restricted to the magnification available — that they were time minimizers that minimize overall mi- the night scope, and that the limited field of vision at gration time from Africa to their Asian and European night prevented the discovery offlocks that arrived along breeding sites). Using radar, they identified the “signa- the shoreline of the Red Sea from the south to the south- ture” wing-beat pattern of Levant Sparrowhawks at night ern palmeries and remained undetected until the next in autumn 1991. This led to a prediction that based on morning. However, the early warning of the numbers ar- 66 Short Communications VoL. 37, No. 1 nving at the roost allowed the trapping team to organize and therebyincrease our trapping success the next morn- the trapping equipment appropriately and during the ing. I conducted seven night watches during the peak study period a record total 368 Levant Sparrowhawk was migration period of the Levant Sparrowhawk in spring trapped (Table 2). This is in contrast to the trapping suc- 1998. Observations were initiated at sunset and contin- cess during the two years (1996, 1997) prior to the night ued until no flocks or individual birds were seen for at observations and four subsequent years (1999-2002) least 30 minutes. I used a Swarovski NC2 night scope (X4 when no such observations were conducted and the magniheation) to time the arrival of the flocks and to numbers of Levant Sparrowhawks trapped was less than estimate their numbers. For the hrst 60 minutes after 200 individuals per season. sunset very few arrivals were noted. An increase in the Data suggest that south ofIsrael a larger than previously number of arrivals was noted between 90-150 min post- reported proportion of the Levant Sparrowhawk popula- sunset. No Levant Sparrowhawks were observed arriving tion resorts to nocturnal flight in order to minimize the after 180 min post-sunset. The early warning ofthe num- time spent over inhospitable areas. Spaar et al. (1998) bers arriving at the roost allowed the trapping team to showed that migratory strategy depend on feeding condi- organize the trapping equipment appropriately and dur- tions en route and that in good conditions a nonstop flight ing the study period a record total 368 Levant Sparrow- strategy of soaring-gliding during daylight hours and flap- hawk was trapped. The data represent the first time that ping-gliding flight during the night is the time minimizing migratory raptors have been observed and identihed at strategy. However, under poor conditions, soaring-gliding close range with a nightscope arriving at a roost site. flight when thermal convection is available and roosting — during the night is the energy- and time-minimizing strat- Resumen. Durante las operaciones de marcaje notamos egy. The fact that 22 121 Levant Sparrowhawks, i.e., 57% que aunque permanecieramos en lavecindad de las plan- of total observed, were observed arriving at a single roost taciones de palma hasta oscurecer, contadas veces vimos site up to two hours after sunset suggests that the latter arribar azores del mediterraneo oriental {Accipiter brevi- appears to be the case for the Ixvant SparrowhawkatEilat. pes), y con todo, a la mahana siguiente vimos grandes Stark and Leichti (1993) argued that nocturnal migrants numeros partiendo de las palmeras en su migracion ha- minimized time to join larger flocks for the next day’s cia el norte a lo largo del valle de la falla Sirio-Africana. migration. Spaar et al. (1998) thought that the very short Predecimos que con base en el numero de aves obser- period oftheir passage in Israel suggests that the migratory vadas en el boscaje de palmas despues del ocaso, podria- timing of the Levant Sparrowhawks was under strong en- mos estimar el volumen de las bandadas que despegarfan dogenous control and that delays in the migratory timing temprano en la mahana .siguiente, y por tanto incremen- was compensated by nocturnal flights, as has been shown tar nuestro exito de capturas en la mahana siguiente. for Tree Pipits {Anthus trivialis, Jenni 1984). In contrast, Lleve a cabo siete rondas nocturnas durante el periodo Kerlinger (1989, 1995) thought that raptors that under- pico de la migracion del azor del mediterraneo oriental take long crossings ofbarriers, and are unable to complete en la primavera de 1998. Las observaciones se iniciaban them during daylight, would resort to noeturnal migration. al caer el sol y continuaban hasta que ninguna bandada However, the above does not entirely explain why a sub- o individuo fuera visto por al menos en 30 minutos. Use stantial proportion ofthe population arrives atEilatseveral lentes nocturnos Swarovski NC2 (X4 de aumento) para hours after dark and do not stop at other human settle- registrar el tiempo de arribo de las bandadas y para es- ments, to the south ofEilat, in the Sinai Peninsula or along timar sus numeros. En los primeros 60 minutos despues the Red Sea coast. Hence, I assume that these species have del ocaso se notaron muy pocos arribos. Un incremento knowledge, based on previous migrations or innate, ofspe- significativo de ellos sc noth 90-150 min. posteriormente cihc staging areas along the migratory route at which they al ocaso. Ningun azor del mediterraneo oriental fue ob- roost and will resort to nocturnal migration to reach them. servado arribando despues de 180 min post-ocaso, El av- The data presented here, which validate previous radar iso previo de los numeros que arribaban a las perchas, studies based on “flight signature” (e.g., Casement 1996, permitio al equipo de captura organizar adecuadamente Stark and Leichti 1993), repre.sent the first time that mi- el dispositivo de captura, y durante el periodo de estudio gratory raptors have been observed and identified at un total de 368 azores del mediterraneo oriental fueron close range with a nightscope arriving at a roost site. atrapados. Los datos representan la primera vez en que During banding operations we noted that although we rapaces migratorias han sido observadas e identificadas remained in the vicinity of the palm plantations until de cerca con unos lentes de vision nocturna, arribando dark we seldom saw Levant Sparrowhawks (Accipiter brev- un sitio percha. ipes) arrive, and yet on the next morning we observed [Traduccion de Cesar Marquez] large numbers departing from the palmeries on their mi- gration north along the Syrio-African Rift Valley. We pre- Acknowi.edgments dieted that based on the number ofbirds observed at the I thank members ofKibbutz Elot for their cooperation palm groves after sunset, I could estimate the volume of and the Israel Nature Reserves Authority for their help. the flocks that would take off early the next morning, Dr. G. Dobler, Swarovski Optics, kindly donated the use March 2003 Short Communications 67 of the N2 night scope for this and other nocturnal stud- Shirihai, H. 1987. The birds ofIsrael. Oxford Univ. Press, ies. R. Spaar, R Kerlinger, K. Bildstein, and an anony- Oxford, U.K. mous reviewer improved an earlier version of the man- and D.A. Christie. 1992. Raptor migration at uscript. Elat. Br. Birds 85:141-186. R. Yosef, D. Alon, G.M. Kirwan, and R. Spaar Literature Cited , 2000. Raptor migration in Israel and the Middle — Casement, M.B. 1996. Migration across the Mediterra- East a summary of 30 years of field research. Tech nean observed by radar. Ibis 108:461-491. Publ. Int. Birding Res. Centre Eilat, Israel. CiARK, W.S, AND R. Yosef. 1997. Migrant Levant Sparrow- Spaar, R. 1997. Flight strategies of migrating raptors; a hawks Accipiter brevipes at Eilat, Israel: measurements comparative study of interspecific variation in flight and timing./. Raptor Res. 31:317-320. characteristics. Ibis 139:523-535. Cramp, S. and K.E.L. Simmons. [Eds.] 1980. Handbook , H. Stark, and F. Liechti. 1998. Migratory flight of the birds of Europe, the Middle East and North strategies of Levant Sparrowhawks: time or energy Africa. Vol. 2. Hawks to bustards. Oxford Univ. Press, minimization? Animal Behav. 56:1185-1197. Oxford, U.K. AND H. Stark. 1996. Migratory flight strategies of Frumkin, R., B. Pinshow, and S. Kleinhaus. 199.5. A re- Levant Sparrowhawks: time or energy minimization? view ofbird migration over Israel./. Ornithol. 136:127- Anim. Behav. 56:1185-1197. Stark, H. and F. Liechti. 1993. Do Levant Sparrowhawks 147. Grieve, A. 1996. Spring raptor movements at Gebel el Accipiter brevipes also migrate at night? Ibis 135:233- 236. Zeit, Egypt. Sandgrouse 18:61-63. Jenni, L. 1984. Herbstzugmuster von Vogeln aufdem Col Yosef, R. 1995. Spring 1994 raptor migration at Elat, Is- rael. /. Raptor Res. 29:127—134. de Bretolet unt besonderer Berucksichtigung nach- 1998a. Two decades of studying bird migration brutzeit licher Bewegungen. Ornithol. Beob. 81:183- . at Eilat: a test case of conflicts and paradoxes. Proc 213. — Int. Seminar Migrating birds know no boundaries. Kerlinger, P. 1989. Flight strategies of migrating hawks. 7orgo.s 28:109-117. Univ. of Chicago Press, Chicago, IL U.S.A. 1998b. Clues to the migratory routes of the east- 1995. How birds migrate. Stackpole Books, Me- . — . ern flyway of the western Palearctics ringing and re- chanicsburg, PA U.S.A. coveries at Eilat, Israel (II- Falconiformes). Vbgelwarte Pennycuick, C.J. 1972. Soaring behaviour and perfor- 39:203-208. mance of some East African birds, observed from a and L. Fornasari. 2000. Biometric differences be- motor-glider. Ibis 114:178—218. tween age and sex classes of Levant Sparrowhawk Ac- Porter, R.F. and 1. Willis. 1968. The autumn migration cipiter breruipes on migration at Eilat, Isr. Israel J. Zool. of soaring birds at the Bosphorous. Ibis 110:520-536. 46:207-214. Safriel, U. 1968. Bird migration at Eilat, Israel. Ibis 110: 283-320. Received 14June 2002; accepted 12 December 2002 /. Raptor Res. 37(l):67-70 © 2003 The Raptor Research Foundation, Inc. Nesting Distribution, Food Habits, and Conservation of Osprey on Boavista Island (Archipelago of Cape Verde) Diego Ontiveros^ Departamento de Biologia Animal Ecologia, Facultad de Ciencias, Universidad de Granada, E-18071 Granada, Spam y Key Words: Osprey, Pandion haliaetus; Boavista-, conser- human impacts such as persecution, disturbances, and vation; diet, distribution. fishery practices (Saurola and Koivu 1987). This raptor eats live fish almost exclusively (Hakkinen 1977, 1978, The Osprey {Pandion haliaetus) is widely distributed Saurola and Koivu 1987) and therefore its distribution is around the world and it has suffered heavilyfrom several restricted to the vicinity of favorable fishing waters; e.g., rivers, lakes, and sea coasts (Poole 1989). ’ E-mail address: [email protected] In ideal conditions Osprey nests are located close to