With An Exe on Raetors Austral Autumn Migration Counts of Raptors in Argentinean Patagonia By Matias A. Juhanf and Sergio H. Seipke2 lUniversidad Nacional de La Plata. Republica de Chile 3006, SanJusto 1754,, . E-mail: [email protected] 2ResearchAssociate, Hawk Mountain .57 n 1230 ~, La Plata 1900, Buenos Aires, Argentina. E-mail: [email protected]

Introduction Methods South America is the only continent whose southern We counted raptors on migration during the autumn of portion experiencesa typical temperate regime of warm 2008 for 16 days (March 17 to April 2) during fair weather summer and cold winter (Chesser1994). Austral migrants only, spending 93 hours at the Chenquecowatchsite. Counts are speciesthat breed in temperate regions and move north began at 9:30 a.m. and ended at 4:00 p.m. For the first two toward tropical latitudes to overwinter Gahn et al. 2004). days,two counters were at the watchsite; afterwards, only Although South America has the world's richest avifauna, MJ counted at the lookout. All migrating raptors at the migrations at its temperate zone are largely unknown count siteswere identified using 8x and 1Oxbinoculars and (Chesser1994). Raptor migrations are a good example of a 20-60x zoom telescope.Raptors were considered migrants this situation. Most raptor migration watchsitesare in the if they appearedon the horizon to the southeast,south or northern temperate zone of North America and Europe, southwestand flew past the watchsite toward the north and relatively few raptors counts have been made in the using powered or soaring flight. southern temperate zone of South America (pavez2000, Whenever possible, raptors were identified to sex, Zalles & Bildstein 2000, Trejo et al. 2007). The purpose color morph and age using field marks we developed in of our study was to conduct the first systematicraptor previous years; emphasizingflight silhouette, underwing migration count using standard migration monitoring and upperwing color patterns, and position of the wings techniquesin northwest Argentinean Andean Patagonia in different flying modes.We took photographs of to improve our understanding of the austral migration of local raptors to study eachindividual for field marks to raptors in the region. differentiate them in the field from migrating raptors. Data were collected using standardizeddaily report and Study Area spreadsheettemplates adapted from HMANA. Wind speed The ChenquecoWatchsite (38°55'42.5"S,71 °21 '42.9"W) and ambient temperaturewas recorded using a Kestrel 2000 is located in the outskirts of Moquehue, a town in Neuquen Pocket Weather Station (Nielsen Kellerman, Chester,PA). province, Argentina (Map 1). The lookout is just above the We sent all the data collected to the HMANA and Hawk tree line near a mountain top (1,788 m a.s.l)over the Mountain Sanctuaryarchives. Mountains. The lookout has a view of 270 degreesto the east. From the southeastthe Moquehue and the Alumine Results lakes can.be s~en,and to the south is ~e volcan~ Lanin. .We counted 164 raptors of 8 .The White- No data ISavailab~e about the weather In the re~on, but In throated Hawk ( albigula) was the most common San Carlos de Bariloche (240 km south of the site, 850 m speciesobserved, accounting for 59% of the individuals a.s.l.),the maximum temperature monthly averagesare 22 °C counted (N=96). Other migrants included Variable Hawk (February) and 6 °C Guly), and the minimum temperature (Buteo polyosoma), Black Vulture (Coragyps atratus), monthly averagesare 6 °C (February)and -2 °C Guly). Most Southern (Caracara plancus), Mountain Caracara precipi~tion (snow) falls from May thro~h -,,:ugust.Th~ (phalcoboenusmagalopterus), Black-chested Buzard- vegetation of the slopes of Andean foothills Includes mlXed (Geranoaetusmelanoleucus), Chimango Caracara(Milvago woods of southern ~eeches(Nothofagus sp.)and Monkey- chimango) and Aplomado Falcon (Falco femoralis) (Table puzzle tr~e (Araucana a.raucana)up to ~,700 m a.s.l.Above 1). Additionally, we recorded (but did not include in the the tree line the ve~~tatlon of the areaIncludes steppe and official count) migrating raptors at 1 km northwest of the grasslandcommunities. lookout between 18:00 and 19:00 including 6 Mountain

Hawk Migration Studies -Spring 2009 Season Summary 7 With An Exe on Raetors

Caracaras,2 Peregrine Falcons (F. peregrinus),1 Chilean Hawks we recorded on migration was a juvenile. Both ages Hawk (Accipiter chilensis),and 1 Aplomado Falcon. are readily identifiably in the field as they show different Hawks: Of 96 White-throated Hawks counted, 87 overall coloration and pattern, and a slightly different flight were adults, 6 were juveniles and 3 were of unknown age. silhouette.We think that this rather unusual ratio may reflect We recorded one single flock of 6 White-throated Hawks a) time partitioning of the migration, i.e., juveniles either migrating together, five flocks with 3 each,and the migrate earlier or later than adults, or b) spatial segregation rest of the birds were observed migrating alone. The peak of the migration, i.e., juveniles take a different route on daywas on March 23 with 18 hawks recorded. We counted their northbound migration. The only local pair of White- 33 Variable Hawks, of which 25 were light morph, 13 were throated Hawks we recorded at the site left six days earlier adults and 12 were juvenile (different stages)and 8 dark than the young they were feeding. More research,especially morph birds, of which 4 were adults and 4 were juveniles. season-longcounts, will be needed to clarify this. The Variable Hawk was migrating alone. The peak day of Variable Hawks are consideredpartial migrants in the this hawk was on March 17 with 9 birds recorded. Both southern part of their range (Ferguson-Leesand Christie hawks migrated using powered and thermal flight, mostly 2001), but this is the first time the specieswas reported on below 500 meters above the lookout. migration in Argentina. Caracaras: We counted 5 adult Mountain Caracarasat Geographic barriers are thought to affect both migration the lookouts and another 6 birds out of the official count routes and the pace of migration (Bildstein 2006). out of which 1 was adult and 5 were juveniles. Of the 6 Constraining physical barriers to migration appear to be Southern Caracaracounted,S were adults and only one almost nonexistent in South America; no large bodies of was juvenile. Both caracarasmigrated using powered flight, water must be crossed,no massive,continent-wide desert mostly below 100 meters above the mountain. exist, and the Andes, the largest mountain range, run north- Not migrating speciesand departure of local individuals: south rather than east-west(Chesser 1994). This apparent Four raptor speciesthat were not migrating were recorded in lack of constraining geographical features may explain the area during the counts; these included 3 pairs of Andean why raptors on migration in southern South America do Condors (Vultur gryphus), 2 Turkey Vultures (Cathartes not gather in major bottlenecks as they do in the Northern aura), a pair of Variable Hawks and 1 male American Hemisphere (e.g.Veracruz River of Raptors). The largest Kestrel (F. sparverius). A local pair of adult White-throated single-daycount recorded was only 18 White-throated Hawks was observed severaltimes feeding a single juvenile Hawk, while Pavez (2000)in southern Chile recorded a at the site. The adults were not seenafter March 23, and the maximum single-daycount of 130 White-throated Hawks. juvenile was not seenafter March 29. Additionally, the local While preliminary, this suggeststhat most of the White- pair of Variable Hawks had two young birds. The young throated Hawk northbound migration at this latitude takes were not seenafter March 30, but the adults stayedin the place west of the Andes. By doing so, hawks would take territory throughout our study period. advantageof the prevailing westerly winds that deflect upwards and "slope-soar" their way to the north. Breeding Discussion habitat of this hawk is restricted to forests in Patagonia,and its wintering ground is along the tropical and subtropical - Little is known about raptor migration in the southern Andes (Ferguson-Le es & Christl "e 2001); there£ ore, the mam" temperate zone of South America, and the only knowledge m1gra" tl "on rou tes wo uld run along this moun tam" range. about raptor migration is from the Chilean Andes th " d d "" b " " "" 0 er raptor spec1es we recor e on m1gratlon also reed 10 (pavez 2000, Zalles & Bildste1O 2000, Trejo et al. 2007). the seet pp 0f Pat agorua" (Ferguson-Le es & Christl "e 2001), so Although we did not count large numbers of hawks, we perh aps are m1grattng"" on broad er fronts uS1Og" routes away provided evidence about raptor mi gration over the Andes from the Andes. in Argentinean Patagonia,including the first report of m1" ttn" gra g Moun~.tn;., Caracaras. Neuquen province has 20 Species of diurnal raptors recorded (Mataraso & Mancini 2004). We counted 8 species The most common hawk counted was the White- m1" tl" t Ch 'VJ t h " on gra on a enqueco wa C S1t e an d recor d e d an

throated Hawk. This hawk was only recorded on migration dditl" al tw " " tl " t " d f th ffi "

"" ." a on 0 spec1es on m1gra on ou S1 eo eo Cl al 10 southern Chile (pavez2000, Trejo et al..2007). EVidence coun,t t0talin g 10 out 0 f 20 (50°/10) 0f the rapt or speCies" tl" suggeststhat White-throated Hawk is alreadyon migration occurring" 10" the area.At the same Ia tude (c. 4O0 S)0f by March 17, and migrates at least through April 11 between b th N tl" d Pal tl" " 0 earc can earc c regions, 89°110(17 out 0f 38°S and 33°S latitude (pavez2000, Trejo et al. 2007, 19)and 93°110(42 out 0f 45), respectl "veI y, 0f the spec1es" this work). Roughly, only one in every 15 White-throated 8 Hawk Migration Studies -Vol. 35, No.2 With An Exe on Raetors recorded are known to migrate to some extent (accordingto Ferguson-Lees,J., & D. A. Christie. 2001. Raptorsof the distributions in Ferguson-Lees& Christie 2001). This rather world.Boston: Houghton Mifflin Co. simple comparison supports the idea that austral raptor Jahn, A. E., D. L. Levey,& K G. Smith. 2004. Reflections migration in the southern cone of South America, while it acrosshemispheres: A system-wide approachto new world involves about half the speciesrecorded in the area,is not migration. TheAuk 121: 1005-1013. comparable in extent to raptor migration in the northern M H F & F M .. 2004 C'L ,L /i. A J h . h atarasso, ...anClnl. .fJeCIf; st vesue I effi1sp ere. . Neuquen. Desarrollado por Neuquentur. Neuquen Patagonia S Argentina.

ummary Pavez,E. F. 2000. Migratory movements of the White- Th~ austral ffi1gratl~n systemcompnses speciesthat. throated Hawk (Buteo albigula)in Chile. Journalof Raptor breed In temperate regions and move north toward trOpical Research34: 143-147.

latitudes to overwinter. We conducted the first austral raptor T . C 11 h L 200 A n S .

... Ar . And P .'VT re)o, ., r. ap onc & .ympson. 7. Migratory m1gratlon count In gennnean ean atagorna. we . d . fj . h ..status of the White-troated Hawk (Buteo albigula): What do counte passing raptors rom a mountaintop watc site In ;> ., .. th kir fM h . N . I we know up to now. OrnztologtaNeotropzcaI18.11-19. e outs ts 0 oque ue town In euquenproVince. n 96 hours spread over 16 days,we counted 164 migratory Zalles,J. L. & K L. Bildstein. 2000. Raptorwatch: A raptors of 8 speciesand recorded two additional species globaldirectory of raptormigration sites. Birdlife International, migrating out of the official count. Cambridge,UK, and Hawk Mountain Sanctuary,Kempton, The White-throated Hawk (Buteo albigula)was the Pennsylvania.~ most common speciesobserved at Chenqueco Watchsite, accounting for 59% (N=96) of the individuals counted, while the Variable Hawk was the second most numerous speciestotaling 20% (N=33) of the count. We recorded Mountain Caracara( megalopterus)on migration; a speciesnot yet reported to migrate. We found ," "" ~~" that 50% of the raptor speciesrecorded in Neuquen province migrated through our study site. This ratio was ! considerably lower than those at the samelatitude in both ii the Neartic (89%) and Paleartic (93%) regions. Acknowledgments This project was supported by Hawk Mountain Sanctuary,Ben Olwine III, the Baillie Fund, Niagara Peninsula Hawkwatch and the American Birding Association. We also thank all Hawk Mountain Sanctuary staff members, especiallyLaurie Goodrich and Keith Bildstein. We are very grateful to the Podestafamily for providing logistics for this expedition. Also we are grateful to el vaquiano y a los caballos that took us to the mountaintop, without their help our work could have not been completed. To our novias for moral support while we were up in the mountain. Literature cited Bildstein, K. L. 2006. Migratingraptors of theworld. their ecologyand conservation.Cornell University Press. Chesser,R. T. 1994. Migration in South America: an o~erview of the austral system.Bird ConservationInternational 4.91-107. BlackVulture. Photo: Steve Byland Hawk Migration Studies -Spring 2009 Season Summary 9 I With An Ele on Raetors

Table I. Migrating raptors recorded and peak day Map I: Geographical location of the Chenqueco of passage of migrants during the austral fall form Watchsite (black square), in Neuquen,Argentina, 17 March through 2 April 2008 at Chenqueco in the southern cone of South America. Watchsite, Neuquen, Argentina. N Total Maximum Peak Count One-day Passage + Brazil Species Count Date BlackVulture 14 6 17 March Black-chestedBuzzard-Eagle 1 1 17 March White-throatedHawk 96 18 23 March VariableHawk 33 9 17 March MountainCaracara 5 2 17March Argentina SouthernCaracara 6 3 20 March ChimangoCaracara 1 1 22 March Aplomado Falcon 1 1 22March Unid. Raptor 7 2 26 March Total 164

0

New HMANA North American Hawk Silhouette Guide Available Free HMANA has published a new silhouette Guide for Hawks seenin North America. This new, 2-page,black-and-white guide features soaring silhouettes and key field marks of 21 migratory hawks regl,llarlyseen in most of North America and is reprinted over the next two pages. The artwork is by Paul Carrier, who developed the silhouette Guide for Hawks Seenin the North East two years ago. This new guide is a significant revision and expansionof that gI,lide,adding 11ississippiKite, , Prairie Falcon and adult male Northern Harrier. If you don't want to damagethis issue of Hawk Migratz'onStudies, you can download and print the guide free for personal, noncommercial use at www.hmana.org. You can also order the guide professionally printed on hea\ry,glossy card stock and laminated for use in the field. Visit wwww.hmana.orgto order the laminated guide. Individual copies are $5 plus $1 postageand handling. Hawk watches,bird clubs, schools,nature shops or any other organization can raise funds by purchasing the guide in bulk at wholesaleprices. For complete information, including bulk pricing, visit ~hmana.org.

10 Hawk Migration Studies -Vol. 35, No.2