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MA•OSA, S. 1994. Goshawk diet in a Mediterranean area ß 2000ß Harriers of the world: their behavior and of northeastern Spain.J. RaptorRes. 28:84-92. ecology. Oxford Univ. Press, Oxford, U.K. --AND P. CORDERO. 1992. Seasonal and sexual vari- SNYDER,N.ER. ANDJ.W. W•LEY.1976. Sexual size dimor- ation in the diet of the Common Buzzard in north- phisin in hawks and of North America. Ornithol eastern Spain.J. RaptorRes. 26:235-238. Monog•.20:1-96. MARTINEZ,J.E., M. CREMADES,I. PAG/i•N,AND J.E CALVO. STERN,P. ANDJ.H. GROWLER.1985. Supplementaryobser- 2004. Diet of Booted Eagles in southeasternSpain. vationson the breeding biologyof the Booted Eagle Pages593-599 in R.D. Chancellor and B.-U. Meyburg in southern Africa. Ostrich 56:151-156. [EDS.],Raptors worldwideß World Working Group on TEMELES,E. 1985. Sexualsize dimorphismof -eaung of Prey & Owls. MMD/BirdLife, Hungary, Bu- hawks:the effect of prey vulnerability.Am. Nat. 125 dapest. 485-499. MASSEMIN,S., E. KORPIMAKLANDJ. W•EHN. 2000. Reversed TOYNE,E.P. 1998. Breeding seasondiet of the goshawk sexual size dimorphism in raptors: evaluation of the Accipitergentilis in Wales. Ibis 140:569-579. hypotheses in kestrels breeding in a temporally VAN DEN BRICK, EH. AND P. BARRUEL. 1972. Guia de cain- changing environment. Oecologia124:26-32. po de los mamiferos salvajesde Europa occidental. MUELLER, H.C. AND K. MEYER. 1985. The of re- Omega, Barcelona, Spain. versedsexual dimorphism in size:a comparativeanal- VE•GA,J.P. 1986. Food of the Booted Eagle (Hieraaetus ysis of the Falconiformes of the western Palearctic. pennatus)in central Spain. RaptorRes. 20:120-123. Pages 65-101 in R.E Johnston [ED.], Current orni- --ANDJ. VI•UELA. 1994. Booted Eagle Hieraaetuspen- thology. Plenum, New York, NY UßS.A. natus.Pages 182-183 in G.M. Tucker and M.E Heath NEWTON,I. 1979.Population ecology of raptors.T. & A.D. lEDS.], Birds in Europe: their conservation status. Poyser,Berkhamsted, U.K. BirdLife International, Cainbridge,U.K. OPDAM,P. 1975. Inter- and intraspecificdifferentiation VENA•LES,B.D. ANDW.N. RIPLEY.2002. Modern applied with respectto feeding ecologyin two sympatricspe- statistics with S, 4th Ed. Springer, New York, NY cies of the Accipitez.Ardea 63:30-54. U.S.A. OVERSg•UC, K., E. KRISTIANSEN,AND P. SUNDE. 1995. Sex- V•LkaRAN,A. 2000. Analisis comparativo de la dieta de specificdiet analysisof the TawnyOwl (Strixaluco) in ambos sexos en el carabo coinfin aluco en la Pen- Norway.J. RaptorRes. 29:137-140. insula Ibtrica. Ardeola 47:203-213. REYNOLr•S,R.T. 1972. Sexual dimorphism in Accipiter WIDEN,P. 1984.Activity patterns and time budgetsin the hawks:a new hypothesis.Condor 74:191-197. goshawkAccipiter gentills in a boreal forest area of cen- SIMMONS,R.E. 1986. Ecologicalsegregation of the Red- tral Sweden. Ornis Fenn. 61:109-112. breasted SparrowhawkAccipiter rufiventris and six co- existing Accipitrine raptors in southern Africa. Ardea Received 6 May 2004; accepted 22 March 2005 74:137-149. AssociateEditor: Juan .JoseNegro

j RaptorRes. 39(2):163-166 ¸ 2005 The Raptor Research Foundation, Inc.

PREDATIONOF SMALL BY RUFOUS-LEGGEDOWL, BARN , AND MAGELLANIC IN ARGENTINEAN PATAGONIA FORESTS

DANIELE. UDRIZPmSAUTHIER, 1 ANAL•A ANDRADE, AND ULYSES F.J. PARDI•dAS CentroNacional Patagtnico, Casilla de correo128, 9120 PuertoMadryn, Chubut,Argentina

KEYWORDS: MagellanicHorned Owl; Bubo magellanicus; reflect foraginginside forestedhabitats. For the southern Rufous-leggedOwl; Strix rufipes; ;Tyro alba; diet;, cone of South America, including Argentina and Chile, szgmodontinerodents. only a few contributionshave addressedthis topic (Mar- tinez andJaksic1996, 1997, Ramlrez-Llorens2003, Trejo Despite the large number of forest owls in the Neo- and Ojeda 2004). tropics, there are few data available on their diets that The Rufous-leggedOwl (Strix rufipes)inhabits dense and old-growthtemperate forests in southernArgentina 1Email address:[email protected] and Chile (Straneckand Vidoz 1995, Martinez andJaksic 164 SHORT COMMUNICATIONS VOL. 39, NO. 2

Table 1. Number and percent frequencyof prey items and proportion of scansorial(SC), arboreal (AR), cursorial (C), and fossorial(S) small mammals in the three analyzedowl pellet samplesfrom Argentinean Patagoniaforest Percent frequencyis in parentheses.

RODENTS MAGELLANIC HORNED OWL RUFOUS-LEGGED OWL BARN OWL

Abrothrixlongipilis (C) -- 7 (6.9) 6 (7.2) Abrothrixolivaceus (C) -- 36 (35.6) 11 (13.3) Chelemysmacronyx (S) 9 (27.3) 1 (1.0) -- Ehgmodontiamorgani (C) 4 (12.1) -- -- Geoxusvaldivianus (S) -- 2 (2.0) 1 (1.2) Irenomystarsalis (AR) -- 7 (6.9) 6 (7.2) Loxodontomysmicropus (C) 20 (60.6) 19 (18.8) 21 (25.3) Ohgoryzomyslongicaudatus (SC) -- 29 (28.7) 38 (45.8) Total 33 101 83 SC and AR (%) -- 35.6 48.2 C and S (%) 100 64.4 51.8

1996, 1997). Diet information about this owl is only prey were identified by comparison with the reference known from few localities in Chile (Martinez and Jaksic collection of the Centro Nacional Patag6nico, 1996, 1997, Diaz 1999). The Barn Owl ( alba) and Puerto Madryn, Argentina, and identificationkeys (Pear- son 1995). The taxonomic criteria follow Galliari et al the Magellanic Horned Owl (Bubomagellanicus; del Hoyo (1996). The minimum number of mammal prey items et al. 1994) are widespreadin South America and nu- wasestimated by countingmandibles. The Rufous-legged merous contributions have described their diets (Pardi- Owl samplewas previously analyzed by O. Pearson (field fias and Cirignoli 2002 and referencestherein). However, notes 1982) and kindly provided to U. Pardifias for in- these works focused on pellet samplesfrom open areas; clusion here. consequently,the knowledgeof owl predationin forested habitatsis extremelylimited. The only availabledata for RESULTS AND DISCUSSION the Barn Owl in a forestedhabitat were reported by Trejo and Ojeda (2004) on the basis of an owl pellet sample We recovered217 prey items,exclusively sigmodontine recovered in Nahuel Huapi Forest (Argentina). , from the examined pellets (Table 1). Only three Here, we report the first data on the diet of the Rufous- specieswere eaten by the Magellanic Horned Owl; most legged Owl in Argentina and the Magellanic Horned Owl of which was the austral greater mouse (Loxodontomysms- m forestedlandscapes. In addition, we presentinforma- cropus).The Rufous-leggedOwl and Barn Owl consumed tion about the small mammalspreyed upon by the Barn sevenand six ,respectively. Both owlspreyed upon Owl in Patagonian forests. the same small mammal assemblage,primarily consum- ing the olivaceousfield mouse (Abrothrixolivaceus), the STUDY AREA AND METhODS long-tailed mouse (Oligoryzomyslongicaudatus), and the Owl pellet sampleswere collectedin three localitiesof austral greater mouse. Diet of MagellanicHorned Owl Neuqutn and Rio Negro provinces (Argentina): Magel- differed from that of Rufous-leggedOwl and Barn Owl lanic Horned Owl (18 pellets), Las Brefias Ranch in the proportion and kind of small mammal species (39ø30'S,71ø02'W, 1437 m elevation,Neuqutn); Rufous- found in pellets (Table 1). These differencesmay be at- leggedOwl (43 pellets), Lago Steffen (41ø32'S,71ø35'W, tributed to the specificforest areaswhere these respec- 730 m, Rio Negro); and Barn Owl (36 pellets), Cacique tive owlsforaged (see StudyArea and Methods). FoyclRanch, Alto Rio Villegas (41ø35'S,71ø31'W, 700 m, Despite the small pellet samplesexamined, we regis- Rio Negro). Las Brcfias Ranch is located in the Pehuen district, Su- tered almostexclusively small mammals related to forest- bantarticphytogcographic province (Cabrera 1971). This ed or bushy-forestedcover types (Pearson 1995). The aus- environment is found between 900-1800 m and is dom- tral greater mouse,heavily preyed upon by the three owls lnated by forestsof pehuen (Araucariaaraucana) associ- studied, was a common sigmodontine in dense fiire- ated with lenga (Nothofaguspumilio) and coligfie cane bushyand coligfiecane formations.The sameis true for (Chusqueaculeou). Lago Steffen and CaciqueFoyel Ranch the long-tailed mouse and the olivaceousfield mouse, are located in the Caducifolious Forest district (sub- main prey items in the diets of the Rufous-leggedOwl antarcticphytogeographic province; Cabrera 1971) and and the Barn Owl. In addition, these owls consumed the are characterizedby the presenceof fiire and coihue (No- thofagusantarctica, N. dombeyi),lenga, and ciprts (Austro- poorly known (in Argentina) Chilean tree rat (Irenomys cedruschilensis). tarsalis),a specialistof Nothofagusforests (Kelt 1993). The Osteologicalremains were picked apart by hand and dominance of forest speciesin the diet of the Rufous- JUNE2005 SHORTCOMMUNICATIONS 165 leggedOwl and Barn Owl suggeststhat theseowls hunted gro. Sobre un total de 217 presas(exclusivamente roe- w•thin the forest. This fact is reinforced by the absence dores sigmodontinos), Oligoryzomyslongicaudatus, of thosespecies characteristic of open areas,like the Pa- Loxodontomysmicropus y Abrothrixolivaceous fueron los mrs tagonianleaf-eared mouse (Phyllotisxanthopygus), the rab- consumidos.Estos resultados, sumados a la baja o nula bit rat (Reithrodonauritus), the silky rat (Euneomyschin- frecuencia de especies de micromamiferos de fireas chilloides),and the southern cavy (Microcaviaaustralis). abiertas, sugieren que las tres rapacesestudiadas cazaron The same is true for the Magellanic Horned Owl, al- en el interior del bosque. Este es el primer estudio de though we cannot discardthe possibilityof forest-steppe dieta para S. rufipesen Argentina y para B. magellanicus ecotone hunting by these raptors. en el bosque patagtnico. The olivaceousfield mouseconstituted a high propor- [Traduccitn de los autores] tion of the Rufous-leggedand Barn Owl diets, being the ACKNOWLEDGMENTS dominant prey in the diet of the former. These results contrastwith those of Trejo and Ojeda (2004) and Mar- We want to thank to H. Povedano, D. Glaz, D. Podestf, tinez and Jacksic(1997), who reported a low consump- S. Cirignoli, E Cremonte, and O. Pearson who collected tion and an apparent avoidanceof this speciesby the samplesor kindly gave information or other help. This work was supported by Consejo Nacional de Investiga- owls, despite its high abundancein the field. Martinez cionesCientificas y T•cnicas (CONICET, Argentina). We and Jaksic (1997), working with the Rufous-leggedOwl appreciatethe improvementsin English usagemade by •n Chile, mentioned the preferenceof this owl for ar- StacySmall through the Associationof Field Ornitholo- boreal and scansorialsmall mammals (e.g., Dromiciopsgli- gists'program of editorial assistance. roides,Irenomys tarsalis, Oligoryzomys longicaudatus) over cursorial ones (e.g., olivaceus,A. longipilis). LITERATURE CITED These authors proposed that different escapetactics or CABRERA,A. L. 1971. Fitogeograf/ade la RepfiblicaAr- detectabilityof cursorialspecies in addition to the sit-and- gentina. Bol. Soc.Argent. Bot. 14:1-43. wait strategyof the Rufous-leggedOwl as an DELHOYO, J., A. ELLiOTt, ANDJ. SARGATAL.1994. Hand- explanationfor the high representationof arborealand book of the birds of the world, Vol. 2. Lynx Edicions, scansorialspecies in the owl's diet. In contrast, our data Barcelona,Spain. showedthat, at least in the studyarea, this owl preyed DIAZ, I. 1999. Food habits of the Rufous-leggedOwl (Stnx upon cursorialand fossorialrodents (64.4%) over arbo- rufipes)in the Mediterranean sclerophyllousforest of real and scansorialspecies (35.6%; Table 1). This fact central Chile. J. RaptorRes. 33:260-264. could be related to the presenceof small open areas GALLIARI,C., U.FJ. PARDff4AS,AND F. GOIN. 1996. Lista (gaps) in the forest, where the cursorialrodents could comentada de los mamiferos Argentinos. Mastozool. be more detectable. These results were in agreement Neotrop.3:39-61. w•th Diaz (1999) who observeda preference of Rufous- KELT,D.A. 1993. Irenomystarsalis. Mamm. Species447:1-3 legged Owl for terrestrial prey in the Mediterranean MA•TI, C.A. 1974.Feeding ecology of four sympatricowls. sclerophyllousforest of central Chile. Condor 76:45-61. In spite of the low number of pelletsanalyzed for Ma- MARTINEZ,D.R. AND EM. JAKS•C.1996. Habitat, relative gellanic Horned Owl, the resultssuggested that this spe- abundance,and diet of Rufous-leggedOwls (Strixru- cies took exclusivelycursorial and fossorialrodents asso- fipesKing) in temperate forest remnants of southern ciated with dense vegetative cover. This finding Chile. Ecoscience3:259-263. demonstrated the capability of this owl hunting inside --AND --. 1997. Selectivepredation on scanso- the forest, although it may be foraging mostly in open rial and arboreal mammals by Rufous-leggedOwls patches.This agreeswith Teta et al. (2001) who proposed (Strixrufipes) in southernChilean rainforest.J. Raptor that horned owlspreferentially consumed open-area spe- Res. 31:370-375. cies rather than arboreal and scansorial ones, as a result PARDIF4AS,U.F.J. AND S. ClmCNOL•.2002. Bibliograf/aco- of its sit-and-waithunting strategy(Marti 1974). mentada sobrelos anflisis de egagrtpilas de avesra- The scarce number of forested sites studied in south- pacesen Argentina. Ornitol.Neotrop. 13:31-59. ern South America may be attributed mainly to the dif- PEA_V,SON, O.P. 1995. Annotated keysfor identifying small ficulty of identifyingowl roostscoupled with a low pres- mammals living in or near Nahuel Huapi National ervation rate of pellets in humid forest environments. Park or Lanln National Park, southern Argentina. Mastozool.Neotrop. 2:99-148. DEPREDACIONDE MAMiFEROSPEQUElqOS POR S7ltlXRUFIPES, RAMIREZLLORENS, P.M. 2003. Ecologia trtfica de Strig•- TYTOALBA Y BUBOMAGELLANICUS EN BOSQUESPATAGONICOS formes en Argentina: Pulsatrixperspicillata (Lechuztn DE ARGENTINA Mocho Grande). M.S. thesis, Univ. Nacional Buenos Aires, Buenos Aires, Argentina. RESUMEN.--Seestudiaron los mamiferosdepredados por STRANECK,R.J AND E VIDOZ. 1995. Sobre el estadotaxont- Bubomagellanicus, Strix rufipesy Tytoalba en tres locali- mico de Strixrufipes (King) y de Strixchacoensis (Cher- dadesboscosas de las provinciasde Neuqufin y P,5oNe- rie and Reichenberger).Ntt. Faunfst.74:1-5. 166 SHORT COMMUNICATIONS VOL. 39, NO. 2

TETA, P., C. PANTI, A. ANDRADE,AND A. PEREZ.2001. Am- alba) in forested habitats of northwestern Argentine plitud y composici6nde la dieta de Bubovirginianus Patagonia. Ornitol.Neotrop. 15:1-5. (Aves,Strigiformes, Strigidae) en la Patagonianoroc- cidentalArgentina. Bol. Soc. Biol. Concep. 72:125-132. Received30 July 2004; accepted6 December2004 TR•jO, A. AND V. OJEDA.2004. Diet of Barn Owl (Tyt0 Associate Editor: Michael I. Goldstein

j. RaptorRes. 39(2):166-168 ¸ 2005 The Raptor ResearchFoundation, Inc.

CHANGES IN SITE OCCUPANCY AND NESTING PERFORMANCE OF PEREGRINE FALCONS IN COLOe•DO, 1963--2004

JAMESH. ENDERSON1 Departmentof Biology,Colorado College, 14 EastCache la PoudreStreet, Colorado Springs, CO 80903 U.S.A.

KEYWORDS: PeregrineFalcon; Falco peregrinus;occupancy gleaned from correspondencewith interestedpeople, of- ratg populationchangg productivity; reproductive success; Col- ten falconers. I also visited several sites in the 1973-75 orado. period that included most of the territories from the ear- lier surveyplus two additional peregrine cliffs found in the interim. The sites visited in 2004 included 15 sites In 1965, ProfessorJoe Hickey held a conference of selectedarbitrarily from thoseincluded in the earlier sur- more than 50 people at the University of Wisconsin to veyperiods. In all, 21 different siteswere surveyedat least review marked declines of severalspecies of bird-eating once in the three periods. and fish-eatingraptors, particularlythe Peregrine Falcon In 2004, I also visited an additional 32 sites found since (Falcoperegrinus; Hickey 1969). By that time, peregrines 1975. I did not include the latter group in the activity were extirpated in parts of Europe and the easternUnit- and occupancycomparisons between periods. The addi- ed Statesand were greatlyreduced in severalother re- tional 32 cliffs were checked becausethey were logisti- gions. The purpose of this paper is to compare territory cally accessiblewhile I visitedhistorical sites, or were re- occupancyand nestingperformance in Colorado in the ported by other observers.They were selectedwithout regard for past occupancyor reproductiveperformance 1960s and 1970s,when the population was in decline, Becauseof small sample size in any one year, I pooled with falcon activitiesand occupancyat most of the same data within the first two periods. As a result, data for as cliffs in 2004. many as three seasonswithin a period were tallied for In 1964, a broad surveyin the RockyMountain region some locations. For this analysis,reproductive perfor- was accomplished (Enderson 1965) and adult pairs in mance by pairs betweenyears at the samesite wascon- Colorado were presentat five (33%) of 15 cliffs visited. sidered independent, but the validity of that notion was Single peregrines were seen at two other sites,and eight not tested. were apparently vacant; only four young were seen at A spottingscope or binocularson a tripod or window mount were used to discover falcons on cliffs. In the two thesesites. Another survey was done in Coloradoin 1973 earlier periods,I usuallywalked the tops of the cliffsin and the resultswere included in a broader regional re- addition to the distant viewing. Unless weather inter- port (Endersonand Craig 1974);eight (44%) pairswere fered, I usuallysearched the cliff for at least4 hr or until found at 18 sitesand only two young were seen. These peregrineswere seen. Incubation, brooding, or food ex- published reports included records from only a single changesusually occurred in that span of time. When year. Becauseadditional unpublisheddata are available fresh excrement was seen, or poor weather interrupted, for Coloradoin other yearsduring thoseearly periods,it searchingwas extended or often repeated on another would be useful to include them in a wider analysisand day. Siteswere excluded from the analysisif I assessed to contrast those historical results with a recent survey that samplingwas inadequate to determine occupancy.I that I completed in 2004. believe the effectivenessof observationswas generally similar between periods, except that in 1963-65 when I METHODS was lessfamiliar with the cliffs and peregrine activitiesat the cliffs.Sites were usuallyvisited once or twiceto verify In the period from 1963-65, I visitedcliffs in Colorado occupancy,and usuallyonce to countyoung. This pattern where peregrines had been reported in the literature or did not changesubstantially between periods, except that in the first two periods I often checked, based on incu- 1 Email address:jendersøn@cøløradøcøllege'edu bation behavior, to see if females had laid eggsas well.