Miguel Ángel Santillán

The ecological role of native and introduced species in the diet of the puma Puma concolor in southern Patagonia

There is evidence for the ecological extinction of the native prey of the puma Puma concolor in north- western Argentine Patagonia. In this study we examine whether this is also the case in southern Patagonia. From 2004 to 2007 we examined the pumas diet in three protected areas and two sheep ranches in Santa Cruz province. A total of 282 puma scats were analysed. In two of the protected areas and in the ranches 60-74% of the pumas diet was native prey. Prey species were primarily guanaco Lama guanicoe, followed by Patagonian mara Dolichotis patagonum, lesser rhea Pterocnemia pennata pennata, Patagonian pichi Zaedyus pichiy and Magellanic penguin Spheniscus magellanicus. In the third protected area the main prey was the European hare Lepus euro- paeus. Our results show a clear difference in the diet of the puma in southern compared to north-western Patagonia. Large native herbivores (i.e. guanaco and lesser rhea) maintain their role as the main prey species for the puma in southern Patagonia. We suggest, therefore, that native prey could be restored to those areas of Argentine Patagonia, such as the north-west, where they are currently ecologically extinct. Facilitating native species recovery and/or restoration and applying more rigorous controls to prevent the introduction of potential alien prey species of the puma, both within and outside protected areas, needs to be evaluated as a regional strategy.

Breeding season habitat selection by Ferruginous Pygmy Owls Glaucidium brasilianum in central Argentina

Capsule The presence of Ferruginous Pygmy Owls Glaucidium brasilianum breeding in the xerophytic forest of Caldén Prosopis caldenia in central Argentina was slightly affected by forest maturity but neither by the structure of vegetation strata at the micro-habitat scale, nor by forest composition (mosaic of forest–grassland or shrubland) or proximity of water bodies at the macro-habitat scale. Aims To assess the habitat characteristics selected by Ferruginous Pygmy Owls during the breeding season. Methods Random transects were performed across a portion of the Luro Natural Reserve by broadcasting Ferruginous Pygmy Owl calls. Locations along these transects were used to carry out a presence/absence habitat analysis at micro- and macro-habitat levels. Results Ferruginous Pygmy Owls were found in the majority of sampled locations. However, their presence was not associated with the vegetation structure and composition around sampled locations. Model outputs suggested similarity among presence and absence locations at both spatial scales, though owls showed a slight preference for areas with older trees and higher edge-density values. Conclusion The Ferruginous Pygmy Owl was more abundant than previously thought in the Caldén xerophytic forest, emphasizing the habitats conservation importance, particularly because of the land-use changes that the La Pampa region is experiencing (e.g. forest exploitation).

Comparison of food habits and prey selection of the white‐tailed kite, Elanus leucurus, between natural and disturbed areas in central Argentina

We studied the food habits of white‐tailed kites (Elanus leucurus, Accipitridae) in central Argentina during austral spring and summer (November to March) and compared prey captured in two different habitat types. Diet was determined by analysing pellets and prey remains collected under nests and roost sites. During the same period small mammals were trapped using pit‐fall traps in Parque Luro reserve with the aim of assessing prey selection by kites. In Parque Luro reserve (semiarid forest), tuco‐tucos (Ctenomys sp., Rodentia) were the main prey in the white‐tailed kite diet, accounting for 75% of the items and 91% of biomass. In agricultural fields, however, there was not a single main prey species, as measured either by number of prey items or by biomass, Calomys sp. (43%) and Akodon azarae (22%) being the main prey in this habitat. The analysis of prey availability in the Parque Luro reserve showed that tuco‐tucos are a seasonally available prey, only captured in spring and summer. During these seasons, the consumption of tuco‐tucos by white‐tailed kites was disproportionately higher than the occurrence of tuco‐tucos, indicating a preference for this species by kites. These results suggest that other prey attributes, such as conspicuousness and social behavior, could be key factors in prey selection by white‐tailed kites.

Nest-Box Occupancy by Neotropical Raptors in a Native Forest of Central Argentina

Abstract Breeding populations of raptors are sometimes limited by nest-site availability and the use of nest boxes to bolster such populations is widespread. In the neotropical forest, little is known about the ecology of cavity-nesting raptors and their use of nest boxes. Here we examine occupancy patterns of nest boxes by five raptor species during eight years in a semiarid forest of central Argentina: the American Kestrel (Falco sparverius), the Spot-winged Falconet (Spiziapteryx circumcincta), the Tropical Screech-Owl (Megascops choliba), the Barn Owl (Tyto alba), and the Ferruginous Pygmy-Owl (Glaucidium brasilianum). We analyze the influence of vegetation type on nest-box selection, report cases of nest usurpation, and present information on the breeding rates of some of these species. The raptor species showed a marked selection for nest boxes surrounded by grassland, where hunting success may be higher, and avoided those nest boxes placed in habitats dominated by dense shrublands. We observed two ...

Diet of the Red-backed Hawk (Buteo polyosoma) in two environmentally contrasting areas of Patagonia

We studied the Red-backed Hawk (Buteo polyosoma) diet by pellet analysis in two areas, the Monumento Natural Bosques Petrificados (MNBP) and Junín de los Andes, located in southern and northwestern Argentinean Patagonia respectively. These areas have different values of primary production mainly due to the differences in mean annual precipitation, being higher in Junín de los Andes. Diets were dominated by mammals in both areas (68.3% and 61% of occurrences). Rodents represented the greatest proportion (66.5%) of prey numbers in MNBP. They represented 92.6% of the biomass. Arthropods were also consumed with a relatively high occurrence (21.4%). In Junín de los Andes, rodents were an important prey (57.1%) but represented only 29.6% of the consumed biomass. In contrast, the introduced European hare (Lepus europaeus) was not frequently consumed (13.5%) but comprised 59.3% of prey biomass. Reptiles were a frequent item, consumed at 25.2% of total prey. The diet of the Red-backed Hawk was significantly different between MNBP and Junín de los Andes. The wider food niche breadth of the Red-backed Hawk in Junín de los Andes was likely attributable to the more even distribution of prey categories. Additionally, a functional response toward European hare consumption was observed, with a higher consumption of this prey at Junín de los Andes. Estudiamos la dieta del Aguilucho común (Buteo polyosoma) por medio del análisis de egagrópilas, en dos áreas: el Monumento Natural Bosques Petrificados (MNBP) y Junín de los Andes, situadas respectivamente en el sur y noroeste de la Patagonia Argentina. La productividad primaria es diferente en ambas áreas, debido principalmente a la cantidad de precipitaciones, que son mayores en Junín de los Andes. Los mamíferos fueron las presas más importantes en la dieta del Aguilucho en ambas áreas (68.3% y 61.0% de ocurrencias). La proporción de roedores en el MNBP fue alta (66.5%), representando el 92.6% de la biomasa total consumida. Otro ítem importante fueron los artrópodos con una ocurrencia del 21.34%. En Junín de los Andes, los roedores fueron también presas importantes en la dieta del Aguilucho común (57.1%), pero representaron solamente 29.6% de la biomasa total consumida. Por el contrario, la liebre europea (Lepus europaeus), una presa introducida, fue consumida con una frecuencia menor (13.5%) pero constituyó el 59.3% de la biomasa total. Los reptiles fueron frecuentemente consumidos (25.2%). En concordancia, la dieta del Aguilucho común fue significativamente diferente entre el MNBP y Junín de los Andes. La mayor amplitud del nicho trófico del Aguilucho común en Junín de los Andes podría ser atribuida a la mayor equidad en la distribución de las categorías presa. Adicionalmente, se observó una respuesta funcional hacia el consumo de liebre europea, siendo mayor en Junín de los Andes.

Ectoparasites In Free-Ranging American Kestrels In Argentina: Implications for the Transmission of Viral Diseases

Abstract We described ectoparasitic species such as chewing lice, mites, and louse flies in free-ranging American Kestrels (Falco sparverius) in the semiarid forest of Argentina. From twenty-two adults and one juvenile American Kestrel captured (fourteen females and nine males) during four breeding seasons between 2005 and 2008, we found in seven birds (six females and one male) two louse species (Laemobothrion tinnunculi and Degeeriella carruthi), one mite species (Ornithonyssus bursa) and one louse fly (Icosta americana). Although the two louse species have been previously reported as parasites of American Kestrels, this is the first record for O. bursa in American Kestrels and the first for I. americana in Argentina. This finding is of particular interest because West Nile Virus (WNV) has been detected in I. americana, which suggests a potential role of this louse fly in the transmission of WNV in raptors in North America. Our results highlight the need for further studies on American Kestrel ectoparasites and also on host-parasite interactions for other neotropical raptors to better understand effects of parasitism on the health of those bird species and to detect possible vectors of infectious diseases. Ectoparásitos En Ejemplares Silvestres De Falco sparverius En Argentina: Implicancias Para La Transmisión De Enfermedades Virales Describimos especies de ectoparásitos, tales como piojos, ácaros y moscas hipobóscidas en ejemplares silvestres de Falco sparverius del bosque semiárido de Argentina. En 22 adultos y un juvenil de F. sparverius (14 hembras y nueve machos) capturados durante las épocas reproductivas correspondientes a los años 2005–08, hallamos en siete aves (seis hembras y un macho) dos especies de piojos (Laemobothrion tinnunculi y Degeeriella carruthi), una de ácaro (Ornithonyssus bursa) y una de mosca (Icosta americana). Mientras que las dos especies de piojos han sido ya previamente reportadas como parásitos de F. sparverius, este es el primer registro para O. bursa en la especie, y el primero de I. americana en Argentina. Este último hallazgo es de particular interés debido a que el Virus del Oeste del Nilo (VON) ha sido detectado recientemente en I. americana, sugiriendo un rol activo de esta mosca en la transmisión del VON en rapaces de Norteamérica. Nuestros resultados destacan la necesidad de realizar nuevos estudios sobre los ectoparásitos de F. sparverius así como también sobre las interacciones hospedador-parásito en otras rapaces neotropicales para no sólo dilucidar los efectos de las parasitosis sobre el estatus sanitario de dichas especies, sino también para detectar posibles vectores de enfermedades infecciosas.

Communal roosting behavior and winter diet of the White-tailed kite (Elanus leucurus) in an agricultural habitat on the Argentine pampas.

Abstract Although the White-tailed Kite (Elanus leucurus) is widely distributed throughout the Americas, winter communal roosting has been recorded only in the Nearctic portion of its range. As a result, data on the food habits of the White-tailed Kite in South America during the nonbreeding season are scarce and, when available, limited to pellets from solitary individuals. Here, we report the communal roosting behavior and the winter diet of White-tailed Kites in an agricultural habitat on the Argentine pampas based on information gathered over three consecutive years (2006–2008). From May to July of each year, we observed an average of 11 (±SD  =  2.8) kites roosting in a grove of Eucalyptus viminalis. Prior to roosting, kites gathered in a tall, dead, and leafless Eucalyptus tree before flying to more densely foliated trees where they spent the night. The diet of kites during winter was composed almost entirely of small mammals, mainly Calomys sp. and Akodon azarae. Because agricultural intensification in the Argentine pampas is ongoing, further studies are needed to gain a complete knowledge of White-tailed Kites in this habitat and of the effects of land-use changes on their foraging and other behavior.

The presence of Argas keiransi Estrada-Peña, Venzal & González- Acuña, 2003 (Acari: Argasidae) in Argentina

Abstract Forty-two larvae of Argas keiransi (Acari: Argasidae) were collected from the Chimango Caracara, Milvago chimango (Falconiformes: Falconidae), at three localities in La Pampa Province, Argentina. Ticks were determined by a combination of palpal segment IV as long as or longer than the other palpal segments, absence of a trumpet-shaped sensillum extending from the capsule of Haller´s organ into the lumen of the tarsus, length of dorsal plate between 180 and 240 μm, length of hypostome between 180 and 205 μm, dental formula 2/2 in the basal third, 2/2 or 3/3 apically, and length of posterolateral setae between 45 and 50 μm. Morphological determination was confirmed by analysis of sequences of the mitochondrial 16S rRNA gene. The results of this work constitute the first Argentinean record of A. keiransi, which has previously been reported only from Chile.

Incubation Period of the Austral Pygmy-Owl (Glaucidium nana): A Correction

The shortest incubation periods known for an owl, 21– 24 d, have been measured in small species such as the African Scops-Owl (Otus senegalensis) and the Elf Owl (Micrathene whitneyi; Marks et al. 1999, König and Weick 2008). In an article on the biology of the Austral Pygmy-Owl (Glaucidium nana) in Chile, Jiménez and Jaksić (1989) noted that Housse (1945) gave an incubation period of 15– 17 d for that species. Housse’s (1945) information on incubation was not supported by data, however, and almost certainly was a conjecture. More recently, Ibarra et al. (2014, 2015) also reported an incubation period of 15–17 d for G. nana in Chile. However, they did not record laying and hatching dates at the same nest (J. Ibarra and T. Altamirano pers. comm.). König et al. (1999) stated that incubation lasts 26–28 d on the basis of observations of a pair of G. nana that nested in captivity (C. König pers. comm.). During their study of wild pairs that nested in boxes in Argentina (Santillán et al. 2010), MAS, DEP, and AT (unpubl. data) determined that incubation lasted from 27–29 d at three nests, which agrees closely with observations of captives by König et al. (1999), and which also is consistent with data from other species of Glaucidium such as Eurasian Pygmy-Owl (G. passerinum), Pearl-spotted Owlet (G. perlatum), Northern Pygmy-Owl (G. gnoma), and Ferruginous Pygmy-Owl (G. brasilianum; Holt and Norton 1986, König and Weick 2008). Thus, at least in species for which data are available, no species of owl is known to have an incubation period shorter than 3 wk. We thank C. König, F.M. Jaksić, J.T. Ibarra, and T.A. Altamirano for shedding light on incubation periods of Austral Pygmy-Owls.

Predation by Geoffroy's cat on ferruginous Pygmy-Owl in Caldén semiarid forest, Argentina

Fil: Santillan, Miguel Angel. Universidad Nacional de La Pampa. Facultad de Ciencia Exactas y Naturales. Departamento de Recursos Naturales. Centro para el Estudio y Conservacion de Aves Rapaces; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina