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First observations of the diet of the Pearl Kite (Gampsonyx swainsonii magnus) in southwestern Ecuador

First observations of the diet of the Pearl Kite (Gampsonyx swainsonii magnus) in southwestern... Revista Brasileira de Ornitologia 27(3): 195–198. ARTICLE September 2019 First observations of the diet of the Pearl Kite (Gampsonyx swainsonii magnus) in southwestern Ecuador 1,5 2,3 4 Adrian Orihuela-Torres , Jorge Brito & Juan Manuel Pérez-García Laboratory of Tropical Ecology and Ecosystem Services, Department of Biological Sciences, Universidad Técnica Particular de Loja, Loja, Ecuador. Department of Biology, Faculty of Sciences, Escuela Politécnica Nacional, Quito, Ecuador. Instituto Nacional de Biodiversidad (INABIO), Quito, Ecuador. Department of Animal Science, Higher Technical School of Agricultural Engineering, University of Lleida, Lleida, Spain. Corresponding author: adrian.orihuela89@gmail.com Received on 21 March 2019. Accepted on 21 July 2019. ABSTRACT: We describe the diet of Pearl Kite (Gampsonyx swainsonii magnus) by pellet analysis collected in an active nest in southwest Ecuador in May 2018. Reptiles were the most consumed taxonomic group both in frequency of occurrence (FO = 46.4%) and in biomass (B = 59.8%), followed by birds (FO = 33.9% and B = 38.3%) and insects (FO = 19.6% and B = 1.8%). Our results showed Pearl Kite as a generalist raptor but with a higher consumption of reptiles, which is according with previous studies in other areas where other subspecies inhabit, despite this subspecies showed a higher consumption of birds. Despite the low sample size, this study is interesting as it is the first one on the diet of the Pearl Kite for Ecuador and also for this subspecies. Basic studies on the trophic ecology of Neotropical raptors such as this are needed. For this reason we encourage further studies to fill existing gaps in knowledge and improve effective long-term conservation strategies. KEY-WORDS: pellets, prey, raptor, reptiles, trophic ecology, tropical dry forest. INTRODUCTION distributed in west Ecuador and northwestern Peru; G. s. swainsonii distributed in Brazil south of Amazon Knowing the trophic ecology of a species is important River to east Peru, north and east Bolivia, Paraguay and not only to understand the ecology of the species itself, N Argentina (Bierregaard-Jr. & Kirwan 2018). Unlike but also to understand the ecology of the community many other Neotropical raptors, Pearl Kite is favoured (Lewis et al. 2004). In addition to helping researchers by deforestation (Ferguson-Lees & Christie 2001) and, understand trophic niches and how they relate to consequently, it is expanding its range of distribution in community structure, studying raptor diets can recent decades, mainly in Central America, southeast of provide valuable information about prey distribution, Brazil and Ecuador (Bierregaard-Jr. & Kirwan 2018). abundance, behaviour, and vulnerability (Geng et al. Despite being a fairly common raptor in most areas 2009). Neotropical region is one of the areas with the where it lives, it is surprising the lack of detailed studies on highest diversity of raptors worldwide (Ferguson-Lees its trophic ecology. This raptor is considered a specialist & Christie 2001), however the knowledge about many in the capture of small lizards (Ferguson-Lees & Christie aspects of the ecology of this group is scarce (Freile et al. 2001), most of these data had been gathered in field 2014, Monsalvo et al. 2018), even for other biological observations or partial diet studies carried out in Central aspects. One of them is the Pearl Kite (Gampsonyx America or northern South America, and are restricted to swainsonii), a small raptor that inhabits dry forests the subspecies G. s. swainsonii and G. s. leonae (Martínez and arid regions of Central and South America (van 1998, Ffrench 2012, Koski et al. 2015, Martínez-Araya & Dort et al. 2010). Three sub species are recognized, G. Gastezzi-Arias 2016, Pineda et al. 2016, Araya-Céspedes s. leonae distributed in southwestern El Salvador, south & Carvajal-Sánchez 2017, Herrera & Acosta-Burgos Honduras, west Nicaragua, Costa Rica and Panama, 2018, Bierregaard-Jr. & Kirwan 2018). As long as we north and east Colombia through Venezuela and know, nothing has been published to date about the diet Trinidad to Guyana and Suriname, south to northeastern of G. s. magnus. Ecuador and Brazil north of Amazon River; G. s. magnus In this survey we describe the diet of the Pearl Kite Diet of Pearl Kite (Gampsonyx swainsonii magnus) Orihuela-Torres et al. Gampsonyx s. magnus in southwestern Ecuador, based on and groups consumed, frequency of occurrence (FO) the analysis of pellets collected from a single active nest. was calculated as the number of individuals of each kind of prey divided by the total number of prey (Formoso et al. 2012, Orihuela-Torres et al. 2017), and biomass METHODS consumed (B) multiplying the average body mass of each prey species by the number of total individuals On May 2018, we located an active nest of Pearl Kite in consumed (Orihuela-Torres et al. 2018). Both indexes were shown as a percentage to facilitate comparison. For the municipality of Zapotillo, province of Loja, southwest o o of Ecuador (4 19'35''S; 80 13'20''W, 244 m a.s.l.). The the calculation of biomass, we used the average mass of breeding territory was located in a semideciduous dry each prey species from Instituto Nacional de Biodiversidad tropical forest, characterized by discontinuous, natural or (INABIO) collection in Quito, Ecuador (https:// induced glades, and the presence of isolated trees (Cueva www.inabioecuador.bio/ufl/collections/). The content obtained as remains of birds, insects and reptiles were & Chalán 2010). The nest was a basket made of loose twigs about 25 cm in diameter at a height of 4 m in a quite fragmented, therefore it could not be deposited in Barbasco (Piscidia carthagenensis), and in which there collections and receive a voucher number. However, this were two fledglings (Fig. 1). material may be used for teaching purposes and will also To determine the diet, pellets were collected from be provided to interested researchers. the ground under the active nest. Pellets were analysed in the laboratory of the University of Loja (Ecuador). Each RESULTS pellet was measured with a digital calliper (± 0.01 mm) and weighed with a precision balance Sartorius LA-230P (± 0.01 g). The identification of prey remains found in A total of 25 pellets were collected and showed the following measures: length (mean = 20.67 mm, SD = each pellet followed Orihuela-Torres et al. (2017). The number of prey was calculated as the number 4.76 mm, range = 15.83–29.27 mm), width (mean = of individuals based on the presence of unique structures, 11.82 mm, SD = 3.12 mm, range = 8.5–17.64 mm), such as elytra of arthropods, jaws of reptiles, feathers and mass (mean = 0.44 g, SD = 0.26 g, range = 0.2–1.2 g). bones of birds, while other parts were not used to avoid We found 56 prey from at least seven species belonging to three different classes: birds (2 spp. at least), reptiles (3 double counting (Manning & Jones 1990). To calculate the biomass of birds not identified, we rely on the size of spp.), and insects (1 family). Prey mass varied from 1 g the bones that were of a medium-sized bird. For each prey (Carabidae) to 30 g (Iguana iguana juvenile). Reptiles were Figure 1. Nest of Pearl Kite (Gampsonyx swainsonii magnus) with one of the two fledglings, in Zapotillo, southwestern E cuador. Revista Brasileira de Ornitologia 27(3): 2019 Diet of Pearl Kite (Gampsonyx swainsonii magnus) Orihuela-Torres et al. the main prey both in frequency of occurrence (46.4%) and prey selection due to a higher local prey abundance and in biomass consumed (59.8%, Fig. 2). Second in rank (Morrison et al. 2008), or adaptation of this subspecies to were birds (FO: 33.9% and B: 38.3%), and then insects consume more birds than the others subspecies. But due (FO: 19.6%, and B: 1.8%). At the species level, Knobbed to the small sample size of our study we cannot support Pacific Iguana (Microlophus occipitalis) was the most statistically any conclusion. abundant prey both in frequency of occurrence (39.3%), In this sense the composition of the diet would as in biomass consumed (47.3%). Although most birds confirm the preference of this raptor for foraging in could not be identified at species level, they appeared open habitats where it would find a higher abundance in a large percentage of the pellets (76%). Carabids also of reptiles such as M. occipitalis (Chávez-Villavicencio et showed a high frequency of occurrence (19.6%), in 32% al. 2018). Likewise, this statement is supported by the of pellets, however their contribution in biomass was presence of birds related to open habitats and bushes scarce (1.8%) (Table 1). such as the Saffron Finch (Sicalis flaveola) (Ridgely & Greendfield 2001). DISCUSSION The diet of Pearl Kite in Zapotillo (SW Ecuador) corresponding to the subspecies Gampsonyx s. magnus, was in accordance with previous occasional data recorded for the other two Pearl Kite subspecies, placing this raptors as generalist, but consuming mainly reptiles (Martínez 1998, Koski et al. 2015, Martínez-Araya & Gastezzi-Arias 2016, Pineda et al. 2016, Araya-Céspedes & Carvajal-Sánchez 2017, Herrera & Acosta-Burgos 2018). The consumption of bir ds in our study seems Figure 2. Frequency of occurrence (FO) and biomass consumed much more common than previously reported (e.g., (B) in percentage of the diet of Pearl Kite (Gampsonyx swainsonii Bierregaard-Jr. & Kirwan 2018). Several hypothesis could magnus) in a breeding territory of Zapotillo, southwestern explain this results, i.e., plasticity in foraging behaviour Ecuador. Table 1. Diet composition of the Pearl Kite (Gampsonyx swainsonii magnus) in a breeding territory of Zapotillo, southwestern Ecuador. The number of individuals consumed of each species is shown (n ind.), frequency of occurrence (FO) in percentage (%), the total biomass consumed (Biomass, in g) and the percentage (Biomass, in %). Class/Order/Family/Species n ind. FO (%) Biomass (g) Biomass (%) Reptilia 26 46.4 362 59.8 Squamata Iguanidae 22 39.3 286 47.3 Microlophus occipitalis Iguana iguana (juvenile) 1 1.8 30 5.0 Polychrus femoralis 1 1.8 22 3.6 Phyllodactylidae Phyllodactylus reissii 2 3.6 24 4.0 Insecta 11 19.6 11 1.8 Coleoptera Carabidae 11 19.6 11 1.8 Birds 19 33.9 232 38.3 Passeriformes Emberizidae Sicalis flaveola 2 3.6 28 4.6 Medium-sized birds 17 30.4 204 33.7 Total 56 100 605 100 Revista Brasileira de Ornitologia 27(3): 2019 Diet of Pearl Kite (Gampsonyx swainsonii magnus) Orihuela-Torres et al. Moleón M., Morales-Reyes Z., Moreno-Opo R., Pérez-García Raptors are very important components in the J.M., Sánchez-Zapata J.A., Zuberogoitia I. & Serrano D. 2016. ecosystems, since they can be used as bioindicators or Roles of raptors in a changing world: from predators to providers key species for community monitoring, in addition to of key ecosystem services. Ardeola 63: 181–234. providing important ecosystem services (Donázar et al. Ferguson-Lees J. & Christie D.A. 2001. Raptors of the world. New 2016). Currently there are large gaps in knowledge of basic York: Cristopher Helm. Ffrench R. 2012. A guide to the birds of Trinidad and Tobago. Ithaca: aspects of raptor ecology in the Neotropics (Buechley et Cornell University Press. al. 2019) such as the composition of diet, phenology and Formoso A.E., Teta P. & Cheli G. 2012. Food habits of the Magellanic reproduction, home range or even population sizes. Basic Horned Owl (Bubo virginianus magellanicus) at southernmost information like this study is necessary to complete these Patagonia, Argentina. Journal of Raptor Research 46: 401–406. gaps, but since the diet varies depending on factors such Freile J.F., Greeney H.F. & Bonaccorso E. 2014. Current Neotropical ornithology: research progress 1996–2011. Condor 116: 84–96. as sex, age, habitat and season (Beeston et al. 2005) it is Geng R., Zhang X., Ou W., Sun H., Lei F., Gao W. & Wang H. 2009. necessary that this knowledge be completed throughout Diet and prey consumption of breeding Common Kestrel (Falco the distribution area, as well as replicated during different tinnunculus) in northeast China. Progress in Natural Science 19: seasons and by age classes. By improving our knowledge 1501–1507. of the trophic ecology of these magnificent birds at the Herrera N. & Acosta-Burgos J.C. 2018. Notes on nesting Pearl Kite (Gampsonyx swainsonii) in El Salvador. Spizaetus 26: 13–19. top of the food chain, we will be able to propose effective Koski D.A., de Oliveira G.S., Valadares-Koski A.P. & Costa H.C. long-term conservation strategies. 2015. Predation of Ameivula nativo (Squamata: Teiidae) by Gampsonyx swainsonii (Accipitriformes: Accipitridae) in Espírito Santo, Brazil. Herpetologia Brasileira 4: 100–101. ACKNOWLEDGEMENTS Lewis S.B., Fuller M.R. & Titus K. 2004. A comparison of 3 methods for assessing raptor diet during the breeding season. Wildlife Society Bulletin 32: 373–85. Field work was supported by the SENESCYT project Manning R.W. & Jones J.K. 1990. Remains of small mammals “Spatio-temporal responses of bird and bat communities recovered from Barn Owl pellets from Crosby County, Texas. to altitudinal gradients and disturbance in three Texas Journal of Science 42: 311–312. Martínez C. 1998. Occurrence of reproductive Little Eagle, Gampsonyx ecosystems south of Ecuador” (PIC-13-ETAPA-004). swainsonii (Aves: Accipitridae) in São Luís do Maranhão. Ararajuba J.M. Pérez-García was supported by a Juan de la Cierva 6: 58–59. research contract by the Ministry of Economy and Martínez-Araya D. & Gastezzi-Arias P. 2016. Establecimiento Competitiveness (FJCI-2015-25632). del Milano Chico (Gampsonyx swainsonii, Aves: Accipitridae) y observaciones del primer registro de anidación en un área urbanizada del Valle Central, Costa Rica. Brenesia 85–86: 65–68. Monsalvo J.A.B., Heming N.M. & Marini M.Â. 2018. Breeding REFERENCES biology of Neotropical Accipitriformes: current knowledge and research priorities. Revista Brasileira de Ornitologia 26: 151–186. Araya-Céspedes O. & Carvajal-Sánchez J.P. 2017. Ampliación del Morrison J.L., Pias K.E., Abrams J., Gottlieb I.G., Deyrup M. & rango de distribución y depredación sobre reptiles de Gampsonyx McMillian M. 2008. Invertebrate diet of breeding and nonbreeding swainsonii (Aves: Accipitridae) en la Zona Norte de Costa Rica. Crested Caracaras (Caracara cheriway) in Florida. Journal of Raptor Zeledonia 21: 60–62. Research 42: 38–47. Beeston R., Baines D. & Richardson M. 2005. Seasonal and between- Orihuela-Torres A., Perales P., Rosado D. & Pérez-García J.M. 2017. sex differences in the diet of Black Grouse Tetrao tetrix. Bird Study Feeding ecology of the Common Kestrel Falco tinnunculus in the 52: 276–281. south of Alicante (southeast Spain). Revista Catalana d'Ornitologia Bierregaard-Jr. R.O. & Kirwan G.M. 2018. Pearl Kite (Gampsonyx 33: 10–16. swainsonii). In: del Hoyo J., Elliott A., Sargatal J., Christie D.A. Orihuela-Torres A., Ordoñez-Delgado L., Verdezoto-Celi A. & Brito & de Juana E. (eds.). Handbook of the birds of the world alive. J. 2018. Diet of the Spectacled Owl (Pulsatrix perspicillata) in Barcelona: Lynx Editions. http://www.hbw.com/node/52965 Zapotillo, southwestern Ecuador. Revista Brasileira de Ornitologia (Accessed on 10 July 2018). 26: 52–56. Buechley E.R., Santangeli A., Girardello M., Neate‐Clegg M.H., Pineda L., de Navas E.M. & Fernández R.A. 2016. New locations for Oleyar D., McClure C.J. & Şekercioğlu Ç.H. 2019. Global raptor and first recor d of nesting Pearl Kite (Gampsonyx swainsonii) in El research and conservation priorities: tropical raptors fall prey to knowledge gaps. Diversity and Distributions 25: 856–869. Salvador. Spizaetus 22: 6–13. Chávez-Villavicencio C., Ibáñez-Álvarez Y. & Charcape-Ravelo Ridgely R.D. & Greenfield P.J. 2001. The bir ds of Ecuador, field gui de. J.M. 2018. Selección de hábitat y composición de la dieta de New York: Cornell University Press. Microlophus occipitalis (Reptilia: Tropiduridae) en Sechura, Piura- van Dort J., Komar O., Juárez-Jovel R.C. & Espinal M. 2010. First Perú. Revista Peruana de Biología 25: 221–228. records of Pearl Kite Gampsonyx swainsonii for El Salvador and Cueva J. & Chalán L. 2010. Cobertura vegetal y uso actual del suelo de Honduras. Cotinga 32: 129–130. la provincia de Loja. Loja: Amazon Graphics. Donázar J.A., Cortés-Avizanda A., Fargallo J.A., Margalida A., Associate Editor: Carla S. Fontana. Revista Brasileira de Ornitologia 27(3): 2019 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Ornithology Research Springer Journals

First observations of the diet of the Pearl Kite (Gampsonyx swainsonii magnus) in southwestern Ecuador

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Revista Brasileira de Ornitologia 27(3): 195–198. ARTICLE September 2019 First observations of the diet of the Pearl Kite (Gampsonyx swainsonii magnus) in southwestern Ecuador 1,5 2,3 4 Adrian Orihuela-Torres , Jorge Brito & Juan Manuel Pérez-García Laboratory of Tropical Ecology and Ecosystem Services, Department of Biological Sciences, Universidad Técnica Particular de Loja, Loja, Ecuador. Department of Biology, Faculty of Sciences, Escuela Politécnica Nacional, Quito, Ecuador. Instituto Nacional de Biodiversidad (INABIO), Quito, Ecuador. Department of Animal Science, Higher Technical School of Agricultural Engineering, University of Lleida, Lleida, Spain. Corresponding author: adrian.orihuela89@gmail.com Received on 21 March 2019. Accepted on 21 July 2019. ABSTRACT: We describe the diet of Pearl Kite (Gampsonyx swainsonii magnus) by pellet analysis collected in an active nest in southwest Ecuador in May 2018. Reptiles were the most consumed taxonomic group both in frequency of occurrence (FO = 46.4%) and in biomass (B = 59.8%), followed by birds (FO = 33.9% and B = 38.3%) and insects (FO = 19.6% and B = 1.8%). Our results showed Pearl Kite as a generalist raptor but with a higher consumption of reptiles, which is according with previous studies in other areas where other subspecies inhabit, despite this subspecies showed a higher consumption of birds. Despite the low sample size, this study is interesting as it is the first one on the diet of the Pearl Kite for Ecuador and also for this subspecies. Basic studies on the trophic ecology of Neotropical raptors such as this are needed. For this reason we encourage further studies to fill existing gaps in knowledge and improve effective long-term conservation strategies. KEY-WORDS: pellets, prey, raptor, reptiles, trophic ecology, tropical dry forest. INTRODUCTION distributed in west Ecuador and northwestern Peru; G. s. swainsonii distributed in Brazil south of Amazon Knowing the trophic ecology of a species is important River to east Peru, north and east Bolivia, Paraguay and not only to understand the ecology of the species itself, N Argentina (Bierregaard-Jr. & Kirwan 2018). Unlike but also to understand the ecology of the community many other Neotropical raptors, Pearl Kite is favoured (Lewis et al. 2004). In addition to helping researchers by deforestation (Ferguson-Lees & Christie 2001) and, understand trophic niches and how they relate to consequently, it is expanding its range of distribution in community structure, studying raptor diets can recent decades, mainly in Central America, southeast of provide valuable information about prey distribution, Brazil and Ecuador (Bierregaard-Jr. & Kirwan 2018). abundance, behaviour, and vulnerability (Geng et al. Despite being a fairly common raptor in most areas 2009). Neotropical region is one of the areas with the where it lives, it is surprising the lack of detailed studies on highest diversity of raptors worldwide (Ferguson-Lees its trophic ecology. This raptor is considered a specialist & Christie 2001), however the knowledge about many in the capture of small lizards (Ferguson-Lees & Christie aspects of the ecology of this group is scarce (Freile et al. 2001), most of these data had been gathered in field 2014, Monsalvo et al. 2018), even for other biological observations or partial diet studies carried out in Central aspects. One of them is the Pearl Kite (Gampsonyx America or northern South America, and are restricted to swainsonii), a small raptor that inhabits dry forests the subspecies G. s. swainsonii and G. s. leonae (Martínez and arid regions of Central and South America (van 1998, Ffrench 2012, Koski et al. 2015, Martínez-Araya & Dort et al. 2010). Three sub species are recognized, G. Gastezzi-Arias 2016, Pineda et al. 2016, Araya-Céspedes s. leonae distributed in southwestern El Salvador, south & Carvajal-Sánchez 2017, Herrera & Acosta-Burgos Honduras, west Nicaragua, Costa Rica and Panama, 2018, Bierregaard-Jr. & Kirwan 2018). As long as we north and east Colombia through Venezuela and know, nothing has been published to date about the diet Trinidad to Guyana and Suriname, south to northeastern of G. s. magnus. Ecuador and Brazil north of Amazon River; G. s. magnus In this survey we describe the diet of the Pearl Kite Diet of Pearl Kite (Gampsonyx swainsonii magnus) Orihuela-Torres et al. Gampsonyx s. magnus in southwestern Ecuador, based on and groups consumed, frequency of occurrence (FO) the analysis of pellets collected from a single active nest. was calculated as the number of individuals of each kind of prey divided by the total number of prey (Formoso et al. 2012, Orihuela-Torres et al. 2017), and biomass METHODS consumed (B) multiplying the average body mass of each prey species by the number of total individuals On May 2018, we located an active nest of Pearl Kite in consumed (Orihuela-Torres et al. 2018). Both indexes were shown as a percentage to facilitate comparison. For the municipality of Zapotillo, province of Loja, southwest o o of Ecuador (4 19'35''S; 80 13'20''W, 244 m a.s.l.). The the calculation of biomass, we used the average mass of breeding territory was located in a semideciduous dry each prey species from Instituto Nacional de Biodiversidad tropical forest, characterized by discontinuous, natural or (INABIO) collection in Quito, Ecuador (https:// induced glades, and the presence of isolated trees (Cueva www.inabioecuador.bio/ufl/collections/). The content obtained as remains of birds, insects and reptiles were & Chalán 2010). The nest was a basket made of loose twigs about 25 cm in diameter at a height of 4 m in a quite fragmented, therefore it could not be deposited in Barbasco (Piscidia carthagenensis), and in which there collections and receive a voucher number. However, this were two fledglings (Fig. 1). material may be used for teaching purposes and will also To determine the diet, pellets were collected from be provided to interested researchers. the ground under the active nest. Pellets were analysed in the laboratory of the University of Loja (Ecuador). Each RESULTS pellet was measured with a digital calliper (± 0.01 mm) and weighed with a precision balance Sartorius LA-230P (± 0.01 g). The identification of prey remains found in A total of 25 pellets were collected and showed the following measures: length (mean = 20.67 mm, SD = each pellet followed Orihuela-Torres et al. (2017). The number of prey was calculated as the number 4.76 mm, range = 15.83–29.27 mm), width (mean = of individuals based on the presence of unique structures, 11.82 mm, SD = 3.12 mm, range = 8.5–17.64 mm), such as elytra of arthropods, jaws of reptiles, feathers and mass (mean = 0.44 g, SD = 0.26 g, range = 0.2–1.2 g). bones of birds, while other parts were not used to avoid We found 56 prey from at least seven species belonging to three different classes: birds (2 spp. at least), reptiles (3 double counting (Manning & Jones 1990). To calculate the biomass of birds not identified, we rely on the size of spp.), and insects (1 family). Prey mass varied from 1 g the bones that were of a medium-sized bird. For each prey (Carabidae) to 30 g (Iguana iguana juvenile). Reptiles were Figure 1. Nest of Pearl Kite (Gampsonyx swainsonii magnus) with one of the two fledglings, in Zapotillo, southwestern E cuador. Revista Brasileira de Ornitologia 27(3): 2019 Diet of Pearl Kite (Gampsonyx swainsonii magnus) Orihuela-Torres et al. the main prey both in frequency of occurrence (46.4%) and prey selection due to a higher local prey abundance and in biomass consumed (59.8%, Fig. 2). Second in rank (Morrison et al. 2008), or adaptation of this subspecies to were birds (FO: 33.9% and B: 38.3%), and then insects consume more birds than the others subspecies. But due (FO: 19.6%, and B: 1.8%). At the species level, Knobbed to the small sample size of our study we cannot support Pacific Iguana (Microlophus occipitalis) was the most statistically any conclusion. abundant prey both in frequency of occurrence (39.3%), In this sense the composition of the diet would as in biomass consumed (47.3%). Although most birds confirm the preference of this raptor for foraging in could not be identified at species level, they appeared open habitats where it would find a higher abundance in a large percentage of the pellets (76%). Carabids also of reptiles such as M. occipitalis (Chávez-Villavicencio et showed a high frequency of occurrence (19.6%), in 32% al. 2018). Likewise, this statement is supported by the of pellets, however their contribution in biomass was presence of birds related to open habitats and bushes scarce (1.8%) (Table 1). such as the Saffron Finch (Sicalis flaveola) (Ridgely & Greendfield 2001). DISCUSSION The diet of Pearl Kite in Zapotillo (SW Ecuador) corresponding to the subspecies Gampsonyx s. magnus, was in accordance with previous occasional data recorded for the other two Pearl Kite subspecies, placing this raptors as generalist, but consuming mainly reptiles (Martínez 1998, Koski et al. 2015, Martínez-Araya & Gastezzi-Arias 2016, Pineda et al. 2016, Araya-Céspedes & Carvajal-Sánchez 2017, Herrera & Acosta-Burgos 2018). The consumption of bir ds in our study seems Figure 2. Frequency of occurrence (FO) and biomass consumed much more common than previously reported (e.g., (B) in percentage of the diet of Pearl Kite (Gampsonyx swainsonii Bierregaard-Jr. & Kirwan 2018). Several hypothesis could magnus) in a breeding territory of Zapotillo, southwestern explain this results, i.e., plasticity in foraging behaviour Ecuador. Table 1. Diet composition of the Pearl Kite (Gampsonyx swainsonii magnus) in a breeding territory of Zapotillo, southwestern Ecuador. The number of individuals consumed of each species is shown (n ind.), frequency of occurrence (FO) in percentage (%), the total biomass consumed (Biomass, in g) and the percentage (Biomass, in %). Class/Order/Family/Species n ind. FO (%) Biomass (g) Biomass (%) Reptilia 26 46.4 362 59.8 Squamata Iguanidae 22 39.3 286 47.3 Microlophus occipitalis Iguana iguana (juvenile) 1 1.8 30 5.0 Polychrus femoralis 1 1.8 22 3.6 Phyllodactylidae Phyllodactylus reissii 2 3.6 24 4.0 Insecta 11 19.6 11 1.8 Coleoptera Carabidae 11 19.6 11 1.8 Birds 19 33.9 232 38.3 Passeriformes Emberizidae Sicalis flaveola 2 3.6 28 4.6 Medium-sized birds 17 30.4 204 33.7 Total 56 100 605 100 Revista Brasileira de Ornitologia 27(3): 2019 Diet of Pearl Kite (Gampsonyx swainsonii magnus) Orihuela-Torres et al. Moleón M., Morales-Reyes Z., Moreno-Opo R., Pérez-García Raptors are very important components in the J.M., Sánchez-Zapata J.A., Zuberogoitia I. & Serrano D. 2016. ecosystems, since they can be used as bioindicators or Roles of raptors in a changing world: from predators to providers key species for community monitoring, in addition to of key ecosystem services. Ardeola 63: 181–234. providing important ecosystem services (Donázar et al. Ferguson-Lees J. & Christie D.A. 2001. Raptors of the world. New 2016). Currently there are large gaps in knowledge of basic York: Cristopher Helm. Ffrench R. 2012. A guide to the birds of Trinidad and Tobago. Ithaca: aspects of raptor ecology in the Neotropics (Buechley et Cornell University Press. al. 2019) such as the composition of diet, phenology and Formoso A.E., Teta P. & Cheli G. 2012. Food habits of the Magellanic reproduction, home range or even population sizes. 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Journal

Ornithology ResearchSpringer Journals

Published: Sep 1, 2019

Keywords: pellets; prey; raptor; reptiles; trophic ecology; tropical dry forest

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