Distribution patterns of diurnal raptors in open and forested habitats in south-eastern Brazil and the effects of urbanization

Abstract

SummaryDiurnal raptors may be highly sensitive to anthropogenic disturbances. We evaluated the diversity and abundance of diurnal raptors at an Atlantic Forest-cerrado transition zone in relation to two habitat types (forest fragments and open habitats) and to urbanization, comparing natural open and forested habitats with corresponding habitats within a large urban area. We sampled 80 points, 20 in each of four habitats (semi-natural and urban forests, seminatural and urban open areas), during 12 months. Diurnal raptors recorded (21 species) included only three out of 10 species with some level of threat in the region. Forested habitats had more species (17) than open habitats (12). Urban areas had only 14 (67%) species, whereas seminatural areas had all 21 species. Diurnal raptors were as abundant in urban areas as in seminatural areas in spite of a loss in species richness in urban areas. A re-analysis without Caracara plancus showed that urban areas had a lower mean number of individuals per point than seminatural areas. Overall species richness usually fluctuated from 14 to 16 species, being slightly higher between January and May than in other months. Overall abundance of diurnal raptors was much higher during summer than during winter. Local extinction may have already occurred for some species of diurnal raptors in the region and will probably shortly include several others. At least C. plancus, a habitat generalist, requires further studies and eventually management actions, since it is able to reach high population numbers in urbanized areas. Furthermore, highly sensitive species that were not recorded require further investigation regarding their conservation status. ResumoRaptores diurnos podem ser altamente sensíveis a perturbaçõ es antropogênicas. Avaliamos a diversidade e a abundância de raptores diurnos em uma região de transição entre Floresta Atlântica e Cerrado em relação a dois tipos de hábitats (fragmentos florestais e hábitats abertos) e à urbanização, comparando hábitats abertos e florestais aos hábitats correspondentes dentro de uma área urbana. Amostramos 80 pontos, 20 em cada um dos quatro hábitats (florestas seminaturais e urbanas, áreas abertas semi-naturais e urbanas) durante 12 meses. Entre os raptores diurnos registrados (21 espécies) estão apenas três das 10 espécies com algum nível de ameaça na região. Mais espécies foram registradas nos hábitats florestados (17) do que nos hábitats abertos (12). Apenas 14 (67 %) espécies foram registradas nas áreas urbanas, enquanto as 21 espécies foram registradas nas áreas semi-naturais. Os raptores diurnos foram igualmente abundantes nas áreas urbanas e nas áreas semi-naturais independentemente da perda de espécies nas áreas urbanas. Uma nova análise sem Caracara plancus mostrou que as áreas urbanas tiveram um menor nú mero médio de indivíduos por ponto do que as áreas semi-naturais. A riqueza total de espécies foi de 14 e 16 espécies, em geral, sendo um pouco mais alta entre janeiro e maio do que Bird Conservation International (2007) 17:367...

Shooting is still a main threat for raptors inhabiting urban and suburban areas of Rome, Italy

“…As found in previous studies (Blair 1996;Chace & Walsh 2006;Eduardo et al 2007), the present research highlighted the presence of several threats and sources of mortality for birds of prey in urban and suburban habitats. Overall, impact with human-made structures was the most frequent cause of admission to the wildlife recovery centre of Rome between 2000 and 2011.…”

Dusting-off the file: A review of knowledge on urban ornithology in Latin America

“…1). In general, urban ornithological studies in Latin America have focused on: (1) urban gradients (Reynaud and Thioulouse, 2000;Leveau andLeveau, 2004, 2005;Juri and Chani, 2005;Faggi and Perepelizin, 2006;Bellocq et al, 2008;Petry and Scherer, 2008;Garaffa et al, 2009;López-Flores et al, 2009;Ortega-Álvarez and MacGregor-Fors, 2009), (2) community comparisons among different urban habitats (Petit et al, 1999;Borges and Guilherme, 2000;Caula et al, 2003;Lucero et al, 2005;Manhães and LouresRibeiro, 2005;Faggi and Perepelizin, 2006;Galina and Gimenes, 2006;Lopes and dos Anjos, 2006;Eduardo et al, 2007;Acevedo and Aide, 2008;Cardozo et al, 2008;MacGregor-Fors et al, 2009a;Ortega-Álvarez and MacGregor-Fors, 2009), (3) bird responses to urban habitat attributes (Leveau andLeveau, 2004, 2006;Faggi and Perepelizin, 2006;MacGregor-Fors, 2008;MacGregor-Fors et al, 2009a;Ortega-Álvarez and MacGregor-Fors, 2009;Suarez-Rubio and Thomlinson, 2009), (4) use of resources by birds within urban systems (Marcondes-Machado et al, 1994;Alves and Pereira, 1998;de Vasconcelos, 1998;Vitali-Veiga and Machado, 2000;Cáceres and Moura, 2003; Baza-Mendonç a and dos Valdés-P...…”

“…Although natural habitats surrounding cities tend to comprise richer bird communities (Borges and Guilherme, 2000;Eduardo et al, 2007), the incorporation of green areas within the urban matrix offers suitable habitat for an important number of bird species (MacGregor-Fors et al, 2009a;Ortega-Álvarez and MacGregorFors, 2009). Specifically, urban parks and natural vegetation remnants within cities have an enormous ecological value for urban systems, as they represent the urban land-uses with highest bird diversity (Faggi and Perepelizin, 2006;Galina and Gimenes, 2006;Lopes and dos Anjos, 2006;Acevedo and Aide, 2008;Cardozo et al, 2008;Ortega-Álvarez and MacGregor-Fors, 2009).…”

“…As Latin American cities develop, land-uses change and habitat fragmentation increases, severely threatening native bird species (Borges and Guilherme, 2000;Serrano do Nascimento et al, 2005;Eduardo et al, 2007;Rodríguez-Estrella, 2007;Ortega-Álvarez and MacGregor-Fors, 2009). In particular, urban development has been associated with high nest predation rates (López-Flores et al, 2009), and decreases in avian reproductive and foraging activities (Escofet and Espejel, 1999).…”

“…To this extent, species associated with open habitats have higher capability of dwelling in highly developed urban environments than forest species (Fonaroff, 1974;Stiles, 1990). In addition, exotic, generalist, granivore, insectivore, and large-sized bird species tend to be favored by urbanization in Latin America (Villanueva-Villanueva and da Silva, 1995;Leveau and Leveau, 2006;Eduardo et al, 2007;González-Oreja et al, 2007;MacGregor-Fors, 2008).…”