Bird species richness and ISSN 1981-8874 composition along three 9 77198188700380 0 1 8 elevational gradients in southeastern Brazil Francisco Mallet-Rodrigues1, Ricardo Parrini2 & Bruno Rennó3 Distribution patterns of biotic com- munities along an elevational gradient are determined by several physical and ecological factors, which can vary with altitude, climate, habitat structure and resource availability (Terborgh 1971, 1977, Noon 1981, Lomolino 2001). Va- riations in these factors along an ele- vational gradient may cause a vertical stratification or ecological zonation in the mountainous regions, resulting in distinct elevational ranges among orga- nisms. Decreasing species richness with in- creasing elevation has been the pattern accepted by some authors (Terborgh 1977, Stevens 1992), but Rahbek (1995) showed that many elevational gradients have mid-elevational peaks in species richness, as initially noted by Terborgh Figure 1. State of Rio de Janeiro with the three study areas in black (1977), and described as the mid-domain (1 – Serra da Bocaina, 2 – Serra de Itatiaia, 3 – Serra dos Órgãos). effect (Colwell & Hurt 1994, Colwell & Lees 2000). Recen- 1993), the Atlantic Forest has been classified into lowland tly, several elevational species richness patterns have been (below 50 m), submontane (50 to 500 m), montane (500 to found along montane gradients (Rahbek 1995, McCain 2005, 1,500 m) and high montane forest (1,500 to 1,900 m) (Veloso 2007, 2009, Cavarzere & Silveira 2012). Patterns such as et al. 1991). Above high montane forests, the landscape is decreasing richness with increasing elevation, low-elevation dominated by high grasslands with depauperate bird species plateau in richness followed by a monotonic decrease, low- richness and a high proportion of endemic species (Vasconce- -elevation plateau with a mid-peak in richness, and unimodal los & Rodrigues 2010, Mallet-Rodrigues et al. 2010). mid-elevational peaks in richness have been found with near- A significant relationship between elevation and the pro- ly equal frequency on mountains around the world (McCain portion of birds endemic to the Atlantic Forest has been 2009). found in the mountains of eastern Brazil. The proportion of While the elevational distribution of birds is quite pronoun- endemism rises gradually with increasing altitude. Nearly ced in tropical forests of the Andes (e.g. Terborgh 1977), the half of the bird species found above 1,800 m in the mountains relatively low and isolated mountains of eastern South Ame- of southeastern Brazil are endemic species (Scott & Brooke rica have a reduced vertical ecological zonation, with few ca- 1985, Mallet-Rodrigues et al. 2010). However, the lowlands ses of replacement of bird species along elevational gradients are also very important because many threatened species are (Willis & Schuchmann 1993). Few studies have focused on found in them (Goerck 1999, Buzzetti 2000, Mallet-Rodri- the elevational distribution of birds in the mountains of eas- gues et al. 2010). Intensive human activity causing the frag- tern Brazil (Holt 1928, Scott & Brooke 1985, Goerck 1999, mentation of lowland and submontane forests is probably the Buzzetti 2000, Rajão & Cerqueira 2006, Rajão 2007, Cavar- main factor responsible for the highest concentration of thre- zere Junior 2010, Mallet-Rodrigues et al. 2010). Although atened species at low elevations. Most of the threatened bird the distribution of montane birds from eastern Brazil does not species live in lowland and submontane forests (Collar et al. have an evident ecological zonation (Willis & Schuchmann 1992, Alves et al. 2000). Atualidades Ornitológicas, 188, novembro e dezembro de 2015 - www.ao.com.br 39 The main objective of this study is to compare the patterns in the elevatio- nal distribution of bird species of three major mountain ranges of southeastern Brazil. Here we describe and compare the species richness, elevational range limits, proportion of Atlantic Forest en- demics, and invasive and threatened spe- cies along the elevational gradient of the three mountain ranges. Material and methods Study regions Our study was conducted in three Figure 2. Bird species richness along the elevational gradient in the three study areas in southeastern major mountain ranges in southeastern Brazil. Brazil (Serra da Bocaina, Serra de Ita- tiaia and Serra dos Órgãos) (Figure 1). Dense rainforests with a rich assembly of plant species and a profusion of lia- nas and epiphytes are predominant in the three regions. Below 800 m the climate is tropical with rains concentrated in the summer (Köppen climate classification categories “Aw”). Above 800 m the cli- mate is mesothermal humid with mode- rate summer (Köppen climate classifica- tion categories “Cfb”). The three regions studied here are considered Important Bird Areas (IBAs) in Brazil (Bencke et al. 2006). Figure 3. Species richness of birds endemic to the Atlantic Forest along the elevational gradient in the three study areas in southeastern Brazil. Serra da Bocaina is a part of the Serra do Mar range, situated on the border of the states of Rio de Janeiro and São Pau- lo. The elevation ranges from sea level to 2,088 m, but to just over 1,600 m in the state of Rio de Janeiro. The Parque Nacional da Serra da Bocaina occupies most of the region. The dense forests (submontane, montane and high mon- tane forests) are distributed throughout much of the region, which is one of the best preserved portions of Atlantic Fo- rest in southeastern Brazil. However, in- creasing human occupation in the region Figure 4. Species richness of invasive birds along the elevational gradient in the three study areas in has threatened the local biodiversity. southeastern Brazil. During 1,350 hours of fieldwork we vi- sited the following localities (all located in the state of Rio de Janeiro): 1) Flo- restão (22º 55’S, 44º 20’W; 0 to 20 m); 2) Bracuí (22º 56´S, 44º 23´W; 100 to 700 m); 3) Funil (23º 00’S, 44º 42’W; 800 to 1,200 m); 4) Perequê (23º 00’S, 44º 31’W; 10 to 40 m); 5) Mambucaba (23º 01’S, 44º 32’W; 0 to 40 m); 6) São Roque (23º 04´S, 44º 41´W; 0 to 250 m); 7) Ariró (23º 05´S, 44º 17´W; 0 to 20 m); 8) Parati-Cunha road (between 23º 12’S, 44º 44’W and 23º 10’S, 44º 50’W; 10 to 1,600 m); 9) Vale dos Veados (22° 48’S, Figure 5. Species richness of threatened birds in the state of Rio de Janeiro along the elevational gra- 44° 37’W; 1,200 to 1,350 m). dient in the three study areas in southeastern Brazil. 40 Atualidades Ornitológicas, 188, novembro e dezembro de 2015 - www.ao.com.br (22º 23’S, 44º 32’W; 550 to 950 m); 3) Penedo (22º 25´S, 44º 31´W; 400 to 750 m); 4) Parque Nacional do Itatiaia (ca. 22º 29´S, 44º 33´W; 500 to 2,700 m); 5) Resende Wetland or “Brejão da Kodak” (22º 26´S, 44º 23´W; 400 m). Serra dos Órgãos is located in the cen- tral region of the state of Rio de Janeiro in the northern section of the Serra do Mar range. Two large protected areas are located in the region – Parque Na- cional da Serra dos Órgãos and Parque Estadual dos Três Picos. The summit of the Serra dos Órgãos exceeds 2,200 m. The rich forests of the region (lowland, submontane, montane and high montane forests) are distributed from lowlands to approximately 2,100 m above sea level. Forests below 100 m are very fragmen- ted or absent due to human activities. Figure 6. The Fork-tailed Pygmy-Tyrant (Hemitriccus furcatus) has often been found in High grasslands are found above the fo- Itatiaia and Bocaina, but in the Serra dos Órgãos it has been recorded only in the Reserva rest line. Low temperatures and frost are Ecológica Guapiaçu, municipality of Cachoeiras de Macacu (Photo: Bruno Rennó). often recorded in the higher areas during the winter. Data on the birds of the Ser- ra dos Órgãos and localities visited in the region (totaling 6,500 hours of fiel- dwork) have been published elsewhere (Mallet-Rodrigues et al. 2010). Methods Fieldwork was conducted between 1989 and 2011 in several localities of the three study regions (see above). We assumed the highest and lowest elevatio- nal records to determine the distribution of each bird species along the elevatio- nal gradient. The interpolation of species occurrences between known elevation occurences has been used to study spe- cies richness patterns along elevational gradients (Rahbek 1997, Nogué et al. 2013). Although this range interpola- tion may overestimate species richness Figure 7. Usually found above 1,000 m, in the state of Rio de Janeiro the Black-capped at mid-elevations (Grytnes & Vetaas Piprites (Piprites pileata) is restricted to the Itatiaia massif (Photo: Bruno Rennó). 2002), it may help overcome some of the Serra de Itatiaia is situated in the southern portion of the limitations of undersampling (McCain 2009). Mantiqueira massif, on the border of the states of Rio de Only qualitative surveys of birds were performed at each Janeiro, Minas Gerais and São Paulo. The Parque Nacional locality. Although the sampling efforts undertaken among de Itatiaia is the oldest national park in Brazil. Itatiaiaçu, the three regions are distinct, the remarkable total of 21,550 with 2,791 m is the highest peak in a region named Agulhas hours of fieldwork (finely distributed along the elevational Negras. To the south of Itatiaia, the Paraiba do Sul River is gradient) is significantly larger than the sampling effort of si- located at 400 m elevation in an area dominated by grass- milar studies (Bencke & Kindel 1999, Goerck 1999, Buzzetti land, scrub and urban environments. The forests in the region 2000, Cavarzere Junior 2010).