The Wilson Journal of Ornithology 124(1): 15-23, 2012 
A NEW AREA OF ENDEMISM FOR AMAZONIAN BIRDS IN THE RIO 
NEGRO BASIN 
SERGIO H. BORGES 1,3 ' 4 AND JOSE M. C. DA SILVA 2 
ABSTRACT.—We describe a new area of endemism for Amazonian birds which we designate as the Jau Area of 
Endemism. This area of endemism in central-western Amazonia north of the Rio Solimoes was identified through 
congruent distributions of six avian taxa: Psophia crepitans ochroptera Pelzeln 1857. Nonnula amaurocephala Chapman 
1921. Pteroglossus azara azara Vieilot 1819, Picumnus lafresnayi pusillus Pinto 1936. Synallaxis rutilans confinis Zimmer 
1935, and Myrmoborus myotherinus ardesiacus Todd 1927. The southern and eastern limits of this area of endemism are 
the middle courses of the Solimoes and Negro rivers, respectively. The northern limits apparently coincide with sandy soil 
vegetation along the middle Rio Negro. The western boundary remains undefined, but could involve the Japura or Iya rivers 
north of the upper Solimoes. Taxonomic studies and expansion of ornithological collections are needed to more precisely 
delimit the Jau Area of Endemism. It is possible the avian taxa restricted to the Jau Area of Endemism are derived through 
parapatric or peripatric speciation events from taxa whose ranges were centered in the Imeri and Napo areas of endemism. 
Alternatively, tectonic events that affect the lower course of the Rio Negro could influence bird distribution in this region if 
they serve as vicariance mechanisms. Received 27 June 2007, Accepted 15 July 2011. 
An area of endemism (AOE) is a "geographical 
region comprising the distributions of two or more 
monophyletic taxa that exhibit a phylogenetic and 
distributional congruence and having their respec¬ 
tive relatives occurring in other such-defined 
regions” (Harold and Mooi 1994:261). Areas of 
endemism are important for at least two reasons. 
First, they represent the smallest geographical 
units for postulating hypotheses about the history 
of their biotas (Cracraft 1988, 1994; Morrone 
1994; Morrone and Crisci 1995). Second, these 
areas are considered priorities for establishment of 
conservation action because they contain unique 
biotas (Fjeldsa 1993, Slallerslidd cl al. 1998). 
There are modern approaches to identifying 
AOEs including parsimony analyses of endemic- 
ity (Morrone 1994. Morrone and Crisci 1995, 
Silva et al. 2004) and optimality criterion (Szumik 
et al. 2002, Szumik and Goloboff 2004). Tradi¬ 
tionally. however, these areas have been identified 
through mapping the congruent geographical 
distribution of taxa based on extensive area of 
sympatry but not necessarily complete overlap of 
distributions (Platnick 1991). 
Eight AOEs have been recognized for birds in 
the Amazonian lowlands (Fig. I; Haffer 1974, 
Departamcnto de Zoologia. Museu Paraense Emilio 
Goeldi. Belem. Para. Brazil. 
‘Conservation International do Brazil, Avenue Nazare. 
541/sala 310. 66035-170, Belem. Para. Brazil. 
Current address: Fundayao Vitoria Amazonica, Rua R/ 
S. casa 07. Quadra Q. Morada do Sol. 69060-080. Manaus. 
AM. Brazil. 
4 Corresponding author; e-mail: sergio@fva.org.br 
1978; Cracraft 1985; Silva et al. 2002). Most 
areas have boundaries coinciding with major 
rivers of the Amazon Basin (Wallace 1852, 
Haffer 1978. Cracraft 1985. Ayres and Clutton- 
Brock 1992). We identified a number of avian 
taxa during a study of bird species distribution 
whose ranges apparently are restricted to the 
lower course of the Rio Negro (Borges 2004a, 
Borges 2007). Mapping the distributions of these 
taxa resulted in identification of an AOE not 
recognized in previous biogeographic anal¬ 
yses (Haffer 1978, Cracraft 1985). Our objec¬ 
tive is to describe the new area of endemism 
based on congruent distributions of six avian 
taxa. 
METHODS 
Study Area .—The study region encompasses the 
right margin of the lower Rio Negro (Fig. 2). Most 
specimens analyzed were collected in Jau National 
Park (JNP), one of the largest (2,272.000 ha) 
protected areas in Brazil. The avifauna of JNP has 
been studied for the last 15 years including 
assessment of species diversity and general eco¬ 
logical requirements for most bird species (Borges 
and Carvalhaes 2000; Borges et al. 2001; Borges 
2004a. b; Borges and Almeida 2011). 
Biogeographic Analysis.— We compiled a list 
of bird species and subspecies recorded in the 
study area (Borges et al. 2001, Borges 20()4a, 
Borges 2007, Borges and Almeida 2011). The 
taxonomic status and distribution of birds re¬ 
corded in the study region were evaluated 
through specimens housed at Museu Paraense 
Emilio Goeldi (MPEG), Museu de Zoologia da 
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