throughout their tropical and subtropical range of distribution , primates occupy a wide variety of different habitats ( fleagle 1999 ) .
few primate species seem to be confined to a single habitat type , e.g. , theropithecus gelada to montane grasslands ( kawai 1979 )
. some others may require the presence of a specific habitat type in at least part of their home range , e.g. , bamboo forest in callimico goeldii ( porter and garber 2004 ) .
however , supposed habitat specialization may actually be the result of limited knowledge of a species that can be specified once additional information becomes available ( defler 1994 ) , and may also be the result of incorrect inference and ignorance of relevant literature .
uakaris ( cacajao ) , and particularly the peruvian red uakari ( cacajao calvus ucayalii , previously included within cacajao calvus rubicundus : hershkovitz 1987 ) , represent an example of the latter case . in a survey in the rio tapiche area in eastern peru , fontaine ( 1978 , 1990 ) encountered cacajao calvus ucayalii on 3 occasions : 1 ) in swamp forest or aguajal ( swamps dominated by the aguaje palm mauritia flexuosa ) ; 2 ) on a restinga ( strip of high - ground forest within a low - ground matrix ) from where the uakaris fled into an aguajal ; and 3 ) on the edge of an aguajal .
 this perception of cacajao calvus ucayalii and of uakaris in general dominates in the primatological literature , despite accumulating evidence to the contrary . in many primatological textbooks and overview articles , uakaris in general
the fact that the first detailed field study on any uakari species reported the closely related white uakari ( cacajao calvus calvus ) to be confined to vrzea ( forest seasonally flooded by white - water rivers ; ayres 1986 , 1989 ; cf . peres 1997 ) may have contributed to cementing this incorrect perception of red uakaris as a flooded - forest specialist .
published evidence for the occurrence of cacajao calvus ucayalii in nonflooded forests seems to be largely ignored . to correct this bias
, we reviewed the available information , both published and unpublished , about habitats where cacajao calvus calvus has been observed .
we hope that this review will correct the perception of this taxon as a flooded - forest specialist .
such a correction is necessary both for scientific reasons , e.g. , for the interpretation of its morphological and behavioral adaptations , and for the sake of appropriate considerations on the conservation of peruvian red uakaris . 

table  iexamples for statements on cacajao calvus ucayalii ( or cacajao in general ) as flooded - forest specialistsstatementsourcespecialized to flooded whitewater and blackwater forestsrobinson et al.1987 , p. 47uakaris
appear to be restricted to the amazonian inundation forest.preston-mafham and preston - mafham 1999 , p. 60they
red uakari occurs nearly always in blackwater flooded forest , while the white subspecies prefers whitewater flooded forest.janson 2001 , p. 325found
in the flooded forests of the white - water rivers of the upper amazondunbar and barrett 2000 , p. 164uakaris ...
[  uakaris ... are specialized to live in seasonally flooded forests.]geissmann 2003 , p. 162white and red uakaris ( cacajao calvus ) being associated with white - water forests ( vrzeas)ferrari 2004 , p. 109they
inhabit flooded forests.nystrom and ashmore 2008 , p. 57 examples for statements on cacajao calvus ucayalii ( or cacajao in general ) as flooded - forest specialists
we studied the available literature and unpublished reports , and compiled personal observations or personal communications on the habitat of cacajao calvus ucayalii . for each area , we extracted information on the habitats where cacajao calvus ucayalii had been observed and categorized these as 1 ) terra firme forest , 2 ) flooded forest , and 3 ) aguajales .
we also compiled the available data on population densities and encounter rates to determine whether habitat influences these variables .
the majority of sites where cacajao calvus ucayalii has been recorded represent terra firme forest ( table  ii ) .
this holds true even if 1 ) quebrada blanco and the estacin biolgica quebrada blanco , which are located on opposite banks of the same river only about 2  km apart , and the nearby sites at quebradas cuchara , palmichal , tahuaillo , tangarana , and tuncho ; and 2 ) agua negra and lago preto on the ro yavar are considered as nonindependent counts , perhaps harboring the same populations of cacajao calvus ucayalii . 

table  iilocalities and habitats in peruvian amazonia where cacajao calvus ucayalii has been recordedlocality coordinateshabitataltitude [ m a.s.l.]population density or encounter ratesourcero tapicheaguajaln.a.n.a.fontaine 1978 , 1990ro tapiche 539s 7400wterra firme , flooded forest , aguajal1101 ) 0.47 grp / km , 7.4 ind / kmbennett et al .
20012 ) 0.78 grp / km , 25.8 ind / kmalto tapicheflooded forestn.a.0.23 grp / kmaquino 1988 , 1990jenaro herreraterra firmen.a.0.07 grp / kmaquino 1978 , 1988 , 1990quebrada blancoterra firme , aguajal120n.a.ramirez 1989 ; bodmer and fang 1987estacin biolgica quebrada blanco ( ebqb ) , 421s 7309wterra firme120n.a.bartecki and heymann 1987 ; siegel 1987 ; heymann 1989 , 1990 ; castro coronado 1991 ; heymann et al . unpubl .
dataheadwaters of quebrada blancoterra firmen.a.n.a.bodmer and fang 1987quebrada cuchara 424s 7310wterra firme , aguajaln.a.n.a.leonard and bennett 1995 , 1996 ; aquino 1998quebrada tunchoterra firme , aguajaln.a.n.a.aquino 1998quebrada palmichalterra firme , aguajaln.a.n.a.aquino 1998quebrada tangarana 424s 7317wterra firmen.a.n.a.ward and chism
2003quebrada tahuaillo 433s 7319waguajaln.a.n.a.ward and chism 2003ro tahuayo area  n.a.0.4 grp / kmbodmer et al .
1988 ; puertas and bodmer 19932.5 ind / kmro orosaterra firmen.a.0.4 grp / kmaquino 1988 , 1990sierras de contamanaterra firme , aguajal>6006.1 grp/100  km , 479 ind/100  kmaquino et al .
carolina 430s 7143wterra firme , flooded forest , aguajaln.a.n.a.aquino 1997 , 1998 ; aquino and encarnacin 1999lago preto ( agua negra ) , ro yavar 428s 7146wterra firme , flooded forest , aguajal90n.a.puertas and bodmer 1993 ; bowler 2007 ; bowler and bodmer 2009upper ro yavarterra
2009population density is given as per survey area ( individuals : ind / km , groups : grp / km ) , encounter rates as per transect length ( individuals : ind/100  km , groups : grp/100  km)n.a .
: no data availablethese sources quote the site as ro blanco or blanco stream ; to avoid confusion with the proper ro blanco , a major affluent of the ro tapiche , the river was renamed quebrada blancothese sources also quote ro blanco , but actually refer to the estacin biolgica quebrada blanco ; see previous footnotethe habitats where cacajao calvus calvus were sighted are not mentioned by the authors , but the census area includes terra firme forest and aguajales , but not flooded forest localities and habitats in peruvian amazonia where cacajao calvus ucayalii has been recorded population density is given as per survey area ( individuals : ind / km , groups : grp / km ) , encounter rates as per transect length ( individuals : ind/100  km , groups : grp/100  km ) n.a .
: no data available these sources quote the site as ro blanco or blanco stream ; to avoid confusion with the proper ro blanco , a major affluent of the ro tapiche , the river was renamed quebrada blanco these sources also quote ro blanco , but actually refer to the estacin biolgica quebrada blanco ; see previous footnote the habitats where cacajao calvus calvus were sighted are not mentioned by the authors , but the census area includes terra firme forest and aguajales , but not flooded forest the highest encounter rates for cacajao calvus ucayalii stem from the sierras de contamana ( table  ii ) , a site that is not only a terra firme forest , but also has a much higher altitude ( 600700  m  a.s.l . ) than any of the other sites .
we here provide clear evidence that cacajao calvus ucayalii occurs not only in flooded forests , but also in terra firme forests and in areas with a mixture of forest types .
the terra firme forests ( or bosques de altura in the terminology of encarnacin 1985 ) include a variety of vegetation types like high terrace forest ( bosque de terraza ) , low hill forest ( bosque de colina baja ) , high hill forest ( bosque de colina alta ) , premontane forest , and aguajales de altura ( see also malleux 1982 , for terminology of peruvian forests ) that are all nonflooded .
therefore , one can not consider cacajao calvus ucayalii as a flooded - forest specialist , as is commonly reported in the literature .
the highest encounter rate and thus probably the highest population density is found at a relatively high altitude ( sierras de contamana ) , untypical for the major part of the amazon lowlands , suggesting that this habitat might be favorable to cacajao calvus ucayalii . however , because the sierras de contamana is an area with very little human disturbance ( aquino et al .
2005 ) , we can not distinguish whether this factor or favorable habitat accounts for the high encounter rate .
cacajao calvus ucayalii have large daily ranging distances ( > 6  km : bowler 2007 ; 7.3  km : leonard and bennett 1996 ) and they may migrate seasonally between different habitats , including flooded forests ( bowler 2007 ) . in the quebrada blanco area ,
810  km away along the ro tahuayo and the lower parts of quebrada blanco .
given the daily ranging distances quoted above , this forest is in the reach of cacajao calvus ucayalii .
nevertheless , neither researchers and their field assistants nor local settlers have ever seen these animals in flooded forest along the ro tahuayo and lower quebrada blanco in the last 25  yr .
aguajales , swamps dominated by aguaje palms ( mauritia flexuosa ) , occur both in forests subject to inundation and in areas of terra firme ( where they are called aguajales de altura ; encarnacin 1985 ) . though mauritia flexuosa may represent an important food resource for cacajao calvus ucayalii in some areas ( aquino and encarnacin 1999 ; bowler 2007 ) , it is probably not essential for the existence of these uakaris , as indicated by their rarity in the sierras de contamana ( aquino et al . 2005 ) .
altogether , we can reasonably conclude that cacajao calvus ucayalii is not a habitat specialist restricted to flooded forests .
together with the report by peres ( 1997 ) of cacajao calvus calvus at a terra firme site , this indicates that habitat requirements and utilization in bald - headed uakaris are much more variable than previously appreciated .
incorrect perceptions of or misconceptions on aspects of the biology of a primate taxon may have several implications .
first , they may lead to erroneous interpretations of the behavioural , ecological , morphological , and physiological adaptations and the evolution of these adaptations .
second , they may lead to bad conservation strategies , particularly when habitat preferences are concerned . though the first implication is mainly academic ,
the second one is of strong practical relevance . in a world , where primate habitats are constantly shrinking and an increasing number of primate taxa is getting closer to extinction , accurate knowledge of habitat requirements are amongst the most basic information needed for conservation efforts .
 in the literature , particularly in primatological books , the peruvian red uakari ( cacajao calvus ucayalii ) is generally considered as a species that is specialized on living in flooded forest , despite existing evidence to the contrary . here 
 we review all available information on habitats where cacajao calvus ucayalii have been observed . 
 most sightings are from terra firme , including palm swamps , or from mixed habitats , including terra firme and flooded forest . 
 therefore , we conclude that the species is not a flooded - forest specialist , but is flexible in its habitat requirements and generally uses terra firme forests or a mixture of habitats . proper recognition of habitat requirements is important for understanding the ecoethological adaptations of a species and for appropriate conservation measures . 
Introduction
Methods
Results
Discussion