290 
THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123. No. 2. June 2011 
Shinipo Valley 
Study Area 
TzipaniValley 
□ 
Santeni Vallew^^Q 
Jb ^ Menkoremon 
, .Ovente'Wf-, 
' - I 
t, * -C~ 
Monte Tabor V' ••Si* • 1 
* 
20 km 
JZL'-Jrtl*? Ce r dcl Sira and Gran Pa j° nal ' Peru and digital elevation model depicting study area and location 
patches are pajonJes (TromScmU ^ ** SeCOndary sites surve y ed opportunistically. Black 
to the south by the valleys of the Tambo and 
Perene rivers (Fig. 1). The Cerros del Sira form a 
linear ridge extending 250 km roughly NNW to 
SSE, and located >100 km east of similar 
elevations in the Andes. The crest of the ridge is 
generally 1,300-1.700 m in elevation but in places 
exceeds 2,200 m. The ridge of the Sira is 
interrupted in two locations: a low (-1,000 in) 
saddle bisecting the range at 09 45' S. and the 
valley of the Unine River at 10 54' S. The spine 
of the Sira on the eastern slope is characterized for 
much of its length by a sheer cliff face intersected 
perpendicularly by steep ridges and valleys that 
descend cast to the Ucayali River. The western 
slope of the Sira descends relatively gradually 
and, at the southern end, levels into a plateau that 
averages -1,200 m in elevation and extends 
50 km to the west at its widest. This plateau is 
locally referred to as the Gran Pajonal, after the 
patches of savanna (“ pajonales ”) scattered over 
its surface, and retains a tenuous connection to the 
foothills of the Andes through a series of 
articulated ridges dividing the Chanchamayo and 
Paehitea valleys. Human population densities are 
low in the region surveyed and consist almost 
entirely of titled Asheninka indigenous commu¬ 
nities, except for a colonist settlement at Oventem 
(Hvalkof 1998). 
Climate .—A government report (ONERN 
1968) provides general climatological data for 
the region. The climate of the Cerros del Sira and 
Gran Pajonal is classified as humid subtropical 
Monthly mean high temperatures at Oventeni m 
the Gran Pajonal range from 28.3 C to 30.1 J C. and 
monthly mean low temperatures from 11-2 t° 
17.8 C. Rainfall at Oventeni averages a moderate 
2.166 mm annually and is concentrated between 
November and April. Weather data from the 
higher elevations of the Cerros del Sira are 
unavailable, but temperatures likely average lower 
