LA SELVA-BRAULIO CARRILLO MAMMALS 



121 



Table 2. Reproductive characteristics of five adult (weight > 36 g) female Oryzomys 

 caliginosus from Heredia Province, Costa Rica.^ 



Date of capture 



Reproductive characteristics 



27 March 1986 



numerous placental scars 



28 March 1986 



3 embryos (1L-2R) 



30 March 1986 



pubic symphysis open, mammae enlarged; released 



8 April 1986 



3 embryos x 24 mm (1L-2R) 



10 AprU 1986 



3 recent placental scars (2L-1R) 



'Additionally, one female weighing 30.0 g had recently given birth; other females weighing 30, 32, 

 and 36 g were nulliparous. Two females weighing more than 36 g were not reproductively active. 



Oryzomys fulvescens 

 Pygmy Rice Rat, Raton 



Pygmy rice rats are found from central Mexico to eastern Panama (Fig. 95). 

 Perhaps as many as four subspecies of Oryzomys fulvescens are found in Costa 

 Rica, although the status of each of these taxa is in need of review. These subspecies 

 include: O. f costaricensis , O. f creper (the subspecies occurring at La Selva), 

 O. f pacificus, and O. f vegetus. 



Pygmy rice rats are the smallest Oryzomys found in Costa Rica and among 

 the smallest of all rodents found in the country. They are nocturnal and semiarboreal. 



Fig. 95. Pygmy rice rat, Oryzomys fulvescens. Photo by B. L. Clauson. 



