126 



NORTH AMERICAN FAUNA 75 



Scotinomys teguina 

 Alston's Brown Mouse, Rat6n 



Alston's brown mouse is found at higher elevations from southern Mexico 

 to the Chiriquf mountains of western Panama (Fig. 98). Two subspecies of Alston's 

 brown mouse occur in Costa Rica, Scotinomys teguina irazu throughout most of 

 the mountainous regions of the country and S. t. apricus in extreme southern Costa 

 Rica. 



Scotinomys is an abundant rodent in a wide variety of habitats. It is apparently 

 highly insectivorous and uses audible high-pitched vocalizations for intraspecific 

 communication. Brown mice are active during daylight as well as at night. 



We captured four adult females in mid- April. One carried two embryos in the 

 left uterine horn with crown-rump lengths of 11 mm; one had four recent placen- 

 tal scars, three in the left uterine horn and one in the right; one was lactating; and 

 one had no embryos. A juvenile male was captured on 13 April. Scotinomys was 

 frequently captured during the day, attesting to the diurnal activity of these insec- 

 tivorous rodents. 



Specimens examined (17)— 2 km N, 0.5 km E of Sacramento, 2,600 m 

 [2 males, 2 females, UNA]; San Jose de la Montana, Paso Llano, 1,800 m [1 male, 

 2 females, 3 unknown, KU]; 9 km S, 11.5 km E of San Miguel, 1,500 and 1,520 m 

 [1 male, 3 females, FMNH; 1 female, UNA]; 5 km E of Vara Blanca, 2,050 m 

 [1 male, 1 female, UNA]. 



Additional records (2)— 1.2 mi N of Angel Falls [2, LACM]. 



Fig. 98. Alston's brown mouse, Scotinomys teguina. Photo by B. L. Clauson. 



