96 



F. BOURLIERE 



be 17-4 and 31-5 weeks respectively. Such figures contrast 

 sharply with a potential longevity of six to eight years, 

 recorded in captivity. 



The same situation occurs in the Tulare kangaroo rat. 

 Fitch (1948) reported that 35-2 per cent of the Dipodomys 

 heermani taken during a four-year live-trapping programme 



Table I 



Summary of survival figures for 12 species and 



SUBSPECIES OF RATS IN MaLAYA (AFTER HARRISON, 1956) 



had records that extended over not more than one month, 

 34 • 2 per cent had records of one to six months on the study 

 area, and only 4-7 per cent had records extending for more 

 than a year. The longest record was 33 months for an in- 

 dividual marked as a partly-grown juvenile. Other instances 

 of short expectation of life at birth in wild rodents are reported 

 by Blair (1953) and Bourhere (1954). 



Larger rodents have a shghtly longer mean longevity in 

 natural conditions. Kalabouchov (1933) found that 31-5 per 



