In four newborn young, total lengths, in mm., were 47, 45, 45, and 42.
From the length-weight relationships shown in Fig. 2, it seems that a
length of approximately 47 mm. is typical of newborn young of average
weight. Martin (1956:388) found a mean weight of 2.8 +- 0.36 grams in
sixteen newborn prairie voles from the Reservation. For a series of 67
other newborn voles representing 27 different litters in seven
different years, I found an average of 2.9 +- .05 grams. Young ranged
in weight from 3.8 to 2.0 grams. Weights of the newborn voles could
not be correlated with season, size, age of females, or food
conditions. However, a distinct trend toward larger size in those
litters that contained fewer young was evident, as shown in Table 4.
Table 4. Weight of Newborn Young, Correlated with Number of Young
per Litter.
==============+============+============+===========
| Mean | Number | Number
Known Young | weight | of litters | of young
Per Litter | in grams | in sample | in sample
--------------+------------+------------+-----------
2 | 3.1 +- .09 | 7 | 13
3 | 3.0 +- .17 | 11 | 28
4 | 2.7 +- .22 | 6 | 17
5 | 2.6 +- .42 | 3 | 9
--------------+------------+------------+-----------