Comparative Ecology of Pinyon Mice and Deer Mice in Mesa Verde National Park, Colorado

by Charles L. Douglas

Table 7—Food and Water Consumption of Peromyscus maniculatus and P. truei When Fed Diets of Different Protein Content. Food and Water Consumption Are Determined for the Grams, or Milliliters, Consumed per Gram of Body Weight per Day; Daily Totals Are also Given.

Peromyscus maniculatus rufinus
Diet per cent protein	No. mice	Food /gram /day ± S. D.	Total grams /day	Water /gram /day ± S. D.	Total water /day
Lab Chow 23	9	.201 .074	4.455	.262 .183	5.751
Hog Chow 36	10	.238 .060	5.232	.496 .186	10.749
Corn 11	11	.149 .044	3.144	.174 .012	3.696
Peromyscus truei truei
Diet per cent protein	No. mice	Food /gram /day ± S. D.	Total grams /day	Water /gram /day ± S. D.	Total water /day
Lab Chow 23	10	.216 .070	6.353	.373 .119	10.880
Hog Chow 36	10	.230 .079	6.966	.653 .189	19.571
Corn 11	10	.158 .010	4.318	.332 .016	9.034

The tendency of both species to eat more of the hog chow than they ate when fed standard laboratory chow may reflect a higher palatability of the hog chow. Both species consumed similar amounts of food per gram of body weight, on each of the diets ([Table 7]). The larger P. truei requires more grams of food per day than the smaller P. maniculatus, but this slight difference in food consumption probably has no effect on the distribution of these species within Mesa Verde.

The results obtained with the low protein diet were strikingly different from those of the first two experiments. In this experiment the same groups of mice were placed on a diet of whole, shelled corn for a period of six weeks. The corn contained less than 11 per cent protein, about three per cent fat, and about 80 per cent carbohydrate.

By the end of the first week, on the low protein diet, all mice had reduced their water intake by about half the amount used per day on the high protein diet ([Table 7]). There was not a statistically significant difference, for either species, between the average amounts of water drunk in the first and in the sixth weeks of the experiment.

The data in [Table 7] show that on all three diets, individuals of P. maniculatus drank less water per gram of body weight than individuals of P. truei. Variation in water consumption was high; some individuals of P. maniculatus that drank more than the average amount for the species, consumed as much water as some individuals of P. truei that drank less than the average amount. In general, individuals of P. maniculatus drank about half as much water each day as individuals of P. truei. Individuals of both species were consistent in their day-to-day consumption.

Table 8—Amounts of Mean Daily Water Consumption as Reported in the Literature for Species of Peromyscus. Figures in Parentheses are Means; Those Not in Parentheses Are Extremes.

	Mean daily ml./gm. wt./day	Water consumption total ml. per day	Temperature	Humidity	Per cent dietary protein	Investigator
	(.262)	(5.70)
P. m. rufinus	.124-.699	2.71-15.07	20-23	low	23	[A]
P. m. rufinus	(.101)	(2.39)	20-25	24-47		[B]
P. m. osgoodi	.16-.25	3.2-4.3	18-22	10-20	23	[C]
	(.126)	(1.74)
P. m. bairdii	.082-.177	1.12-2.72	21	25-68		[D]
P. m. bairdii	.124-.182	(2.37-3.17)	20-25	24-47		[B]
	(.372)	(10.80)
P. t. truei	.224-.561	7.0-16.92	20-23	low	23	[A]
P. t. truei	(.085)	(2.77)	20-25	24-47		[B]
P. l. nov.	.057-.117	1.36-2.29	21	25-68		[D]
P. l. nov.		(5.36)	18	62.5		[E]