Vo 1. 13, ilo. C 
Page 3 
remains intriguing, however, because in the vicinity of both grounds an 13-acre 
site was plowed and 10 acres of a 20 -acre redtop meadow were burned for the 
express purpose of providing suitable sites for booming--but no booming occurred 
on either site. 
6 . Rabbi t (lanageroent G. 0. Rose 
The energy consumed by cottontail rabbits has been measured, and the energy 
assimilated has been estimated, from late February through June, as described in 
til/RL 13(2) :4-5* The estimates of energy assimilated are also estimates of 
energy metabolized, since these are adult rabbits and growth is negligible. 
Rabbits maintained in outdoor pens in late February, early April, early 
liay, mid-iiay, early June, and mid-June consumed averages of 412, 3>5> 405; 475; 
370 ; and 3^2 kcal of commercial rabbit chow per day, which, with an assimila¬ 
tion efficiency of 03 percent, represents 2 o 0 , 24.,, 305; 233; 233; and 241 kcal 
of energy assimilated per day. Rabbits kept in outdoor cages consumed averages 
of 334; 323; 303 ; 27^; 237; and 24C kcal of rabbit chow per day, and assimilated 
210 , 206 , 1 ^ 5 ; 175 ; 143; and 155 kcal per day, respectively, for the six time 
periods mentioned above. The greater amounts of energy assimilated (and hence 
the greater amounts metabolized) by the penned animals represent their greater 
activity, compared with that of animals confined in the much smaller cages. 
A decreasing trend in energy utilization from late winter to early summer 
appears to exist for the caged animals, but none is evident for those in the 
pens. 
Higher energy requirements at low winter temperatures than at high summer 
temperatures may be expected in homoiothermic animals, hence the decreasing 
trend in energy utilization by the caged animals. The animals in the pens* 
although requiring less energy for thermoregulation in the summer than In 
winter, may be more active in the summer, thus obscuring their reduced 
requirement for thermoregulation. 
