144 
Edward M. Lunk 
DISCUSSION 
My sample, though admittedly small, nonetheless produced a 
strongly significant relationship between a massdength ratio (head 
length, in this case) and total body fat content in cottontails in the 
area studied. Total mass and head-length, in particular, are readily 
obtained from live cottontails handled by one person in the field. 
Because of the demonstrated relationship between the index and to- 
tal body fat content, the index could indicate habitat quality for 
cottontails, though the relationship between body fat and habitat 
could be complex. 
Jacobson et al. (1978) postulated a positive correlation between 
adequacy of diet and fat stores. Chapman et al. (1977) observed a 
geographic gradient of increasing body fat in western Maryland co- 
inciding with increasing severity of winter weather. Thomas (1987) 
however, postulated that leporids could optimize fat storage with 
the likelihood of predation and starvation so that rabbits in low 
quality habitats would tend to begin winter with higher fat levels 
than those in better quality habitats. Jacobson et al. (1978) and 
Chapman et al. (1977) observed seasonal fluctuations in several con- 
dition and fat indexes as well as variations between sexes, though 
female cottontails tended to be in better condition in the spring 
than were males. Due to possible sex and season effects on body 
fat, sex ratios of samples and the season of application should be 
standardized. This preliminary model should be verified on an 
independent set of data before being used as a predictor of fat 
content. 
Lack of significant relationship between fat and body length 
could have been partly due to inaccurate measurements caused by 
inconsistent body extension. Bailey (1968) described such error in 
measuring total body length (tip of nose to tip of fir at end of 
fully extended hind legs) of live cottontails. Use of calipered head- 
length avoids errors related to body extension. If sufficiently accu- 
rate measurements of total length could be obtained, total length 
might prove to be a better predictor. Usefulness of other body di- 
mensions should be investigated. 
ACKNOWLEDGMENTS — I wish to thank Terry Coffey, Dennis 
Herman, the NCSU Department of Animal Science and Hershell Ball, 
the NCSU Department of Food Science, for use of equipment, mate- 
rials, and lab space and for advice on the chemical analyses. Carl 
Betsill, North Carolina Wildlife Resources Commission, made valu- 
able suggestions at the beginning of the study and provided support 
