Monteith et al. (2009) examined the maternal life history characteristics of white-tailed deer (Odocoileus virginianus) originating from the Black Hills in southwestern South Dakota and from eastern South Dakota. Because litter size and dam size affects offspring weight the investigators used proportional birth mass (dam mass/total litter mass) as a measure of reproductive investment by deer.
data(deer)The dataframe contains 6 columns
Birth.YrYear of birth.
Litter.sizeNumber of offspring.
RegionCategorical variable with two factor levels. BH = Black Hills, ER = Eastern Region.
Dam.weightDam weight in kg.
Total.birth.massMass of litter in kg.
Prop.massTotal birth mass divided by dam weight.