data_first_reproduction.txt:

data: age at first reproduction as asubset of the data (age_at_first_reproduction) and all data categorized in two discrete age classes (reproductive_age_category)
age: known age at first reproduction
earlier_first_ reprodction: earlier first reproduction (1) or later first reproduction (0)
sex: female or male
PopSize: number of territories (i.e., the number of scent-marking pairs and family groups) during the monitoring season that preceded reproduction
PrimOri: primiparous litters were defined as litters where both parents were first-time breeders (yes) and multiparous litter when at least one of the parents had bred before (no)
PartExp: reproductive experience of the partner for a given first-time breeder whether the partner had bred before (yes) or not (no)
F: inbreeding coefficient
ImmRel: immigrant relationship classified as first immigrant descendants (F1), second immigrant descendants (F2), third-generation immigrant descendants (F3), or native inbred (native_inbred)