Adoption of non-genetic offspring occurs in a variety of species, but is rare in equids. We report a case of adoption by a free-ranging, feral mare (Equus caballus) and compare the maternal care received by her genetic offspring (born 1995) to that of her adopted offspring (born 1996) for the first 30 weeks of development. We compare five measures of care: 1) total time spent suckling, 2) mare aggression during suckling, 3) number of mare-terminated suckling bouts, 4) contact maintenance, and 5) mare-foal distance. For most behaviors, we detected no difference in the mare's treatment of the two foals, however, mare-foal distance was greater for the genetic offspring. We compare hypotheses regarding the reasons for adoption, offering post-partum physiological state as a potential driver.
Aggression Data
aggression by mares during suckling; data collected in the field; Microsoft Excel; MareCat.=mare category; FoalCat=foal category; TOD=time of day; em=early morning; lm=late morning; ea=early afternoon; la=late afternoon; TotAgg=total number of aggressive acts by mares during suckling.
Contact Data
contact maintenance between mares and foals; data collected in the field; Microsoft Excel; foalcat=foal category;perc.app=percent of movements that were approaches by the foals; perc.leave=percent of movements that were leaves by the foals; diff.percapp.percleave=%approaches-%leaves by the foals
Distance Data
distance between mares and foals; data collected in the field, Microsoft Excel; MareCat=mare category; FoalCat=foal category; TOD=time of day; EM=early morning; LM=late morning; EA=early afternoon; LA=late afternoon; Distmeters=distance between mares and foals in meters.
Dist Data AmNat 051713.csv
Intake Rate Data
intake rate (suckling bouts/hour*suckling bout duration) by foals; data collected in the field; Microsoft Excel; MareCat=mare category; FoalCat=foal category; SUEM=number of suckling bouts in the early morning; SULM=number of suckling bouts in the late morning; SUEA=number of suckling bouts in the early afternoon; SULA=number of suckling bouts in the late morning; TotSU=total number of suckling bouts; TotTime Hrs= total hours foals were watched; su.per.hr=suckling bouts per hour; sec.per.bout=duration of bouts in seconds; su.hr.sec.bout=suckles/hour * seconds/bout.
Suckling Termination Data
termination of suckling by the mares; data collected in the field; Microsoft Excel; TOD=time of day; em=early morning; lm=late morning; ea=early afternoon; la=late afternoon; Term=terminator of suckling; m=mare; f=foal; Termdum=dummy variable for terminator of suckling; 1=mare; 0=foal.
Term Data AmNat 051713.csv
Weather Data
temperature and precipitation data for 1995 and 1996; data collected from National Climate Data Center. 2009. (accessed August 17, 2009), http://www.ncdc.noaa.gov/oa/climate/climatedata.html#monthly; Microsoft Excel; T=temperature; max=maximum; min=minimum; sumprcp=sum precipitation.
1995_1996 weather.xlsx