Definitions of variables included in the data files

File S1:

"Bird" = bird ID            
"sex" = sex where 1 = male and 2 = female            
"Natal_nest"  = ID of the nest in which the chick hatched     
"Treatment"  = brood size treatment group      
"Nestmates_above" = number of heavier competitors on d15
"Weight_D11"  = weight in g on d11    
"AvTarsus_D55"  = average tarsus length in mm on d55  
"TLday4"  = T/S ratio on d4        
"TLday55"  = T/S ratio on d55        
"Weight_CB_in"  = weight in g at start of cognitive bias experiment 
"LFTrialsFlip" = number of trials to learn to lid flip   
"DTDaysCritMW" = number of sessions to learn POS/NEG discrimination   
"TEpropNgo"  = proportion of NEG trials with a go response in testing     
"POS_mean"   = mean latency to probe in POS test trials     
"NEG_mean"    = mean latency to probe in NEG test trials   
"MazurK"  =  impulsivity measure from Bateson et al. 2015 paper

File S2:

"Date"   = date on which data were collected       
"Replicate"   = experimental replicate (1-4)  
"Phase"   = phase of the experiment (TE = test phase)      
"Trial"   = trial number      
"Bird"    = bird ID     
"Valence"   = type of trial (1-5)    
"Reinforcement" = whether trial was reinforced where 1 = yes and 0 = no
"LatencyAttack" = latency to probe lid in s