Figure 1.
A) Mean number of complete song bouts produced by male starlings during 2 test days after vehicle treatment and two test days after treatment with the opioid receptor antagonist naloxone; n = 14 in each condition, B) Mean bouts of feeding and drinking over the 2 test days for vehicle and naloxone treated males; C) Mean total times a male starling initiated song during 2 test days after treatment with vehicle and 2 test days after treatment with the opioid receptor agonist fentanyl; n = 14 in each condition, D) Mean bouts of feeding and drinking over the 2 test days for vehicle and fentanyl treated males. * indicates p< 0.05. Figures A and B redrawn from data reported in (Riters et al., 2005). Figures C and D redrawn from data reported in (Schroeder and Riters, 2006).