Personality influences habituation behaviour in ungulates

Clair CC. Aversive conditioning increases short-term wariness but does not change habitat use in black bears associated with conflict

Conflict between humans and black bears (Ursus americanus) occurs throughout North America with increasing public demand to replace lethal management with non-lethal methods, such as aversive conditioning (AC). AC aims to teach animals to associate negative stimuli with humans or their infrastructure. We sought to test the efficacy of AC using radio-collared black bears in Whistler, British Columbia, by monitoring individuals and assigning those in conflict with people to control or treatment groups. We measured wariness using overt reaction distance, displacement distance, and reaction to researchers before, during and after executing 3-5-day AC programs that consisted of launching projectiles at bears in the treatment group. We also assessed predictors of successful AC events (i.e., leaving at a run), changes in bear use of human-dominated habitat during the day and at night, and the effects of including a sound stimulus to signal the beginning and end of AC events. Among treated bears, overt reaction distance increased by 46.5% and displacement distance increased by 69.0% following AC programs, whereas both overt reaction distance and displacement distance decreased over time among control group bears. Each additional AC event during the previous 30 days increased likelihood of bear departure in response to researcher presence by 4.5%. The success of AC events varied among individuals, declined with distance to cover, and increased with exposure to previous AC events. Projectiles launched from guns were slightly more effective at causing bears to displace compared to those launched from slingshots, and sound stimuli decreased the likelihood of a successful AC event. AC did not alter diurnal use by bears of human-dominated habitat. Our results suggest that AC effectively increases short-term wariness in black bears but does not alter bear use of human-dominated spaces, highlighting the importance of proactive attractant management and prevention of food conditioning.

Individual differences in response to alcohol and nicotine in zebrafish: Gene expression and behavior

Alcohol and nicotine are psychoactive substances responsible for serious health consequences. Although the biological mechanisms of alcohol and nicotine have been studied extensively, individual differences in the response to these drugs have received little attention. Here we evaluated gene expression and behavior of bold and shy individuals after acute exposure to alcohol and nicotine. For this, zebrafish were classified as bold and shy individuals based on emergence tests, and then fish were exposed to 0.00, 0.10, and 0.50% alcohol or 0.00, 1.00, and 5.00 mg/L nicotine and their anxiety-like and locomotor behavior was observed. After behavioral assessment, brain mRNA expression (ache, bdnf, gaba1, gad1b, th1, and tph1) was evaluated. Locomotion patterns differed between profiles depending on alcohol and nicotine concentration. Anxiety increased in shy fish and decreased in bold fish after exposure to both drugs. Alcohol exposure induced an increase in tph1 mRNA expression in bold fish, while bdnf mRNA expression was increased in shy fish. Nicotine increased ache, bdnf, and tph1 mRNA levels in both profiles, but at higher levels in bold fish. Based on our research, we found that alcohol induces anxiogenic effects in both bold and shy zebrafish. Additionally, shy individuals exposed to a low concentration of nicotine exhibited stronger anxiety-like responses than their bold counterparts. These findings further support the validity of using zebrafish as a dependable tool for studying the effects of drugs and uncovering the underlying mechanisms associated with individual variations.