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The strength of an animal's behavioural response to human presence has often been used as an index of an animal's susceptibility to disturbance. However, if behavioural responsiveness is positively related to the animal's condition, this may be an inappropriate index, as individuals showing little or no response may in fact be those with most to lose from changing their behaviour. We tested the link between individual state and responsiveness by manipulating condition via the provision of supplementary food for turnstones, Arenaria interpres, on rocky shores. Birds at one site were fed 450 g of mealworms at low tide every day for 3 days while birds at another site acted as a control. On the fourth day, using a standardized disturbance protocol, we recorded flush distances, flight lengths and the amount of time between predator scans for birds in both flocks. After a break of 3 days, the treatments were then swapped between sites and the procedure repeated for a total of six trials. Birds whose condition had been enhanced showed greater responsiveness to standardized human disturbance, flying away at greater distances from the observer, scanning more frequently for predators and flying further when flushed. These findings suggest that our current management of the impact of human disturbance may be based on inaccurate assessments of vulnerability, and we discuss the implications of this for refuge provision

Animal. --- Assessment. --- Behaviour. --- Bird. --- Choice. --- Control. --- Distance. --- Food. --- Human. --- Management. --- Predator. --- Provision. --- Refuge. --- Response. --- Responses. --- Strength. --- Susceptibility. --- Time. --- Treatment.

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The present study assessed alterations in mesolimbic enkephalin (ENK) mRNA levels after predator [2,5-dihydro-2,4,5-trimethylethiazoline (TMT)] and non-predator (butyric acid) odor encounter and/or light-dark (LD) testing in CD-1 mice immediately, 24, 48 and 168 h after the initial odor encounter and/or LD testing. The nucleus accumbens, ventral tegmental area, basolateral (BLA), central (CEA) and medial amygdaloid nuclei, prelimbic and infralimbic cortex were assessed for fos-related antigen (FRA) and/or ENK mRNA as well as neuronal activation of ENK neurons (FRA/ENK). Mice exposed to TMT displayed enhanced freezing and spent less time in the light of the immediate LD test relative to saline- or butyric acid-treated mice. Among mice exposed to TMT, LD anxiety-like behavior was associated with increased FRA in the prelimbic cortex and accumbal shell and decreased ENK-positive neurons in the accumbal core. Mice displaying high TMT-induced LD anxiety exhibited increased ENK-positive neurons in the BLA, CEA and medial amygdaloid nuclei relative to mice that displayed low anxiety-like behavior in the LD test after TMT exposure. In the BLA and CEA, 'high-anxiety' mice also displayed increased FRA/ENK after TMT exposure and LD testing. In contrast to neural cell counts, the level of ENK transcript was decreased in the BLA and CEA of 'high-anxiety' mice after TMT exposure and LD testing. These data suggest that increased FRA may regulate stressor-responsive genes and mediate long-term behavioral changes. Indeed, increased ENK availability in mesolimbic sites may promote behavioral responses that detract from the aversiveness of the stressor experience

Accumbens. --- Activation. --- Activity. --- Amygdala. --- Anxiety-like behavior. --- Anxiety. --- Area. --- Behavior. --- Behavioral-responses. --- Butyric acid. --- Cortex. --- Defensive behavior. --- Double dissociation. --- Emotional responses. --- Enkephalin. --- Experience. --- Exposure. --- Expression. --- Extended amygdala. --- Fos-related antigen. --- Freezing. --- Gene. --- Genes. --- Individual-differences. --- Infralimbic cortex. --- Infralimbic. --- Level. --- Light. --- Long-term. --- Male-rats. --- Mice. --- Neuronal. --- Neurons. --- Nucleus accumbens. --- Nucleus-accumbens. --- Nucleus. --- Odor. --- Posttraumatic-stress-disorder. --- Predator odor. --- Predator. --- Prelimbic. --- Response. --- Responses. --- Self-stimulation. --- Stressor. --- Test. --- Time. --- Unconditioned fear. --- Ventral tegmental area.