Response to food restriction, but not social information use, varies seasonally in captive cardueline finches.

For songbirds, temperate winters can impose severe conditions on songbirds that threaten survival, including shorter days and often lower temperature and food availability. One well-studied mechanism by which songbirds cope with such conditions is seasonal acclimatization of thermal metabolic traits, with strong evidence for both preparative and responsive changes in thermogenic capacity (i.e., the ability to generate heat) to low winter temperature. However, a bird's ability to cope with seasonal extremes or unpredictable events is likely dependent on a combination of behavioral and physiological traits that function to maintain allostatic balance. The ability to cope with reduced food availability may be an important component of organismal response to temperate winters in songbirds. Here we compare responses to experimentally reduced food availability at different times of year in captive red crossbills (Loxia curvirostra) and pine siskins (Spinus pinus) - two species that cope with variable food resources and live in cold places - to investigate seasonal changes in the organismal response to food availability. Further, red crossbills are known to use social information to improve response to reduced food availability, so we also examine whether use of social information in this context varies seasonally in this species. We find that pine siskins and red crossbills lose less body mass during time-restricted feedings in late winter compared to summer, and that red crossbills further benefit from social information gathered from observing other food restricted red crossbills in both seasons. Observed changes in body mass were only partially explained by seasonal differences in food intake. Our results demonstrate seasonal acclimation to food stress and social information use across seasons in a controlled captive environment and highlight the importance of considering diverse physiological systems (e.g., thermogenic, metabolic, digestive, etc) to understand organismal responses to environmental challenges.

Obligate versus rich patch opportunism: evolution and endocrine mechanisms.

Opportunistic breeding has been hypothesized to evolve in response to rare or unpredictable resource pulses. In this traditional view of opportunism, individuals invest heavily in reproduction whenever conditions are permissive for breeding, perhaps at the expense of investment in survival. We term this strategy 'obligate opportunism' (OBO). We also present an additional strategy that could account for the evolution of opportunism. High mobility may allow individuals to move between rich patches of resources that are spatially or temporally unpredictable, reducing exposure to food scarcity and taking advantage of breeding opportunities. This strategy, which we term 'rich patch exploiter' (RPE), predicts that investment in survival-enhancing processes may occur at the expense of reproduction despite high resource availability. We review examples to determine which opportunists better match predictions from the OBO strategy or the RPE strategy and then review endocrine profiles in the context of the two strategies.

Early findings from a pharmacokinetically designed double-blind and placebo-controlled study of lithium for adolescents comorbid with bipolar and substance dependency disorders.

1. This manuscript reports the early findings from a National Institute on Drug Abuse funded study of lithium for adolescents dually diagnosed with bipolar and substance dependency disorders. The authors elected to publish early findings in the hope that it would accomplish a twofold mission. 2. The first part would be to encourage other investigators to participate in research in this area and the second would be to heighten the awareness of clinicians that adolescents presenting with either one of these disorders might also have the other. 3. The early findings demonstrated the feasibility of recruiting, retaining and monitoring this complex population on an outpatient basis. 4. Steady-state serum lithium levels were pharmacokinetically placed in the study range, 0.9-1.3 mEq/L. Preliminary results are encouraging in finding lithium more effective than placebo for alleviating both the substance dependency and the mood disordered symptomatology. 5. The characteristics of the study population to date have been chronicity of both disorders, impairment in the severe range in multiple areas of functioning, and strong family histories for both affective and substance use disorders. The substance dependency was to both alcohol and marijuana; but all subjects also had marked polydrug abuse. 6. In order to best monitor lithium compliance and drug/alcohol use during protocol, randomly timed weekly serum and urine assays were obtained. 7. The implications of these early findings for the outcome of this acute phase study and for the development of longitudinal treatment strategies are discussed.