When food access is challenging: evidence of wood mice ability to balance energy budget under predation risk and physiological stress reactions

2019 ◽  
Vol 73 (11) ◽  
Author(s):  
M. Carmen Hernández ◽  
Álvaro Navarro-Castilla ◽  
Kathryn Wilsterman ◽  
George E. Bentley ◽  
Isabel Barja
2019 ◽  
Author(s):  
Ma Carmen Hernández ◽  
Álvaro Navarro-Castilla ◽  
Isabel Barja

AbstractForaging decisions must balance the energy gained, the time investment and the influence of key environmental factors. In our work, we aimed to examine the importance of predation risk cues and experience in the feeding efforts and decision-making process when a novel food resource is presented. To achieve this, free ranging wood miceApodemus sylvaticuswere live-trapped in “Monte de Valdelatas” (Madrid) by setting 80 Sherman traps in 4 plots. Traps were subjected to two food access difficulties three-night consecutive treatments: open plastic bottles and closed bottles, both using corn as bait. To generate predation risk, we set fox faeces in half of the traps in each plot. Also, we considered indirect predator cues as the moon phase. We analyse whether mice had bitten the bottles and the area gnawed of each bottle was measured. We discovered that mice feeding decisions and efforts were driven by food access difficulty, experience and predation risk. The ability of mice to properly balance their energy budget was probed since they bit and performed bigger orifices in the closed bottles, hence, individuals can adapt the feeding effort when a new food source is available. Moreover, experience was determinant in the use of this new resource since recaptured mice gnawed the bottles more successfully and the skill was improved each time an individual was recaptured. Additionally, direct predation risk cues prompt mice to bite the bottles whereas the effect of different moon phases varied among the treatments. This is the first study that provides direct evidence of wild mice formidable efficacy to exploit a new nutrient resource while deepening in crucial environmental factors that shape decision-making procedure.


2020 ◽  
Vol 312 (2) ◽  
pp. 122-132
Author(s):  
R. I. Monarca ◽  
J. R. Speakman ◽  
M. L. Mathias

Author(s):  
J. Widdows ◽  
B. L. Bayne

Mytilus edulis L. is shown to acclimate to high and low temperature under laboratory conditions. The warm and cold acclimation of oxygen consumption, filtration rate and assimilation efficiency are described for groups of animals maintained at three food-cell concentrations. Complete acclimation (Precht's type 2) of oxygen consumption and filtration rate occur within 14 days. There is no change in assimilation efficiency within the 28-day experimental period. The results are integrated and discussed in the context of a simple energy budget. In terms of the energy budget there exists a marked contrast between warm and cold acclimation. An “index of energy balance” is proposed in order to assess the state of the energy balance. When animals are fed above the maintenance requirement the energy budget remains in an equilibrium state during cold acclimation, whereas the acclimation to a warm temperature regime disrupts the balance and represents a physiological stress. During warm acclimation, prior to the re-establishment of an energy equilibrium the blood sugar level increases, suggesting that the animal is required to mobilize and utilize its energy reserves.


PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5967 ◽  
Author(s):  
Susana Rodrigues ◽  
Joana S. Paiva ◽  
Duarte Dias ◽  
João Paulo S. Cunha

Background Stress at work has been broadly acknowledged as a worldwide problem and has been the focus of concern for many researchers. Firefighting, in particular, is frequently reported as a highly stressful occupation. In order to investigate firefighters’ occupational health in terms of stress events, perceptions, symptoms, and physiological reactions under real-world conditions, an ambulatory assessment protocol was developed. Methods Seventeen firefighters’ cardiac signal was continuously monitored during an average of three shifts within a working week with medical clinically certified equipment (VitalJacket®), which allows for continuous electrocardiogram (ECG) and actigraphy measurement. Psychological data were collected with a software application running on smartphones, collecting potential stressful events, stress symptoms, and stress appraisal. Results A total of 450.56 h of medical-quality ECG were collected, and heart rate variability (HRV) analysis was performed. Findings suggest that although ‘fire’ situations are more common, ‘accidents’ are more stressful. Additionally, firefighters showed high levels of physiological stress (based on AVNN and LF/HF HRV metrics) when compared to normative healthy population values that may not be diagnosed using merely self-reports. Discussion The proposed ambulatory study seems to be useful for the monitoring of stress levels and its potential impact on health of first responders. Additionally, it could also be an important tool for the design and implementation of efficient interventions and informed management resolutions in real time. Potential applications of this research include the development of quantified occupational health (qOHealth) devices for real life monitoring of emergency personnel stress reactions.


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