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Gang-Min Deng

and 4 more

1. Global warming is rapidly emerging as a universal threat that could alter the distribution of many animal species and change their morphology, physiology, behavior and life history. The heat dissipation limitation (HDL) hypothesis proposes that females’ reproductive performance is limited by their capacity to dissipate heat. Although exposure to wind is known to increase heat exchange, its effect on reproductive performance is unknown. 2. In this study, the effect of simulated wind on the energy budget and milk energy output of female striped hamsters (Cricetulus barabensis) was measured under cool (21°C) and hot (32.5°C) ambient temperatures and the preference of hamsters for windy conditions in lactating females was tested both in the laboratory and the wild. 3. Females lactating at 32.5°C significantly decreased their energy intake and milk output, and raised lighter offspring than those lactating at 21°C. Exposure to wind significantly increased both energy intake during lactation and heat loss at both temperatures. Females lactating at 32.5°C considerably increased their reproductive output when exposed to wind. Moreover, females kept at an ambient temperature of 21°C preferred sheltered conditions whereas those kept at 32.5°C preferred exposure to simulated wind. We captured significantly more lactating female hamsters on windy days in summer and on calm days in spring. Wrapping a glass vessel in the fresh pelt of a striped hamster significantly reduced the rate of both water loss and cooling. 4. These findings support the HDL hypothesis; high ambient temperatures do appear to limit the energy intake and reproductive output of lactating hamsters. Small mammals lactating under hot conditions may be able to utilize the cooling properties of wind to increase their energy intake and milk production, and thereby their reproductive output and fitness.