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Comparison of energy budget and digestive tract morphology in Hwamei Garrulax canorus between winter and summer.

WU Meng-si, ZHAO Li-dan, WANG Run-mei, ZHENG Wei-hong, LIU Jin-song**   

  1. (School of Life and Environmental Sciences, Wenzhou University, Wenzhou 325035, China)
  • Online:2015-04-10 Published:2015-04-10

Abstract:

Seasonal changes in the energy requirements of birds affect their ability to obtain and digest food. Increased food intake, hypertrophy of the gastrointestinal tract and the consequent increased absorption of nutrients may be viewed as responses by wintering birds to physical and biotic seasonal habitats. In the present study, seasonal changes in body mass, gross energy intake (GEI), fecal energy (FE), digestible energy intake (DEI), as well as length and mass of the digestive tract, were measured in Hwamei (Garrulax canorus) caught in the wild in Wenzhou, Zhejiang. Fourteen Hwamei birds were captured in mist nets in July of 2013 and January of 2014. Body mass was determined immediately upon capture with an electronic balance. The caloric contents of the dried food and feces were then determined using an oxygen bomb calorimeter. GEI, FE, DEI and digestibility were calculated. The digestive tract (stomach, small intestine and rectum) of each bird was measured and weighed. The stomach, small intestine and rectum were rinsed with saline to remove all gut contents and reweighed. These organs were then dried at 60 ℃ to a constant mass. As predicted, GEI and DEI were significantly higher in winter than in summer. The wet and dry masses of the total digestive tract, stomach and small intestine were greater in winter than in summer, and the magnitude of these parameters in both seasons was positively correlated with GEI and DEI. It is suggested that Hwamei is able to increase GEI and DEI to compensate for the higher daily energy expenditure in winter. Hwamei shows physiological adjustment in digestive tract size in winter to cope with significant increases in energy intake.
 

Key words: urban expansion, vegetation, Hangzhou Bay area, night-light data, NDVI