Effects of helpers on Blue-tailed Bee-eater (Merops Philippinus) breeders during the provisioning period.

• Main Authors: Feng-Wei Chen, 陳鋒蔚
• Other Authors: Shiao-Wei Yuan
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/03287070221380216362

碩士 === 國立臺灣大學 === 森林環境暨資源學研究所 === 98 === This thesis includes two chapters: the first one is the literature review of the causation of cooperative breeding, as well as the relatedness between each group members, and the benefits and costs of group members; the second one is the study of cooperative breeding of Blue-tailed Bee-eaters（Merops philippinus）conducted in Kinmen in 2008. This population of Blue-tailed Bee-eaters in Kinmen exhibit cooperative breeding as well as colonial breeding and migratory behavior. The reason for their cooperative breeding behavior might be different from other territorial bird species. Therefore, in order to understand whether the effects of helper were additive or compensatory, I recorded the provision rates of breeders and helpers to determine the degree of investment. To clarify the relatedness between breeders and helpers, and to deduce the possible benefits to the helpers, the blood samples were analyzed. The results suggested that the food resource was not an important factor for their reproductive success. Between the nests with and without helpers, there were no significant differences in clutch size (4.94 0.24 vs 4.75 0.22), nestling period (27.06 0.83 vs 28.58 0.90 days), fledging success (0.87 0.05 vs 0.86 0.06), predation rate of nestlings (0.13 0.05 vs 0.14 0.06),weight (39.67 0.54 vs 39.46 0.64 g), tarsus length (14.33 0.22 vs 15.08 1.13 mm), tail length (88.97 0.66 vs 89.46 0.78 mm), and provision rate of breeders and helpers combined together; the provision rate of un-helped breeders was significantly higher than helped breeders (p=0.0144). The prediction of the optimal breeder investment model suggested that the provision rates of the breeders were decreased in the nests with helpers. It was suggested that the effects of helpers is compensatory, and the energy saved by breeders might enhance their survival rate or the opportunity of future reproduction. There were 9 male and 3 female helpers, and only one helper was the son of the male breeder. Besides, the relatedness ( ) between males within the same group were not significantly different from random expectation of relatedness between all males ( ) (p=0.474). It implied that the breeders and helpers were not relatives. The result of the generalized linear mixed model suggested that the presence of helper, time-period of a day, offspring age, and weather were the important factors to the provision rate of the breeders. The presence of the helpers probably reduced the workload of breeders. The lowest provision rate of the breeders occurred during 0600-0800 and the highest occurred during 0800-1000. The breeders fed more food after the tube-falling period of nestlings than before tube-falling. The breeders fed least on rainy days and highest on mostly clear days.