宜蘭水田紅冠水雞族群量變化與生殖生態學

Population Fluctuation and Breeding Ecology of Common Moorhen in the Rice Paddies of Yilan

黃仲霙(Jung-Ying Huang) ； 林亞立(Ya-Lih Lin) ； 袁孝維(Hsiao-Wei Yuan)

《宜蘭大學生物資源學刊》 6卷1期 (2010/12) Pp. 45-57

https://doi.org/10.6175/job.2010.61.16

摘要

紅冠水雞（Gallinula chloropus）是一種適應力很好且世界分布廣泛的秩雞科鳥類，在台灣的水田內也常見其棲息活動。為瞭解水田地景變化及人為經營擾動對紅冠水雞族群量與生殖行為的影響，本研究於2006年7月至2007年10月進行調查，調查區位於宜蘭縣冬山鄉永美社區，面積約247.47公頃。調查項目包括紀錄樣區內各水田區塊水位與植被高度、紅冠水雞成鳥及幼鳥數量、鳥巢的巢形值與巢位環境因子，並觀察生殖行為。依水田地景變化及稻作活動所產生的干擾，水田一整年的狀態可區分為蓄水休耕期、翻土插秧期、稻作生長期、收割休息轉作期及田菁翻田期等「五個稻作經營分期」。族群量變化及分布在各稻作經營分期呈現顯著差異，其中稻作生長期提供足夠生殖棲息的植被環境且干擾低，族群量最高；蓄水休耕期因無人為干擾，少量植被便足夠提供群體聚集時的生存棲息，族群量次高。由此可知，族群數量受稻作經營活動的影響呈現明顯的消長。生殖季節時，各稻作經營分期間的成鳥數及幼鳥數也呈現顯著差異。成鳥在高植被的稻作生長期數量最高，為偏好之生殖環境，其他分期則明顯的因稻作活動及地景改變而數量降低；幼鳥的數量主要與成鳥的繁殖行為及繁殖成功率有關。因此，水田的地景變化與干擾主要對紅冠水雞的族群量有影響。研究期間發現紅冠水雞成功與失敗的孵卵巢數分別為33及23個，生殖成功率58.9%。成功巢與失敗巢的巢形值或巢位選擇皆無顯著差異。生殖失敗的原因主要為稻作經營所產生的人為平擾，其次為巢掠食者的破壞。此外，另紀錄紅冠水雞之親鳥於夜間協助幼鳥保暖使用的育幼巢70個。在不同棲息地的孵卵巢及育幼巢數有顯著的差異，蓄水田內紅冠水雞對育幼巢的需求明顯增加，推測為缺少足夠植被以供幼鳥夜棲，故築巢供成鳥夜間為幼鳥維持體溫。孵卵巢及育幼巢的巢形值並無顯著差異，但比較水田內兩種巢的巢位選擇，孵卵巢較育幼巢具有高植被的需求，應為避敵考量。將巢位與隨機點的環境因子進行比較，發現孵卵巢具有較高植被需求，且離田埂較遠，而育幼巢則離道路與田埂較遠，兩種巢的巢位選擇因使用方式不同而產生不同的避敵策略。再分別與隨機點相較，兩者都比隨機點的水深較淺，似為了降低築巢時的負擔。由此可知，棲息在水田上的紅冠水雞族群與生殖皆受稻作活動影響，在生殖季節則因稻作活動造成的不同地景形成不同的生殖策略。

關鍵字

秧雞科 ； 生殖行為 ； 築巢行為 ； 濕地

並列摘要

Common Moorhen (Gallinula chloropus) is an adaptable and widely distributed member of the Rallidae around the world. The Common Moorhen in Taiwan often inhabits in the rice paddy. In order to understand the population dynamics and the breeding behaviors of the Common Moorhen rendered by the variation of landscape and the artificial disturbance that come along with paddy field management, a survey was conducted on a 247.47-hactare site located in the Dongshan Township, Yilan County from July 2006 to October 2007. We recorded the presence and appearance of vegetation, the water depth of each paddy patch, the numbers of the adult and the young in the Common Moorhen population, the features of nests, the environmental indices around the nest, the particular reproduction behaviors of the Common Moorhen, and data of other related information. Based on the impacts occurred on each rice paddy patch and the disturbance rendered by cultivating management, the yearly environment of rice paddy was divided into the following five periods: 1. water immerging and fallow, 2. plowing and rice seedlings transplanting, 3. rice growing, 4. rice harvesting and sesbavia planting, and 5. plowing and water flooding. Results reveal that the fluctuation and distribution of Common Moorhen population studied depended highly on the five management periods stated above. During the rice growing period, vegetation provided sufficient shelter for moorhens to inhabit, which rendered the highest population size. The water immerging and fallow period showed the least landscape variation and human disturbance of the patches in the study area; therefore, presented the second highest population size. Furthermore, the numbers of the adult varied with the management periods during the breeding season. Each of the five management periods created its special inhabiting environment to the moorhen, and affected the number of the adult profoundly. The number of the juvenile moorhen apparently related to the reproductive behavior (and successful ratio) of the adults. Facts indicate that the moorhen population was highly affected by the cultivating activities in the rice paddy. During the survey period, 33 reproductive success and 23 reproductive failure nests were recorded. The reproductive success rate was 58.9 %. No significant correlation among the features of the nests and the surrounding environmental factors were detected. The major factors related with reproductive failure were the cultivating activities and nest predators. In addition, the Common Moorhen studied built two types of nests. Fiftey-six egg nests and 70 brood nests were recorded, the ratios of the two nest types were significantly different among the five management periods, and there were more brood nests than egg nests in water immerging paddies. Features of these two types of nest were of no difference. Possibly owning to the anti-predator strategy, compared to brood nests, egg nests were found more often in high vegetation covered spots. In comparison with the randomly selected measurement spots in the same patch, the environmental indices around the egg nests appeared to be in need of more vegetation shelter and farther away from the levees, which may be a response to anti-predator strategy. The lower water level observed on the egg nest spots may be due to energy conservation consideration of the parents during nest building works. Results from similar comparison between the brood nest and the random selected point showed that the brood nest has the same requirement as the egg nest does on the site factors of farther distance from the levee and lower water level. In conclusion, the variation of landscape and artificial disturbance rendered by rice paddy management are the major cause of the individual reproductive success of the Common Moorhen and the number of adults in the population . The Common Moorhen in the rice paddy alters their breeding strategies to be in accordance with the five cultivating management period.

並列關鍵字

Rallidae ； breeding behavior ； nesting behavior ； wetland