大安森林公園五色鳥之繁殖生態與巢洞特徵

Abstract

五色鳥(Psilopogon nuchalis)為臺灣特有種鳥類，繁殖季為4-8月，屬於初級洞巢鳥類，廣泛分布於中低海拔森林。臺北市大安森林公園基於安全考量，整理移除不健康或枯死的樹木，使五色鳥築巢材料減少。本研究於2016年設置41個三種人工巢箱提供五色鳥築巢選擇，分別為11個無挖洞段木、20個有挖洞段木、10個長方形巢箱，同時觀察天然巢洞的使用情形，並探討氣溫、雨量、天然巢洞形質資料及巢洞方位對繁殖成功的影響，並比較2015年五色鳥繁殖情形，於2015年與2016年的繁殖初期，五色鳥皆先使用人工巢箱。在產卵日方面，2015年人工巢箱早於天然巢，2016年人工巢箱之產卵日與天然巢洞同一日。在孵化日方面，2015年人工巢箱先於天然巢洞，2016年天然巢洞先於人工巢箱。研究發現五色鳥在築巢期對人工巢與天然巢洞選擇無差異。孵化成功率受產蛋前沒有降雨連續天數影響。繁殖成功率受樹木胸高直徑(p=0.019)、洞口同高樹木遮蔽情況(p=0.032)、巢洞垂直巢深(p=0.003)、巢洞水平巢深(p=0.021)影響，推測五色鳥使用天然巢洞特徵為胸高直徑34.9±6.9公分，洞口枝條遮蔽情形6.92±16.4%，垂直巢深15±11.0公分，水平巢深11.2±2.8公分。天然巢洞選擇方面，巢高與樹高正相關，洞口枝條遮蔽情況與巢洞水平長呈負相關；五色鳥繁殖成功的天然巢洞朝西南，可能原因為繁殖期盛行西南風，可讓巢洞內部保持乾燥，日落時可藉由太陽溫暖巢洞有關。

The Taiwan barbet (Psilopogon nuchalis) is an endemic bird species in Taiwan, and its breeding season is from April to August. It’s a primary cavity-nesting bird and is widely distributed in mid- and low-elevation forests. For safety reasons, unhealthy or dead trees were removed from the Daan Forest Park, thus reducing nesting materials for Taiwan barbet. In this study, the effect of artificial nest boxes on the breeding situation of the Taiwan barbet was evaluated. In 2016, three types of artificial nest boxes (41 in total) were installed to provide nesting options for Taiwan barbets, including 11 non-digging logs, 20 digging logs, and 10 rectangular nest boxes. Meanwhile, the utilization situation of natural nests was monitored. The effects of temperature, rainfall, as well as tree morphology and entrance of natural nest cavities on breeding success were investigated, and the breeding situations in 2015 and 2016 were compared. Both in 2015 and 2016, artificial nest boxes were used first in the early breeding stage by Taiwan barbets. In terms of spawning date, the artificial nest boxes were earlier than the natural nest cavities in 2015, while no difference was observed in 2016. As for the hatching date, artificial nest boxes preceded natural nest cavities in 2015, whereas natural nest cavities preceded artificial nest boxes in 2016. The study found that Taiwan barbets showed no specific preference between artificial nest boxes and natural nest cavities during the nesting period. Hatching success was influenced by the number of consecutive days without rainfall before spawning. Breeding success was influenced by the diameter of trees at breast height (p=0.019), the shading of branches at the same height of the cavity (p=0.032), the vertical depth of the nest cavity (p=0.003), and the horizontal depth of the nest cavity (p=0.021). It was inferred that natural nest cavities of Taiwan barbets were featured by 34.9 ± 6.9 cm in diameter at breast height, 6.92 ± 16.4% shading of branches at the same height as the cavity, 15 ± 11.0 cm in vertical nest depth, and 11.2 ± 2.8 cm in horizontal nest depth. For the selection of natural nest cavities, nest height was positively correlated with tree height, and the shading of branches at the cavity entrance was negatively correlated with the horizontal nest depth. The nest cavities associated with successful breeding of Taiwan barbets were southwest facing. This is possibly because of the prevailing southwest wind during the breeding season, which could keep the interior of the nest cavities dry, as well as the sun warming the nest cavities at sunset