How far do birds disperse seeds in the degraded tropical landscape of Hong Kong,China?

Information on seed dispersal distances is critical for understanding plant species persistence in habitat fragments and vegetation recovery when disturbance is reduced. In the degraded upland landscape of Hong Kong (22°N), the bulbuls Pycnonotus sinensis and P. jocosus are responsible for a large proportion of seed movements. Dispersal distances were estimated from gut passage times (GPTs) and movement patterns determined by radio-telemetry. Estimates were also made for the hwamei, Garrulax canorus. Seven adult P. sinensis and four adult G. canorus were tracked in winter, and six juvenile P. sinensis, three juvenile P. jocosus and two juvenile G. canorus in summer. GPTs were 5–122 min in the bulbuls and 18–61 min in the hwamei. Most 10-min movements were <100 m for the bulbuls and <50 m for the hwamei, but the largest were >1300 m for both bulbuls and 940 m for the hwamei. Displacement-time graphs generally levelled off rapidly, with median displacements <60 m after an hour, except with summer juvenile bulbuls. Median displacements during median gut passage times for seeds from single-seeded fruits were 40, 116 and 131 m, respectively, for winter adult P. sinensis and summer juvenile P. sinensis and P. jocosus. Maximum observed displacements during the maximum measured GPTs were >1 km for all bulbuls. Estimated dispersal distances were shorter for hwameis. The radio-telemetry results were supplemented by 49 h of visual observations, during which 1,510 bird movements across open areas were observed, 64% by P. sinensis, 13% by P. jocosus, and 0.5% by G. canorus. The bulbuls, therefore, connect habitat fragments in upland Hong Kong for plants with fruits within their maximum gape width.     

中国鹎科鸟类的数值分类研究

以亚种为分类单位,对中国鹎科鸟类32个亚种进行了数值分类。共选择44个数量性状、40个质量性状和44个比例性状,用4种聚类方法计算。表明:以质量性状的分类结果最好。综合性状(质量性状加数量性状)的分类对鹎科的传统分类提出了新建议:将原来的4个属合并为2个属,将原来的5个亚种分成3个独立的种。