黑嘴端凤头燕鸥台湾海峡群体是否已出现杂交型子二代

Are they Individuals of the F_2 Generation of Sterna bergii x Sterna Bernsteini

2010年，我们提出，黑嘴端凤头燕鸥（Sterna brnsteini）于繁殖季节可被视为具3个群体，由南至北分别为台湾海峡群体、大舟山群岛群体及中国北方沿海群体。

In 2010, we suggested that, during the breed- ing season, the Chinese crested tern Sterna bern- steini（ hereafter CCT） might be considered as to comprise three flocks - 1 ） the Taiwan Straits flock, 2） the Greater Zhoushan Archipelago flock, and 3） the northern Chinese coast flock, in accordance with the appearance of the bird from the SE Chinese coast to the north EI. In 2011, we reported several cases of possible hybridization between Sterna bergfi and the apparent hybrid Sterna bernsteini in the CCT Taiwan Straits flock i2, and we also provided new evidence of the existence of the CCT＇s northern Chi- nese coast flock E3. Then, in 2012, we reported the apparent hybrid CCTs also found at Matsu Archi- pelago, the （main） breeding site of those CCTs of the Taiwan Straits flock E41 On 15th June 2013 at 16： 39, Cai Weihe found a male great crested tern Sterna bergfi （hereafter GCT） mating with an apparent hybrid female CCT at the Min River estuary of central Fujian, SE China's Mainland （Photo 1）, and soon after, at 16： 51, Cai saw the pair resting on mud （Photo 2, the apparent hybrid on the left）. Later on, from late August to the beginning of September, Wang Jianhua and an- other Matsu birder, Wang Wenzhong, regularly saw another apparent hybrid CCT （the left bird on Photo3） at Matsu with a GCT, and they seemed to be a pair. Comparing the amount of black on the bill of the apparent hybrid CCT on Photo 1 ＆ 2 with the appar- ent hybrid CCT on Photo 3 （the left bird）, they are clearly two different individuals. And, the apparent hybrid bird on Photo 3 is also different from all the apparent hybrid CCTs that we have far recorded in nearly lacking black near the bill tip. Moreover, all those apparent hybrid CCTs that we had recorded in 2011 and 2012 were normal CCT size （i. e., slightly smaller than GCT） and had normal CCT leg length （i. e., slightly shorter than on GCT）, though the color of theirmantle （back and entire upper surface of the wings） was slightly differ- ent 2.] Whereas, this time, both the apparent hybrids on Photo 2 and Photo 3 appeared somewhat larger than their respective GCT mates. Since, in 2011, we had already recorded mating behavior be- tween the apparent hybrid CCTs and the GCTs 2 and now two years have passed, we therefore sug- gest that that two apparent hybrids on Photos 1, 2, ＆ 3 may be individuals of the F2 generation of hybrid- ization, and the apparent larger size possibly sug- gestive of heterosis.