花尾榛鸡的非对称性比和成体存活率

1999至2002年，在法国东南部的阿尔卑斯山，通过无线电追踪方法研究了花尾榛鸡的性比问题。首先，我们通过直接观测无线电标记雄性的配对比例，在消除可能的捕捉误差后，发现繁殖种群性比为1．26（即未配对的雄性占21％）。然后，我们估计了标记个体的存活率和繁殖成功率。在假设窝扩散时幼体的性比平衡的前提下，通过两性和两个年龄组（幼体，〈10月龄的个体；成体〉10月龄的个体）的确定性统计模型，得到的理论性比为1．22（即未配对的雄性占18％），这一结果与实际观测的性比十分接近。我们认为，雌性死亡率高导致的两性存活率差异可以解释雄性性比偏高现象。我们进而讨论了花尾榛鸡整个分布区内居间强度的非对称性比的适应意义，以及在衰退的花尾榛鸡种群中雌性数量极端不足的后果[动物学报52（4）：655—662，2006]。

Skewed sex ratio and differential adult survival in the hazel grouse Bonasa bonasia

The spring sex ratio of a radio-tracked hazel grouse population was studied in the south-eastern French Alps from 1999 to 2002. Mating rate of radio-tagged males in April was first checked by direct observations, which gave a sex ratio of 1.26 (21% of solitary males), after correction for capture bias. Secondly, we estimated survival rates and reproductive success of radio-tagged hazel grouses. Assuming a balanced sex ratio of juveniles at brood break-up, we calculated a theoretical sex ratio using a two deterministic demographic model with two sexes and two age class (immature ＜ 10 months old, adult ＞ 10 months old). The theoretical sex ratio was either 1.23 or 1.29, depending on the model used.We conclude that the observed higher survival of adult males vs adult females could explain male-biased sex ratio. We discuss the advantage of a moderately unbalanced sex ratio in hazel grouse, and we note the possible value of sex ratio indices for predicting population trend [Acta Zoologica Sinica 52 (4): 655 -662, 2006].