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首页> 外文期刊>Dansk Ornitologisk Forenings Tidsskrift >Breeding biology and population dynamics of a colonial seabird: The Razorbill
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Breeding biology and population dynamics of a colonial seabird: The Razorbill

机译：殖民地海鸟的育种生物学和人口动态：Razorbill

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This paper presents the results of a 29-year study (1983-2011) of the biology and population dynamics of Razorbills Alca torda breeding on Graesholmen in the central Baltic Sea. During the study years, the breeding population increased from c. 250 pairs in 1983 to 1200 pairs in 2011 (380%). Though variable, the mean annual survival was high (93-95%) for breeding adults, as was the overall survival of immature birds (57.7% up to the age of four years) returning to breed on Graesholmen. Mean age of first breeding was 4 years, but around 23% of the birds started to breed when 3 years old. First and second year birds visited the colony regularly but did not breed. Generally, older females laid larger eggs earlier in the breeding season and had a higher breeding success than females breeding for the first time. Overall, breeding success averaged 71-75% in seven study plots. Mean hatching date was 19 June (23 May - 6 August). Fledging chicks were recorded in the period 22 June - 15 August and the mean fledging age was 19 days. Chicks fledging early in the season were significantly larger and heavier than late fledging chicks, but no difference was found in post-departure survival. Sprats Sprattus sprattus were the main food (90%) supplied to the chicks. Average rate of non-breeding among adult birds with previous breeding experience was 3%. Average divorce rate was 14.5% and was highest (26%) among the youngest and lowest (3.1%) among the oldest breeding birds. Around 50% of the ringed chicks returning to breed on Graesholmen did so in their natal subcolony. Once settled, local nest-changes over the years occurred among 44% of the birds, but < 2% moved to a completely different subcolony. Some young birds, perhaps a few percent, emigrated to other Razorbill colonies, mainly in the Baltic. Inter-colony movement of immature birds was a regular feature, and 37 Razorbills ringed as chicks in other Baltic countries were resighted on Graesholmen, 15 of these as breeders. Most of the adult breeding birds from Graesholmen wintered in the southern Baltic, while some first and second year birds entered the Kattegat and the North Sea.
机译：本文介绍了29岁的研究（1983-2011）的razorbills Alca Torda育种中央波罗的海的Graesholmen生物学和人口动态的结果。在研究年度期间，育种人口从C增加。 2011年1983年的250对1200对（380％）。虽然变量，平均年生存率高（93-95％）用于繁殖成年人，但在Graesholmen返回繁殖的未成熟鸟类的整体存活率（57.7％，达到四年的57.7％）。第一次育种的平均年龄是4年，但是当3岁时，约23％的鸟类开始繁殖。第一和第二年鸟定期访问了殖民地，但没有繁殖。一般来说，年龄较大的女性在繁殖季节早些时候奠定了较大的鸡蛋，并且比第一次育种比女性更高的育种成功。总体而言，育种成功平均为71-75％，七个研究情节。平均孵化日期是6月19日（8月23日至8月6日）。剩余的小鸡在8月22日 - 8月22日，平均剩余年龄为19天。在本赛季早期的小鸡比晚剩余的小鸡更大，更重，但在出发后生存中没有发现差异。 Sprats Sprattus Sprattus是小鸡的主要食物（90％）。以前育种经验的成人鸟类的平均非育种率为3％。平均离婚率为14.5％，最年轻，最低（3.1％）中最高（26％）在最古老的繁殖鸟类中。在他们的Natal子群中，大约50％的戒指雏鸡返回品种繁殖。曾经定居，多年来的当地巢变化发生在44％的鸟类中，但<2％的人迁移到完全不同的子彩色。一些幼鸽，也许几个百分之几，移植到其他拉鼠殖民地，主要是在波罗的海。未成熟的鸟类的殖民区间运动是一个常规功能，37个Razorbills在其他波罗的海国家的小鸡被称为Graesholmen，其中15个作为育种者。来自Graesholmen的大多数成人繁殖鸟类在南波罗的海中冬天，而一些第一个和第二年的鸟类进入了Kattegat和北海。

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