下蛋的日期和下蛋的順序，會影響幼雛們之性別比率

這是一篇個人覺得蠻有趣的研究報告！

生公ㄟ啦是生母ㄟ???!!! 真正有趣味喔

Elizabeth A. Krebs, David J. Green, Michael C. Double, Richard Griffiths 這幾位老大們，
在 Behavioral Ecology and Sociobiology 提到～～

『下蛋的日期和下蛋的順序，會影響幼雛們之性別比率』

觀察標的．．．一樣是紅草
有趣吶
以下為該段之摘要
敬請享用

Abstract:

We examine the patterns of sex allocation in crimson rosellas Platycercus elegans, a socially monogamous Australian parrot. Overall, 41.8% of nestlings were male, a significant female bias. However underlying this population-level bias were non-random patterns of sex allocation within broods. Broods produced early in the season were female-biased, but the proportion of males in a brood increased as the breeding season progressed. Female rosellas may obtain greater fitness benefits from early-fledging daughters than sons because daughters can breed as 1-year-olds whereas sons do not breed until they are at least 2 years old. Laying date and laying sequence also interacted to influence the sex ratio of eggs. The sex of early-laid eggs strongly followed the brood level pattern, whereas the sex of middle- and late-laid eggs did not change significantly as the season progressed. Nevertheless, late-laid eggs were very unlikely to be male at the end of the season. We argue these differing seasonal patterns reflect the relative costs and benefits to producing early-hatched males and females at different times of the season. Female rosellas appear to maximise the probability that daughters are able to breed early but to minimise competitive asymmetries within the brood. In particular, late-hatched male chicks are disadvantaged if their oldest sibling is male, explaining the dearth of broods containing late-hatched males at the end of the breeding season.
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個人心得：

紅草是一夫一妻制到終老的鳥種，所以我當初家裡的胖藍（公）不幸陣亡後，我隔了約八九個月才開始幫母藍草找新丈夫，也儘量朝著目標公鳥也喪偶半年以上的標準下去尋找，這是主要的原因

這些動物學家們在紅草棲息地，離地四米以上的樹，架設了四十六個巢箱，每隔間隔五十米放置一個
歷經四年，約每年都取得四十二組有效樣本

在野外，紅草的繁殖，生男生女，深受環境因子與幼鳥本質之影響
而生男生女，由母體決定，非如蜥蜴烏龜般，生男生女與蛋之孵化溫度有關
在繁殖季開始之時，母雛鳥除了數量遠大於公雛鳥之孵化數，通常先下的蛋也是母雛
有趣的是，在繁殖季越往後，相反了，公雛鳥之孵化數會漸漸增加，而母雛鳥數會逐漸減少
但是～最終，在比率上，依舊是----母＞公

全世界最乾燥的陸塊～～澳洲，紅草的食物來源深受降雨量之影響
假使，某年降雨量減少，導致食物來源減弱，母鳥會孵出更多之母雛
食物來源充虞，則公雛會增加

然！若是某某小公雛，其前面有哥哥先出生，那牠會倒楣一點，會長得跟偶一樣較為短小瘦扁

為什麼會有如此之現象？！
因為紅草的原性佔了蠻大的因素
1.公的大塊頭比母的大約15%，跟豬一樣，浪費資源 ^+++++++++^
2.母的較公的早熟，早換羽！沒收聘金沒關係，早點交男朋友離家去
3.母的離巢後，離家很遠
4.母的體質較差，且有未知之致死基因
5.應該還有，我忘了

大致上是這樣

上述紅草之現象，大部分之鳥類亦是如此