The Ecology and Behaviour of Black-billed

and Yellow-billed Magpies

by Tim Birkhead

Illustrated by

DAVID QUINN

T&AD POYSER

London

CHAPTER 1

Magpies

In spite of his evil reputation the magpie is regarded by most persons who are not breeders of pheasants with exceptional interest.

——W.H.Hudson (1934)

尽管喜鹊声名狼藉，但对于大多数非雉鸡养殖者而言，它仍备受瞩目。

——W.H.哈德森（1934）

Attractive, artful and aggressive are all terms which have been used to describe magpies, and they are all accurate. Few bird species outside the tropics can compete with the magpie for looks: its crisp, iridescent black and white plumage together with its elongated tail gives it a distinctly exotic appearance. The magpie’s artfulness may be the result of human persecution. Two or three hundred years ago the magpie was a popular bird in Europe, but as soon as it came into conflict with man’s interests over the preservation of gamebirds it was heavily persecuted. Not surprisingly the magpie had to adopt a more clandestine life-style in order to survive, hence its reputation for furtiveness. The recent expansion of European magpies into urban areas has led to concern for songbird populations, and magpies certainly appear to be aggressive in the way they take fledgeling birds. However, as always, there are two sides to this story.

“迷人”、“狡黠”和“好斗”都是用来描述喜鹊的词汇，且这些描述都十分贴切。在热带以外的地区，很少有鸟类能与喜鹊的外貌相媲美：它那鲜明的、带有虹彩的黑白羽毛，加上修长的尾巴，赋予了它一种独特而异域风情的外观。喜鹊的狡黠或许是人类迫害的结果。

两三百年前，喜鹊在欧洲曾是广受欢迎的鸟类，但一旦因保护猎禽而与人类利益发生冲突，便遭到了严厉的迫害。毫不奇怪，喜鹊为了生存不得不采取更隐秘的生活方式，因此才有了狡猾的声誉。近年来，欧洲喜鹊向城市地区的扩张已引发了人们对鸣禽种群的担忧，而且喜鹊在捕食雏鸟时的表现确实显得相当凶猛。然而，正如往常一样，这件事也有两面性。

Considering how common and widespread the magpie is in Europe, Asia and western North America, surprisingly little was known about its ecology and behaviour until recently. Although there was a mass of anecdotal information available, it was not until the mid-1970s, when several detailed field studies were initiated, that we started to appreciate the intricacies of magpie ways. These studies have revealed, for example, the magpie’s rather loose marital arrangements; the complex hierarchical relationships among young, non-breeding birds; and the various strategies that they use in the intense competition for breeding space.

考虑到喜鹊在欧洲、亚洲和北美西部如此常见且分布广泛，令人惊讶的是，直到最近，人们对其生态和行为的了解仍然十分有限。尽管有大量轶闻资料可供参考，但直到20世纪70年代中期，随着几项详细的野外研究的启动，我们才开始真正领会喜鹊习性的复杂性。这些研究揭示了喜鹊较为松散的婚姻关系；年轻非繁殖鸟类之间复杂的等级关系；以及它们在激烈的繁殖地竞争中采用的各种策略。

The magpie is a member of the crow family (Gorvidae), of which there are some 102 species (Goodwin 1986). The magpie’s name is a contraction of Magot Pie, a Middle English name for the bird … the first part of the name appears to have no reference to the birds’ habit of picking maggots from the backs of sheep . . ., but it is derived from the French Margot, adiminutive of Marguerite, but also signifying a Magpie, perhaps from its noisy chattering, in which it is popularly supposed to resemble a talkative woman. The second part of the name is supposed to come through French from Latin pica which refers to the black and white coloration of the birds. (Linsdale 1937)

喜鹊属于鸦科（Gorvidae），该科约有102个物种（Goodwin 1986）。喜鹊的名称是“Magot Pie”的缩写，是中世纪英语中对这种鸟类的称呼……名称的前半部分似乎与这种鸟从绵羊背上啄食蛆虫的习性无关……，而是源自法语“Margot”，这是“Marguerite”的昵称，但也指代喜鹊，这或许源于其喧闹的叽喳声，人们普遍认为这种叫声酷似健谈的女性。该名称的后半部分据推测是通过法语从拉丁语“pica”演变而来，该词指代这种鸟类黑白相间的羽色。（Linsdale 1937）

The magpie’s present name was first recorded in 1605 and gradually replaced the French spie’ (used since at least 1200), and ‘piannet’ of northern England. The latter term is a combination of’pie’ and ‘Annet’ a pet form of the once common Christian name Agnes. After the publication of Thomas Pennant’s British Zoology (Birds) in 1768 the name ‘Magpie’ became standard (Lockwood 1984).

喜鹊的现名最早见于1605年的记载，并逐渐取代了法语中的“spie”（至少自1200年起便已使用）以及英格兰北部的“piannet”。后者是由“pie”与“Annet”（即曾经常见的基督教名字Agnes的昵称形式）组合而成的。1768年托马斯·彭纳特（Thomas Pennant）的《英国动物学（鸟类篇）》（British Zoology (Birds)）出版后，“Magpie”这一名称便成为标准名称（Lockwood 1984）。

There are two species of magpie, the Black-billed Pica pica, which occurs throughout much of the northern hemisphere (Fig. 1), and the Yellow-billed Pica nuttalli which is restricted to a small area in California. John James Audubon wrote: ‘I have conferred on this beautiful bird the name of a most zealous, learned and enterprising naturalist, my friend Thomas Nuttall’. Nuttall (1786-1859) was a Yorkshire ornithologist who travelled widely in the western United States, including California.

喜鹊有两个物种：分布于北半球大部分地区的黑嘴喜鹊（Pica pica）（图1），以及仅限于加利福尼亚州一小片区域的黄嘴喜鹊（Pica nuttalli）。约翰·詹姆斯·奥杜邦写道：“我将这位热忱、博学且富有进取精神的自然学家——我的朋友托马斯·纳塔尔——的名字，赋予了这只美丽的鸟。”纳塔尔（1786-1859）是约克郡的一位鸟类学家，他曾广泛游历美国西部，包括加利福尼亚。

My aim in this book is to consider both species and to summarize and compare what is known about their biology. However, I make no apologies for emphasizing those aspects which have interested me most, namely their social behaviour and breeding ecology. I have also used my long-term study of magpies conducted near Sheffield, England, as a base-line with which to compare other studies, not because this study is better than any others, but because many of the results have not previously been published.

本书旨在探讨这两个物种，并总结和比较目前已知的关于它们生物学特征的知识。不过，我毫不掩饰自己对其中最感兴趣的方面——即它们的社会行为和繁殖生态学——给予了更多关注。此外，我将自己在英国谢菲尔德附近进行的关于喜鹊的长期研究作为基准，以此与其他研究进行比较。这样做并非因为这项研究比其他研究更优越，而是因为其中许多结果此前尚未发表。

The present range of the Black-billed Magpie in the Palearctic Region extends from Ireland in the west to the Kamchatka Peninsula in the eastern USSR. On the basis of some fossil evidence Voous (1960) suggested that

magpies originally occurred throughout the Northern Hemisphere, but that during the Pleistocene period, 1 to 10 million years ago, they became extinct in North America, except for a small, relict population in California. These subsequently became the present-day Yellow-billed Magpie. The Black-billed Magpie is thought to have recolonized North America from Asia some time after the last glaciation, and probably around 40,000 years ago when there was a land-bridge between the two continents. The ranges of the two species of magpie in North America do not overlap: the closest they get is about 50 miles (80km). Even if they did meet, the birds have been isolated for so long that they are probably now sufficiently distinct to avoid interbreeding. Despite the differences between Black-billed and Yellow-billed Magpies it is clear that they share a great many characteristics. Indeed, the morphological feature which now separates the two species, namely the yellow billof nuttalli, may be due to a very small genetic difference. Support for this idea comes from the fact that there are several records of European magpies possessing yellow beaks (Linsdale 1937).

黑嘴喜鹊在古北界目前的分布范围西起爱尔兰，东至苏联境内的堪察加半岛。基于一些化石证据，Voous（1960）提出，

喜鹊最初分布于整个北半球，但在100万至1000万年前的更新世时期，除加利福尼亚州的一个小型残存种群外，它们在北美洲已灭绝。这些残存种群后来演化成了现今的黄嘴喜鹊。人们认为，黑嘴喜鹊是在末次冰期之后从亚洲重新定居北美洲的，时间大约在4万年前，当时两大洲之间还存在陆桥。北美洲这两种喜鹊的分布范围并不重叠：它们最近的距离约为50英里（80公里）。即便它们曾有过接触，由于长期隔离，两者现已足够分化，应能避免杂交。尽管黑嘴喜鹊与黄嘴喜鹊存在差异，但显然它们共享许多特征。事实上，如今区分这两个物种的形态特征——即nuttalli亚种的黄色喙——可能源于极微小的遗传差异。支持这一观点的证据在于，有数份记录显示欧洲喜鹊曾拥有黄色喙（Linsdale 1937）。

When I started writing this book I decided to treat the North American Black-billed Magpie Pica pica hudsonia and Eurasian Pica pica as a single species, as others have done. However, on making a few comparisons it became clear that these two forms are very different from each other. Goodwin (1986) made a similar point by suggesting that the Yellow-billed Magpie and North American Black-billed Magpie are more similar to each other than they are to the Eurasian one. As we shall see, there is now good evidence for this. I have therefore tried to make it quite clear throughout this book when I am discussing the North American Black-billed Magpie or the Eurasian form. However, to save writing these names out in full each time I sometimes refer to them as ‘North American magpies* and ‘Eurasian magpies’, and use the term ‘magpie’ to cover both of them. If I discuss some aspect of the biology of Eurasian magpies based on studies made in Europe I use the term ‘European magpie*. Yellow-billed Magpies are referred to by their full name.

在着手撰写本书时，我决定效仿其他学者，将北美黑嘴喜鹊（Pica pica hudsonia）与欧亚喜鹊（Pica pica）视为同一物种。然而，经过一番比较后，很明显这两者之间存在显著差异。古德温（Goodwin，1986）曾提出类似观点，认为黄嘴喜鹊与北美黑嘴喜鹊之间的相似度，远高于它们与欧亚喜鹊之间的相似度。正如我们将看到的，目前已有充分证据支持这一观点。因此，在全书中，我始终尽力明确区分讨论对象是北美黑嘴喜鹊还是欧亚形态。不过，为避免每次都写出全称，我有时会将它们简称为“北美喜鹊*”和“欧亚喜鹊*”，并使用“喜鹊”这一术语来统称二者。如果我基于欧洲的研究来讨论欧亚喜鹊的某些生物学特征，则使用“欧洲喜鹊*”这一术语。黄嘴喜鹊则始终使用其全称。

DISTRIBUTION

分布

The magpie occurs across much of the Northern Hemisphere (Fig. 1). In the Old World it has a continuous range from Britain and Ireland in the west, through Europe and the USSR to China and Kamchatka in the east. It occurs as far north as 70°N in Europe and as far south as 15°N in Saudi Arabia. In North America the magpie is confined mainly to the western side of the continent, from north-western Alaska to northern Arizona, New Mexico and western Texas (Fig. 2). The Yellow-billed Magpie has a small, restricted range, occurring only in California in the Sacramento and San Joaquin valleys, and in coastal valleys south of San Francisco Bay (Fig. 2). Both species are sedentary throughout much of their range.

喜鹊广泛分布于北半球的大部分地区（图1）。在旧大陆，其分布区呈连续带状，西起英国和爱尔兰，经欧洲和苏联，东至中国和堪察加半岛。在欧洲，其分布最北可达北纬70°；在沙特阿拉伯，最南可达北纬15°。在北美洲，喜鹊主要分布于大陆西部，从阿拉斯加西北部延伸至亚利桑那州北部、新墨西哥州及得克萨斯州西部（图2）。黄嘴喜鹊的分布范围较小且局限，仅见于加利福尼亚州的萨克拉门托河谷和圣华金河谷，以及旧金山湾以南的沿海河谷（图2）。这两个物种在其大部分分布范围内均为定居型鸟类。

At first sight it seems odd that the magpie should be confined to the western part of North America. However, Linsdale (1937) noticed that its range coincides almost exactly with what has been described as a ‘Cold Type Steppe Dry Climate’. Within this range magpies typically breed at altitudes up to 3000 m in areas of sagebrush, woodland along river courses adjacent to meadows and fields. A detailed analysis, using Christmas bird counts and climatological information, showed that summer temperatures and humidity were the factors limiting the magpie’s abundance and distribution (Bock & Lepthien 1975). Although suitable habitat exists to the south of its present range, summer temperatures in those desert regions are apparently too high. Again, areas of suitable habitat occur on the Central Plains to the east, butthese are probably too humid. To the north the magpie’s distribution is limited by dense boreal forest, which it does not penetrate.

乍看之下，喜鹊仅分布于北美西部似乎有些奇怪。然而，林斯代尔（Linsdale，1937）注意到，其分布范围几乎与所谓的“冷型草原干旱气候”完全吻合。在此范围内，喜鹊通常在海拔高达3000米的地区繁殖，栖息于荨麻丛、沿河林地以及毗邻草地和田野的区域。通过结合“圣诞节观鸟调查”数据与气候学信息进行的详细分析表明，夏季气温和湿度是限制喜鹊种群数量及分布范围的关键因素（Bock & Lepthien 1975）。尽管其现今分布区以南存在适宜栖息地，但那些沙漠地区的夏季气温显然过高。同样，东部的中原地区也有适宜的栖息地，但这些地区可能过于潮湿。向北，喜鹊的分布受到茂密北方针叶林的限制，它们无法穿透这些林区。

The Yellow-billed Magpie occupies much warmer areas than the Black billed Magpie in North America, and its range is described as having a ‘Hot Summer Mediterranean Type Climate’ (Linsdale 1937). Restricted to California and oak-savannah habitat, the Yellow-billed Magpie’s geographic range is about 150 miles (240 km) wide by 500 miles (800 km) north to south. Summer temperatures enjoyed by Yellow-billed Magpies are about 8°C hotter than those experienced by Black-billed Magpies. Conversely the latter species is exposed to winter temperatures at least 20 °C colder than Yellow-billed Magpies ever experience. The factors which determine why particular bird species occur where they do are often obscure, and the distribution of the two North American magpies could be due either to the direct effects of climate on the birds themselves, or to its indirect effects on their food supply. Some elegant experimental studies by Hay worth and Weathers (1984), involving the measurements of magpie body temperatures and metabolic rates under a range of conditions, showed quite clearly that each species is physiologically adapted to its own type of summer climate.

黄嘴喜鹊在北美栖息的地区比黑嘴喜鹊更为温暖，其分布区被描述为具有“夏季炎热的地中海型气候”（Linsdale 1937）。黄嘴喜鹊仅分布于加利福尼亚州的橡树稀树草原栖息地，其地理分布范围东西宽约150英里（240公里），南北长约500英里（800公里）。黄嘴喜鹊所处的夏季气温比黑嘴喜鹊高出约8°C。反之，黑嘴喜鹊所处的冬季气温则比黄嘴喜鹊经历的低至少20°C。决定特定鸟类物种为何分布于特定区域的因素往往难以捉摸，这两种北美喜鹊的分布差异，可能是气候对鸟类本身产生的直接影响，也可能是气候对其食物供应产生的间接影响。Hayworth 和 Weathers（1984）进行了一些精妙的实验研究，涉及在各种条件下测量喜鹊的体温和代谢率，这些研究非常清楚地表明，每个物种在生理上都适应了其特有的夏季气候。

There have been no comparable studies of climate and the distribution of magpies in the Old World. Such an investigation would be interesting especially if it included mauritanica and asirensis, the races of magpie occupying North Africa and Saudi Arabia, respectively, where it is considerably hotter and more arid than elsewhere in the range. Detailed information on the distribution of the magpie exists for various parts of western Europe, derived from atlas studies conducted during the past twenty years. The British Trust for Ornithology’s Atlas survey (Sharrock 1976) conducted between 1968 and 1972, shows (Fig. 3) that the magpie is widespread in England and Wales, but absent from many parts of Scotland. The lack of magpies in Scotland may be partly due to there being less suitable habitat, but also to intensive persecution by gamekeepers during the last century. Over much of Britain magpie numbers have increased dramatically since the 1960s (see Chapter 6). The exception is eastern England, where numbers had been kept low by game keepers, but were further reduced during the 1950s and 1960s by changes in agricultural practices, including the use of pesticides, the loss of hedgerows and the widespread loss of grassland resulting from an increase in arable farming. A decrease in grassland which magpies rely on for foraging (see Chapter 10), and the loss of suitable nesting trees inevitably led to a massive reduction in magpie numbers in that region (Cooke 1979).

目前尚无关于旧大陆地区气候与喜鹊分布之间关系的类似研究。此类研究将颇具意义，尤其是若能将分别栖息于北非和沙特阿拉伯的喜鹊亚种——毛里塔尼亚亚种（mauritanica）和阿西伦西亚亚种（asirensis）——纳入其中，因为这些地区的气候比该物种分布范围内的其他地区更为炎热干燥。根据过去二十年间开展的图集研究，目前已掌握西欧各地喜鹊分布的详细信息。英国鸟类学会于1968至1972年间开展的图集调查（Sharrock 1976）显示（图3），喜鹊在英格兰和威尔士分布广泛，但在苏格兰的许多地区却不见踪影。苏格兰缺乏喜鹊，部分原因可能是适宜栖息地较少，但也与上世纪猎场管理员的残酷迫害有关。自20世纪60年代以来，英国大部分地区的喜鹊数量急剧增加（参见第6章）。东英格兰地区是个例外，该地区数量曾因狩猎管理员的控制而保持在较低水平，但在20世纪50年代和60年代，由于农业实践的变化——包括农药的使用、树篱的消失以及因耕地面积增加导致的草地大面积丧失——其数量进一步减少。喜鹊赖以觅食的草地减少（参见第10章），加上适宜筑巢的树木减少，不可避免地导致该地区喜鹊数量大幅减少（Cooke 1979）。

RACES OF MAGPIES

喜鹊的种类

Thirteen races or subspecies of the Black-billed Magpie are recognized by Vaurie (1959), and their ranges are shown in Fig. 1. The North American Black-billed Magpie Pica p. hudsonia has a range which is isolated from all others. The same is true of the Arabian Magpie P. p. asirensis, P. p. mauritanica of north-west Africa, and P. p. camtschatica of the Sea of Okhotsk region. The various subspecies differ from each other in a number of ways, including body size, the relative size of their wings, tail and bill, and the relative amounts of black and white in the plumage. Within Europe and North Africa there is a trend for magpies to increase in size, and to have more white on their wing and rump, as one goes from the southern to the northern parts of their range. There is also a trend as one moves from Europe eastwards across Asia for magpies to have much more white on the wing, longer wings, and a greener gloss on the black feathers. Descriptions of the different races can be found in Stegmann (1927), Linsdale (1937), Vaurie (1959) and Goodwin (1986). My own measurements and descriptions of all races, based on material in the British Museum, are presented in Appendix 1.

Vaurie（1959）共认出了13个黑嘴喜鹊的亚种，其分布范围如图1所示。北美黑嘴喜鹊（Pica p. hudsonia）的分布范围与其他所有亚种均不相连。阿拉伯喜鹊（P. p. asirensis）、西北非的毛里塔尼亚喜鹊（P. p. mauritanica）以及鄂霍次克海地区的堪察加喜鹊（P. p. camtschatica）的情况亦是如此。各亚种在多个方面存在差异，包括体形大小、翅膀、尾羽和喙的相对尺寸，以及羽毛中黑白两色的相对比例。在欧洲和北非地区，随着分布范围从南部向北部延伸，喜鹊体型呈现增大趋势，其翅膀和臀部白色比例也随之增加。此外，从欧洲向东穿越亚洲时，喜鹊的翅膀白色比例显著增加，翅膀变长，黑色羽毛上呈现出更浓郁的绿色光泽。关于不同亚种的描述可参见Stegmann（1927）、Linsdale（1937）、Vaurie（1959）和Goodwin（1986）的著作。本人基于大英博物馆藏标本对所有亚种进行的测量与描述，详见附录1。

The north-south trend in magpie size within Europe suggests that like many other bird species, body size is correlated with temperature, being larger in cooler areas. I checked for this kind of effect using data on wing lengths from the British Museum for all 13 races of P. pica and the Yellow-billed Magpie. Although there was a negative correlation in the expected direction between wing length and July temperature (mean daily maxima) it was not significant (r = -0.480, 12 d.f., p < 0.1, > 0.05). The correlation between wing length and winter temperature was even weaker, so some factor(s) other than temperature must help to explain the variation in magpie body size.

欧洲境内喜鹊体型呈现的南北差异趋势表明，与许多其他鸟类一样，其体型大小与温度相关，在较冷的地区体型更大。我利用大英博物馆提供的所有13个喜鹊亚种（P. pica）及黄嘴喜鹊的翼长数据，对这种效应进行了验证。尽管翅长与7月气温（日均最高气温）之间存在预期方向的负相关关系，但该相关性并不显著（r = -0.480，自由度12，p < 0.1，> 0.05）。翅长与冬季气温之间的相关性甚至更弱，因此除温度之外，还必须有其他因素有助于解释喜鹊体型大小的变异。

Unfortunately there has been no recent study of the taxonomic status of the different races based on morphological features, appearance, or biochemistry. Nor have there been many studies of the ecology or social behaviour of Asian magpies. As will become apparent later in the book, ecological conditions play a central role in determining the social aspects of any species’ lives. Some of the Asian races of magpies live in ecologically severe climates and would be particularly interesting in this respect. For example bottanensis, which lives high up in the Himalayas in Tibet, and the Arabian race asirensis, occupying the mountainous regions of Saudi Arabia, are just waiting to be studied!

遗憾的是，近期尚未有研究基于形态特征、外观或生物化学指标来探讨不同亚种的分类地位。关于亚洲喜鹊的生态学或社会行为的研究也寥寥无几。正如本书后文将阐明的，生态条件在决定任何物种的社会生活方面都起着核心作用。亚洲喜鹊的某些亚种栖息于生态条件严酷的气候带，从这一角度来看尤为引人关注。例如，栖息于西藏喜马拉雅山脉高海拔地区的bottanensis亚种，以及占据沙特阿拉伯山区地带的阿拉伯亚种asirensis，正等待着研究者的深入探索！

Relatively little is known about Eurasian magpies outside western Europe (but see Eigelis 1964; Kekilova 1978; Doo-Pyo and Koo 1986), and all the Asian races would repay further study. In this book I will, through necessity, concentrate on the North American and European races of the Black-billed Magpie and on the Yellow-billed Magpie. European and North American Black-billed Magpies differ morphologically in several respects: notably in body size (see Appendices 1-4) and iris colour. The Old World Magpies have uniformly dark brown irides, whereas the relatively small American race hudsonia has a brown iris with a white outer ring. On the basis of this feature and the difference in voice between the two forms, Brooks (1931) felt that they should be considered separate species. This is discussed further in Chapter 12.

关于西欧以外地区的欧亚喜鹊，目前所知甚少（但参见 Eigelis 1964；Kekilova 1978；Doo-Pyo 和 Koo 1986），而所有亚洲亚种都值得进一步研究。出于必要，本书将重点探讨黑嘴喜鹊的北美和欧洲亚种，以及黄嘴喜鹊。欧洲和北美的黑嘴喜鹊在形态上存在若干差异：最显著的是体型大小（参见附录1-4）和虹膜颜色。旧大陆的喜鹊虹膜均为深褐色，而体型相对较小的美洲亚种hudsonia则具有褐色虹膜并带有白色外环。基于这一特征以及两种形态在鸣声上的差异，Brooks（1931）认为应将其视为独立物种。相关内容将在第12章中进一步讨论。

MORPHOMETRICS : SEX AND AGE DIFFERENCES IN BODY SIZE

形态测量学：体型在性别和年龄上的差异

There are no differences in the plumage of the two sexes: male and female magpies of both species are virtually identical in appearance. However, in all populations that have been examined males are larger than females. Most of the information which is available is for European and North American birds; few data exist for magpies in other areas (see Linsdale 1937). The most frequently taken measurements are body weight, wing length (chord), maximum tail length, bill length and depth; and for these, females are about 10% smaller than males (Fig. 4). In all studies the differences in body weight and linear measurements between the sexes were statistically significant (Appendix 2). However, as Fig. 4 shows, some overlap in measurements exists between the sexes, so no single measurement can be used to sex magpies. However, by taking several measurements in combination, using a procedure dauntingly referred to as discriminant function analysis (DFA), it is possible to determine the sex of a magpie much more accurately. The simplest form of DFA uses two characters, such as body weight and wing length. These are plotted against each other and a line calculated which best separates the two sexes. This technique has been used successfully for both Black-billed and Yellow-billed Magpies (Fig. 4). Mark Reynolds was able accurately to determine the sex of 96% of the Yellow-billed Magpies he caught in this way, and Scharf (1987) had a similar success for Black-billed Magpies in Edmonton, Canada. In the studies of Kavanagh (1986, 1988) and Reese and Kadlec (1982) the differences between the sexes were slightly less marked, but by using five different measurements 93% and 89% respectively of all adult birds could be sexed correctly.

两性在羽色上并无差异：这两个物种的雄雌喜鹊在外观上几乎完全相同。然而，在所有已调查的种群中，雄性体型均大于雌性。现有的资料大多来自欧洲和北美的鸟类；其他地区的喜鹊数据则寥寥无几（参见 Linsdale 1937）。最常测量的指标包括体重、翼长（弦长）、最大尾长、喙长和喙深；就这些指标而言，雌鸟比雄鸟小约10%（图4）。在所有研究中，两性之间的体重和线性测量值差异在统计学上均具有显著性（附录2）。然而，如图4所示，两性之间的测量数据存在一定重叠，因此无法仅凭单一测量指标来判定喜鹊的性别。不过，通过结合多项测量数据，并采用一种被称为判别函数分析（DFA）的复杂程序，可以更准确地确定喜鹊的性别。最简单的DFA方法使用两个特征，例如体重和翼长。将这两个特征绘制成图，并计算出一条能最好地区分两性的一条线。该技术已成功应用于黑嘴喜鹊和黄嘴喜鹊（图4）。马克·雷诺兹（Mark Reynolds）通过这种方法，成功准确判定了其捕获的96%黄嘴喜鹊的性别；而沙夫（Scharf，1987）在加拿大埃德蒙顿对黑嘴喜鹊的研究中也取得了类似的成功。在卡瓦纳（Kavanagh，1986、1988）以及里斯和卡德莱克（Reese and Kadlec，1982）的研究中，两性之间的差异略微不那么明显，但通过使用五项不同的测量指标，分别有93%和89%的成年鸟类被正确地判别了性别。

The Yellow-billed Magpie is about 10% smaller than the smallest populations of North American Black-billed Magpie. The sexes also differ in body size: Linsdale (1937) gives the mean weight of males as 175 g ± 9.1 (N = 17) and females as 146.1 g ± 12.1 (N = 15). In his study of Yellow-billed Magpies Nico Verbeek (1973) found no overlap in the weights of male and female: the lightest male weighed 165 g and the heaviest female 158 g (see also Fig. 4). Despite this, Yellow-billed Magpies are no more sexually dimorphic than some populations of magpies elsewhere (see Appendix 3).

黄嘴喜鹊的体型比北美黑嘴喜鹊中最小的种群小约10%。两性在体型上也存在差异：Linsdale（1937）给出的雄性平均体重为175克±9.1（N=17），雌性为146.1克±12.1（N=15）。Nico Verbeek（1973）在对黄嘴喜鹊的研究中发现，雄性和雌性的体重没有重叠：最轻的雄性体重为 165 克，最重的雌性体重为 158 克（另见图 4）。尽管如此，黄嘴喜鹊的性二态性并不比其他地方的一些喜鹊种群更明显（见附录 3）。

If a mated pair of magpies is seen side by side, the size difference between the sexes is almost always apparent. When I was catching adult magpies to colour-mark them, I tried to predict their sex by eye, by comparing their size with that of their partner. On checking which bird incubated (only the female incubates), I found that my visual size assessment could always separate the sexes accurately. There are also differences in the behaviour of the two sexes, including their position during courtship and copulation, and begging by females (Baeyens 1979). However, if these were the only differences, field workers might have to wait a long time to sex their birds.

如果看到一对成对的喜鹊并排站立，两性之间的体型差异几乎总是显而易见的。当我捕捉成年喜鹊进行颜色标记时，我会通过肉眼观察，将它们的体型与伴侣进行比较，以此推测其性别。在核查哪只鸟负责孵卵（只有雌鸟会孵卵）时，我发现我的视觉体型评估总能准确区分两性。两性在行为上也存在差异，包括求偶和交配时的体位，以及雌鸟的乞食行为（Baeyens 1979）。然而，如果仅存在这些差异，野外工作者可能需要等待很长时间才能确定鸟类的性别。

It is possible to distinguish first-year from older magpies from the shape and appearance of the first (outermost) primary (Linsdale 1937; Erpino I968a). The sickle-shaped first primary is unique to magpies (Pica), and in adults has a relatively small black tip, whereas in first-year birds this feather is less curved and has much more black on the tip (Fig. 5; see also Appendix 1). Young magpies do not moult their wing and tail feathers until the summer after they are hatched, so the amount of black on the first primary separates birds in their first calendar year from older ones. In addition, the feathers of first-year birds are usually more abraded, less glossy and slightly more brownish in colour than those of adults. One consequence of the difference in abrasion is that first year birds usually have rounded tips to their outermost tail feathers, whereas in adults these are always square.

可以通过第一（最外侧）初级飞羽的形状和外观来区分一岁鸦和成年鸦（Linsdale 1937；Erpino 1968a）。镰刀状的第一初级飞羽是喜鹊（Pica）的特有特征，成鸟的黑色羽尖相对较小，而第一年鸟的这根羽毛弯曲度较小，且羽尖的黑色部分明显更多（图5；另见附录1）。幼鸦在孵化后的第一个夏天之前不会换羽，因此第一根初级飞羽上的黑色部分可将第一年龄的鸟与成年鸟区分开来。此外，第一年龄鸟的羽毛通常比成年鸟的羽毛磨损更严重、光泽度更低，且颜色略带褐色。羽毛磨损程度的差异导致了一年龄鸟最外侧尾羽的羽尖通常呈圆形，而成年鸟的羽尖则总是呈方形。

First-year magpies also differ from older birds by being about 5-10% lighter in weight, and having a shorter tail (by about 10%). For a sample of Irish birds the size differences between these two age categories, treating each sex separately, were all statistically significant (Kavanagh 1986). In contrast, a sample of North American magpies showed very few significant differences between age classes (Scharf 1987). However, for both samples the greatest difference was in tail length (Appendix 3).

一岁喜鹊与成年鸟的区别还在于体重约轻5%至10%，且尾巴较短（约短10%）。在一组爱尔兰喜鹊样本中，将两性分别处理后，这两个年龄组之间的体型差异均具有统计学意义（Kavanagh 1986）。相比之下，一组北美喜鹊样本显示，不同年龄组之间几乎没有显著差异（Scharf 1987）。然而，对于这两组样本而言，最大的差异均体现在尾长上（附录3）。

Chuck Trost and Cheryl Webb (personal communication) noticed a number of other differences between young and old North American Black-billed Magpies. First-year birds have pink mouths (dark in older birds), a grey iris (dark brown in older birds), a white tip to their bill (dark in older birds), and a dark nictitating membrane, without an orange spot (see below). Interestingly, they found that adult birds reverted to this juvenile plumage during the autumn when they were moulting – the possible reasons for this are discussed later (Chapter 12).

查克·特罗斯特和谢丽尔·韦布（私人通信）注意到北美黑嘴喜鹊的幼鸟与成鸟之间还存在许多其他差异。一岁鸟的嘴部呈粉红色（成鸟为深色），虹膜为灰色（成鸟为深棕色），喙尖呈白色（成鸟为深色），且瞬膜呈深色，没有橙色斑点（见下文）。有趣的是，他们发现成鸟在秋季换羽期间会恢复这种幼鸟羽色——关于此现象的可能原因将在后文（第12章）中讨论。

PLUMAGE AND MOULT

羽毛与换羽

The magpie’s striking black and white plumage hardly requires a detailed description. The black feathers of both species usually have a high gloss, appearing blue, purple, bronze, or green in different lighting conditions. For further information see Appendix 1, Linsdale (1937) and Goodwin (1986). In juvenile Eurasian and North American magpies there is often a bare patch of bluish-grey skin behind the eye (see Chapter 12). In the North African race mauritanica this patch is present in adult birds and is a bright cobalt blue. Its function is unknown. A smaller patch of skin in the same area is yellow in the Yellow-billed Magpie, along with the beak and, according to Linsdale (1946), the claws and soles of the feet. However, I never saw either of the two latter features in my examination of birds during the breeding season: the claws and soles were black. In adults of both species the nictitating membrane is white and bears a small, bright orange spot. Exposure of this membrane is used in courtship and aggressive displays, but its precise function is unknown (Gwinner 1966).

喜鹊醒目的黑白羽色几乎无需赘述。这两个物种的黑色羽毛通常光泽度极高，在不同的光照条件下会呈现蓝色、紫色、青铜色或绿色。更多信息请参见附录1、Linsdale（1937）和Goodwin（1986）。欧亚及北美喜鹊的幼鸟眼后常有一块蓝灰色的裸露皮肤（参见第12章）。在北非亚种mauritanica中，成年鸟也具有这一斑块，且呈鲜亮的钴蓝色。其功能尚不明确。在黄嘴喜鹊身上，同一区域内有一小块黄色皮肤，其喙部以及据Linsdale（1946）所述的爪部和脚底均为黄色。然而，我在繁殖季节对鸟类进行观察时，从未见到后两项特征：爪部和脚底均为黑色。这两种鸟类的成鸟眼睑膜均为白色，并带有小块鲜艳的橙色斑点。在求偶和攻击性展示中会露出该膜，但其确切功能尚不明确（Gwinner 1966）。

The sequence of moults in North American and European Magpies is apparently identical (Linsdale 1937). As in almost all corvids, adult magpies undergo a single, annual moult after breeding, and within a few weeks of fledging young birds undergo an incomplete post-juvenile moult (see Fig. 6). This involves the replacement of the entire body plumage, but not the wing and tail feathers, which are replaced only when the birds are about 12 months old. The first full moult at the end of their first year usually starts about one month before that of older birds (Holyoak 1974a). In both first-year and older birds the replacement of the primaries takes about 95 days to complete. The body feathers are also replaced over this period, but mainly during the middle three or four weeks. Holyoak (1974a) has pointed out that magpies start their moult rather later than most other British corvids and suggests that this is due to the relatively long period (four to six weeks) of care they provide for their young after fledging. In Britain the annual moult of adult birds starts towards the end of June and is completed sometime in September, with females moulting about a week later than males (Seel 1976). Since moulting birds sometimes have a conspicuous lack of feathers on the head, the difference in the timing of moult between the sexes was often apparent among my colour marked birds.

北美和欧洲喜鹊的换羽顺序显然是相同的（Linsdale 1937）。与几乎所有鸦科鸟类一样，成年的喜鹊在繁殖后每年进行一次换羽，而幼鸟在离巢后的几周内会经历一次不完全的幼鸟期后换羽（见图6）。此次换羽涉及全身羽毛的更新，但翅羽和尾羽除外，这些羽毛仅在鸟类约12个月大时才会更换。第一年结束时的首次完全换羽通常比成年鸟早约一个月开始（Holyoak 1974a）。无论是一岁鸟还是成年鸟，初级飞羽的更换大约需要95天才能完成。在此期间，体羽也会被替换，但主要集中在中间的三到四周。Holyoak（1974a）指出，喜鹊开始换羽的时间比英国大多数其他鸦科鸟类稍晚，并认为这是因为它们在雏鸟离巢后仍会对其进行相对较长的照料（四到六周）。在英国，成鸟的年度换羽通常于6月底开始，并在9月某时完成，其中雌鸟的换羽时间比雄鸟晚约一周（Seel 1976）。由于换羽中的鸟类头部有时会出现明显的羽毛缺失，在我那些经颜色标记的鸟类中，两性换羽时间的差异往往十分明显。

The pattern of moult and sequence of plumages in the Yellow-billed Magpie is similar to that for the Black-billed Magpie (Verbeek 1973). Moult starts towards the end of the nestling period in late May, continues through the period of post-fledging care and is completed by late September or October. From start to finish the moult of an individual bird lasts about 4.5 months. Juveniles start their body moult in early August but, because they do not moult their wing or tail feathers, can complete it within 3.5 months, by October.

黄嘴喜鹊的换羽模式和羽色变化顺序与黑嘴喜鹊相似（Verbeek 1973）。换羽始于5月下旬雏鸟期结束之际，持续至离巢后抚育期，并于9月下旬或10月完成。单只鸟类的换羽过程从开始到结束约持续4.5个月。幼鸟于8月初开始躯体换羽，但由于其翅羽和尾羽不参与换羽，因此可在3.5个月内完成，即10月前完成。

Black-billed Magpies with abnormally coloured plumage have been recorded quite frequently in both North America and Europe. These include uniformly white, fawn and grey birds, but the most common colour aberrations involve birds in which the areas which are usually black are grey or brown (Linsdale 1937; Vader et at. 1979).

在北美和欧洲，羽色异常的黑嘴喜鹊都有相当频繁的记录。其中包括全身纯白、浅褐色和灰色的个体，但最常见的色异现象是：通常应为黑色的部位呈现灰色或棕色（Linsdale 1937；Vader 等 1979）。

STUDIES OF MAGPIES

关于喜鹊的研究

This book is based to a large extent on relatively recent studies made of Black-billed and Yellow-billed Magpies in North America, and magpies in Europe. Those studies made over a number of years and involving individually marked birds have yielded the most detailed information on breeding biology and social behaviour. A list of the main studies and the type of information they have provided is presented in Table 1 and their locations are shown in Fig. 7. For those interested in earlier published work on both species of magpie, Linsdale’s (1937) book provides a wonderfully comprehensive account.

本书在很大程度上基于近年来对北美黑嘴喜鹊和黄嘴喜鹊以及欧洲喜鹊的研究。这些历时多年、涉及个体标记鸟类的研究，提供了关于繁殖生物学和社会行为的最详细信息。表1列出了主要研究及其所提供的信息类型，图7则展示了这些研究的地理分布。对于那些对这两种喜鹊的早期出版物感兴趣的读者，林斯代尔（Linsdale，1937）的著作提供了一份极为全面的综述。

STUDYING MAGPIES

研究喜鹊

The aim of this section is to provide a feel for the methods which I and my research students used during our study of magpies. The study started in the spring of 1977 and continued through the hard work of three research students, Keith Clarkson, Simon Eden and Sandy Goodburn, until the end of the 1986 breeding season. Because the study was very much a joint venture, I refer to it as ‘our’ study. We worked in the Rivelin Valley, on the eastern side of Sheffield, which is known to have supported a high density of magpies at least since about 1890 (Dixon 1900). The area consists of farmland devoted to grazing cattle and horses. The fields are relatively small and separated by drystone walls, typical of northern England. The valley bottom contains a small stream along the length of which is an area of mixed woodland. Throughout the area there are other small patches of woodland as well as numerous isolated bushes and trees. The altitudinal range of the study area is from 110m in the valley bottom to 300 m on the top. The main part of the study area was 1 square kilometre in area, but we also searched for nests and colour-marked birds in surrounding areas (Fig. 8).

本节旨在介绍我和我的研究生在研究喜鹊期间所采用的方法。该研究始于1977年春季，在三位研究生——基思·克拉克森（Keith Clarkson）、西蒙·伊登（Simon Eden）和桑迪·古德伯恩（Sandy Goodburn）——的辛勤努力下，一直持续到1986年繁殖季结束。由于这项研究本质上是一项合作项目，我将其称为“我们的”研究。我们的研究地点位于谢菲尔德东部的里维林谷地，据记载，该地区自1890年左右起便拥有高密度的喜鹊种群（Dixon 1900）。该区域主要由用于放牧牛马的农田构成。田地面积相对较小，并由干石墙分隔，这在英格兰北部十分常见。谷底有一条小溪，沿溪而下是一片混交林地。整个区域内还散布着其他小片林地，以及众多孤立的灌木和树木。研究区的海拔范围从谷底的110米至山顶的300米。研究区的主体面积为1平方公里，但我们也在周边区域搜寻鸟巢和佩戴颜色标记的鸟类（图8）。

In order to examine the magpie’s social behaviour it was essential to have individually recognizable birds. When the study started I attempted to catch adults with large baited crow traps, but without success. Magpies were extremely wary about any kind of trap, and even during hard winters they never entered traps to obtain food. This situation contrasts markedly with North American Black-billed Magpies, which are much more amenable to trapping. Robert Brown (1957), for example, in his two-year study trapped no fewer than 540 magpies using baited traps. Having abandoned this trapping method I started to use the same technique that Gert Baeyens developed in her study (described subsequently by Scharf 1985). This involved presenting territorial birds with a decoy magpie in a small cage surrounded by monofilament nooses. The territory owners responded by attempting to attack or court the caged decoy, and in the process got their feet caught in the nooses. When this happened I sprinted towards the bird to grab it before it extricated itself. The ‘sprint’ was an essential, if somewhat undignified part of the procedure, since if left to its own devices a magpie could often remove the nooses from its feet within a few seconds. On some occasions this technique worked extremely well and I caught both members of a pair simultaneously. Unfortunately, this happened all too rarely; at other times the birds would either fail to see the decoy, or would call to it from a safe distance, or even worse, the wild magpies would attack the decoy without getting caught. The quality of the decoy made a large difference too; the most effective bird I had was a wild-caught female given to me by Gert Baeyens. This bird called noisily as soon as I placed her in the decoy cage, attracting the wild birds. As a female she had the advantage of attracting both sexes: wild females approached in order to attack, but interestingly, a male’s behaviour differed according to the location of his mate. If the male was alone, he would approach the decoy and court her, but if while doing this his partner started to approach, his behaviour would switch instantly to aggression . . . Scientists are not supposed to be anthropomorphic, but the human analogy is obvious. Other decoys which I used included hand reared males and females and none of these was very effective. I estimated that I caught one bird for every ten hours of trapping using this technique. Moreover since the decoy could not be left unattended, it was not very efficient! Consequently, we more or less stopped trapping in this way but relied on colour-marking every nestling in and around the study area. This involved a large number of colour-ring combinations, but it worked well, mainly because young Magpies in our study area dispersed very little.

为了研究喜鹊的社会行为，必须能识别出每只个体。研究开始时，我曾尝试用大型带诱饵的乌鸦陷阱捕捉成年喜鹊，但未获成功。喜鹊对任何类型的陷阱都极其警惕，即使在严冬时节，它们也绝不会为了获取食物而进入陷阱。这种情况与北美黑嘴喜鹊形成了鲜明对比，后者对陷阱的接受度要高得多。例如，罗伯特·布朗（Robert Brown，1957）在其为期两年的研究中，利用诱饵陷阱捕获了不下540只喜鹊。放弃这种捕获方法后，我开始采用格特·贝恩斯（Gert Baeyens）在其研究中开发的技术（随后由Scharf于1985年描述）。该方法是将一只假喜鹊置于小笼中，周围布满单丝绳套，以此引诱领地内的喜鹊。领地主鸟会试图攻击或求偶笼中的诱饵，在此过程中脚部便会陷入套索。此时我会迅速冲向鸟儿，在它挣脱前将其抓获。这种“冲刺”虽略显狼狈，却是操作中不可或缺的一环，因为若放任自流，喜鹊往往能在几秒内将套索从脚上解开。有时这种技巧效果极佳，我能同时捕获一对喜鹊中的两只。遗憾的是，这种情况实在太少；其他时候，鸟儿要么没看到诱饵，要么在安全距离外向它鸣叫，更糟的是，野生的喜鹊会攻击诱饵却未被捕获。诱饵的质量也起着关键作用；我用过最有效的是一只由格特·贝恩斯（Gert Baeyens）赠送的野生雌鹊。只要我把它放进诱饵笼，它就会大声鸣叫，吸引野鸟前来。作为雌鸟，它有吸引两性鸟类的优势：野雌鸟会靠近试图攻击，但有趣的是，雄鸟的行为会根据伴侣的位置而有所不同。若雄鸟独自行动，它会靠近诱饵并对其求偶；但若在此过程中其伴侣开始靠近，它的行为会瞬间转为攻击……虽然科学家不应进行拟人化，但这种人类行为的类比显而易见。我使用的其他诱饵还包括人工饲养的雌雄鸟，但这些都不太有效。据我估算，使用这种方法每捕获一只鸟需要花费十小时。此外，由于诱饵不能无人看管，效率实在不高！因此，我们基本停止了这种捕鸟方式，转而依靠给研究区域内及周边的所有雏鸟进行彩色标记。这需要大量颜色的环志组合，但效果很好，主要是因为我们研究区域内的年轻喜鹊活动范围非常有限。

All birds were given metal, numbered British Trust for Ornithology rings. In addition, nestling magpies were given a unique combination of three Darvic colour rings: a total of 854 chicks were ringed during the study. The relatively small number (37) of full-grown birds we caught was marked with colour rings and sometimes patagial wing tags. Wing tags were ideal for identifying birds at a distance (we could read tags up to 1 km away through a telescope), but they did not last as long as colour rings and we gave up using them after a few years. We rarely had trouble reading colour rings, mainly because the grass in the whole area was kept quite short by livestock, and the birds were relatively tame and allowed us to approach to within 10 metres or less in a car. Magpies have remarkably strong beaks and to minimize the chance of them removing colour rings we always sealed them with glue: very few colour rings were ever lost even after six or more years of wear. Overall, from about 1980 we had 60-70% of the population colour-marked and were able to follow the fortunes of many birds throughout their entire lives.

所有鸟类均被佩戴了英国鸟类学会（British Trust for Ornithology）发行的带编号金属环。此外，雏喜鹊还被佩戴了由三枚达维克（Darvic）彩色环组成的独特组合：研究期间共为854只雏鸟进行了环志。我们捕获的成年鸟数量相对较少（37只），这些鸟被佩戴了彩色环，有时还佩戴了翼膜标签。翼标非常适合远距离识别鸟类（我们通过望远镜在1公里外就能读取标签），但其使用寿命不如彩色环，因此我们使用几年后便放弃了。我们很少遇到读取彩色环的困难，主要是因为该区域的草地因牲畜活动而保持得很短，且鸟类相对温顺，允许我们驾车靠近至10米以内。喜鹊的喙异常坚硬，为尽量减少它们摘除彩色环的可能性，我们总是用胶水将环密封：即使佩戴六年以上，丢失的彩色环也寥寥无几。总体而言，从1980年左右开始，我们对该种群的60%至70%进行了彩色标记，并得以追踪许多鸟类在其整个生命周期中的命运。

The magpie’s annual cycle (Fig. 6) determined our seasonal pattern of fieldwork, most of which was conducted between October and June. During this period the central square of the study area was visited every second day on average. Our routine was to make use of the numerous roads and tracks to slowly drive through and scan the entire study area looking for magpies. The position of colour-marked birds was recorded on large-scale maps of the area, and at regular intervals these results were used to determine the location and size of territories and home ranges (see Chapter 2). Fifty sightings of each marked bird were needed to determine accurately its territory boundaries, using the maximum polygon method (Odum & Kuenzler 1955). We made few observations between July and September mainly because the birds, which were moulting during these months, spent much of their time sitting quietly in dense vegetation and were difficult to see. Throughout the winter we created small feeding stations at various locations, providing soaked wheat grain to attract the birds. This allowed us to conduct a roll-call of the non-breeding birds. We also used feeding stations to examine the magpie’s food-hoarding behaviour.

喜鹊的年度活动周期（图6）决定了我们野外工作的季节性安排，其中大部分工作是在10月至6月期间进行的。在此期间，我们平均每隔一天就会走访研究区域的中心区域。我们的常规做法是利用众多道路和小径，缓慢驾车穿行并扫描整个研究区域，寻找喜鹊的踪迹。我们会在该地区的大比例尺地图上记录上色标记鸟类的定位，并定期利用这些数据确定领地及活动范围的位置与大小（参见第2章）。为准确测定每只标记鸟类的领地边界，需采用最大多边形法（Odum & Kuenzler 1955），且每只鸟需记录50次观测数据。7月至9月期间，我们的观测记录较少，主要是因为这些月份正值鸟类换羽期，它们大部分时间都静静地栖息在茂密的植被中，难以被发现。整个冬季，我们在不同地点设置了小型喂食站，提供浸泡过的麦粒来吸引鸟类。这使我们能够对非繁殖期的鸟类进行点名统计。我们还利用喂食站来考察喜鹊的储食行为。

During the breeding season we located every nest in the main part of the study area, and as many nests as possible in the surrounding area. Nests were found before egg laying started by simply looking for birds carrying nest material. In the early part of the season, before the trees came into leaf, this was relatively easy, but later we had to check trees and bushes individually for nests. Magpies in our study area nested either in dense hawthorn bushes less than 5 metres above the ground, or in the tops of large trees like beeches or oaks, 25 metres or more above the ground. Checking nests in these types of situation required different tactics, but both were particularly hard on trousers: my research students always said that tree-climbing claimed three or four pairs of trousers each season. -Hawthorns required a thick coat and stout footwear, whereas tall trees required trainers and rock-climbing equipment. At the outset I climbed trees without ropes or any other aids, but soon realized the stupidity of this. Several rock-climbers made suggestions about the equipment and techniques we could use to climb trees, but all were rather reluctant to demonstrate these themselves. We ended up using a helmet, harness, caving rope, slings and ascenders, making sure we were attached to the tree at all times. With these items, experience, and sometimes a lot of nerve, there was no nest in the study area we couldn’t reach. However, gaining access to the nest was only part of the operation; once there we had to count, weigh and measure the eggs or chicks. Even just getting the eggs or chicks out of a nest at the top of a tall tree with a stiff breeze blowing could induce horrible knee tremors (accurately referred to as “sewing-machine leg’ by Mark Reynolds). In these conditions it was usually necessary to bring the nest contents to the bottom of the tree to make measurements, although we avoided this wherever possible since it disturbed the birds more and doubled the amount of climbing to be done. This was a serious consideration since with over one hundred nests to check, there were sometimes 20 to 30 tall trees to be climbed each day. One of the worst aspects of tree-climbing was having an audience: several nests were located in the grounds of a small, rural hospital and on warm spring days the patients were sometimes wheeled outside in their beds to watch us climb. We could sometimes overhear them asking each other if they thought we would fall . . . with the usual jokes about our being in the right place if we did.

在繁殖季节，我们定位了研究区主区域内的每一个巢穴，并在周边区域尽可能多地定位了巢穴。在产卵开始前，我们通过观察携带筑巢材料的鸟类，便找到了这些巢穴。在繁殖季初期，树木尚未发芽时，这项工作相对容易，但后来我们不得不逐一检查树木和灌木丛以寻找巢穴。我们研究区域内的喜鹊，要么在离地不到5米的茂密山楂灌木丛中筑巢，要么在离地25米或更高的大树（如山毛榉或橡树）树冠顶端筑巢。在这些不同环境下检查鸟巢需要采取不同的策略，但两者都对裤子特别“不友好”：我的研究生们常说，每季爬树都要“牺牲”三四条裤子。——在山楂树上需要穿厚外套和结实的鞋子，而在高大树木上则需要运动鞋和攀岩装备。起初我爬树时不使用绳索或其他辅助工具，但很快意识到这种做法是多么愚蠢。几位攀岩者曾就树木攀爬的装备与技巧提出建议，但他们都颇为不情愿亲自示范。最终我们采用了头盔、安全带、洞穴探险绳、绳套和上升器，确保自己始终与树干保持连接。凭借这些装备、经验，以及有时需要的大胆勇气，研究区域内没有哪个鸟巢是我们无法抵达的。然而，接近鸟巢仅是整个操作的一环；抵达后，我们还必须对鸟蛋或雏鸟进行计数、称重和测量。即便只是在强风呼啸中，从高耸树顶的鸟巢中取出鸟蛋或雏鸟，也会引发可怕的膝盖颤抖（马克·雷诺兹将其准确地称为“缝纫机腿”）。在这种情况下，通常必须将巢内物品搬到树底进行测量，尽管我们尽可能避免这样做，因为这会更打扰鸟类，而且会使需要攀爬的次数增加一倍。这是一个需要认真考虑的问题，因为有超过一百个巢穴需要检查，有时每天要爬二三十棵高树。爬树最糟糕的一点是总有观众：几个鸟巢位于一家乡村小医院的院子里，在温暖的春日里，病人们有时会被推着病床到外面观看我们攀爬。我们偶尔能听到他们互相询问是否觉得我们会摔下来……还伴随着惯常的玩笑，说如果真摔下来，那倒是在“恰当的位置”。

We kept our nest checks to a minimum to reduce disturbance, and on average each nest was checked four times: twice during laying, once at the time of hatching, and a final visit to ring and weigh the chicks 14 days after hatching.

为了尽量减少干扰，我们将巢穴检查次数控制在最低限度，平均每个巢穴检查四次：产卵期间两次，孵化时一次，以及孵化后第14天进行最后一次检查，对雏鸟进行环志和称重。

A NOTE ON STATISTICS

关于统计数据的说明

I have tried throughout the text to keep the use of statistics to a minimum and I hope the text is readable despite their occasional inclusion. Statistics are used primarily in conjunction with results not published elsewhere. Means are presented ± one standard deviation (SD).

在全书中，我尽量减少了统计数据的运用，尽管偶尔仍会涉及，但希望本文仍能通俗易懂。统计数据主要用于说明尚未在其他地方发表的研究结果。均值以±一个标准差（SD）的形式呈现。

SUMMARY

摘要

The derivation and history of the magpie’s name is described. There are two closely related species: the Black-billed Magpie and the Yellow-billed Magpie. The former has a wide geographic range across much of the Northern Hemisphere. The Yellow-billed Magpie is confined to California. Thirteen races of Black-billed Magpie are currently recognized, some being better differentiated than others. Sex and age differences in body measurements are described: in both species males are larger than females. Among European populations first-year birds are smaller than adults. The sequence of moult and the annual cycle are described. All recent major field studies of magpies are tabulated. The various trapping, marking and observation techniques used in studying magpies are presented.

文中阐述了喜鹊名称的由来及其历史。该物种有两个近缘物种：黑嘴喜鹊和黄嘴喜鹊。前者分布范围广泛，遍及北半球大部分地区；而黄嘴喜鹊则仅限于加利福尼亚州。目前已确认黑嘴喜鹊有13个亚种，其中部分亚种的差异比其他亚种更为显著。文中描述了体尺的性别与年龄差异：在这两种物种中，雄性均比雌性体型更大。在欧洲种群中，第一年鸟的体型小于成年鸟。文中还描述了换羽顺序及年度生活周期。所有近期关于喜鹊的主要野外研究均以表格形式列出。文中介绍了研究喜鹊所采用的各种诱捕、标记和观察技术。