15 Mimicry among Birds

In the class of birds there are a number of cases that make some approach to mimicry¹, such as the resemblance of the cuckoos, a weak and defenceless group of birds, to hawks³ and Gallinace?. There is, however, one example which goes much further than this, and seems to be of exactly the same nature as the many cases of insect mimicry which have been already given. In Australia and the Moluccas there is a genus of honeysuckers called Tropidorhynchus, good sized birds, very strong and active, having powerful grasping claws and long, curved, sharp beaks⁴. They assemble together in groups and small flocks, and they have a very loud bawling⁵ note, which can be heard at a great distance, and serves to collect a number together in time of danger. They are very plentiful⁶ and very pugnacious⁷, frequently driving away crows, and even hawks, which perch⁸ on a tree where a few of them are assembled. They are all of rather dull and obscure colours. Now in the same countries there is a group of orioles, forming the genus Mimeta, much weaker birds, which have lost the gay colouring of their allies the golden orioles, being usually olive-green or brown; and in several cases these most curiously⁹ resemble the Tropidorhynchus of the same island. For example, in the island of Bouru is found the Tropidorhynchus bouruensis, of a dull earthy colour, and the Mimeta bouruensis, which resembles it in the following particulars:— The upper and under surfaces of the two birds are exactly of the same tints¹⁰ of dark and light brown; the Tropidorhynchus has a large bare black patch round the eyes; this is copied in the Mimeta by a patch of black feathers. The top of the head of the Tropidorhynchus has a scaly¹² appearance from the narrow scale-formed feathers, which are imitated by the broader feathers of the Mimeta having a dusky line down each. The Tropidorhynchus has a pale ruff formed of curious recurved feathers on the nape (which has given the whole genus the name of Friar birds); this is represented in the Mimeta by a pale band in the same position. Lastly, the bill of the Tropidorhynchus is raised into a protuberant¹³ keel at the base, and the Mimeta has the same character, although it is not a common one in the genus. The result is, that on a superficial examination the birds are identical, although they have important structural¹⁴ differences, and cannot be placed near each other in any natural arrangement. As a proof that the resemblance is really deceptive¹⁵, it may be mentioned that the Mimeta is figured and described as a honeysucker in the costly¹⁶ “Voyage de l’Astrolabe,” under the name of Philedon bouruensis!

Passing to the island of Ceram, we find allied¹⁷ species of both genera. The Tropidorhynchus subcornutus is of an earthy brown colour washed with yellow ochre, with bare orbits, dusky cheeks, and the usual pale recurved nape-ruff. The Mimeta forsteni is absolutely identical in the tints of every part of the body, the details of which are imitated in the same manner as in the Bouru birds already described. In two other islands there is an approximation towards mimicry, although it is not so perfect as in the two preceding cases. In Timor the Tropidorhynchus timoriensis is of the usual earthy brown above, with the nape-ruff very prominent, the cheeks black, the throat nearly white, and the whole under surface pale whitish brown. These various tints are all well reproduced in Mimeta virescens, the chief want of exact imitation being that the throat and breast of the Tropidorhynchus has a very scaly appearance, being covered with rigid¹⁸ pointed¹⁹ feathers which are not imitated in the Mimeta, although there are signs of faint dusky spots which may easily furnish the groundwork of a more exact imitation by the continued survival of favourable²⁰ variations in the same direction. There is also a large knob at the base of the bill of the Tropidorhynchus which is not at all imitated by the Mimeta. In the island of Morty (north of Gilolo) there exists the Tropidorhynchus fuscicapillus, of a dark sooty brown colour, especially on the head, while the under parts are rather lighter²¹, and the characteristic ruff of the nape is wanting. Now it is curious that in the adjacent island of Gilolo should be found the Mimeta ph?ochromus, the upper surface of which is of exactly the same dark sooty tint¹¹ as the Tropidorhynchus, and is the only known species that is of such a dark colour. The under side is not quite light enough, but it is a good approximation. This Mimeta is a rare bird, and may very probably exist in Morty, though not yet found there; or, on the other hand, recent changes in physical geography may have led to the restriction²² of the Tropidorhynchus to that island, where it is very common.

Here, then, we have two cases of perfect mimicry and two others of good approximation, occurring between species of the same two genera of birds; and in three of these cases the pairs that resemble each other are found together in the same island, and to which they are peculiar²³. In all these cases the Tropidorhynchus is rather larger than the Mimeta, but the difference is not beyond the limits of variation in species, and the two genera are somewhat alike in form and proportion. There are, no doubt, some special enemies by which many small birds are attacked, but which are afraid of the Tropidorhynchus (probably some of the hawks), and thus it becomes advantageous²⁴ for the weak Mimeta to resemble the strong, pugnacious, noisy, and very abundant Tropidorhynchus.

My friend, Mr. Osbert Salvin, has given me another interesting case of bird mimicry. In the neighbourhood of Rio Janeiro is found an insect-eating hawk² (Harpagus diodon), and in the same district a bird-eating hawk (Accipiter pileatus) which closely resembles it. Both are of the same ashy tint beneath, with the thighs²⁵ and under wing-coverts reddish brown, so that when on the wing and seen from below they are undistinguishable. The curious point, however, is that the Accipiter has a much wider range than the Harpagus, and in the regions where the insect-eating species is not found it no longer resembles it, the under wing-coverts varying to white; thus indicating that the red-brown colour is kept true by its being useful to the Accipiter to be mistaken for the insect-eating species, which birds have learnt not to be afraid of.

1 mimicry   

n.（生物）拟态，模仿

参考例句：

• One of his few strengths was his skill at mimicry.他为数不多的强项之一就是善于模仿。
• Language learning usually necessitates conscious mimicry.一般地说，学习语言就要进行有意识的摹仿。

2 hawk   

n.鹰，骗子；鹰派成员

参考例句：

• The hawk swooped down on the rabbit and killed it.鹰猛地朝兔子扑下来,并把它杀死。
• The hawk snatched the chicken and flew away.老鹰叼了小鸡就飞走了。

3 hawks   

鹰( hawk的名词复数 )； 鹰派人物，主战派人物

参考例句：

• Two hawks were hover ing overhead. 两只鹰在头顶盘旋。
• Both hawks and doves have expanded their conditions for ending the war. 鹰派和鸽派都充分阐明了各自的停战条件。

4 beaks   

n.鸟嘴( beak的名词复数 )；鹰钩嘴；尖鼻子；掌权者

参考例句：

• Baby cockatoos will have black eyes and soft, almost flexible beaks. 雏鸟凤头鹦鹉黑色的眼睛是柔和的，嘴几乎是灵活的。 来自互联网
• Squid beaks are often found in the stomachs of sperm whales. 经常能在抹香鲸的胃里发现鱿鱼的嘴。 来自互联网

5 bawling   

v.大叫，大喊( bawl的现在分词 )；放声大哭；大声叫出；叫卖（货物）

参考例句：

• We heard the dulcet tones of the sergeant, bawling at us to get on parade. 我们听到中士用“悦耳”的声音向我们大喊，让我们跟上队伍。 来自《简明英汉词典》
• "Why are you bawling at me? “你向我们吼啥子？ 来自汉英文学 - 中国现代小说

6 plentiful   

adj.富裕的，丰富的

参考例句：

• Their family has a plentiful harvest this year.他们家今年又丰收了。
• Rainfall is plentiful in the area.这个地区雨量充足。

7 pugnacious   

adj.好斗的

参考例句：

• He is a pugnacious fighter.他是个好斗的战士。
• When he was a child,he was pugnacious and fought with everyone.他小时候很好斗，跟每个人都打过架。

8 perch   

n.栖木，高位，杆；v.栖息，就位，位于

参考例句：

• The bird took its perch.鸟停歇在栖木上。
• Little birds perch themselves on the branches.小鸟儿栖歇在树枝上。

9 curiously   

adv.有求知欲地；好问地；奇特地

参考例句：

• He looked curiously at the people.他好奇地看着那些人。
• He took long stealthy strides. His hands were curiously cold.他迈着悄没声息的大步。他的双手出奇地冷。

10 tints   

色彩( tint的名词复数 )； 带白的颜色； （淡色）染发剂； 痕迹

参考例句：

• leaves with red and gold autumn tints 金秋时节略呈红黄色的树叶
• The whole countryside glowed with autumn tints. 乡间处处呈现出灿烂的秋色。

11 tint   

n.淡色，浅色；染发剂；vt.着以淡淡的颜色

参考例句：

• You can't get up that naturalness and artless rosy tint in after days.你今后不再会有这种自然和朴实无华的红润脸色。
• She gave me instructions on how to apply the tint.她告诉我如何使用染发剂。

12 scaly   

adj.鱼鳞状的；干燥粗糙的

参考例句：

• Reptiles possess a scaly,dry skin.爬行类具有覆盖着鳞片的干燥皮肤。
• The iron pipe is scaly with rust.铁管子因为生锈一片片剥落了。

13 protuberant   

adj.突出的，隆起的

参考例句：

• The boy tripped over a protuberant rock.那个男孩被突起的岩石绊了一下。
• He has a high-beaked nose and large protuberant eyes.他有着高鼻梁和又大又凸出的眼睛

14 structural   

adj.构造的，组织的，建筑（用）的

参考例句：

• The storm caused no structural damage.风暴没有造成建筑结构方面的破坏。
• The North American continent is made up of three great structural entities.北美大陆是由三个构造单元组成的。

15 deceptive   

adj.骗人的，造成假象的，靠不住的

参考例句：

• His appearance was deceptive.他的外表带有欺骗性。
• The storyline is deceptively simple.故事情节看似简单，其实不然。

16 costly   

adj.昂贵的，价值高的，豪华的

参考例句：

• It must be very costly to keep up a house like this.维修这么一幢房子一定很昂贵。
• This dictionary is very useful,only it is a bit costly.这本词典很有用，左不过贵了些。

17 allied   

adj.协约国的；同盟国的

参考例句：

• Britain was allied with the United States many times in history.历史上英国曾多次与美国结盟。
• Allied forces sustained heavy losses in the first few weeks of the campaign.同盟国在最初几周内遭受了巨大的损失。

18 rigid   

adj.严格的，死板的；刚硬的，僵硬的

参考例句：

• She became as rigid as adamant.她变得如顽石般的固执。
• The examination was so rigid that nearly all aspirants were ruled out.考试很严，几乎所有的考生都被淘汰了。

19 pointed   

adj.尖的，直截了当的

参考例句：

• He gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。
• She wished to show Mrs.John Dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。

20 favourable   

adj.赞成的，称赞的，有利的，良好的，顺利的

参考例句：

• The company will lend you money on very favourable terms.这家公司将以非常优惠的条件借钱给你。
• We found that most people are favourable to the idea.我们发现大多数人同意这个意见。

21 lighter   

n.打火机，点火器；驳船；v.用驳船运送；light的比较级

参考例句：

• The portrait was touched up so as to make it lighter.这张画经过润色，色调明朗了一些。
• The lighter works off the car battery.引燃器利用汽车蓄电池打火。

22 restriction   

n.限制，约束

参考例句：

• The park is open to the public without restriction.这个公园对公众开放，没有任何限制。
• The 30 mph speed restriction applies in all built-up areas.每小时限速30英里适用于所有建筑物聚集区。

23 peculiar   

adj.古怪的，异常的；特殊的，特有的

参考例句：

• He walks in a peculiar fashion.他走路的样子很奇特。
• He looked at me with a very peculiar expression.他用一种很奇怪的表情看着我。

24 advantageous   

adj.有利的；有帮助的

参考例句：

• Injections of vitamin C are obviously advantageous.注射维生素C显然是有利的。
• You're in a very advantageous position.你处于非常有利的地位。

25 thighs   

n.股，大腿( thigh的名词复数 )；食用的鸡（等的）腿

参考例句：

• He's gone to London for skin grafts on his thighs. 他去伦敦做大腿植皮手术了。 来自《简明英汉词典》
• The water came up to the fisherman's thighs. 水没到了渔夫的大腿。 来自《简明英汉词典》