OBSERVATIONS ON THE BEHAVIOUR OF BIRDS IN SOUTHERN RHODESIA

Maclean, G. L. 1974. The breeding biology of the Rufouseared Warbler and its bearing on the genus Prinia. Ostrich 45: 9–14.

The Rufouseared Warbler Prinia pectoralis, a common species of the Kalahari scrub, nests after rain at any time of the year. Nest construction and nest sites are described. The clutch is normally three or four eggs. Incubation takes 12 to 13 days and the nestling period is 11 to 13 days. Data suggest that the Rufouseared Warbler is not a member of the genus Priniu, the generic position it currently occupies.     

迁飞过程中昆虫的行为:对风温场的适应与选择

本文综述了昆虫在迁飞过程中对大气物理环境的各种行为反应,有边界层气象的理论重新审视迁飞种群的时空分布,提出了“边界层顶现象”的概念。即边界层顶的低空逆温和低空急流为迁飞种群提供了最适宜的风温场,迁飞种群在边界层顶集聚成层,并通过定向理一步修饰其位移方位,表现出对风温场的主动选择能力和对大气结构和运动的高度复杂的适应性反应。进一步深化对“边界层顶现象”的认识,对迁飞性害虫的异地预测具有重要的理论意义     

切变流场中红细胞取向与变形行为的研究

用新型激光衍射仪研究了不同粘度的切变流场中ＤＩ、（ＤＩ）ｄ、（ＤＩ）ｏｒ随流场切变率的变化,结果表明：１．在切应力τ＝０．２Ｎ／Ｍ２附近,ＲＢＣ从‘Ｃ＝０’轨道取向向‘Ｃ＝∞’过渡。２．（ＤＩ）ｄ在不同粘度的悬浮介质中对切交率的依赖关系不同,存在一临界形度,当悬浮介质的粘度小于该值时,由于ＲＢＣ的翻滚会出现ＤＩ＝０的现象。３ＲＢＣ群体由稳定的坦克履带式运动概型向混乱的翻滚运动概型转化的过程中,存在一能量转化的过渡过程。     

THE BIRDS OF BLYTHSWOOD AND SOME NOTES ON BIRDS OF THE DISTRICT

Wintle, C. C. &; Taylor, P. B. 1993. Sequential polyandry, behaviour and moult in captive Striped Crakes Aenigmatolimnas marginalis. Ostrich 64:115-122.

Captive Striped Crakes showed sequential polyandry, the female laying for a second male when the clutch of her first mate was about to hatch. Where aviary space permitted each male set up a breeding territory and each female defended a larger area encompassing the territories of one or two males. Non-territorial subordinate males and females did not breed. The female initiated breeding by attracting the male and soliciting copulation, and the male incubated the eggs and cared for the young. Incubation took 17–18 days, the chicks left the nest at 4–5 days of age and were fully grown and capable of flight at 46–53 days. Breeding occurred from September to March and males normally reared two broods per season. Territoriality was evident only during the breeding season. Juvenile plumage was a duller version of the sexually dimorphic adult plumage; post-juvenile moult bean at 13–15 weeks and was complete at 21 weeks. Remex moult was simultaneous and a complete moult regular1 occurred twice a year in adults, in December and April (males) and September and March/April (females).     

孔子鸟与鸟类的早期演化

大量孔子乌标本的出现,使得我们能够识别这一早期鸟类的一些前所未知的形态特征。依据这些特征,并结合近年来中国发现的其他中生代鸟类资料,我们可以进一步探讨早期鸟类研究中存在的某些问题,诸如鸟类飞行的起源等。孔子鸟头骨的最典型特征是进步的角质像的出现和原始眶后骨的完全保留。孔子鸟的眶后骨和颧骨相连接,这一特征尚未见于其他鸟类。由于始祖鸟也已缺失了眶后骨,因此眶后骨在孔子鸟中的存在,进一步证实了始祖鸟在早期鸟类演化中的旁支地位,同时也表明,鸟类真正的祖先比我们以往所了解的更加原始。孔子鸟保留了三个指爪。第三指爪（中间一个）常较退化,这和飞羽附着第三指有关。发育的趾爪及指爪,显示孔子鸟适应攀援树木的生活。基本愈合的尾椎和尚不完善的飞行器官,不仅支持这一假设,而且可能还表明,孔子鸟尚不能从地面起飞。孔子鸟尚未发育小冀羽,这也更加证实了其飞行的原始性。孔子鸟的某些个体,保存一对长的尾羽,这可能代表雄性的特征。另一些个体的头部还保留装饰性羽毛。数百件个体的集中发现或许还表明,孔子鸟具备了某些现生鸟类集群性的行为方式。个体大小的变化在早期鸟类飞行能力演化中的作用十分显著。早白垩世的反鸟类的成员都明显小于始祖鸟和孔子鸟,加之拥?     

THE BIRDS OF TASMANIA: ECOLOGY AND EVOLUTION

SUMMARY Tasmania, about the size of Ireland, separated from the Australian mainland by 140 miles of sea, and isolated for about the last 12,000 years, has 104 species of native breeding land-birds, with the addition of ten introduced species. The environment is described; in particular the vegetation is classified into nine natural types and three produced by European man; and the distribution of the bird species among these is defined and discussed. The other vertebrates are briefly considered. No extinction is definitely known to have taken place as a result of European settlement except of the Tasmanian Emu (and of course Tasmanian Man). An attempt is made to reconstruct the Late Pleistocene history of Tasmania and its vegetation, with special reference to the Last Glaciation, when the island would have been joined to the mainland. When the avifauna is divided into categories, water-birds, raptors, etc., it is found to have much the same proportional composition as the Australian mainland avifaunas with which it is compared, though it consists of many fewer species. The vegetation types of the colder and wetter areas of Tasmania house far fewer species of birds than the drier and warmer habitats. The 104 breeding species include 14 endemics, which are considered in detail, and 27 endemic subspecies. As shown by comparison with other islands, the total proportionate endemism is extraordinarily high for a recent continental island (though it is actually lower than that in the remote ecological island formed by the sclerophyll of southwestern Western Australia). A contributory cause may be that Tasmania is not regularly visited by land-birds from the continent (though at least one-fifth of the Tasmanian species are partial or total migrants in winter). The most noteworthy endemics are two monotypic genera, Lathamus and Acanthornis, and the Native Hen Tribonyx mortierii, which has become flightless apparently in the face of a formidable array of local predators. Considerations of climate and habitat suggest that at least half the avifauna, including 19 of the endemic subspecies and six of the members of superspecies, arrived in Tasmania some time after the amelioration of the Last Glaciation began, some 18,000 years ago. Geographical considerations suggest that four of those six members of superspecies existed in their present form when the land-bridge to the mainland was cut, 12,000 years ago. Certain habitats, widespread over southeastern Australia during the glaciation, are now virtually confined to Tasmania where they form the stronghold of certain species, such as the Pink Robin Petroica rodinogaster, which occur only as relicts on the mainland. The endemic Scrub Tit Acanthornis magnus is practically confined to such habitats, where its ecology suggests it would have been well adapted to glacial conditions. Among the local endemics there is a strong tendency for colouration to be more saturated than on the continent of Australia (Gloger's rule) but there is less consistency in tendency to greater size (Bergmann's rule). A noteworthy proportion of the Tasmanian species have duller plumage than their mainland relatives, usually with an assimilation to female or juvenile plumage—unexpected in an island as big as Tasmania with so considerable an avifauna.     

THE ECOLOGY AND BEHAVIOUR OF THE LONG-TAILED TIT

The behaviour and ecology of a population of Long-tailed Tits in Wytham Great Wood, Oxford, were studied between October 1970 and June 1971. Flocks were found to have a stable composition in autumn, and to occupy fairly discrete territories which they defended against other flocks.
In spring the population was reduced by about 50% and in the pre-nesting period flocks formed only in cold weather or just before going to roost. These flocks occupied the same territories as the autumn flocks and the individuals composing them eventually nested within the flock territory.
Predation of nests was heavy, increasing to a peak in the first half of May. Only nine pairs out of 36 managed to rear young successfully. At six out of these nine nests, supernumerary birds helped to feed the young, but it seems unlikely that this increased their success, since all young hatched fledged successfully. The presence of supernumerary birds at the nest was accompanied by frequent hover-displays by all the adults.
The distribution of nests in relation to habitat shows that there is a preference for scrub rather than mature woodland, although the latter is used extensively for feeding during the winter. There appears to have been a radical change in the height of nest-sites in Wytham Great Wood between 1955–57 and 1971, and this is probably due to predation.     

SOARING BEHAVIOUR AND PERFORMANCE OF SOME EAST AFRICAN BIRDS, OBSERVED FROM A MOTOR-GLIDER

Various species of soaring birds were studied by following them in a motor-glider, mainly over the Serengeti National Park, Tanzania. The characteristics of thermal convection in the study area are described in general terms. The two vulture species of the genus Gyps live by scavenging among the herds of migratory ungulates, especially Wildebeest. They are not territorial, and gather in large numbers on kills. When raising young they may be obliged by game movements to forage at long distances from their nests. Their cross-country performance is adequate for a foraging radius of over 100 km in dry-season conditions. Their ability to compete with Spotted Hyaenas is thought to depend partly on this factor and partly on an advantage in arriving early at kills. These two species appear to find food more by watching other vultures than by searching for it directly. The Lappet-faced and White-headed Vultures are thought to be sedentary, and to depend on thorough searching of a fixed foraging territory, rather than on following migratory game. They have lower wing loadings than the Gyps vultures, and were not seen cross-country flying. They never gather in large numbers. The Hooded Vulture is a solitary nester, but it does fly across country, and does gather at kills. Vultures soar individually, and seem to be good at exploiting such phenomena as thermal streets. They do not travel in flocks. Tawny and Martial Eagles react positively to the glider, and are suspected of regarding it as potential prey. White Storks migrate between Europe and Africa, and also travel about within East Africa, by thermal soaring. They soar in flocks, and unlike vultures rely on co-ordinated social behaviour to locate thermals. In choosing their route, they often fail to react to obvious weather signs. They enter cumulus clouds from the bottom when thermalling, but probably do not climb far above cloudbase. Marabou Storks soar individually, but also sometimes travel in flocks. When doing so, they show less lateral spreading than White Storks, which reduces the effectiveness of the flock as a thermal-finding unit; on the other hand, they do seem to react to visible weather signs, like vultures or glider pilots. White Pelicans, which travel by thermal soaring between different lakes in the Rift Valley, show the most highly co-ordinated social soaring behaviour. Unlike White Storks, they fly in formation even when circling. Storks and pelicans showed more signs of alarm when approached by the glider than did the vultures or birds of prey. This could be due to their being preyed upon in flight, for instance by Martial Eagles. The basis of conventional thermal cross-country flying is outlined, and it is explained why the high wing loadings of the Gyps vultures are appropriate to their peripatetic habits. A method of thermal soaring without circling is discussed, and shown to be more readily feasible for small than for large birds. Some differences in soaring techniques between birds and glider pilots are interpreted in the light of this calculation. A case in which Black Kites apparently used this technique to soar in random turbulence is described. The cross-country speed attainable by thermal soaring should be similar to the cruising speed under power in both large and small birds. Rough calculations of the energy costs suggest that a large bird (White Stork) should reduce its fuel consumption by a factor of 23 by soaring rather than flying under power, whereas this factor would be only 2–4 for a small bird (Bonelli's Warbler). Other reasons why thermal soaring is an advantageous means of travel for large but not for small birds are also indicated.