摘要:

SummaryThe Calf birdPerissocephalus tricolorwas studied in the Kanuku Mountains of southern Guyana for three months (January‐April 1970), during which time almost daily visits were paid to a lek of four adult males.The adult males owned perches about 30 ft up in understorey trees, where they displayed and called throughout much of the day. Four immature males also visited the lek, particularly in the morning and evening. The immatures also wandered, feeding and occasionally calling together, over an area of forest of approximately 3 miles by half a mile. There was a hierarchy among the adult and immature males, the dominant males owning the most coveted perches at the lek.The male's most far‐reaching call, the “moo call”, is a co‐operative advertising call, in that birds calling together adjust the timing of their calls so as to follow each other and not overlap. The adult males perform a number of silent agonistic displays on their lek perches. Periodically, adult and immature males and sometimes a female invade the vicinity of a lek perch, usually that of the dominant male. Once a female was briefly mounted by the dominant male on his lek perch during an invasion. On other occasions females visited the lek but no mating occurred.The food of the males attending the lek was recorded by the daily collection of a total of 2,500 regurgitated fruit seeds (mostly drupes) from below the perches. Males also regularly take insects, but in smaller quantities.Three nests were found. The nest is an extremely light structure built entirely of fine twigs. A single egg was laid in each nest. All the nests (and two old ones) were within half a mile of the lek. Two of the nests were only 5 yards apart and the eggs were laid in them within 10 days of each other.The incubation period at one nest was 26–27 days and the fledging period approximately 27 days. The chick on hatching was covered in bright orange‐chestnut down. It was fed mostly on insects (predominantly Orthoptera) brought by the female in her beak. There was no evidence of a male attending the nest.The Calfbird's nesting and lek behaviour is compared with that of other species

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb02600.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SummaryEgg‐laying in Woodpigeons in central London lasts from March until September in normal years, with peak production in April and May, contrasting markedly with some rural areas in England where few clutches are completed before May and the peak months are July and August. Both appear to be determined by food supplies; London birds feed mainly on bread, supplemented by vegetable foods, which is in ample supply. so that they require much less time for feeding than rural birds in winter and early spring. They are thus able to breed over the whole period for which they are apparently physiologically capable. Breeding success in central London is almost double that in Cambridgeshire and nearly 50% above that in other rural areas, due to markedly lower predation, especially at the egg stage. The factors governing the breeding seasons of different populations of Woodpigeons are discusse

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb02601.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SummaryFungi have regularly been recorded on feathers removed from birds. Cellulose‐decomposing spores which are merely carried on the feathers were common on birds sampled in Britain, but were fewer than expected on the basis of random distribution on birds sampled in India. Hyaline‐spored fungi were less common on Indian birds, and more abundant on British birds than expected. Keratinophilic fungi, which are related to the dermatophytes, were particularly associated with related groups of birds: thus Turdus spp. regularly yielded Arthroderma curreyi, and partridges were contaminated with Ctenomyces serratus. Chrysosporium spp. were widespread on birds in India and Britain. Where associations have been shown, feather fats from these birds stimulate, or do not depress the growth of the keratinophilic fungi. Otherwise, feather fats were inhibitory to the fungi. The temperature relationships of the fungi, showing no growth at 40°C, would explain the restriction of the keratinophilic fungi to the outer, contour feathers, and of dermatophytes mainly to the non‐insulated parts of the birds' s

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb02602.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SummaryVarious 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 genusGypslive 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 theGypsvultures, 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 theGypsvultures 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 b

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb02603.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SummaryModern geological ideas on ocean‐floor spreading are briefly reviewed. Pangea began to break up at the end of the Trias, but Africa, Antarctica and Australia remained together or close to each other till the end of the Cretaceous. The position of western New Guinea at the start of the Miocene could have been approximately where Arnhem Land is now, and at the start of the Pliocene somewhat north of the present‐day Aru Islands. Its size until the end of the Pliocene was much smaller than it is today.Friedmann's proposal for the evolutionary spread ofChrysococcyxtherefore demands that the whole process occurred since about the start of the Pliocene. There may not have been enough time in these seven million years for the evolutionary dispersal of a genus of parasitic cuckoos halfway round the world. His proposal also regardsC. osculansas an awkward throw‐back, and leaves a gap between species in New Guinea and southeastern Asia that is not bridged by intermediates.If a stock of cuckoos had been in Gondwanaland before it broke up, that stock could have given rise to the genusCacomantisand the forerunners ofC. osculans.The lineage ofosculanswould have quickly given rise to a lineage of glossy cuckoos that then divided into two branches. One could have penetrated Africa, south of where Madagascar then was, produced the speciesklaas, cupreus, capriusandflavigularis(an aberrant end‐product), and much later, after Madagascar had drifted south from India (having been separate from Africa since the Cretaceous), colonised Asia wheremaculatusandxanthorhynchuswould have differentiated. The other line could have differentiated, perhaps more slowly, in Australia intobasalts, lucidus, ruficollisandmalayanut (minutillus).When Australia had drifted near enough to the Malay Archipelago and as New Guinea grew,ruficollisandminutilluscould have moved forward to colonise the islands, whereminutilluswould have produced the many racesoimalayanusandmeyeriidifferentiated as an aberrant end‐product.This proposal overcomes some of the objections to Friedmann's theory because it arranges events to accord better with geological developments and avoids the evolutionary discontinuities of his proposal. The migratory habits of the cuckoos, thought by Friedmann to be significant, are discounted as evidence for evolutionary history. The parasitic habits are re‐interpreted. Better data are presented for the parasitic behaviour ofbasalisandlucidus;they suggest that both species are sophisticated and probably host‐specific parasites. Jensen&Jensen (1969) have already given evidence that some African glossy cuckoos are highly host‐specific. There seems to be a trend of decreasing parasitic sophistication in Australian species, correlated with the possible age of the species. In Africa parasitism seems to be far in advance of that in Australia, probably because the opportunities for parasitism are far better in Africa. These trends and differences in parasitic behaviour are compatible with an evolutionary spread from Gondwanaland.The crucial question is whether the stock ofCacomantisandChrysococcyxcould have existed before the break‐up of Gondwanaland, i.e. before the early Eocene. The present fossil record suggests that this is unlikely, but the paucity of fossils and the difficulties of palaeoclimates do not seem to be insuperable and it is suggested that a southern origin for these cuckoos should be con

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb02604.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SummaryThis paper describes the way in which a new pair of McCormick's Skua became established in a vacant area in a breeding colony. The pair worked out from a central point to meet neighbouring birds on the original boundaries so that these became re‐established. Within three days of settling most of the vacant area was claimed and the pair was behaving as a recognised member of the breeding group. Eggs were laid in the first season.Following comparison with other species it is proposed that the stability found in territory boundaries from year to year arises because territories becoming vacant are occupied by replacement pairs while neighbours are inhibited from encroaching on the

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb02605.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SummaryEighteen species of sea–birds were observed from CSS ‘Hudson’ in the South Atlantic between the Rio de la Plata and Tierra del Fuego in late January and late February 1970. Major feeding areas were noted off Mar del Plata, the Valdes Peninsula and Tierra del Fuego, Argentina, the first two in rich modified or unmodified water of the subantarctic Falkland Current, associated with upwelling. The southernmost area had most birds, the northernmost fewest. A temperate–latitude assemblage including Yellow–nosed Albatross and Cory's Shearwater occurred off Mar del Plata in warmed water of subantarctic (Falkland Current) origin. South of 39°S these two species were replaced by Black–browed Albatross and Great Shearwater in cold offshore water of the Falkland Current. Off the Valdes Peninsula Black–browed Albatross, Great and Sooty Shearwaters, White–chinned Petrels and family groups of Magellanic Penguins occurred near the edge of highly–productive water of the Falkland Current. The largest feeding area, east of Tierra del Fuego, had Magellanic and Rockhopper Penguins, Great Shearwaters, King Cormorants, South American Terns and jaegers, but no oceanographic information is available. At 50°S prions and diving petrels appeared for the first time, marking a possible oceanographic discontinuity or proximity to colonies on the Falkland Islands. Several common species of the South Atlantic were not seen on the transect including Cape Pigeon, Southern Fulmar, Soft–plumaged Petrel, Schlegel's Petrel and Pediunker. Kelp Gull, South American Tern, Manx Shearwater and jaegers were rare or absent far from land. New southern limits for the western South Atlantic Ocean were established for Cory's and Manx Shearwaters, and the Great Shearwater was observed for the first t

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb02606.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb02607.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb02608.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb02609.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY