摘要:

SummaryData are based on more than 200 h of observation at Ethiopia's Lake Shala from 1966 to 1972.Except for differences in size of bill, there are no useful field characters separating male and female Sacred Ibis. The breeding plumage is described; vivid blood‐red colour underneath the wings and the ornamental plumes are especially obvious when nesting commences.Physical and biological features of Lake Shala, Ethiopia, and its nesting islands are described; the species of birds nesting on the Shala islands are given.Ibises nest at Shah from March to August; no nesting has been recorded from September to February during the last months of the ‘big’ rains through the main dry season. Nesting normally begins in the ‘small’ rains (between 14 March‐24 April), although instances were recorded as early as 1 March and as late as 20 August. The ibises normally nest once per year, although it is possible that occasionally a second nesting may occur after an unsuccessful first attempt.The ibises at Shala nest in discrete groups; several nesting groups may form on any or all of the islands; the number of groups attempting to nest varied from year to year. Nesting activity begins when males arrive and establish pairing territories, usually in a small tree but sometimes on the ground. When females and other males arrive at the pairing territories, pair formation ensues. At this time males perform forward threat, modified forward threat, pursuit flight, supplanting attack and modified snap displays, while both sexes perform stretch and bow displays. Once established, the pair abandons the pairing territory and moves to the nesting area, usually near but always distinct from the pairing territory, and establishes a nest‐site territory. Most members of the nesting group move to the nesting area on the same day. Copulation then takes place, and is followed by collection of nest material, usually by the male. Nests are built close together. The average area of 10 nests measured was 0.09 m2. Nests are usually less than 20 cm thick and are made of many small branches and sticks.The average clutch in 34 nests was 2.24 eggs; the average size of 34 eggs was 63.4×43.5 mm. Incubation probably begins when the clutch is complete. Both sexes incubate, and the incubation period probably lasts 28–29 days.The development of the young is described. The young leave the nest‐site territory when 14–21 days old. Although they are capable of some flight when 35–40 days old, the young do not leave the colony until they are 44–48 days old. In the colony, both parents care for the young. Usually only one parent at a time is with the young. The parents recognize their own young and are usually recognized by them. The behavioural interactions between young and parents are described.Fledging success in 1968 was 1.06 young per pair. The number of pairs successfully rearing young varied annually from none to 81%, on average over six years (1966–70, 1972) 35%.Predation at the breeding colonies is minimal. The food of one one‐month old chick consisted of beetle larvae, lepidopteran larvae and beetles. Feeding areas, although undetermined, must be widespread.Inter‐specific competition between Sacred Ibis and other nesting birds at Shala is discussed.Among possible factors stimulating nesting at Shala one, fairly heavy rainfall, seems to be especially important. It is also suggested that especially heavy rain‐storms cause ibises to abandon the colonies, and

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1974.tb00124.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryGuy's HermitPhaethornis guy, a large forest hummingbird, was studied for 21/2years in the Northern Range of Trinidad. Regular observations made at a lek of 16 males showed that leks are occupied from November until the beginning of July, and that individual birds retain their lek territories from year to year and use the same perches.The usual song is a monosyllabic note regularly repeated, but the quality of the note varied between different leks and between different parts of a lek, and a few males had a disyllabic song. Young males join the lek between April and June and learn the song of their immediate neighbours. Their plumage, when they first join, is similar to a female's, with distinct pale super‐ and subciliary stripes. The acquisition of the dark head of the adult male probably takes four years.Before they land on their lek perches, males perform an elaborate aerial display in which the red gape is flashed open and a loudtockis uttered. When males visit each other they rapidly change places on the lek perch, the airborne bird performing the tock‐display over the perched bird. A similar tock‐displaying with changing of place occurs when females visit males; twice these were seen to culminate in mounting. Periodically all males at the lek ‘false‐mate’ with a leaf or other piece of vegetation near their lek perches, after tock‐displaying above it. Young males false‐mate much more frequently than older males.The breeding season lasts for eight months, the peak of breeding coinciding closely with the period when the two most important sources of nectar (Heliconia bihaiandPachystachys coccinea) are available. Males occasionally visit nests, and possibly assist in defending them. Undefended nests are quickly dismantled by other birds in search of nest‐material. Of 19 nests found before the clutch was complete, five (26%) were successful. The incubation period is 17–18 days, and the fledgin

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1974.tb00125.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryThe natural testis cycle and associated changes in bill colour of the House SparrowPasser domesticusare described. Subjects were wild‐caught at three different times in the breeding cycles:in February when the testes were small and contained only spermatogonia, in May when they were fully recrudesced and contained bunches of spermatozoa and in late July at a time when spontaneous gonad regression was occurring as the birds entered their photo‐refractory phase. Each sample was divided into eight separate groups which were given a range of artificial asymmetric skeleton photo‐periods generalized as LD 6 +1/2:131/2; the1/2‐h light pulse was given at a different point in the dark period in each group.The birds entrained to skeleton schedules simulating complete photoperiods of up to 12 h duration as if the start of the long light pulse was dawn. However, with long‐day simulations (e.g. 6L 111/2D1/2L 6D which simulates an 18 h photoperiod) the birds entrained to the start of the short light pulse to give an effective photoperiod of 121/2h (that is,1/2L 6D 6L 111/2D). The skeleton schedules simulating 14 h and 16 h were interpreted as such in February and were not effective in causing testicular induction, but they were apparently read as days of 161/2h and 141/2h in May, and as such maintained active spermatogenesis. The differences are discussed in terms of the changed frequency of a circadian oscillator. When birds captured in July were held on the various skeleton light schedules refractoriness was ended for most the subjects, as was proved by subsequently exposing them to a complete 16‐h photoperiod. Exceptions were the birds in the group given the 14‐h simulation, for these entrained as they had in May and so were effectively receiving a long 161/2‐h day. The discussion presents evidence to show that photoperiods in excess of 14 h cause the light sensitive phase of a circadian oscillator responsible for luteinizing hormone secretion to be phased into the non‐inductive period of darkness. Rehabilitation of the interstitial components of the testis is apparently inhibited in s

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1974.tb00126.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryThe male Splendid Sunbird has only one song type, each note of which has a simple frequency/time profile. An analysis of the songs of males from several localities near Legon (5.63° N, 0.19° N) showed that there are clear‐cut song dialects characterizing each population. Those parts of the song giving rise to dialects are the time interval between consecutive pairs of notes (the time interval pattern) and the frequency/time profile of each note.The dialects were preserved over a period of three years (the duration of the study) and there was little variation in the song of a ringed bird over a period of two months. The boundary between dialects is apparently quite sharp, occurring perhaps within a distance of 50 m.Marked geographical variation in the song occurs, and is expected because of the mosaic of dialects that presumably exist throughout the sunbird's range in southern Ghana. For dialects to be effective in keeping populations together, those characteristics of the song which give rise to dialects should be readily and quickly discerned and need not require a statistical demonstration. This condition holds for the song of the Splendid Sunbird.The results are compared with the ideas of Nottebohm (1964) and Thielcke (1969) on the maintenance and usefulness of song diale

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1974.tb00127.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1974.tb00128.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryA new population of African reed warblers,Acrocephalus baeticatus hopsoni, is described from Lake Chad. Its characters, together with those of unallocated material from Senegal, Eritrea and Tibesti, are intermediate between the PalaearcticA. dumetorumand other races ofA. baeticatus. It is concluded thatdumetorumis conspecific withA. baeticatus, and by priority becomesA. baeticatus dumetorum. The merits ofA. palustris, A. scirpaceusandHippolais pallidafor inclusion in anA. baeticatussuperspecies are considered, but allow no firm conclusion.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1974.tb00129.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryThe Giant HummingbirdPatagona gigaswas studied in highland Ecuador in 1968–70. The northern and southern limits of its known distribution were extended, but east‐west range and altitudinal limits were as restricted as noted by other authors. Its distribution elsewhere in South America is also reviewed, as are the taxonomy of various populations and breeding records. It is concluded that northern Ecuador is not reached by migrants from central Chile.Locally,Agave americanawas the principal source of nectar, and the Ecuadorian range of the bird corresponds with the distribution of this plant. Further south, where the birds occur over a wider range of elevations, other plants are visited. It is suggested that the availability of nectar and the presence of competitors in combination determine the distribution of the Giant Hummingbird. The Ecuadorian population is probably prevented from northward extension by conditions unsuitable forAgave americana. There is evidence that this plant is exotic to Ecuador; its introduction may have permitted the Giant Hummingbird to expand its range from P

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1974.tb00130.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1974.tb00131.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1974.tb00133.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1974.tb00134.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY