共查询到20条相似文献,搜索用时 15 毫秒
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Oschadleus, H.D., Underhill, G.D. & Underhill, L.G. 2000. Timing of breeding and primary moult of the Masked Weaver Ploceus velatus in the summer and winter rainfall regions of South Africa. Ostrich 71 (1 & 2): 91–94. Timing of breeding and moult is analysed in the Masked Weaver Ploceus velatus. It is common throughout southern Africa, which is largely a summer rainfall area. This species expanded its range into the Western Cape, a winter rainfall region, in the twentieth century. The peak breeding period is one month earlier in the winter rainfall area (September to November) than in the summer rainfall area (October to December). The mean starting date of primary moult is one month earlier in the winter rainfall area (9 January) than in the summer rainfall area (15 February). The duration of primary moult is similar in both regions (74 days in the winter rainfall area and 80 days in the summer rainfall area). 相似文献
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The regression methods frequently used to estimate the parameters associated with primary moult in birds are unsatisfactory. Results obtained using least squares regression, and various ad hoc adaptations, are so obviously incorrect that many authors have fitted lines ‘by eye’ (Newton 1968, Thomas & Dartnall 1971, Elliott et al. 1976, Morrison 1976, Appleton & Minton 1978). In a comparison of seven regression methods, estimates of the average starting date varied between 29 June and 31 July, completion date between 2 and 24 October, and duration of moult between 72 and 109 days for the Redshank Tringa totanus, in spite of the very large sample of 1482 observations (Summers et al. 1983). In this paper we present a new approach to the analysis of primary moult and develop a mathematical model specifically designed for moult data. 相似文献
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This study of primary moult in the Lapwing, using conventional methodology, shows that the duration is considerably longer than was estimated previously by a novel technique based on the collection of discarded primaries from roost sites. 相似文献
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The regression methods frequently used to estimate the parameters associated with primary moult in birds are unsatisfactory. Results obtained using least squares regression, and various ad hoc adaptations, are so obviously incorrect that many authors have fitted lines 'by eye' (Newton 1968, Thomas & Dartnall 1971, Elliott et al. 1976, Morrison 1976, Appleton & Minton 1978). In a comparison of seven regression methods, estimates of the average starting date varied between 29 June and 31 July, completion date between 2 and 24 October, and duration of moult between 72 and 109 days for the Redshank Tringo totonus, in spite of the very large sample of 1482 observations (Summers et al. 1983). In this paper we present a new approach to the analysis of primary moult and develop a mathematical model specifically designed for moult data. 相似文献
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Little is known about the biology of waders wintering in southern Asia; this paper deals with the Grey Plover Pluvialis squatarola, a species extensively studied only in western Europe. Adult Grey Plovers wintering in southeastern India underwent primary moult in autumn; the duration was estimated to be 127 days, with mean starting date 1 September and mean completion date 5 January. Some first-year Grey Plovers initiated primary moult in late winter and spring, and completed this moult the following spring. The average mass of adults on arrival in September was 200 g, fluctuated close to 220 g from October to February, and increased to 280 g near the end of May. The mass variation did not show the January peak observed in western Europe. Breeding productivity, measured as the percentage of first-year birds in winter catches, varied between 5% and 70% over six years, and showed a positive correlation with that of Dark-bellied Brent Geese Branta b. bernicla in western Europe and Curlew Sandpipers Calidris ferruginea in South Africa. 相似文献
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Ron W. Summers Gunnar Thor Hallgrimsson David Aiton Brian Etheridge Jacquie Heaton Bob Swann 《Bird Study》2013,60(3):357-368
Capsule Iceland is a stop‐over site for a population of Purple Sandpipers that winter in Britain. Here, they accumulate fuel loads for onward migration along with birds that have wintered in Iceland. Aims To establish whether Purple Sandpipers from Britain stop‐over in Iceland during spring migration and, if so, to describe their population structure, changes in mass and moult. Methods Purple Sandpipers were cannon‐netted on the coast of the Reykjanes Peninsula in southwest Iceland during May 2003 and 2005. Birds were aged, sexed (some by DNA) and standard biometric measurements made. Active body moult was scored. Results Bill and wing lengths showed that the Purple Sandpipers we caught were similar to one of the populations that winter in Britain rather than Icelandic breeding birds. There were more males than females throughout the migration period (63% males for first‐year‐birds and 67% for adult birds). Accounting for a bias due to a higher percentage of males in a less usual habitat (muddy/sandy bays), the values for rocky sites were 52% males for first‐year birds and 62% for adults. The percentage of first‐year birds was 19% in 2003 and 32% in 2005, though the latter figure was biased by catches in muddy/sandy bays where there was a higher percentage of young birds. The percentage of first‐year birds was 25% on just the rocky shores in 2005. Many birds were in latter stages of body moult, and males were slightly in advance of females. Increasing mass showed that they were preparing for onward migration. The average increase of 0.58 g per day was similar to the rate measured in Orkney at an earlier point on the migration route. However, a high turnover of birds could be the reason for these low values. By late May, and close to the assumed departure date, the Purple Sandpipers of the different age/sex classes had fuel indices of 24–29% (33–42% of the lean mass). This was lower than that for the high Arctic sandpipers (Knots and Sanderlings) leaving southwest Iceland for Greenland and Canada. Conclusions Our study confirmed that Purple Sandpipers do stop‐over in Iceland, and the possible lower rate of fuel accumulation and smaller amount stored, compared with Knots and Sanderlings, suggests a different migration pattern. 相似文献
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Lorenzo Serra 《Journal of avian biology》2001,32(4):377-380
Feather wear is the natural degradation and breakage of feather structure during the interval between moults. Different rates of feather wear have been observed for primaries of free-living populations of several species of passerines and waders, and this variability has been linked to different concentrations of melanins. In this study primary moult duration explained 59% of the variation in annual rates of primary abrasion (percentage wing length loss) of seven Grey Plover wintering populations, while migration distance explained 14%. The analysis suggests that primary moult duration plays a key role in determining primary durability and hence primary quality. Long distance migrants might evolve more durable primaries, despite the higher predation risks and energetic costs of a prolonged moult. Partial or complete pre-breeding primary moults of first-year waders and complete biannual moults of some passerines might have evolved under selective forces favouring migration with unabraded primaries. 相似文献
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We describe the migration, biometrics and moult of Red Knot Calidris canutus canutus in southern Africa and compare them with the biometrics and moult of Calidris canutus islandica in northern Europe to examine possible adaptations to different environments during the non‐breeding season. Northward and southward migration of C. c. canutus took place along the coast of Western Europe and there was one recovery in West Africa (Mauritania), suggesting a coastal migration round West Africa rather than migration across the Sahara, as recorded in other waders. Adult Knots in South Africa had no additional fattening in November–January (fat index of 7%), in contrast to C. c. islandica wintering in Britain. This is consistent with the theory that extra fat is required only where food shortages are likely. The bills of canutus were longer than those of islandica but their wings were shorter, confirming the sub‐specific assignments and origin of this population. The average duration of primary moult in South Africa was 95 days, shorter than that of other Arctic‐breeding waders that moult in South Africa, but longer than of islandica moulting in Scotland (77 days). Mean starting and completion dates were 20 July and 5 October for islandica and 25 October and 28 January for canutus. The timing and duration of primary moult for these two subspecies suggest that waders need to complete moult before the northern winter when food supplies are limited, whilst waders in benign climates face no such pressures. First‐year canutus either retained old primaries for much of their first year or had a partial moult of inner or other primaries. Adults departed on northward migration in mid‐April, having attained a mean departure mass of c. 190 g (maximum 232 g). The mean fat index at this time was 24% (maximum 29%) and the fat‐free flight muscle mass increased. The predicted flight range of 4000 km falls short of the distance to the first likely refuelling site in West Africa, suggesting that birds rely on assistance from favourable winds. 相似文献
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We investigated the effects of body mass and latitude on primary moult duration from published data of migrating shorebirds that moult exclusively on the wintering grounds. Non‐phylogenetic and phylogenetic models demonstrated that body mass and latitude correlate with moult duration in a non‐additive way: the models predict different latitudinal relationships for smaller and larger shorebirds, and in the northern hemisphere, primary moult duration increased allometrically with body mass (exponent = 0.17), whereas in the southern hemisphere, primary moult duration was not correlated with body mass. If birds optimize feather quality and if slower moult yields sturdier feathers, the fast primary moult of northerly wintering shorebirds indicates additional selection pressures at work. 相似文献
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Nicolaas A. M. Verbeek 《Journal of Ornithology》1977,118(1):87-92
Summary Timing of primary moult in relation to the breeding cycle is presented for 113 actively moulting adult Herring Gulls and 79 Lesser Black-backed Gulls from Walney Island, England. Moult in both species occurred about when the eggs hatched in mid-May. The entire Herring Gull population began to moult the primaries within a period of 50 days. Lesser Black-backed Gulls started to moult 10 days later than Herring Gulls but many birds were not yet moulting as late as 5. August when I left the study area. It is suggested that the population of Lesser Black-backed Gulls consists of residents and migrants and that the former begin to moult earlier than the latter.
Der zeitliche Ablauf der Handschwingenmauser von Silber- und Heringsmöwe
Zusammenfassung Bei 133 ad. Silber- und 79 ad. Heringsmöwen von Walney Island, England, wurde der Beginn der Handschwingenmauser in Beziehung zum Brutzyklus untersucht. Bei beiden Arten setzte die Mauser ungefähr Mitte Mai zum Zeitpunkt des Schlüpfens der Jungen ein. Alte Silbermöwen begannen innerhalb von 50 Tagen mit der Handschwingenmauser. Die Heringsmöwe fing etwa 10 Tage später an, doch hatten manche Individuen noch bis Anfang August nicht mit der Mauser begonnen. Die Heringsmöwen-Population auf Walney besteht vermutlich aus Stand- und Zugvögeln; erstere scheinen früher zu mausern.相似文献
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L. G. UNDERHILL R. P. PRYS-JONES R. J. DOWSETT P. HERROELEN D. N. JOHNSON M. R. LAWN S. C. NORMAN D. J. PEARSON A. J. TREE 《Ibis》1992,134(3):286-297
The Willow Warbler Phylloscopus trochilus is one of the few bird species that undergoes two primary moults a year, a post-nuptial moult in the breeding area and a moult in the wintering area. Primary-moult data for Willow Warblers from Finland, Sweden, Britain, the Netherlands, Belgium. Guinea-Bissau, Uganda, Kenya, Malawi, Zambia, Zimbabwe, Botswana and South Africa are analysed. The parameters of primary moult (mean starting date, standard deviation of starting date, and duration) are estimated using the techniques of Underhill & Zucchini (T.988 Ibis 1 30: 358–372) and Underhill, Zucchini & Summers (1990 Ibis 132: 118-12 3). The scheduling of moult in relation to theother main components of the annual cycle, breeding and migration, is considered. The mean durations of post-nuptial moult for P. t. trochilus and P. t. acredula are 36.5 and 38.3 days, respectively; the start and termination of moult for P. t. trochilus are about 3.5 days later for each degree of latitude northwards, and the start and termination of moult for P. t. acredula, are about 10 days later than that of the most northerly populations of P. t. trochilus studied. Females start their postnuptial moult about 10 days later than males. Southward migration commences as soon as post-nuptial moult is complete. There is an increasing constraint on the timing of breeding and post-nuptial moult events at higher latitudes, leading to overlap between them. The duration of pre-nuptial moult is longer than that of post-nuptial moult, and is completed shortly prior to northward migration. 相似文献
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Yosef Kiat 《Journal of avian biology》2018,49(5)
Wing and tail morphology strongly affect flight performance which may consequently decline during feather moult due to the creation of feather gaps in the flight‐surface. Hence, the size and shape of moult‐related gaps may directly affect flight capacity. Here, I examined the divergent rectrix moult sequence compared to the more common distal moult sequence. In the divergent moult, the focus of rectrix moult is shifted from the tail centre (R1; rectrices numbered distally from mid‐tail outward) to another rectrix (R2 or R3), and then rectrices are moulted bidirectionally, towards the tail centre and outwards. The result of this moult sequence is the splitting of the tail gap into multiple smaller gaps. Using a large moult database including 5669 individuals of 47 Western Palaearctic passerine species, I found evidence of divergent moult sequence for only seven species. Using comparative and experimental approaches, I found that the divergent rectrix sequence is correlated with higher moult speed and lower aerodynamic cost. Furthermore, the divergent rectrix sequence is more common among adults than juveniles. This work focused on the feather moult sequence – a seldom studied aspect of the avian life‐history. I propose that moult‐related aerodynamic costs may be an important evolutionary factor not only in moult speed, but also in moult sequence. 相似文献
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《Biometric Technology Today》2002,10(2):8-11
Btt runs its survey on the lesser-known and lesser-used biometric technologies once every two years. These technologies often suffer from a lack of funding and credibility making it extremely difficult for them to gather momentum. This year, however, the amount of progress made is impressive and it seems that at least two of the biometrics could warrant their own surveys in the not too distant future… 相似文献
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《Biometric Technology Today》2001,9(3):6-7
While good progress is being made with biometrics as a technology, acceptance in the broader sense is still not meeting expectations. There are many reasons for this state of affairs, but one common problem seems to be the high level of misunderstanding between vendors and end users. Proposals for a new jargon-busting methodology called Bantam could help remedy the situation. 相似文献
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