摘要:

SUMMARYOspreysPandion haliaetusnested at a site near Loch Garten, Inverness‐shire continuously from 1959 to 1973. Each year the Royal Society for the Protection of Birds has organized a continuous watch on the eyrie in the breeding season. The detailed records kept of the activities of Ospreys at the nest by those participating in the watch were analysed and the results presented here.Ospreys are migratory and arrived in the breeding area in early April. Nesting material was usually added to an existing eyrie platform. The male collected more material than the female. The female lined the nest cup. The extent of nest building activity and the frequencies of mating and other activities prior to laying varied markedly from year to year. These differences may have been related to changes in the identity of the nesting female, but the birds were not individually marked. Both sexes incubated but the female took the greater share and normally incubated at night. When the young hatched they were brooded by the female. The female stayed in the vicinity of the nest for most of the time until the young fledged at about 53 days old. The male Osprey caught almost all the fish eaten by his mate and young during the breeding season. The number of fish caught per day increased markedly after the young hatched. PikeEsox luciusand TroutSalmo truttawere the main species taken, and some Rainbow TroutSalmo gairdneriiwere identified. There were seasonal and diurnal changes in the size and the species composition of the catch. The effects of weather conditions on hunting are examined. The occurrence of Ospreys other than the resident birds at the nest site is described.The behaviour of another pair of Ospreys which repeatedly failed to hatch eggs is described. There was an instance of egg eating in this pair, and some differences in behaviour were found between these birds and those at Loch Garten whose breeding success was good.The breeding biology of Ospreys is compared with that of other British diurnal birds of prey. In other species the female leaves the young unguarded at some stage in the nestling period and hunts food for them, whereas female Ospreys do not usually hunt in the nesting perio

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1976.tb03513.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThis paper presents objective methods for measuring moult and uses them to describe the pattern and rate of the complete moult as a component of the annual cycle inCorvus corone, C. frugilegus, C. monedula, Pica picaandGarrulus glandariusin Britain.The basis of the methods used to measure the rate of moult was the dry weight of the whole plumage and its component tracts and feathers. Within whole tracts of flight feathers showing diversity of size, the longer feathers grew in length a little faster than the others by accumulating feather material very much faster. Thus, for the flight feathers at least length by itself was a poor indicator of size, but, if first related to weight, could be used to predict weight. Hence, to enable realistic comparisons to be made between different flight feathers and tracts of flight feathers on a given individual bird or on individuals of different species, a ‘units’ system was created which would take account of such variations in size. This information provided a standard against which the growth of new flight feathers in a specimen collected in the field could be measured. The progress of moult in each tract was indicated by the sum of the units. In addition, for both the flight feathers and all other tracts, the duration of moult was measured from the start and finish in each tract as indicated by the proportion of birds having either growing or entirely fully‐grown feathers in each tract.In the annual cycle body weight and abdominal fat weight were at a maximum in mid‐winter and at a minimum in mid‐summer inCorvus; variations in these items were apparently absent inG. glandarius.InCorvusprobably only post‐second‐year birds breed, but inP. picasome second‐year individuals do so as well; also, increase in testes size in second‐year males was greatest inP. pica.The patterns of the relative seasonal timing of the start and finish of moult in each tract were most similar in the threeCorvusspecies, in which moult in the whole plumage began in the primary tract and finished in tracts on the body;P. picadiffered principally in the extended growth of the secondary tract;G. glandariusdiffered in that moult began in the dorsal tract. By summing the data from individual tracts, a measure of the rate of growth in the whole plumage was obtained: all five species moulted at essentially the same time of year.In the primary, secondary, tertiary and rectricial tracts the seasonal accumulation of dry weight of feather material in each tract followed a sigmoid pattern; in the alula tract dry weight increased most rapidly at the beginning. These patterns were correlated with the numbers of feathers growing at different stages in each tract. The primary tract accumulated dry matter at the highest relative rate, while the rectricial, secondary, tertiary and alula tracts did so at successively lower rates. The maximum relative rate of increase in dry weight in any given tract of flight feathers was fairly similar in all five species, but was possibly related inversely to body weight. Maximum absolute rates of increase in dry tract weight were also calculated.During the springtime period when non‐moulting and moulting birds were present simultaneously in the population, no difference could be detected between these groups in any species in body and fat weights; in individuals obtained together with evidence of reproductive activity, few had begun primary moult, but in post‐second‐yearC. frugileguswith branchers, males began before females; inC. coroneandC. frugilegustestes weight was lower in moulting than in non‐moulting birds.In conclusion, some aspects of moult for furth

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1976.tb03514.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe relationship between nesting density and breeding success of Herring GullsLarus argentatuswas studied on the Isle of May, Scotland, in 1968. Herring Gulls nesting at the most common density started laying earlier in the season than those nesting at lower or higher densities. Therefore, although the overall spacing of nests was uniform, the nest density of birds laying later in the season progressively approached a random distribution. The onset of laying occurred in synchronized groups within the colony. Late‐laid clutches were commonly situated on the periphery of the colony where the density of nests was lowest. When the laying period was divided into four time periods, in each period the tendancy was for birds nesting at the most common density to have the highest clutch‐size, hatching and fledging success, and to rear the most chicks per pair to fledging. In addition, birds which spaced their nests most uniformly, presumably as a consequence of territorial behaviour, were the most successful pare

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1976.tb03515.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARYChanges in the fat and flight muscle protein reserves of adult Red‐billed QueleasQuelea queleawere followed in two colonies in Tanzania and Botswana. At the start of a breeding attempt the protein reserves were higher that at any other time of the year, particularly in females which had heavier flight muscles (non‐fat dry weight) than did the (larger) males at that time. The pre‐breeding increase in the labile component of the muscle protein (the actual protein reserve) is calculated at 80% for females, but only 14% for males. The fat reserve was only increased slightly at the beginning of the breeding attempt.In both sexes, though for different reasons, the protein and fat reserves fell rapidly during the first few days of the attempt, in some individuals to dangerously low levels. During the incubation period there was rapid recovery while the situation during the rearing period appeared to vary between colonies.It is proposed that the proximate control of breeding is provided by the individual's own body condition, and particularly the state of its protein reserves. No environmental releasers are required for the birds to breed at the appropriate time of the year.Individual females producing two, three and four egg clutches differed in the rate at which their reserves fell during egg formation. The results are used to support the view that in this quelea the actual clutch‐size produced on any occasion is the largest the female can produce before becoming too enfeebled. Thus, clutch‐size appears to be determined phenotypically downward from a maximum which is indirectly under geneti

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1976.tb03516.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1976.tb03517.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1976.tb03518.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1976.tb03519.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1976.tb03520.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1976.tb03521.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1976.tb03522.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY