A Statistical Analysis of the Nesting Seasons of Birds in Western Malesia
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THE SARAWAK MUSEUM JOURNAL |
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Title :
A Statistical Analysis of the Nesting Seasons of Birds in Western Malesia. |
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Author :
P.R. Wycherley |
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Abstract:
The seasonal nature of the nesting activity of birds resident in equatorial South East Asia has been discussed by Gibson-Hill (1952), Voous (1950), Ward (1969) and Wells in Medway and Wells (1976) and in Wells (1988). The earlier authors commented on nesting activity in relation to rainy seasons or to solar cycles. Wells discussed the aggregate data for breeding and moulting of those resident forest birds which are predominantly insectivorous and probably depend exclusively on arthropods to feed their young. The peak of breeding in the Malay Peninsula occurs March-April and of moulting four months later. Wells related breeding to seasonal abundance of food and avoidance of a dearth of the fledglings’ diet While food supply is influenced by climatic factors either directlyor through forest phenology. Wells did not consider rain or the lack of it to be a likely proximate stimulus to breed and that small variations in day length would be too prone to interference by local day to day conditions, especially in forest, to serve such a function. Physiological timing dependent on the accumulation and depletion of internal food reserves was postulated as such a mechanism. Accumulation is influenced by the external food supply and factors determining it, while depletion is more rapid when reserves are utilised in moulting as well as for breeding. The Nesting Activity Index of McClure and Hussain (1968) is a scale of 0 to 100, in which the index for any calender month (or shorter period) is in proportion to 100 for that in which most nesting activity is recorded. They calculated the Nesting Activity Indices for their own records at Rantau Panjang, Selangor, and those of Edgar (1933) at Sitiawan, Perak, of Spittle (1949) at Changi, Singapore and of the following given in Gibson-Hill (1952), namely, of Banks (1950)near Kuching, Sarawak, of Ryves in Negeri Sembilan, of Ryves and Madoc in Selangor, of Madoc in Pahang and of Coope and Edgar in Perak. Their indices for North Borneo (Sabah) based on the observations of Ryves (Banks 1950, Gibson-Hill 1952) are omitted from the following analyses, because Ryves recorded in two separate localities for only five and three months respectively.
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| DOI: XXXX |
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How to cite:
P.R. Wycherley. (1990). A Statistical Analysis of the Nesting Seasons of Birds in Western Malesia. The Sarawak Museum Journal, XLI (62): 285-304 |
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References
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