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n Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie - Broeigedrag en -sukses van tuinduiwe : oorspronklike navorsing

Volume 32, Issue 1
  • ISSN : 0254-3486
  • E-ISSN: 2222-4173
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Abstract

Broei-aktiwiteite van tuinduiwe () in die Bloemfonteinse stadsgebied vind dwarsdeur die jaar plaas met 'n afname gedurende die laat somermaande wanneer seisoenale reënval in die streek 'n hoogtepunt bereik. Nesstrukture is relatief primitief en word gekenmerk deur 'n losse samestelling van nesmateriaal op opgehoopte, droë voëlmis. Broeisels van twee eiers is die mees algemene grootte en die eiers word gewoonlik binne twee dae ná mekaar gelê. Beide ouers is by die broeiproses van meer as twee weke betrokke, waartydens die eiers 'n progressiewe afname in massa ondergaan. Pas uitgebroeide neskuikens is met geel dons bedek en is grootliks hulpeloos. Egte vere begin eers ná die eerste week te voorskyn kom, en vanaf die derde week kan individue wankelrig rondbeweeg. Afgesien van die eerste paar dae na uitbroei, handhaaf neskuikens van seldsame enkeleier-broeisels deurgaans 'n laer liggaammassa as dié van normale broeisels. Die broeisukses van 247 broeipare vir hierdie studie is 34%. Eierverlies is hoër as die mortaliteitsyfer van neskuikens, en word veral deur klimaatsfaktore soos reënval geaffekteer. Predasie blyk die belangrikste faktor te wees wat die mortaliteitsyfer van neskuikens beïnvloed. Antagonistiese interaksie tussen krans- en tuinduiwe, asook moontlike intraspesie-aggressie, speel egter ook 'n beduidende rol.


Breeding activities of feral pigeons () in the Bloemfontein urban area occur throughout the year with a decrease during the late summer months when seasonal rainfall in the region reaches a peak. Nest construction is relatively primitive and is characterised by a loose composition of nesting material on accumulated dry bird droppings. Two eggs represent the most common clutch size and eggs are usually laid within two days of each other. Both parents are involved in the incubation process lasting more than two weeks, during which the eggs undergo a progressive decrease in mass. Recently hatched nestlings are covered in yellow down and are largely helpless. True feathers only start to emerge after the first week, and from the third week individuals can move about unsteadily. Apart from the first number of days after hatching, nestlings of rare single egg clutches constantly maintain a body mass lower than those from an average clutch. The overall success of 247 breeding pairs for this study was 34%. Egg loss is higher than the mortality rate of nestlings, and is mainly affected by climatic factors such as rainfall. Predation appears to be the most important factor influencing nestling mortality. Aggressive interactions between speckled pigeons and rock doves, however, as well as possible intraspecific aggression also play a significant role.

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/content/aknat/32/1/EJC134831
2013-01-01
2019-12-10

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