SENSORY CONTROL OF CLUTCH SIZE IN THE ZEBRA FINCH (TAENIOPYGIA-GUTTATA)

Authors
Citation
S. Haywood, SENSORY CONTROL OF CLUTCH SIZE IN THE ZEBRA FINCH (TAENIOPYGIA-GUTTATA), The Auk, 110(4), 1993, pp. 778-786
Citations number
17
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Ornithology
Journal title
ISSN journal
0004-8038
Volume
110
Issue
4
Year of publication
1993
Pages
778 - 786
Database
ISI
SICI code
0004-8038(1993)110:4<778:SCOCSI>2.0.ZU;2-W
Abstract
An analysis of the mechanism responsible for controlling clutch size w as carried out in the Zebra Finch (Taeniopygia guttata) by manipulatin g the number of eggs present in the nest during laying. Sensory cues i nvolved were also investigated. Stimulation from the eggs present in t he nest during the second and third day of the egg-laying period deter mined how females cease to lay in this species. Disruption of ovarian follicular growth was triggered on the third day of laying, 6 +/- 1 h after the onset of light (14L:10D), by tactile stimulation. Contact wi th eggs also was required to induce the onset of sensitivity to the st imulus responsible for ending laying. The hypothesis that individual v ariations in clutch size (four to six eggs) are caused by early disrup tion of follicular growth for smaller clutches versus late disruption for larger clutches was tested. The timing of follicular disruption sh owed no significant variation between females (n = 12) in relation to clutch size. There is good evidence that this result, established in d omesticated Zebra Finches, holds true for wild Zebra Finches as well. Individual variation in clutch size resulted from the variable number of growing follicles that, once follicular disruption has been trigger ed, were able to complete the rapid-growth phase and ovulate.