The problem of optimal clutch size in a tritrophic system: the oviposition strategy of the thistle gallfly Urophora cardui (Diptera, Tephritidae)

Oecologia ◽  
1996 ◽  
Vol 108 (2) ◽  
pp. 293-302 ◽  
Author(s):  
Gunter Freese ◽  
Helmut Zwölfer
Keyword(s):  
Clutch Size ◽  
Tritrophic System ◽  
Oviposition Strategy ◽  
Optimal Clutch Size

Is there an Optimal Clutch Size in Snow Geese?

1987 ◽  
Vol 130 (6) ◽  
pp. 839-863 ◽  
Author(s):  
R. F. Rockwell ◽  
C. S. Findlay ◽  
F. Cooke
Keyword(s):  
Clutch Size ◽  
Snow Geese ◽  
Optimal Clutch Size

Competition, the Fitness of Offspring, and Optimal Clutch Size

1975 ◽  
Vol 109 (970) ◽  
pp. 677-699 ◽  
Author(s):  
Warren Y. Brockelman
Keyword(s):  
Clutch Size ◽  
Optimal Clutch Size

Clutch size and initiation date of ospreys: natural patterns and the effect of a natural delay

1993 ◽  
Vol 71 (11) ◽  
pp. 2141-2146 ◽  
Author(s):  
Christoph Steeger ◽  
Ronald C. Ydenberg
Keyword(s):  
Clutch Size ◽  
Food Availability ◽  
Reproductive Value ◽  
Canada Geese ◽  
Breeding Performance ◽  
Nestling Period ◽  
Optimal Clutch Size ◽  
Primary Nest ◽  
Clutch Initiation

We studied the breeding performance of ospreys (Pandion haliaetus) in southeastern British Columbia from 1987 to 1990. Clutch size, brood size, and the number of young fledged per nest all declined significantly as clutch initiation date was delayed. The quality of later born young as measured by growth rate and the number of fault bars in rectrices did not seem to be reduced. Behavioural observations of the flight-hunting performance of six focal males demonstrated that food availability did not decline in the course of the nestling period. Clutch initiation of some osprey pairs was naturally delayed when their nests were occupied by Canada geese (Branta canadensis). Nest occupation delayed clutch initiation by 9.4 days on average, and reduced clutch size by 0.2 eggs. Osprey pairs possessing an alternate nest were not delayed by the presence of geese in their primary nest, and did not reduce clutch size, suggesting that the clutch size reduction was a direct response to the delay, rather than to the presence, of geese. The results do not support the reduced food availability or reduced breeding commitment hypotheses for seasonal clutch size decline. The data conform to the predictions of the hypothesis that the optimal clutch size is set by a trade-off between the declining reproductive value of later hatched nestlings and the delay required to be able to enlarge the clutch.

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