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|Title:||Parent-Offspring Conflict and the Allocation of Parental Investment in the Feral Pigeon (Columba Livia) (Nestling Growth, Concorde Fallacy, Food Limitation)|
|Author(s):||Droge, Dale Lyle|
|Department / Program:||Zoology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Feral pigeons (Columba livia) increased feeding of offspring in response to playback of recorded begging calls. Parent-offspring conflict can account for these results, if parents cease responding to offspring demands when costs of investment are relatively high. This hypothesis was tested by giving a group of birds food mixed with pebbles which increased the adult birds' foraging time. Fathers did not feed offspring with playbacks more often than controls in the group with increased foraging costs. In a second group without pebbles, fathers fed offspring significantly more often when recorded calls were played. Females fed only young offspring in response to playback. The probability of a male responding to increased demand was positively correlated with reproductive success indicating possible benefits for paying attention to offspring demands. Parental investment in pigeons most closely corresponds to a situation where the level of investment is a compromise between parent and offspring optima.
The increased foraging costs created an opportunity to investigate the effect of food limitation on parents and offspring. Offspring in the high cost group had significantly smaller asymptote weights, but the growth rate did not differ between groups. Both high and low adults lost weight relative to the previous year, but high cost parents lost significantly more weight overall. High cost parents had significantly longer periods of time between clutches.
Parental investment decisions may be affected by (1) the expected benefits from continued investment; (2) the amount of past investment; and (3) fixed timing of investment by parents. Six-day-old and two-day-old nestlings were reciprocally crossfostered to give broods with greater or less than normal growth rates from the parents' perspective. Peak weights of the control group were significantly larger than either age-manipulated group. The interval between clutch initiations did not differ between groups, suggesting potential expected benefits were not recognized. The weight and interclutch interval results support the fixed timing of investment hypothesis. Abandonment rates marginally support the hypothesis of investment according to expected benefits.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986.
|Date Available in IDEALS:||2015-05-14|