Term of Award

Summer 1998

Degree Name

Master of Science

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Department

Department of Biology

Committee Chair

C. Ray Chandler

Committee Member 1

Stephen P. Vives

Committee Member 2

John W. Parrish

Abstract

Male and female birds often differ in the amount of parental care they provide to nestlings. To quantify possible sex differences in parental care of American Kestrels (Falco sparverius), I conducted 130 hours of nest observations from April - June 1997 at 23 nest boxes at Fort Gordon military installation in east-central Georgia. I observed a total of 482 prey deliveries during brood intervals one (nestlings 1-6 d of age), two (7-12 d), three (13-18 d), four (19-23 d), and five (24-fledging). For all brood intervals combined, females provisioned nestlings at a significantly higher total rate (2.5 vs. 1.2 feeds /hr) and per capita rate (0.61 vs. 0.38 feeds/nestling/hr) than males. However, these differences were not significant within each brood interval.

Sex ratio of the brood (as described by proportion male) did not affect provisioning or per capita rates of adult kestrels. However, female provisioning rates were correlated with the sex ratio of the brood but female per capita rates were not. Male provisioning and per capita rates were not correlated with the sex ratio of the brood. After combining both male and female data, adult provisioning rates were correlated with the sex ratio of the brood but per capita rates were not.

For all brood intervals combined, male and female provisioning rates were positively correlated with brood size, but this pattern was not apparent within most brood intervals. Combined male per capita rates were negatively correlated with brood size, but female per capita rates were not found to be correlated with brood size. Combined male and female provisioning rates were correlated with brood size whereas combined male and female per capita rates were not correlated with brood size.

Although male and female provisioning rates were quantitatively similar within each brood interval, they differed qualitatively in the food delivered to the nest. Males delivered significantly more lizards (approximately 50% of identified items) to the nest than females (approximately 4% of identified items); females delivered significantly more insects (approximately 50% of identified items) than males (less than 1% of identified items).

Male and female provisioning rates were correlated to each other suggesting that male and females respond similarly to some provisioning cues, however, male and female per capita rates were not correlated. Provisioning rates and per capita rates did not increase with nestling age. Percent of food cached also did not vary with nestling age.

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