Record Details
An investigation of the feeding pattern of caged white-crowned sparrows, Zonotrichia leucophrys gambelli (Nuttall), in relationship to vernal fat deposition
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | An investigation of the feeding pattern of caged white-crowned sparrows, Zonotrichia leucophrys gambelli (Nuttall), in relationship to vernal fat deposition |
| Names |
Moldenhauer, Ralph Roy
(creator) Gordon, Kenneth L. (advisor) |
| Date Issued | 1965-04-16 (iso8601) |
| Note | Graduation date: 1965 |
| Abstract | Zonotrichia leucophrys gambelii is a strongly migratory race of white-crowned sparrow that exhibits a marked deposition of fat during the vernal migratory period. The physiological basis for fat deposition is a positive energy balance which results from a photo-periodically induced hyperphagia. Simultaneously with the increased caloric intake there is an adjustment of the intermediary metabolism so that the excess calories are deposited as fat rather than glycogen. The possible mechanism by which the intermediary metabolism is altered was the subject of this investigation. It was surmised that a photoperiodically stimulated change in the feeding pattern, along with hyperphagia, might induce the metabolic alterations necessary for lipogenesis and fat deposition. This idea was prompted by investigations with force-fed rats and rats limited to a two-hour feeding period per day. Ten immature Z. 1. gambelii were confined individually to small breeding cages modified to measure perch and feeding activity. The feeding activity was recorded by means of a mechanically operated feeder which electrically activated a pen on an Esterline-Angus recorder whenever the bird placed its head in the feeder to obtain food. The motor activity was registered similarly with each movement of a perch-activated microswitch. Recordings of the feeding and perch activity were made continuously throughout the premigratory and migratory periods of March, April and May. During the experimental period the birds were weighed at least twice a week with observations of molt being recorded. Prenuptial molt, fat deposition and Zugunruhe occurred essentially at the same time and magnitude as previously reported for caged and wild white-crowned sparrows. The median date for the onset of fat deposition was determined as April 11 ± 1 day. With fat deposition the mean body weight of six birds increased from 26.5 grams to 34.3 grams in 13 days. Prenuptial molt occurred at maximum intensity during the first ten days of April. The median date for the onset of Zugunruhe was determined as April 17. The mean daily feeding and perch activity of six birds were determined for five one-week periods chosen in relationship to fat deposition. The feeding activity was analyzed by the frequency, the number of feeding periods in each half-hour per bird per day, and by the duration, the total number of minutes spent at the feeder in each half-hour per bird per day. The perch activity was presented as the number of activity units per half-hour per bird per day. The results indicated a general feeding pattern with two phases: a morning phase characterized by numerous trips to the feeder of short duration interrupted by the high motor activity of the bird, and an afternoon phase distinguished from the morning phase by low perch activity and relatively less frequent feeding periods of longer duration. The feeding day was initiated almost invariably at the beginning of the morning civil twilight. The termination of the feeding day, before and after hyperphagia, was relatively constant and somewhat independent of the increasing evening photoperiod. During hyperphagia the last feeding period occurred gradually later for each succeeding day. Hyperphagia was evident in the feeding patterns of the weeks before and during fat deposition. For the week prior to fat deposition, the duration increased to 3.8 minutes/half-hour/bird/day and 112 minutes/bird/day from 3.6 minutes/half-hour/bird/day and 97 minutes/bird/day of the preceding week. The duration during the week of fat deposition increased to 4.7 minutes/half-hour/bird/day and 142 minutes/bird/day. The frequency showed similar results. The mean environmental temperature increased for each week. During hyperphagia no change in the over-all feeding pattern was indicated from those of other weeks. Under the conditions of this investigation, it was concluded that there appears to be no change in the food intake pattern of Z. 1, gambelii which can be construed as a mechanism for inducing metabolic alterations necessary for vernal fat deposition. |
| Genre | Thesis/Dissertation |
| Topic | Sparrows |
| Identifier | http://hdl.handle.net/1957/48067 |
