I used approximatley 10,000 records from the North American Nest Record Card Program, over 2000 records from the Western Foundation of Vertebrate Zoology, and nearly 1000 records from Canadian sources to obtain data on the phenology of the nesting season and clutch size of a widespread altricial bird, the Red-winged Blackbird (Agelaius phoeniceus L.). I assess the compatability of nest record cards and clutch collection slips, for estimating nesting phenology and clutch size for the redwing and give suggestions for improving nest record. / My approach to the study of geographic variation in clutch size has been to use large data sets to map patterns of variation in life history traits, look at the relationship of single variables as predictors of clutch size, and then use all variables in a multiple regression model. I examine four hypotheses that have been proposed to account for geographic variation in clutch size: daylength, density-dependent food limitation, food availability independent of density, and the "eggs-in-one-basket" hypothesis. The variables used to predict clutch size were latitude, longitude, length of the breeding season, intraspecific local abundance, and 5 climatic variables. / Clutch size of the redwing varies in a complex pattern in North America. Mean clutch size ranges from 2.77 in Costa Rica to 4.30 in Alaska. The daylength hypothesis is generally supported, because latitude is the most important predictor in the multiple regression model. However, clutch size also varies from east to west. The density-dependent food limitation hypothesis is not supported because local abundance is not a good predictor of mean clutch size and annual migration is not taken into account. The "eggs-in-one-basket" hypothesis is not strongly supported because redwings have multiple broods at high and middle latitudes. However, the length of the breeding season is retained as a predictor variable in the most conservative multiple regression model. My results are most consistent with the hypothesis that geographic variation in clutch size is related to large-scale patterns of variation in food availability. / Source: Dissertation Abstracts International, Volume: 47-07, Section: B, page: 2739. / Thesis (Ph.D.)--The Florida State University, 1986.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75888 |
| Contributors | ENGSTROM, RICHARD TODD., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 155 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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