Southern, William E.
M.S. (Master of Science)
Department of Biological Sciences
The effects of nest location and density on Ring-billed Gull, Larus delawarensis, reproductive success were studied. Two colonies were used, one (Bird Island Colony), located on an island in Lake Huron and the other (Calcite Colony), a larger colony, on a man-made peninsula on the mainland of northern Michigan. The Calcite Colony had 184 nests used in the study and the Bird Island Colony had 315 nests. Nest location was found to affect reproductive success. Nest near the fringe of both colonies had a significantly lower reproductive success than those in the center (Calcite Colony X2c = 7.076 Bird Island Colony X2c = 33.173). This was manifested through hatching success. Each colony had a significantly lower hatching success for the fringe of the colony than for the center of the colony (Calcite Colony X2c = 8.668; Bird Island Colony X2c = 47.674). There was no significant difference in the chick survival in the fringe compared to the center of each colony (Calcite Colony X2c = 0.016; Bird Island Colony = 1.922). Colony size affected reproductive success, the larger colony (Calcite Colony) had a significantly higher reproductive success. It was felt that geographical location and human activity played a role in the reproductive success difference. No correlation between nest density and reproductive success was found in either colony. Nest density is not a factor in reproductive success of Ring-billed Gulls.
Dexheimer, Marilyn, "Reproductive success relative to nest location and density in ring-billed gull colonies" (1973). Graduate Research Theses & Dissertations. 4735.
x, 40 pages, 4 unnumbered pages
Northern Illinois University
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