biology of "peak" and "late" nesting ring-billed gulls, granite island, lake superior
abstract
late-nesting ring-billed gulls in this study laid fewer
and smaller eggs and hatched fewer young than earlier nesting
pairs. birds nesting late in the season appeared to lack
sufficient stimuli for incubation, as indicated by their
increased restlessness on the nest and higher desertion rates.
factors affecting their behavior include physical condition
and social and environmental stimuli. late-nesting gulls had
a lower body weight and condition index than peak-nesting
gulls. their smaller egg size was attributable to decreased
amounts of albumen. analyses of blood metabolites and
hormones were inconclusive. it is suggested that the low
reproductive success experienced by "late"-nesting ring-billed
gulls in this study results predominantly from factors during the incubation period.
collections
- retrospective theses [1604]