Birds of Indian Subcontinent

Colony Site Selection by Eared Grebes in Minnesota

Publication Type:Journal Article
Year of Publication:1993
Authors:Boe, JS
Journal:Colonial Waterbirds
Date Published:1993
ISBN Number:07386028
Keywords:Fulica, Fulica americana, Fulica atra, Podiceps, Podiceps nigricollis, Podicipedidae, Rallidae
Abstract:From 1987-1989, I used ground measurements and aerial photography of marked colonies to describe and study the selection of 12 colony sites on nine Eared Grebe (Podiceps nigricollis) breeding wetlands in Minnesota. Colonies were located in moderately dense to sparse green or dead emergent vegetation or on surface mats of filamentous green algae or submerged aquatic macrophytes. All colony sites were near open water or channels and two were near larid colonies. Wave action generated by high winds destroyed seven of 15 colonies (44% of 2370 nests) marked or examined in this study. Nest predation, almost exclusively by American Coots (Fulica americana), was low (< 3% in any colony). Distance from shore (0.09 to 1.5 km) seemed a compromise between terrestrial predator pressure and higher waves associated with a deeper, less vegetated wetland center. Mean water depth at the colony sites ranged from 50 to 120 cm; one colony may have abandoned its nests when water depths became too shallow-while another colony site was in the deepest water available on a wetland during a drought year.
Short Title:Colonial Waterbirds
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith