Birds of Indian Subcontinent

Nest Distance Mediates the Costs of Coloniality in Eared Grebes

Publication Type:Journal Article
Year of Publication:1997
Authors:Hill, WL, Jones, KJ, Hardenbergh, CL, Browne, M
Journal:Colonial Waterbirds
Date Published:1997
ISBN Number:07386028
Keywords:Fulica, Fulica americana, Fulica atra, Podiceps, Podiceps nigricollis, Podicipedidae, Rallidae
Abstract:We examined the behaviors and reproductive characteristics of 4 Eared Grebe (Podiceps nigricollis) colonies located at the Malheur National Wildlife Refuge in eastern Oregon that varied in nesting density. In 1993, we studied 2 colonies found on 2 different lakes, whereas in 1994 we conducted a within-lake comparison of 2 sub-colonies. During both years, nearest neighbor distances differed significantly between the colonies investigated. Breeding pairs were significantly more aggressive at those colonies with smaller distances among nests. Within each year, there was a greater rate of intraspecific brood parasitism and egg loss at the higher density colony. Infanticide occurred at high rates when nests were very densely packed, whereas a relatively high rate of predation by American Coots (Fulica americana) resulted when nests were quite dispersed. Thus, in spite of the distinct breeding characteristics of Eared Grebes, many disadvantages associated with nesting density in seabirds also have an impact on these colonially breeding waterbirds.
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