Breeding pair and reproductive estimates of a recently expanded Red-necked Grebe (Podiceps grisegena) population in parkland Manitoba

Abstract

Conservation of wildlife populations requires reliable information on population size, trends, and demographic processes.
Such information is sparse for Red-necked Grebe (Podiceps grisegena), a species that is vulnerable to changing wetland conditions in the prairie pothole region. During 2008–2019, I collected breeding pair and reproductive estimates of a recentlyexpanded Red-necked Grebe population on 109 semi-permanent and permanent wetlands (mean ± SE: 2.92 ± 0.41 ha, range 0.01–24.2) in agriculturally-dominated habitat in southwestern Manitoba, Canada, to determine population status and reproductive success. I also looked for effects of changing wetland water levels and the presence of conspecifics and/or wetland size on productivity. Red-necked Grebe breeding densities were the highest reported for solitary-nesting pairs in North America and the breeding population currently appears to be stable. I found that chicks/breeding pair are mostly lower but chicks/successful pair are similar or greater than values reported from other studies. Pairs breeding with conspecifics appeared to be as productive as those on single-pair wetlands. Productivity was positively associated with wetland water levels suggesting that prolonged drought or climate change leading to warmer, drier summers on the prairies could reduce Rednecked Grebe breeding populations.