Snowy Plover reproductive success in beach and river habitats

• Published in: Journal of field ornithology 2005-10, Vol.76 (4), p.373-382
• Main Authors: Colwell, MA, Millett, C B, Meyer, J J, Hall, J N, Hurley, S J, McAllister, SE, Transou, AN, LeValley, R R
• Format: Article
• Language: English
• Subjects: Charadrius alexandrinus nivosus; Freshwater; Marine
• ISSN: 0273-8570
• DOI: 10.1043/0273-8570(2005)076[0373:SPRSIB]2.0.CO;2

Poor reproductive success has contributed to the decline and low population size of the federally listed Western Snowy Plover (Charadrius alexandrinus nivosus), especially where it breeds on coastal beaches used by humans for recreation. From 2001-2004, we compared reproductive success of color-marked plovers breeding on ocean beaches with those on gravel bars of the lower Eel River in coastal northern California, one of six recovery units as identified by the species' recovery plan. In three of four years, more plovers (54-64%) nested in river than beach habitats, but this pattern was reversed in the last year of the study when 62% of plovers used beaches. Each year, a higher proportion of clutches hatched and more chicks fledged from river than beach habitats, producing a disproportionate number of yearlings recruited into the local population from the river. On average, river-nesting males tended significantly fewer eggs, hatched similar numbers of chicks, and fledged significantly more young compared with males breeding on beaches. Corvids were more prevalent in river habitats in two of four years, but beaches consistently had significantly greater human activity. These habitat differences in reproductive success exist despite efforts to manage predators (e.g., exclosures around nests) and humans (e.g., signs, fencing, and vehicle restrictions) on beaches and almost no management of river habitats.Original Abstract: Exito reproductico de Charadrius alexandrinus en habitats de playas y riosUn exito reproductivo pobre ha contribuido a la merma del playero (Charadrius alexandrinus) particularmente cuando este anida en habitats de playas utilizadas por humanos para la recreacion. De 2001-2004, comparamos el exito reproductivo de playeros que fueron anillados en playas y en graveros del rio Eel que se encuentra en la parte norte de California. Esta es una de las seis localidades mencionadas en el Plan de Recuperacion de esta especie que ha sido listada. En tres de los cuatro anos, una mayor cantidad de playeros (54-65%) anidaron en el habitat de rio que en el de playa, aunque este patron se invirtio en el ultimo ano de estudio (64%). Cada ano una mayor proporcion de camadas eclosionaron y un numero mayor de polluelos dejaron el nido en habitats de rios que en los de playa, produciendo una desproporcion numerica de volantones de un ano, reclutados en la poblacion del rio. En promedio, los machos que atendieron polluelos en rios tuvieron que incubar menos hue