Mating System and Reproductive Success of a Small Population of Polygamous Snowy Plovers

• Published in: The Wilson bulletin (Wilson Ornithological Society) 1986-03, Vol.98 (1), p.15-37
• Main Authors: Warriner, John S., Warriner, Jane C., Page, Gary W., Stenzel, Lynne E.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Autoecology; Aviculture; Biological and medical sciences; Bird nesting; Breeding; Breeding seasons; Charadrius alexandrinus; Chicks; Eggs; Female animals; Fundamental and applied biological sciences. Psychology; Incubation; Male animals; Marine; Mating behavior
• ISSN: 0043-5643; 2162-5204

This six-year study describes the breeding of a partly resident, partly migrant population of Snowy Plovers (Charadrius alexandrinus) in California. Migrants arrived between 6 January and 27 April, with females preceding males. Migrant males did not pair as early as resident males, whereas resident and migrant females paired at about the same time. Early pairbonds often were with the same mate in two consecutive years. Egg laying occurred from 23 March to 13 July. Replacement clutches were initiated between 11 April and 11 July, typically seven days after loss of the preceding one, and usually with the same mate. Over the season, the time required for a pair to complete the three-egg clutch decreased from five days to four days. During egg laying, males spent more time in the nesting territory and on the incomplete clutch than did females. Incubation averaged 28.4 days early in the season, but only 26.9 days late in the season. During daytime, males averaged only 10.7% of the incubation time, but they appeared to be the main incubators at night. Over six years, 58.2% of 189 clutches hatched at least one chick. Females normally deserted hatched young within six days; males attended the young for 29 to 47 days. Fledging typically occurred at about 31 days of age. Over six years, 39% to 42% of 296 chicks fledged. After deserting broods, at least 22 of 60 females renested with new mates. At least 10 of 18 males fledging chicks before 1 July renested with new mates, and in at least 13 of 27 cases, males losing broods before 1 July renested, usually with new mates. Males appeared to outnumber females by 1.4:1. Sexual differences in survival rates are nearly sufficient to account for the difference in sex ratio. We suggest that the female's serial polyandry may be a facultative response to a skewed sex ratio.