Lifetime reproductive success of Snowy Plovers in coastal northern California

Conserving threatened and endangered species requires knowledge of breeding productivity and factors that cause variation in reproductive success. We summarized 13 years of lifetime reproductive success (LRS) data for 195 individually marked Snowy Plovers (Charadrius nivosus) breeding in Humboldt County, CA. Reproductive success was highly skewed among individuals with 13% of individuals (nmales = 12, nfemales = 14) producing ~50% of fledglings; by contrast, 71% (n = 64) of males and 72% (n = 76) of females produced 2 or fewer during their lifetime. Variance in LRS was best explained by substrate (~100% of Akaike weight), with plovers breeding on gravel having significantly higher LRS compared to those on sandy substrates. Other measures of habitat quality, including use of nest exclosures, as well as corvid and human activity, were not significant predictors of LRS. Results indicated that enhancing the cryptic nature of substrates (for eggs and chicks) may be a productive means of increasing reproductive success in this threatened species.