Temporal covariation of lesser scaup demographic rates

The continental population of scaup ( Aythya affinis and A. marila) fell to >30% below the 1955-2008 average, and ~3 million birds below the North American Waterfowl Management Plan (NAWMP) goal of 6.3 million. Reviews of long-term databases noted a decrease in the sex and age ratios (number of females relative to males and number of immatures relative to adults, respectively) of lesser scaup in the U.S. harvest. These results indicate that recruitment and female survival of lesser scaup has declined during this period. Recruitment is the product of several demographic rates, including female survival during the breeding season, breeding propensity, nesting success, and duckling survival. Previous life-cycle models were unable to investigate [...]