Kyle Cutting

Thesis title: NUTRIENT ALLOCATION STATEGIES IN EGG FORMATION OF FEMALE LESSER SCAUP (AYTHYA AFFINIS) ON LOWER RED ROCK LAKE, RED ROCK LAKES NATIONAL WILDILFE REFUGE

Abstract: North American lesser and greater scaup (A. affinis and A. marila, respectively) numbers have been declining for nearly 3 decades. Reasons are unclear for the decline; however, female lesser scaup are arriving at breeding areas in poorer body condition than historically, possibly resulting in reduced female breeding propensity. Breeding propensity, defined as the probability that an adult will breed in a given year, is an important determinant of population growth in ducks. However, little is known regarding breeding propensity in lesser scaup, or factors affecting this vital rate. Current population models assume breeding propensity to be high, although this may not be true for scaup. Breeding season survival is also an important determinant of population growth in ducks, and tends to be inversely related to breeding propensity. Current population models assume breeding propensity to be high, although this may not be true for scaup. Evidence indicates breeding-propensity may have declined in lesser scaup females over the last 3 decades. Understanding the relationships among female spring body condition and breeding propensity in lesser scaup is consequently an integral component to understanding the continental decline of the species.

Our objectives are to 1) assess how spring body condition and lipid accumulation strategies influences breeding propensity, 2) investigate nutrient allocation and acquisition strategies used in clutch formation, and 3) estimate breeding propensity using radio telemetry and hormone analysis. During spring migration scaup rely on staging areas to replenish nutrient reserves in order to achieve optimal body condition to initiate breeding activities. Recent evidence suggests that declines in habitat quality may be reducing body condition and the proportion of female scaup that breed each year. Nutrient reserves acquired from foods consumed on wintering and spring-staging areas can influence body condition upon arrival to the breeding areas and reproductive performance in ducks. Currently, the relative contribution of endogenous versus exogenous nutrient reserves used to fuel breeding activities and egg formation in lesser scaup is unknown, although scaup are believed to use an intermediate nutrient strategy. Few estimates of breeding propensity exist in North America and are likely to be a limiting factor in recruitment of ducks. Recently, Martin et al. (2007) completed a study assessing breeding propensity in lesser scaup in Alaska and concluded breeding propensity was lower than the assumed estimate used in waterfowl population models in which every bird is assumed to breed.

Research Interest: Stable isotope techniques, blood metabolite profiles, migration strategies, body condition, breeding propensity, nesting ecology, and egg formation in birds.

I am interested in nutrient allocation strategies in egg formation of birds during the breeding season. I am also interested in how arrival body condition to the breeding grounds influences reproductive output of birds.