Thesis (Ph. D.)--Louisiana State University and Agricultural and Mechanical College, 2006. / Title from PDF t.p. (viewed on May 9, 2006). Vita. Includes bibliographical references.

In the mid-1980's until the late 1990's, Lesser Scaup (<i>Aythya affinis</i>)populations in the boreal forest declined and have remained at historical low levels since that time. This has resulted in a population well below conservation goals. Potential causes for this population decline include a reduction in productivity, which could be related to changes in boreal forest habitat, nutritional condition during reproduction, or due to contaminants acquired during migration or wintering. Though several studies have assessed contaminant levels in Lesser Scaup on wintering, staging and migration routes, relatively little data exist from northern boreal forest areas, one of the core breeding habitats of the Lesser Scaup population and where population declines appear to be most severe. To this end,male Lesser Scaup were trapped from sites in the northern boreal forest in 2004 and 2005 to assess trace element contaminant levels. Previous research has shown that trace elements including cadmium and selenium can influence hormonal status in waterfowl. Specifically, a positive relationship between cadmium and corticosterone and a negative correlation between liver selenium and corticosterone have been observed. The purpose of this study was to test the hypothesis that trace element contaminants can influence hormonal status and related physiological functions in male Lesser Scaup, and that interactions between contaminants, physiological variables such as body condition and social status can modify expression of toxic effects. Blood samples were collected from trapped males to assess stress related changes in blood chemistry (corticosterone, testosterone, glucose and thyroxine) and males were then collected for contaminant analysis and assessment of reproductive physiology. The geometric mean levels of kidney cadmium, liver selenium and liver mercury were 9ppm, 4.33 ppm, 1.31 ppm dry weight respectively. Several variables and interactions including pair status, cadmium, selenium, mercury, body condition and body size influenced corticosterone levels. In male Scaup with high cadmium levels, corticosterone was negatively related to liver selenium in birds with good body condition (R2=0.701,n=9, P=0.005) but not in birds with poor body condition (R2=0.033, n=10,P=0.61). Likewise, in birds with high cadmium, a negative association was found between liver mercury and corticosterone in structurally smaller males (R2=0.491,n=10, P=0.024), whereas no such relationship was found in larger males(R2=0.307, n=9, P=0.12). In birds with low cadmium and low mercury, selenium and corticosterone were negatively correlated (R2=0.568, n=10, P=0.012) while no association was found in males with high mercury (R2=0.325, n=10, P=0.085). Unpaired birds had higher corticosterone than in ducks with low cadmium(F1,17=6.70, P=0.023), while there was no difference between groups in ducks with high cadmium. Glucose levels were not influenced by contaminants or other variables in this study (R2=0.551, F21,17=0.99, P=0.51). Thyroxine levels were positively correlated to mercury levels in paired birds (R2=0.485, n=19, P<0.001)but were not related in unpaired birds (R2=0.063, n=20, P=0.28). Thyroxine levels also showed a relationship with date of capture (F1,37=6.77, n=39, P=0.014). Pair status was influenced by body condition and body size (P2 =9.997, df=2, P=0.007)with larger birds being in better condition and larger, while hormone levels and testicular morphology did not appear to influence pair status. Mass of testes (F9,27=0.45, P=0.90) and testosterone concentrations (F10,28=0.31, P=0.10) were not influenced by contaminant levels, body condition or body size. Seminiferous tubule diameter was positively related to testes mass (R2=0.397, n=39, P<0.0001) and negatively related to liver selenium levels (R2=0.123, n=39, P=0.009). To clarify the influence of selenium on corticosterone, captive male Lesser Scaup were fed diets dosed with selenomethionine. Dose groups accumulated different levels of selenium (control group=0.19 ng/ml, 7.5 ppm group=0.74 ng/ml and 15 ppm=1.01 ng/ml) (F2,12=155.12; P<0.001) but this appeared to have no effect on corticosterone levels (Wilks Lambda=0.659, F4,10=1.29, P=0.34) or behavioral patterns (Wilks Lambda=0.659, F4,10=1.294, P=0.34) in captive birds. Results from the field portion of this study support the hypothesis that trace element levels can influence hormonal status in wild Lesser Scaup and that interactions of contaminants and physiological variables can modify expression of toxic effects. Studies such as this one display the complex nature of biological systems and emphasize the importance of considering interactions between different contaminants and other variables to clearly assess their influences on physiology.

The lesser scaup (Aythya affinis, henceforth scaup) population decreased during the 1980s and has remained below conservation objectives. With two-thirds of the breeding population nesting in boreal forests, it is imperative to understand how changes in habitat features and landscape changes could negatively impact breeding scaup; this information could also help to guide waterfowl conservation and management programs. It has been hypothesized that landscape modifications, such as agricultural and oil exploitation activities, could adversely affect scaup reproductive performance. Female scaup were collected by shooting in the boreal forest fringe of central Alberta during within the first two weeks of June 2008 and 2009, corresponding to the early laying period. Collection location was determined using a hand-held GPS device and body mass (BM, g) was recorded immediately. When scaup carcasses were dissected, ovaries were removed and weighed. Rapidly growing follicles (RGF) and oviductal follicles (OF) were subjected to radioimmunoassay to quantify amount of ovarian corticosterone (OCORT) deposited into follicles. Nest initiation date (NID) was determined by counting and subtracting the number of postovulatory follicles (POF) from collection date. Natural landscape features and habitat disturbances within 100 m, 250 m, 500 m, 1500 m, and 5000 m buffers of each scaup collection location were quantified, and then normalized using z-score transformation. General linear modeling was applied to BM, OCORT and NID across each of the five buffer sizes using a priori candidate models. Natural landscape and habitat disturbance parameters were model-averaged to obtain 85% confidence intervals to determine which habitat features best predicted BM, NID, and OCORT. Model-averaging revealed that the amount of natural water body habitats were negatively correlated to scaup OCORT at the 100 m and 500 m buffer zones, and negatively correlated to scaup BM at 1500 m and 5000 m buffer zones. A combination of natural water bodies (BOGSFENS, SWAMP, WATER, and WETLAND) were negatively correlated to NID across all buffer sizes tested, AGRIC disturbance was positively correlated to NID at the 100 m and 1500 m buffer zones, WELLS were negatively correlated to NID at the 1500 m buffer zone, while TRANSPORT showed varied responses at the 1500 m and 5000 m buffer zones. Post-hoc exploratory analyses were conducted to assess whether variation in OCORT, BM, and NID was related to habitat features operating at more than one spatial scale. This analysis revealed models incorporating more than one spatial scale were competitive when compared to the original a priori model sets at the 250 m buffer zone, with post-hoc models performing better than a priori models. This study highlights the need for a holistic approach to conservation management, considering not only local habitat characteristics and disturbances in the immediate vicinity of breeding waterfowl, but extending beyond and incorporating regional landscape attributes.

In the mid-1980's until the late 1990's, Lesser Scaup (<i>Aythya affinis</i>)populations in the boreal forest declined and have remained at historical low levels since that time. This has resulted in a population well below conservation goals. Potential causes for this population decline include a reduction in productivity, which could be related to changes in boreal forest habitat, nutritional condition during reproduction, or due to contaminants acquired during migration or wintering. Though several studies have assessed contaminant levels in Lesser Scaup on wintering, staging and migration routes, relatively little data exist from northern boreal forest areas, one of the core breeding habitats of the Lesser Scaup population and where population declines appear to be most severe. To this end,male Lesser Scaup were trapped from sites in the northern boreal forest in 2004 and 2005 to assess trace element contaminant levels. Previous research has shown that trace elements including cadmium and selenium can influence hormonal status in waterfowl. Specifically, a positive relationship between cadmium and corticosterone and a negative correlation between liver selenium and corticosterone have been observed. The purpose of this study was to test the hypothesis that trace element contaminants can influence hormonal status and related physiological functions in male Lesser Scaup, and that interactions between contaminants, physiological variables such as body condition and social status can modify expression of toxic effects. Blood samples were collected from trapped males to assess stress related changes in blood chemistry (corticosterone, testosterone, glucose and thyroxine) and males were then collected for contaminant analysis and assessment of reproductive physiology. The geometric mean levels of kidney cadmium, liver selenium and liver mercury were 9ppm, 4.33 ppm, 1.31 ppm dry weight respectively. Several variables and interactions including pair status, cadmium, selenium, mercury, body condition and body size influenced corticosterone levels. In male Scaup with high cadmium levels, corticosterone was negatively related to liver selenium in birds with good body condition (R2=0.701,n=9, P=0.005) but not in birds with poor body condition (R2=0.033, n=10,P=0.61). Likewise, in birds with high cadmium, a negative association was found between liver mercury and corticosterone in structurally smaller males (R2=0.491,n=10, P=0.024), whereas no such relationship was found in larger males(R2=0.307, n=9, P=0.12). In birds with low cadmium and low mercury, selenium and corticosterone were negatively correlated (R2=0.568, n=10, P=0.012) while no association was found in males with high mercury (R2=0.325, n=10, P=0.085). Unpaired birds had higher corticosterone than in ducks with low cadmium(F1,17=6.70, P=0.023), while there was no difference between groups in ducks with high cadmium. Glucose levels were not influenced by contaminants or other variables in this study (R2=0.551, F21,17=0.99, P=0.51). Thyroxine levels were positively correlated to mercury levels in paired birds (R2=0.485, n=19, P<0.001)but were not related in unpaired birds (R2=0.063, n=20, P=0.28). Thyroxine levels also showed a relationship with date of capture (F1,37=6.77, n=39, P=0.014). Pair status was influenced by body condition and body size (P2 =9.997, df=2, P=0.007)with larger birds being in better condition and larger, while hormone levels and testicular morphology did not appear to influence pair status. Mass of testes (F9,27=0.45, P=0.90) and testosterone concentrations (F10,28=0.31, P=0.10) were not influenced by contaminant levels, body condition or body size. Seminiferous tubule diameter was positively related to testes mass (R2=0.397, n=39, P<0.0001) and negatively related to liver selenium levels (R2=0.123, n=39, P=0.009). To clarify the influence of selenium on corticosterone, captive male Lesser Scaup were fed diets dosed with selenomethionine. Dose groups accumulated different levels of selenium (control group=0.19 ng/ml, 7.5 ppm group=0.74 ng/ml and 15 ppm=1.01 ng/ml) (F2,12=155.12; P<0.001) but this appeared to have no effect on corticosterone levels (Wilks Lambda=0.659, F4,10=1.29, P=0.34) or behavioral patterns (Wilks Lambda=0.659, F4,10=1.294, P=0.34) in captive birds. Results from the field portion of this study support the hypothesis that trace element levels can influence hormonal status in wild Lesser Scaup and that interactions of contaminants and physiological variables can modify expression of toxic effects. Studies such as this one display the complex nature of biological systems and emphasize the importance of considering interactions between different contaminants and other variables to clearly assess their influences on physiology.

Master of Science / Department of Biology / David A. Haukos / Abstract–Duckling Survival Lesser scaup (scaup) populations have been experiencing continent-wide decline since the 1980s. It is important to have complete understanding of the critical factors influencing population change (e.g., duckling survival, nesting success, and health) to advance our understanding of population dynamics and improving species conservation. Duckling survival is a primary driver of scaup demography. I conducted a capture-mark-recapture study using Cormack-Jolly-Seber models in Program MARK to compute apparent daily survival and recapture probabilities for 3256 individually marked ducklings with 620 recaptures during 2010 to 2013. The most parsimonious survival model based on a priori hypotheses found that Julian hatch date squared was the most significant predictor of survival and consistent through all four years. Mass at hatch also was significant as a quadratic effect. Duckling survival to 30 days ranged from 29.0 to 80.0. During this study, stabilizing selection played a significant role in duckling survival, which indicates that there was trade-offs for selection of an optimal timing of hatch on survival and a cost associated with hatching too early or too late and being too heavy or to light. / Abstract–Nest-Site Selection There is a hierarchical process of behavioral and environmental processes that influence habitat selection, which inherently influences the survival and fitness of that individual and contributes to population growth. I investigated nest fate, spatial attributes, and all relationships between high and low-water levels with habitat attributes (distance to upland, distance to open water, nearest neighbor distance) of located nests using general linear models in SAS, t-tests in R, and Hot Spot Analysis in ArcGIS of 481 nests over eight years. In low-water years, successful nests (X̅ = 1153 m) were located 22.0% farther from upland than unsuccessful nests (X̅ = 944 m), but support for a similar relationship was lacking in high-water years. Successful nests were located 21.0% and 23.0% (i.e., 49 and 50 m) closer to conspecific nests than unsuccessful nests in low and high-water levels, respectively. In both high and low-water level years, clusters of nests initiated later in the season coincided with Hot Spots for nest fate (i.e., high-quality habitat patches, clusters of successful nests), whereas areas that tended to be selected first, evidenced by clusters of nests initiated earlier, tended to overlap with clusters of Cold Spots for nest fate. The core Hot Spot for nest fate was in the same spot in both water level conditions and located in flooded emergent vegetation in the heart of Lower Red Rock Lake furthest from any upland habitat. Three out of six Cold Spots for nest fate both in high and low-water years were located in emergent vegetation on the perimeter of Lower Red Rock Lake adjacent to uplands. Density-dependence seems to be a factor affecting late-nesting scaup females that are apparently cuing in on the reproductive performance of conspecifics when determining where to nest. Therefore, management actions focused on survival and reproductive success of scaup should consider managing water levels and habitat for later nesting scaup to increase adult survival and ultimately recruitment of ducklings. / Abstract – Blood Parasite Prevalence Blood parasites, per se, do not lead to direct mortality, but instead reduce the health of individual birds, which may ultimately lead to decreased reproductive success. Evidence has shown that presence of blood parasites can reduce fitness, body condition, and reproductive success of waterfowl. For many avian species, the cost of reproduction is manifested as a negative relationship between female breeding effort and breeding season survival, with trade-offs occurring when these adaptive choices become detrimental to future reproductive performance. Blood was drawn for parasite load determination from 112 individual adult scaup captured from 2011to 2012 via spotlighting and drive-trapping. Parasite prevalence was determined through blood assays that were created using a two-slide wedge technique. Relationships among seasonal heterophile:lymphocyte ratio (a proxy for health), body mass at time of capture (throughout pre-, during, and post-breeding periods), breeding status (females only), and Julian date of capture (date of capture) of capture with parasite prevalence were analyzed using linear (lm) regression models in R 2.15.2. The blood parasite infection rate was 5.0%, with prevalence differing by gender with 33.3% of males positive for blood parasites compared to 1.0% of females. The presence of blood parasites did not affect health, fitness, or breeding status of scaup. A quadratic relationship was found with body mass and date of capture, indicating that body mass increased from pre-breeding period to the breeding period and decreased significantly at the end of the summer during molt. A negative relationship between the heterophile:lymphocyte ratio of female scaup and date of capture (i.e., the health of scaup females was greatest during the pre-breeding period after which it consistently decreased until the molting period). A strong negative correlation between heterophile:lymphocyte ratio and body mass was found in both genders, which indicated that scaup in poor body condition were also in poor health at the end of the breeding season.

Environmental conditions on wintering or spring-staging areas may influence subsequent reproductive performance in migratory birds. These cross-seasonal effects may result from habitat loss and degradation (e.g., via contamination) which in turn reduce reproductive success, particularly in waterfowl that use stored nutrients for reproduction. North American lesser scaup (<i>Aythya affinis</i>) and white-winger scoter (<i>Melanitta fusca</i>) numbers have declined over the past 20 years, particularly in the boreal forest, and remain well below conservation goals, whereas ring-necked duck (<i>A. collaris</i>) numbers have increased. Environmental changes on scaup and scoter wintering and staging areas have raised concern about possible cross-seasonal effects on birds arriving on breeding grounds. The spring condition hypothesis (SCH) purports that many female scaup fail to acquire sufficient nutrients in late winter and spring, causing a decrease in breeding propensity and productivity. The contaminant hypothesis proposes that increased exposure to contaminants (particularly selenium [Se]) on wintering and staging areas has decreased scaup productivity. Accordingly, I compared body condition and studied Se concentrations in scaup, scoters and ringnecks to test the condition and contaminant hypotheses. <p>Scaup had similar body condition to ringnecks, and had similar body mass compared to scaup collected near Yellowknife, NT, in 1968-70. There was no relationship between scaup and ringneck nutrient levels and claw tip carbon, nitrogen or hydrogen isotope values, suggesting that arrival body condition likely was not related to location or diet several months prior. Instead, scaup and ringnecks nutrient levels may be more affected by feeding or habitat conditions on or near the breeding grounds. Scaup had slightly higher liver Se concentrations than ringnecks, but levels in both species were below recognized harmful threshold concentrations; I found no relationship between Se and breeding propensity, or between Se and somatic lipid or protein stores. Scoters had much higher Se concentrations, yet contrary to predictions, there were positive relationships between Se and both lipid stores and breeding status. Follicle [Se] in scaup was below threshold concentrations; despite high liver Se in scoters, egg and follicle levels also were well below threshold concentrations. Using both body composition analysis and stable-isotope analysis I determined that scoters derive egg protein from their breeding ground diet, which likely prevents Se deposition from somatic protein to eggs, and egg lipids are apparently derived from somatic tissues. In all three species, liver Se concentrations were significantly correlated with claw tip ä15N. As the claw tip likely represents assimilated diet from 2-5 months prior to sampling, this correlation suggests that Se in these boreal breeding species is carried over from wintering and staging areas. <p>Overall, results did not support either the spring condition or contaminant hypotheses. Scaup and scoters are late-nesting species, with highest pair densities occurring at the northern extent of their range. Maximum ring-neck pair densities occur at more southern latitudes. Ring-necks also nest earlier and appear to be more flexible in timing of nest initiation. Therefore, it is possible that due to climate change, early spring conditions alter the optimal timing of nest initiation to the detriment of late-nesting species such as scaup and scoters, and favour earlier nesters like ringnecks. Further research into this mismatch hypothesis is warranted.

Environmental conditions on wintering or spring-staging areas may influence subsequent reproductive performance in migratory birds. These cross-seasonal effects may result from habitat loss and degradation (e.g., via contamination) which in turn reduce reproductive success, particularly in waterfowl that use stored nutrients for reproduction. North American lesser scaup (<i>Aythya affinis</i>) and white-winger scoter (<i>Melanitta fusca</i>) numbers have declined over the past 20 years, particularly in the boreal forest, and remain well below conservation goals, whereas ring-necked duck (<i>A. collaris</i>) numbers have increased. Environmental changes on scaup and scoter wintering and staging areas have raised concern about possible cross-seasonal effects on birds arriving on breeding grounds. The spring condition hypothesis (SCH) purports that many female scaup fail to acquire sufficient nutrients in late winter and spring, causing a decrease in breeding propensity and productivity. The contaminant hypothesis proposes that increased exposure to contaminants (particularly selenium [Se]) on wintering and staging areas has decreased scaup productivity. Accordingly, I compared body condition and studied Se concentrations in scaup, scoters and ringnecks to test the condition and contaminant hypotheses. <p>Scaup had similar body condition to ringnecks, and had similar body mass compared to scaup collected near Yellowknife, NT, in 1968-70. There was no relationship between scaup and ringneck nutrient levels and claw tip carbon, nitrogen or hydrogen isotope values, suggesting that arrival body condition likely was not related to location or diet several months prior. Instead, scaup and ringnecks nutrient levels may be more affected by feeding or habitat conditions on or near the breeding grounds. Scaup had slightly higher liver Se concentrations than ringnecks, but levels in both species were below recognized harmful threshold concentrations; I found no relationship between Se and breeding propensity, or between Se and somatic lipid or protein stores. Scoters had much higher Se concentrations, yet contrary to predictions, there were positive relationships between Se and both lipid stores and breeding status. Follicle [Se] in scaup was below threshold concentrations; despite high liver Se in scoters, egg and follicle levels also were well below threshold concentrations. Using both body composition analysis and stable-isotope analysis I determined that scoters derive egg protein from their breeding ground diet, which likely prevents Se deposition from somatic protein to eggs, and egg lipids are apparently derived from somatic tissues. In all three species, liver Se concentrations were significantly correlated with claw tip ä15N. As the claw tip likely represents assimilated diet from 2-5 months prior to sampling, this correlation suggests that Se in these boreal breeding species is carried over from wintering and staging areas. <p>Overall, results did not support either the spring condition or contaminant hypotheses. Scaup and scoters are late-nesting species, with highest pair densities occurring at the northern extent of their range. Maximum ring-neck pair densities occur at more southern latitudes. Ring-necks also nest earlier and appear to be more flexible in timing of nest initiation. Therefore, it is possible that due to climate change, early spring conditions alter the optimal timing of nest initiation to the detriment of late-nesting species such as scaup and scoters, and favour earlier nesters like ringnecks. Further research into this mismatch hypothesis is warranted.

Scaup (Aythya spp.) are suspected of consuming substantial quantities of fish from Arkansas commercial baitfish and sportfish farms. We investigated the foraging ecology and depredation impact of scaup on farms by surveying ponds and collecting scaup during two autumn-winters (2016-2018) in Arkansas. Scaup abundance and fish they consumed were highly variable between winters. More scaup were present and they ate more fish during the second winter (2017-2018) than the previous winter. In the second year, there were an estimated 874,941 scaup use-days and 18% of Lesser Scaup diet was fish. We found that scaup use of ponds was more likely in colder winters and on larger Golden Shiner, Fathead Minnow, and Lepomis spp. ponds stocked at high densities. These results will inform stakeholders on the extent of losses of fish to these birds, and methods to efficiently allocate resources for timely harassment of scaup from fish ponds.