Dry, yolk-free ducklings were ground in an electric grinder, and two homogenate carcass samples per individual were extracted for neutral lipids and redried. P.Monaghan, and Total lipid reserve was carcass lipid plus lipid contained in yolk sacs; similarly, total protein was carcass lean dry mass plus yolk sac lean dry mass. Ornithological Council Special Publication, Ornithological Council, Washington, DC. %PDF-1.5 However, large eggs contained proportionately greater amounts of dry yolk and lipid in Mute Swans (Cygnus olor; Birkhead 1984), Mallards (Anas platyrhynchos; Birkhead 1985), American Coots (Fulica americana; Alisauskas 1986), and Blue-winged Teal (Anas discors; Rohwer 1986), implying that chicks from these eggs could have larger yolk reserves; our results support this conjecture. Their bright … We used log-log regression to estimate a and b of the function y = axb; when a slope (b) = 1.0 (isometry), component mass, y, increases in direct proportion to egg (or duckling) mass, x. D. G.Krementz. Ruddies often lay eggs in each others' nests and in those of other ducks and marsh birds. Conservation. Sin embargo, polluelos grandes presentaron relativamente mayores reservas en el saco vitelino que polluelos pequeños. All collection and handling procedures were approved by the University of Saskatchewan's Committee on Animal Care (Protocol 980022) on behalf of the Canadian Council on Animal Care, and in concordance with federal permits issued by the Canadian Wildlife Service (CWS98-M015, CWS99-M020). D. C.Houston. � thesis, University of Saskatchewan, Saskatoon, SK, The effect of egg size variability on thermoregulation of Mallard (. Para evaluar por qué los polluelos que eclosionan de huevos grandes sobreviven mejor que polluelos provenientes de huevos pequeños, cuantificamos la variación en la composición y calidad de huevos y polluelos en relación al tamaño del huevo en Oxyura jamaicensis. jP Egg incubation stage averaged 15 ± 3 days (range = 11–22 days), but stage, and interactions of stage with egg mass or yolk-free duckling mass, did not affect the foregoing relationships (ANCOVA, all F < 2.1 and P > 0.14). We revisited all nests after clutch completion, and measured maximum length and breadth of all eggs (with dial calipers, to the nearest 0.1 mm). Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2, Canada. Mean ± SD (g) for components of Ruddy Duck eggs and ducklings (sample size) collected near Minnedosa, Manitoba, in 1998 and 1999. Eggs averaged 62.7 ± 1.5 mm long (range = 58.0–65.9 mm) and 46.0 ± 1.1 mm wide (43.3–48.1 mm), and weighed 74.1 ± 4.3 g (60.5–83.8 g). Mass of newly hatched ducklings (r2 = 0.94, n = 20) and total lipid content (r2 = 0.62) were directly related (b = 1.0) to fresh egg mass. The water index for Ruddy Duck ducklings was 3.9, suggesting their tissues were more functionally developed than those of Northern Pintails (5.9; Duncan 1988) and American Coots (4.3; Alisauskas 1986), but comparable to those of King Eiders (3.7; Anderson and Alisauskas 2002). Within-clutch trade-offs between the number and quality of eggs: experimental manipulations in gulls. Most variation in egg lipid (82%), total water (90%) and total energy (91%) was explained by fresh egg mass. Young: Leave the nest within a day after hatching, are able to swim and dive well immediately. Variación en el Tamaño, Composición y Calidad de los Huevos y Polluelos de Oxyura jamaicensis. 1985); albumen was not analyzed because it contains negligible amounts of lipid (<1%; Carey 1996). SAS/STAT user's guide. Ruddy Duck (Oxyura jamaicensis) eggs, and the accuracy of this model was then tested by correlating actual incubation age against the incubation age predicted from the egg floatation model. Water, lipid, and lean dry mass for 20 dry, yolk-free ducklings and 20 dry yolk sac samples from the same individuals from 1999 were determined similarly as for egg yolks. Sketches are after Harrison (1978). However, direct manipulation of egg or chick composition would be most informative (Bernardo 1991, Sinervo 1993). An unknown number of Redhead and Ruddy ducklings hatched from eggs deposited intraspecifically. 1987). We revisited a subsample of active nests to collect fresh eggs for egg composition analysis (30 eggs <24 hr old from 17 nests in 1998; 20 eggs from 12 nests in 1999). Internal constraints on growth in birds, p. 266–287. 1979, Hepp et al. Adult females lay the largest eggs in proportion to body size of all anatids, and energy costs to produce eggs (one egg day−1) are the highest among waterfowl (Alisauskas and Ankney 1994). Egg size was a poor predictor of duckling lipid content in Wood Ducks (Aix sponsa; Hepp et al. However, large ducklings had proportionately larger yolk sac stores than did small ducklings. Composition of Blue-winged Teal eggs in relation to egg size, clutch size, and the timing of laying. Delta Waterfowl Foundation (Delta Waterfowl and Wetlands Research Station), Canadian Wildlife Service (Environment Canada), Natural Sciences and Engineering Research Council of Canada (operating grant to RGC), and University of Saskatchewan provided financial and logistical support. R. G., We thank Todd Arnold and Wendy Reed for support and helpful discussions; Shannon Badzinski, David Dobkin, Stuart Slattery, and two anonymous reviewers provided constructive manuscript reviews. Water averaged 67% (n = 20), and water index (excluding yolk sac water) ranged from 3.8 to 4.8 (4.2 ± 0.3). The proportion of yolk in Ruddy Duck eggs was similar to that of Maccoa Ducks (38%, O. maccoa; Siegfried 1969), but lower than some other anatids (Lack 1968b). 2000). Analysis of covariance (ANCOVA; using Type III sums of squares) was used to test separately whether egg and duckling components varied between years (PROC GLM; SAS Institute 1990) following Sokal and Rohlf (1995). Cold-hardiness of the newly hatched young in relation to ecology and distribution in ten species of European ducks. Ash content was determined by combustion of lean carcass samples in a muffle furnace at 550°C for 12 hr. Variation in the composition of the eggs and chicks of American Coots. Fresh eggs were weighed on an electronic Mettler balance (to the nearest 0.01 g), boiled for 5 min to solidify contents, and reweighed after cooling (Ricklefs 1982). Relationship between body composition and homeothermy in neonates of precocial and semiprecocial birds. 1), whereas mass of carcass water, total lipid, lean dry, total ash and ash-free lean increased in direct proportion (b = 1.0) to dry yolk-free duckling mass. Water index varied from 3.7 to 4.1 (3.9 ± 0.1).
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