Large Ruddy Duck eggs produced heavier ducklings with proportionately greater yolk reserves, and this may partly explain why wild Ruddy Duck ducklings hatching from large eggs had better body condition (Pelayo 2001). Components were manually separated; wet mass of shell (shell membranes were added to albumen; Alisauskas 1986, Arnold 1989), albumen and yolk were recorded (to the nearest 0.01 g), and then dried (60–65°C) to constant mass. Ash content was determined by combustion of lean carcass samples in a muffle furnace at 550°C for 12 hr. 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. 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). Composition of Blue-winged Teal eggs in relation to egg size, clutch size, and the timing of laying. 1987). ftypjp2 jp2 Yjp2h ihdr - H colr ,res resdK�� K�� rescK�� K�� jp2c�O�Q ) H - H - �R �\ #"wv�v�v�o o n�gLgLgdPPPEW�W�Wa�d Kakadu-v6.3.1�d Y Kdu-Layer-Info: log_2{Delta-D(MSE)/[2^16*Delta-L(bytes)]}, L(bytes) Thus, large ducklings also had greater total lipid reserves, an advantage that could enable them to survive better than small ducklings during the first few days after hatching. 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). A field guide to the nests, eggs and hatchlings of North American birds. Water content, thermogenesis, and growth rate of skeletal muscles in the European Starling. 1979, Hepp et al. 2000). Ducklings are preyed upon by Black-crowned Night-Herons, Ring-billed Gulls, California Gulls, mink, and raccoons. Resumen. Ruddy Ducks and other stifftails: their behavior and biology. Por lo tanto, los polluelos grandes también presentaron una mayor reserva total de lípidos, ventaja que podría permitirles sobrevivir mejor que a los polluelos más pequeños durante los primeros días luego de la eclosión. Biological Reviews of the Cambridge Philosophical Society, Habitat ecology of Nearctic–Neotropical migratory landbirds on the nonbreeding grounds, Advancing scientific knowledge and conservation of birds through inclusion of conservation social sciences in the American Ornithological Society, Mixed evidence for effects of stewardship on Least Tern reproductive success in coastal Mississippi, About the American Ornithological Society, Receive exclusive offers and updates from Oxford Academic, Copyright © 2020 American Ornithological Society. Component mass could also increase at a slower (b < 1.0, negative allometry) or faster (b > 1.0, positive allometry) rate with increasing x; we used a 95% confidence interval (CI) to determine whether b = 0 (no relationship between x and y) or 1.0. Descriptive statistics of untransformed data are reported as means ± SD. !��)3�\��8�3A��� ����1O�{m��@��ޤ�q��R����VX�������8l�� ���~�(G�p � +[rG`X��Ѓ�� W�5���� C. D.Ankney, and Ash-free lean dry mass was calculated by subtracting ash mass from lean dry carcass mass. �� Sin embargo, polluelos grandes presentaron relativamente mayores reservas en el saco vitelino que polluelos pequeños. Age-specific changes in the major body components and caloric values of growing Wood Ducks. Correlates and consequences of egg size variation in wild Ruddy Ducks (, M.Sc. D. G.Krementz. Yolk-free ducklings and yolk sacs were dried (60–65°C) to constant mass, placed in plastic bags, and frozen for 4 months. M.Konarzewski. Likewise, b = 0.33 or 3.0 was used when b was calculated from mixed volumetric and linear measurements. Large precocial offspring with greater energy reserves presumably could benefit from reduced risk of starvation during bad weather (Ankney 1980), additional energy for foraging and evading predators (Anderson and Alisauskas 2001), or enhanced thermoregulation (Rhymer 1988).

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