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). 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. We used ordinary least-squares regression (PROC REG; SAS Institute 1990) to evaluate relationships between egg and duckling composition estimates and respective egg and duckling masses, enabling us to compare our results with other studies (see Hill 1995). Relationship between dry residual yolk sac mass (g) and dry yolk-free mass (g) of Ruddy Duck ducklings (n = 20) from Minnedosa, Manitoba, 1999 (solid line). Their bright … jP
Lipid and ash-free lean dry masses comprised 40% and 52% of dry yolk-free carcass mass, respectively. jP
%���� Dry yolks of 20 eggs collected in 1999 were ground, and the mass of neutral lipids was determined by extraction with petroleum ether (Dobush et al. The effect of apparatus, extraction time, and solvent type on lipid extractions of Snow Geese. Consistent with this hypothesis, large ducklings generally do survive better than small ones (Pelayo 2001). Ash-free lean dry mass was calculated by subtracting ash mass from lean dry carcass mass. A field guide to the nests, eggs and hatchlings of North American birds. Ruddy duck males migrate to breeding grounds before females and pair shortly after. Large Ruddy Duck eggs produced larger ducklings than small eggs did. 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. Intraspecific variation in egg composition. The Ruddy Duck (Oxyura jamaicensis) is a small-bodied diving duck that produces large, precocial ducklings (Lack 1968a, Johnsgard and Carbonell 1996). 2000). Laying extremely large eggs could enable Ruddy Ducks to counteract late nesting and low renesting rates (Bellrose 1980, Tome 1987). 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). Special thanks to landowners of Minnedosa for access to land, and to Pete Fast (1998) and Josh Traylor (1999) for lab and field assistance. A strong positive correlation existed between actual incubation age and predicted age suggesting that model accuracy was high. Lipids comprised 61% of the dry yolk sac and, overall, yolk sacs contained 26% of total lipid reserves available to newly hatched ducklings. Resumen. We opened the peritoneal cavity, removed the yolk sac, and weighed (to the nearest 0.01 g) the yolk sac and wet yolk-free carcass. Mortality during the breeding season, p. 396–422. Dried yolks were placed in sealed bags and frozen for 4 months. Jeffrey T. Pelayo, Robert G. Clark, Variation in Size, Composition, and Quality of Ruddy Duck Eggs and Ducklings, The Condor, Volume 104, Issue 2, 1 May 2002, Pages 457–462, https://doi.org/10.1093/condor/104.2.457. Guidelines to the use of wild birds in research. M.Konarzewski. Ruddies often lay eggs in each others' nests and in those of other ducks and marsh birds. Dry, yolk-free ducklings were ground in an electric grinder, and two homogenate carcass samples per individual were extracted for neutral lipids and redried. Relationship between body composition and homeothermy in neonates of precocial and semiprecocial birds. Intraspecific variation in egg size and egg composition in birds: effects on offspring fitness. In general, tissue maturity is inversely related to water content (Ricklefs et al. The effect of offspring size on physiology and life history: manipulation of size using allometric engineering. The body lipid index for Ruddy Ducks (0.78) also is greater than those for Northern Pintail (0.74; Duncan 1988), King Eider (Somateria spectabilis; 0.53; Anderson and Alisauskas 2002), Wood Duck (0.30, 0.48; Clay et al. D. G.Krementz. Water averaged 67% (n = 20), and water index (excluding yolk sac water) ranged from 3.8 to 4.8 (4.2 ± 0.3). The ducklings hatch well-developed and active, receiving minimal care from the mother and none from the father. D. J.Stangohr,
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. � We assumed that lean dry yolk residue and dry albumen were mostly protein (Sotherland and Rahn 1987), and that shell was primarily mineral (Arnold 1989). However, large ducklings had proportionately larger yolk sac stores than did small ducklings. 15 0 obj <>stream Bigger eggs produced larger, more mature ducklings provisioned with greater energy reserves and, presumably, these large ducklings survive better. 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). 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). Correlates and consequences of egg size variation in wild Ruddy Ducks (, M.Sc. Shipping cost is $50.00 per pair. Lack (1968b) found similar proportions of yolk in small and large eggs across several species of Anatidae, and surmised that large eggs would not produce offspring with larger yolk reserves. Analysis of covariance (ANCOVA; using Type III sums of squares) was used to test separately whether egg and duckling components varied between years (PROC GLM; SAS Institute 1990) following Sokal and Rohlf (1995). Masses of lean dry yolk, wet albumen, water fraction in albumen, and total egg water increased in direct proportion to fresh egg mass (all b = 1.0). Catabolism of egg lipid yields energy about 66% more efficiently than breakdown of protein (Ricklefs 1977), so egg energy is closely correlated with yolk mass. Egg size has been considered a good predictor of quality because size is positively correlated with lipid and protein content (Ankney 1980, Rohwer 1986, but see Arnold 1989). (fP$#�0a!��*�"0�1L�մ_.�Y�����0+�i����vV�I�t�[���r�}s!J�y:�i� �ޜiW��۴�����I\G.��l����;*}��7~9�'����������z��w���:Sz���y�9"��U�Y����'���P�_�ou�9�����Hj+�*��_�7F�/�v/}uh���� 1987). However, direct manipulation of egg or chick composition would be most informative (Bernardo 1991, Sinervo 1993). 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). Variation in the composition of the eggs and chicks of American Coots. endstream endobj 16 0 obj <>stream ;*�H��w �r}�t�]/ϳ��yJՌ��o��ۆ�p�D��g#w�G���Iы�9=S�V�StER��u��t��� Egg size was a poor predictor of duckling lipid content in Wood Ducks (Aix sponsa; Hepp et al. The residual yolk sac provides nutrients to chicks, contributing to tissue synthesis and growth of the digestive system (Peach and Thomas 1986). 1987), and Mallard (0.45; Rhymer 1988). Lipid and protein content (indexed by lean dry mass) accounted for 64% and 36% of the dry yolk, respectively. Ducklings were then euthanized with Halothane (Gaunt and Oring 1997). North American Ruddy Ducks have their origins in North America and also the Andes Mountains of South America. D. L.,
Descriptive statistics of untransformed data are reported as means ± SD. La masa fresca de los huevos promedió 74.1 ± 4.3 g (DE), pero varió entre 60.5 y 83.8 g. A pesar del gran tamaño de los huevos en relación al tamaño corporal de la hembra, y de una diferencia de 1.4 veces en la masa entre el huevo más pequeño y él más grande, la mayoría de los componentes del huevo aumentaron en proporción directa con la masa fresca del huevo.