Correlates and consequences of egg size variation in wild ruddy ducks ( Oxyura jamaicensis)
Therefore, to determine why ducklings from larger eggs could have enhanced survival probabilities, I examined relationships between size, composition, and quality (indexed by lipid and energy content) of eggs and ducklings. Allometric regressions showed that most egg constituents increased in direct proportion (bs = 1.0) to fresh egg weight, but larger eggs contained proportionately more energy than smaller eggs (b > 1.0). In addition, dry yolk-free duckling weight increased proportionately less (b < 1.0) with fresh egg weight, but larger eggs produced ducklings with greater yolk reserves. Yolk sac weight also increased proportionately more with increasing dry yolk-free duckling weight. Although proportional composition of eggs was similar among large and small eggs, larger eggs contained more total energy than did smaller eggs, and therefore produced ducklings with larger yolk stores. Overall, larger ducklings may be better able to survive adverse conditions because they are in better condition, have larger energy reserves that buffer them against starvation, and likely have better thermoregulatory capabilities than smaller individuals.
Advisor:Alisauskas, Ray; Wobeser, Gary; Smith, Jan; Hill, Michael
School:University of Saskatchewan
School Location:Canada - Saskatchewan
Source Type:Master's Thesis
Date of Publication:07/07/2009