We examined the relationship between embryo development and egg hardness in two ground nesting bird species, the red-legged partridge (Alectoris rufa; n = 165 eggs) and the quail (Coturnix japonica; n = 148 eggs). For both species, we observed a strong effect of developmental stage on egg hardness. Eggs near hatching were significantly weaker than unincubated eggs (partridge: 18 and 23N, respectively, and the quail 7 and ION, respectively). We additionally explored the effect of incubation on egg hardness in a control sample of non-fertilised quail eggs (i.e., without embryo development). The control eggs maintained in the incubator for the full incubation time (17 days) were significantly harder (7-9N) than eggs containing fully developed chicks (5-7N). Thus, the incubation conditions of high temperature and humidity alone seem not to have a significant effect on egg hardness, and support the important effect of calcium uptake.
|Number of pages||7|
|Journal||Journal of Experimental Zoology Part A: Ecological Genetics and Physiology|
|Publication status||Published - 1 Aug 2007|
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Animal Science and Zoology
- Molecular Biology