Distressed and Feeling Blue
Biliverdin is not only a pretty blue pigment. Biliverdin, the tetrapyrrole responsible for the blue-green coloration observable in the photo of the egg that I posted, is also a precious antioxidant.
Morales et al. tracked 48 female Pied Flycatchers (Ficedula hypoleuca) on montane nesting grounds in central Spain. After observing nest construction, researchers intervened. In the case of the control group, they merely removed and promptly replaced the nest in the nest box. For members of the test group, however, nests were permanently removed, and subjects began re-building immediately. In the test group, a negative correlation factor between egg color and levels of antioxidant in blood plasma of hens was reported. In the control group, there was no correlation.
“To the best of our knowledge, this is the first evidence that blue eggs are not free — there is a big price that the females are paying” said Dr. Judith Morales, but this decrease in plasma antioxidant was only measurable under conditions of distress.
The point is that the daily pressures of seeking a nest site, procuring nest materials, and laying gorgeous blue eggs (since that is the only signal that her partner appreciates anyway) is intense! Some hens just cannot handle it all! Some hens are (oxidatively) stressed out!!!