There are a few species though, that somehow cheated the system. The females evolved to lay their eggs in a different bird species nest. This phenomenon is called brood parasitism. They then do not have to raise their children, but leave it to another struggling mother not of her kind to do the work. The bird not only drops her eggs off into the nest, but many times also inhales the eggs of the other mothers, getting a meal in while disguising the fact that there is a new egg present. This arms race between the two species has been going on where the poor working mothers evolve ways to distinguish between the foreign egg and her own, but the parasitic birds are becoming better and better at disguising their eggs. They also have their eggs hatch slightly faster than the rest of the eggs in the nest. Therefore, they get the best treatment and first dibs at the energy of the mother as she scrounges for food to feed and raise the foreign child. There have been hypothesis that the opening of the foreign baby's mouth with its inner bright coloring is simply enough to initiate the fixed action potential of this hard working mother to feed it, even if the bird baby looks and sounds absolutely nothing like her species.
These parasitic behaviors are starting to be favored with increasing deforestation. The populations of brood parasites are increasing, which is increasing the chances that the host mother will be unfortunate enough to be caught with one. Therefore, the populations of the host birds are slowly but surely decreasing.
Posted by Abbie Saranteas
I remember learning about these birds in class. I am glad that you went into more detail about how this process is completed. I would have to say that this behavior is disturbing, but follows the "survival of the fitness" idea pretty well.
ReplyDeleteHowever, I hope that humans do not follow this part of nature.
Posted by: Em Arsenault
I find it very interesting that this species partakes in such a risky behavior, as one of their primary goals in life is to reproduce successfully and pass on their genes. What if the host realizes the chick is a fraud and chooses not to raise it? This laziness, although it conserves energy on the mother's part, seems as through it would do more harm then good. I was also wondering if this species learn songs and if so, wouldn't the foreign chick have a hard time learning it since their template would be different?
ReplyDeletePosted by Sara Corey
Thank you for your feedback Em and Sarah. Emily, I agree, this behavior does follow the "survival of the fittest" idea very well. Sarah, when comparing the costs vs benefits for the animal, it is important to realize that it is through the perspective of a certain animal. Although it will be very good for the mother to keep raising the foreign bird, it is extremely costly for the mother because the mothers goal is to pass on her genes, not the genes of other birds. Therefore, she is using her energy to pass another birds genes on, which this energy is being lost from her particular babies that have her genes. Therefore, there is no good in this situation from the mothers point of view.
ReplyDeletePosted by Abbie Saranteas
What about when the host species dies out? Won't the parasitic species then have a hard time raising their own young since the mothers are no longer suited to it? This could be interesting and may end in the extinction of both species. I want to see what happens, it's quite an experiment.
ReplyDeletePosted by Mike Selden