Nazca Booby and Siblicide: Jenner and Cuckoo.

We were fortunate enough to be in Galapagos and to be precise on Genovesa Island where two of the three main Boobies are abundant.

What I did not realise was that this Nazca Booby practices Siblicide: 

 

From Galapagos Wild Life

The Nazca booby, like its relatives, practices siblicide; however, it takes siblicide to a whole different level. While the female typically lays two eggs, the parents never raise two young. The first egg is normally laid four to nine days before the other. This asynchrony is directly proportional to the hatching asynchrony, which is among the longest of all birds. This delay is a death sentence for the second chick that hatches, as the first can easily push it out of the nest, and it does so in every case, without fail. Once outside of the nest, the parents do not acknowledge the unwanted chick and it quickly dies from either starvation, temperature change or predation.

Siblicide is not uncommon among boobies. However, blue-footed booby chicks practice what is known as facultative siblicide, in which they kill the weaker chick only if there is not enough food. On the contrary, Nazca booby siblicide is obligate and unconditional. Experts are still not certain as to the cause for this unreserved murder between siblings. It is possible that the fierce trait developed as a result of recurrent food scarcity, as by killing its weaker sibling the older chick would be entitled to all of the resources that the parents bring. On the other hand, it is possible that the siblicidal allele was developed due to some past selection pressure, such as food scarcity, and was never lost.



All Photos ©2019 Am Ang Zhang

It reminded me of Jenner and his observation of Homicide in Cuckoos:

When I visited his home in Glouscestershire, the curator of the small museum, who was extremely knowledgeable, took pride in telling us how Jenner’s great work on Cowpox vaccination upset the medical establishment on the one hand, and how his observation on the murderous ways of the Cuckoo newborns upset the gentlemanly world of the Ornithologists on the other. It was the Royal Society that awarded him a Fellowship for his keen observation.

His work on Cowpox vaccination in the prevention of Smallpox was met with hostile responses. The medical world that was dominated by London at the time could not accept that a country doctor had made such an important discovery. Jenner was publicly humiliated when he brought his findings to London. However, what he discovered could not be denied and eventually his discovery was accepted – a discovery that was to change the world.