Example of a Lack of Brain Wiring: Large Bird Chicks on Island let Mice Kill them

Apr 14, 2007 at 2:16 PM
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"Hordes of giant mice are devouring endangered seabird chicks on a remote South Atlantic island and may be pushing some of the birds to extinction, scientists report." This is the lead-in to a news report by National Geographic.

For me what is amazing is that these bird chicks which are still a lot larger than the mice let the mice attack and eat them without fighting back. Their brains just are not wired to give a defensive response to animals that are small and non-bird like.

These mice are also in the process of evolving larger sizes in order to become better preditors. So we see early stage evolution at work.

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Fascinating. Though, I do pity the birds.

This is actually not the first time something like this has happened...

over the centuries, homo sapiens has been responsible for extinctions of mammals quite larger than them. In fact, there is convincing evidence that homo sapiens is responsible for the mass extinction of 57 large mammalian species on the north american continent 12,000 to 10,000 years ago. (Why am I talking about humans? Because the extinction of large mammals by them is analagous to the killing of larger seabird chicks by mice). Why did these large mammals allow themselves to be killed? Because they had not been coevolving with humans (being relatively isolated before a migration of humans over from asia to north america and ensuing population expansion), and so, did not have an innate fear of humans as a predator. There were no analagous extinctions in Africa or Asia at this time, ruling out the hypothesis that climate change was the reason for the extinctions, and also being explained by the fact that humans had been coevolving with the large mammals there for thousands of years. Similarly to the isolation of species on N. America, an island is a situation where you can have species that have been isolated from other species and when you introduce a predator, they might not recognize the new animal to be a predator. Species can literally be slaughtered to extinction. And if its something like large mice-- rats have been responsible for the many extinctions of birds and reptiles on whatever island or new land that they have been introduced to. They specifically eat the eggs and the young, and the prey species, having no innate fear from many hundreds to thousands of years of coevolution, are quite defenseless.

I got my information from Chapter 10, Human Impacts of the past, from the 6th extinction--patterns of life and the future of humankind, by richard leakey and roger lewin. Haven't read the whole book but bet it would be a fascinating read.

[this is good]

Relatedly, In many species this sort of behavior is often the result of a parasite. For example, in rats (or maybe it's mice, I can't remember) there is a parasite that will cause them to be extra "brave" and subsecquently easier for cats to catch them. The reason? The parasite wants to be inside the cat, and this is its way of getting there.