Decline in Number of Toucans Affecting Brazilian Forests

You read that right: the decline in the number of toucans is affecting the composition of Brazilian forests. It probably wouldn't surprise anyone if there were a report that the decline in forested areas was having a negative impact on wildlife, which I suspect is true.

But in this case, a reduction in the toucan population is actually having an effect on the types of palm tree (juçara) that grow in Brazil. According to a report from NPR, here is what's happening. 

Toucans, because of their large bills, are able to eat large seeds from palm trees that produce them. They then disperse these seeds when they defecate, which allows palm trees with larger seeds to continue to flourish. 

With the decline in the number of toucans, there has been a relative increase in the number of palm tress which produce smaller seeds, compared to those which produce larger seeds. This is because smaller birds are able to eat the smaller seeds, so the trees with smaller seeds are continuing to propagate. In fact, palms with smaller seeds are starting to dominate the forest.

In other words, the decline in the toucan population is leading to a decline in the population of palm trees which have large seeds. 

OK, that's interesting, but.....who cares, and why does this matter?

According to the article, here's why it matters:

"it turns out that smaller seeds aren't so good. They dry up and die faster than big ones in hot, dry weather. And scientists predict that climate change will make parts of Brazil hotter and drier, so much so that the juçara may not survive."

It's easy to dismiss environmentalists as "tree huggers" or as idealists who care more about some obscure form of plant or animal than they do about human beings. After all, if humans never altered the environment to develop the land and build structures, we'd all be living in the wilderness. But at the very least, we should be aware of the harm that our development may be causing. 

This is a cautionary reminder of what can happen as we clear the land and its wildlife in order to develop it for human habitation and promote economic growth. 

As the article states:

"in this case, humans actually altered the genetic makeup of a wild palm tree population — in just a century, indirectly, and by accident." 

The take-away is that there are both expected and unexpected consequences to all of our actions, and in some cases, by the time we're aware of what those consequences are, it may be too late to do anything about it.

Update June 1:

Estadão has published an article (in Portuguese) which describes the issue in greater detail. The original article is from the magazine Science, but the full content is only available online to paid subscribers.