.png/606px-Starling_(PSF).png "Starling")
This post was imported from my personal blog, as I make the transition to having a professional blog.
There’s an interesting news report in Environmental Science & Technology that hormone pollutants can cause birds to sing more complex songs. Where do these hormones come from? We produce them in our bodies, and we take extra hormones through various medications, and then we pee them out. They end up at the sewage treatment plant, where they’re either poured into a river or lake, or in some places they can get spread onto farm fields in solid waste (yes, using our own poo as fertilizer) or treated water (for irrigation). More importantly though, I think, are the loads of hormones we give to dairy cows, beef cattle, swine, chickens, goats, sheep, buffalo, emu, etc. We feed them hormones constantly, and those hormone supplements don’t magically disappear (they do degrade a little, but not completely). They end up coming out the other end.
What Markman and colleagues have found is that when those hormones get sucked up into worms, and then those worms get eaten by songbirds, it can cause problems for songbird populations. The lady birds looking for a babydaddy make their decisions about who to get with based partially on how well the dude can sing. A male songbird who is doing really well physically is able to turn up his hormones a bit and develop more brain capacity for song complexity. The result is that his singing prowess is normally a good indicator of how well-off he is. The study showed that worms tainted with hormones and endocrine-disruptors (hormone-like pollutants) caused male starlings to over-develop their singing skills, and now the female starlings are more likely to chose a loser to mate with, possibly someone she never would have picked if he wasn’t taking hormones. Will songbird couples around the world start having below-average babies? Or are there some ladies out there who care more about other qualities in a mate? Will we start seeing more songbirds in the coming years who don’t put so much trust in songs? (In which case, we may eventually stop calling them songbirds…) Either way, it’s creepy what kind of world you’re paying for when you buy a hamburger.
I’ve refrained from making the “canary in a coal mine” analogy, because screwing up bird populations is bad enough in-and-of itself. But, so far, we’ve noticed birds and fish having trouble with all of our hormones… what’s next?
