DISCLAIMER: The following is purely speculative. The opinions within are only held by me, not other smart scientists.
Take a look at the following pictures. Ask yourself, what doesn't belong?
One of these things is not like the other... One of these things just doesn't belong...
Studying conservation biology, I have to often wonder, what actually is out of place here? The bird? Or the people? The buildings? The walls and fences?
Regardless of what should or should not exist in these places, it's all been thrown together now, so what is there to do? How to react?
We often look at these 'urban birds' (I'm going to call them) and think, "Oh, great, they can live in among humans. They are everywhere on campus/in the neighborhood/in the park. They'll be just fine in the long run. These are not the species we need to be concerned with."
But is this true? Is having the ability to live within human society a good thing for an individual? for a species?
A quick google for health benefits of 'green spaces' and 'natural diets' would try to convince you that even for humans, separating yourself from the average western lifestyle improves your overall fitness and well-being. What would make us think that birds that scavenge around a park for discarded french-fries are any healthier than the people whose diet consists of these high-starch, low-protein meals.
As humans, we seem easily tricked that quantity bests quality when it comes to food. We're lured by advertisements for extra value meals, and I at least always seem to have room for the chips piled high on my plate, even when the sandwich was enough. However, eating the extra chips, in a society of excess, doesn't make me healthier.
Could this also be lowering the health of our urban birds? Not enough good stuff, like the seeds they would eat in a natural environment, to go around?
Well this may be OK if only sub-par individuals were living like this. If only individuals that didn't win the competition for the better field/garden/forest territories ended up in the trashcan at McDonald's.
But what if these urban birds, like us, are drawn like a moth to the flame? There's so much food to go around. What if they prefer the suburban lifestyle? They could stuff themselves silly on the rubbish people toss aside. Maybe the trash can at McDonald's is the preferred habitat. What if urban birds are flocking to the cities and poisoning themselves on our discards?
Well in that case we may have a problem on our hands.
At this point you should be picturing a big vortex of death with urban birds flying willing into the center.
You may be thinking, "Rach, you're nuts." Or, "What kind of bird would prefer to live in a city? This would never happen."
Enter: House Sparrow
If you know anything about birds or invasive species, you'll know that these guys are not exactly struggling in their world population. Listed as 'least concern' by the IUCN, the house sparrow has become a common resident on virtually every continent. They've been so successful in their colonization because of their omnivorous abilities and their close association to human development. Studies have even indicated that the little finches prefer suburban environments over large green spaces.
Ironically enough, their populations have started to see a major decline in the last 50 years or so. Now red-listed by the Royal Society for the Protection of Birds in their native UK, house sparrow populations have decreased by over 70% since 1977. One of the possible reasons suggested by the British Trust for Ornithology is "Reduction in the availability of favoured food."
Could the ubiquitous house sparrow be the passenger pigeon of our era? Disappearing as no one watches.
Something to ponder.
