If you are interested in conservation biology or ecology, you are no doubt aware that we are currently experiencing a period of rapid, mass extinction. While extinctions have happened many times previously, their causes have been natural. In contrast, the current mass extinction is the result of human activities. With this knowledge it is impossible not to feel depressed at times. And yet I think Lindsey’s post (March 14, 2014), hit on an important, often-overlooked reason for hope: wildlife can be resilient and adaptable.
This week I would like to continue the topic Lindsey discussed. She described a pleasant hike in California through a lovely natural area adjacent to the east side of the San Francisco Bay, just west of Berkeley. As she explored further, she discovered that this biodiverse, serene area was actually sitting atop a former hazardous waste disposal site! The abundance of wildlife that had re-colonized the area was a happy ending to an unfortunate era in the region’s history.
Examples of recolonizations are popping up all over the world – often in unlikely places! I think one of the most interesting aspects of these recoveries is where they are happening: in the hearts of cities! Many cities and other urban areas have recently undertaken massive efforts to restore green spaces, through reclamation of brown field zones, vacant lots, etc. And wildlife has noticed!
I recently visited one such place – the Heinz National Wildlife Refuge, in Philadelphia. The refuge preserves the largest remaining tidal marsh in Pennsylvania, along with non-tidal wetlands, woods, and rivers. The refuge is home to a diversity of vertebrates and yet it is located in an unlikely area – adjacent to I-95, a heavily utilized railway, and beyond these, the Philadelphia International Airport! As I walked the trails that weave throughout the refuge, I saw owls, shore birds, fish, deer, and turtles. And since I study bioacoustics, I was most intrigued by the odd combination of sounds – an orchestra of traffic, plane and train noise, combined with joyful bird songs and persistent frog choruses.
Located adjacent to a trifecta of noise pollution sources (I-95, railway, and the Philadelphia International Airport!), the Heinz NWR preserves the largest remaining tidal marsh in Pennsylvania. A white-tailed deer standing beneath I-95 observes Jenny as she hikes the trails (bottom center). A passive acoustic recorder strapped to a tree allows bioacousticians to spy on wildlife – and the sounds they make – without needing to be present (bottom right).
Sounds from Heinz NWR 1
Sounds from Heinz NWR 2
Even if the green space exists, how can these animals, whose fitness rests solely on their abilities to hear each others’ mating calls, survive in such a noisy, urbanized area? I still don’t have an answer to this question. It may be that these species are not doing well at all because of the noise pollution. But perhaps the story is sunnier – maybe those that call the refuge home are somehow adapted to their noisy environment. Or perhaps these species are simply more resilient, hardier species. We can learn so much by studying species that do seemingly well in these urban landscapes and soundscapes, instead of solely focusing on the factors driving the extirpations of others. I think these urban habitats offer us incredible opportunities to explore evolution and ecology!
The Lizard Log 