Wednesday, 4 April 2012
Globe trotting birds
Once again I find myself off jet-setting, this has been quite a big year for it. This time to England to attend the conference of the British Ornithologists' Union. I've been in the UK a few weeks now, having a long overdue catch up with some friends, and plugging away at the PhD thesis. A few milestones were met last week, I finished the first draft of my final data chapter, and the first publication to come out of my PhD "Arboreal arthropod sampling methods for urban trees" is now available online with the Journal of Insect Conservation.
Naturally, it wasn't long after arriving in London before I was checking out the local avifauna. Given the paucity of bird habitat in highly developed areas, such as central London, features that may seem fairly 'rubbishy' habitat can play an important role in maintaining at least some biodiversity. Hence the vegetated railway-side vegetation provided a few opportunities for getting my bird geek on and spotting a few of the feathered locals (train-spotting?) on my way out of London. A few pigeons, some sparrows, chaffinches, blackbirds, starlings, thrushes, dunnocks... wait a minute... looks I'm not the only one who's been doing some jet-setting. In the past year I've been lucky enough to travel in both islands of New Zealand, Australia, southern Africa (SA and Namibia), and now England. In the towns and cities in all these areas, spanning three continents, there is a high degree of overlap in the bird communities. So what's the story?
This 'biotic homogenisation' is one of the byproducts of urban development. Worldwide, local species suffer from high rates of localised extinctions in urban areas, while concurrently cosmopolitan species, such as pigeons and sparrows move in. The precise details behind this shift remain unclear, as so many aspects of the environment are modified by urbanisation, at scales ranging from soil microbial activity right through to wholesale atmospheric and temperature changes. I'll save going into these in more detail for another post though. So should we be concerned about this biotic homogenisation? I argue yes, for several reasons, two of which I'll outline briefly.
First is species conservation. As the area of urbanisation spreads through urban sprawl, species of conservation concern are increasingly found in towns and cities. In such situations, there is the danger that what may have been a localised extinction could potentially become a total extinction. This is further exacerbated by the fact that urban centres tend to occur in biological hotspots, such as river mouths and estuaries (again, think London), largely due to historic trade reasons.
Second is national identity. The avifauna of an area is one of its most visual and defining characteristics. Coincidently, I've just come from a lecture on the cultural value of Polish 'stork villages', where people travel from miles around to visit small villages, where the rooftop nesting storks can outnumber the human inhabitants. As a New Zealander travelling overseas, perhaps being known around the world colloquially as a 'kiwi' means this relationship between avifauna and national identity is particularly pertinent to me right now.
So how do we go about reversing this biotic homogenisation? That's the six million dollar question. If anyone has a quick and easy solution, do let me know. In the meantime, I'll keep plugging away on my research on how urban tree-scaping may play a role.
City birds... an urbanised ibis, a photograph instantly recognisable as Australian.