Prior to urban development, Sydney's native bushland was populated by large numbers of small insect- eating birds,such as the superb fairy-wren and the eastern yellow robin.Today homeowners prefer to landscape their backyards with tall trees and manicured lawns,an environment that provides little protection for small birds.But one bird's trash is another's treasure. Gardens filled with flowering plants and fruit trees favour omnivorous birds such as currawongs, bowerbirds, and the city's most despised resident-the noisy miner bird.'They're a real winner in cities,'Australian Museum ornithologist Richard Major says.' The predominant driver in the decline of small birds is that we've made a suitable environment for native noisy miners.
More than half the world's human population resides in cities,and urban development continues to increase all over the world.By 2030,the United Nations projects five billion people will live in cities.Associate Professor Dieter Hochuli,a biologist at the University of Sydney,believes that we need to understand how cities are changing the ecology of the systems they are built on,and how plants and animals are adapting to them'.
While some species can survive in relatively small areas,mammals have been confined to patches of bushland scattered around Sydney and its nearby national parks. However, the rabbit-sized, long-nosed bandicoot has discovered the advantages of venturing out of Sydney Harbour National Park and into suburban gardens. 'They forage for invertebrates in the grass and like the surrounding habitat to nest and escape from predators,Catherine Price,a research associate with the University of Sydney,says. Price is trying to understand what encourages the little mammal into urban environments.' We don't know if it's an overflow from the park,or it they've got particular survival traits that allow them to evade dogs and cats, and use the urban habitat that benefits them,' she says.
The golden orb spiders in Sydney are fatter and fitter than species found elsewhere and Professor Hochuli and his team are trying to understand why. 'We're trying to determine whether it's more food or the urban heat...,as it's up to four degrees warmer in the city.'Hochuli has also found some varieties of ant more at home in the city.The green ant, known for its painful bite,will build a nest where there is space and food,regardless of whether it's a backyard or a sports oval.'It's remarkable how many things persist in city environments,' he says. The decline in birds that eat small invertebrates means these populations grow unchecked, allowing them to chew their way through the foliage of the city's trees.
Questions
1. is not clear why one small animal is moving from its natural environment.
2. Hot weather might positively affect the health of a species.
3. Sydney's residential gardens suit some species better than others.
4. Research into the natural world's responses to urban settings is vital.