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TPO 3 Lecture 1 Environmentalscience
Narrator: Listen to part of a lecture in an environmental science class.
Professor:Now, we've been talking about the loss of animal habitat from housing developments, uh …, growing cities – small habitatlosses. But today I wanna begin talking about what happens when habitat is reduced across a large area. There are, of course,animal species that require large areas of habitat, and some migrate over very long distances. So what's the impact ofhabitat loss on those animals – animals that need large areas of habitat? Well, I'll use the humming birds as an example.Now you know a humming bird is amazingly small, but even though it's really tiny, it migrates over very long distances,travels up and down the western hemisphere – the Americas, back and forth between where it breeds in the summer and thewarmer climates where it's spent the winter. So you would say that this whole area over which it migrates is its habitatbecause on this longdistance journey, it needs to come down to feed and sleep every so often, right? Well, the humming birdbeats its wings – get this – about 3 thousand times per minute. So you think, wow, it must need a lot of energy, a lot of food,right? Well, it does. It drinks a lot of nectar from flowers and feeds on some insects, but it's energyefficient too. You can'tsay it isn't. I mean, as it flies all the way across the Mexico Gulf, it uses up none of its body fat. But that doesn't mean itdoesn't need to eat. So humming birds have to rely on plants in their natural habitat. And it goes without saying, but theopposite is true as well, plants depend on humming birds too. There are some flowers that can only be pollinated by thehumming birds. Without its stopping to feed and spread pollen from flower to flower, these plants would cease to exist. Butthe problem, well, as natural habitat along these migration routes is developed by humans for housing or agriculture orcleared for raising cattle, for instance, there is less food available for migrating humming birds. Their nesting sites areaffected too, the same by the same sorts of human activities. And all of these activities pose a real threat to the hummingbird population. So help them survive, we need to preserve their habitats. And one of the concrete ways people have beendoing this is by cleaning up polluted habitat areas and then replanting flowers, um, replanting native flowers that hummingbirds feed on. Promoting ecological tourism is another way to help save their habitat. As the number of visitors, eco-touristswho come to humming bird habitats to watch the birds, the more the number of visitors grows, the more local businesses'profit, so ecological tourism can bring financial rewards, all the more reason to value these beautiful little creatures in theirhabitat, right? But to understand more about how to protect them to support the humming birds the best we can, we've gotto learn more about their breeding, nesting sites and migration routes, and also about the natural habitats we find there. Thatjust helps us determine how to prevent further decline in the population. A good research method, a good way to learn more,is by running a banding study. Banding the birds allows us to track them over their lifetime. It's been a practice that's beenused by researchers for years. In fact, most of what we've known about humming birds comes from banding studies, wherewe capture a humming bird and make sure all the information about it, like its weight and age and length, are all recordedand put into an international information database. And then we place an extremely lightweight band on one of its legs, well,what looks like a leg, although technically it's considered part of the bird's foot. Anyway, these bands are perfectly safe,and some humming birds have worn them for years with no evidence of any problems. The band is labeled with trackingnumber, oh, and there is a phone number on the band for people to call for free, to report a banded bird to be found orrecaptured. So when a banded bird is recaptured and reported, we learn about its migration route, its growth, and how longit has been alive, its lifespan. One recaptured bird was banded almost 12 years earlier – she was one of the oldest hummingbirds on record. Another interesting thing we learned is that some humming birds no longer use a certain route. They travel by a different route to reach their destination. And findings like these have been of interest to biologists and environmentalscientists in a number of countries who are trying to understand the complexities of how changes in a habitat affect thespecies in it.
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