| Hi. |
| Today we're going to be looking at animals in urban environments |
| and I'm going to be telling you about some research on how they're affected by these environments. |
| Now, in evolutionary terms, |
| urban environments represent huge upheavals, |
| the sorts of massive changes that usually happen over millions of years. |
| And we used to think that only a few species could adapt to this new environment. |
| One species which is well known as being highly adaptable is the crow, |
| and there've been various studies about how they manage to learn new skills. |
| Another successful species is the pigeon, |
| because they're able to perch on ledges on the walls of city buildings, |
| just like they once perched on cliffs by the sea. |
| But in fact, |
| we're now finding that these early immigrants were just the start of a more general movement of animals into cities, |
| and of adaptation by these animals to city life. |
| And one thing that researchers are finding especially interesting |
| is the speed with which they're doing this - |
| we're not talking about gradual evolution here - |
| these animals are changing fast. |
| Let me tell you about some of the studies that have been carried out in this area. |
| So, in the University of Minnesota, |
| a biologist called Emilie Snell-Rood and her colleagues |
| looked at specimens of urbanised small mammals such as mice and gophers |
| that had been collected in Minnesota, and that are now kept in museums there. |
| And she looked at specimens that had been collected over the last hundred years, |
| which is a very short time in evolutionary terms. |
| And she found that during that time, |
| these small mammals had experienced a jump in brain size when compared to rural mammals. |
| Now, we can't be sure this means they're more intelligent, |
| but since the sizes of other parts of the body didn't change, |
| it does suggest that something cognitive was going on. |
| And Snell-Rood thinks that this change might reflect the cognitive demands of adjusting to city life - |
| having to look in different places to find food, for example, |
| and coping with a whole new set of dangers. |
| Then over in Germany at the Max Planck Institute, |
| there's another biologist called Catarina Miranda |
| who's done some experiments with blackbirds living in urban and rural areas. |
| And she's been looking not at their anatomy but at their behaviour. |
| So as you might expect, she's found that the urban blackbirds tend to be quite bold - |
| they're prepared to face up to a lot of threats that would frighten away their country counterparts. |
| But there's one type of situation that does seem to frighten the urban blackbirds, |
| and that's anything new - anything they haven't experienced before. |
| And if you think about it, that's quite sensible for a bird living in the city. |
| Jonathan Atwell, in Indiana University, |
| is looking at how a range of animals respond to urban environments. |
| He's found that when they're under stress, |
| their endocrine systems react by reducing the amount of hormones such as corticosterone into their blood. |
| It's a sensible-seeming adaptation. |
| A rat that gets scared every time a subway train rolls past won't be very successful. |
| There's just one more study I'd like to mention which is by Sarah Partan and her team, |
| and they've been looking at how squirrels communicate in an urban environment, |
| and they've found that a routine part of their communication is carried out by waving their tails. |
| You do also see this in the country, but it's much more prevalent in cities, |
| possibly because it's effective in a noisy environment. |
| So what are the long-term implications of this? |
| One possibility is that we may see completely new species developing in cities. |
| But on the other hand, it's possible that not all of these adaptations will be permanent. |
| Once the animal's got accustomed to its new environment, |
| it may no longer need the features it's developed. |
| So, now we've had a look... |