1Hi.
2Today we're going to be looking at animals in urban environments
3and I'm going to be telling you about some research on how they're affected by these environments.
4Now, in evolutionary terms,
5urban environments represent huge upheavals,
6the sorts of massive changes that usually happen over millions of years.
7And we used to think that only a few species could adapt to this new environment.
8One species which is well known as being highly adaptable is the crow,
9and there've been various studies about how they manage to learn new skills.
10Another successful species is the pigeon,
11because they're able to perch on ledges on the walls of city buildings,
12just like they once perched on cliffs by the sea.
13But in fact,
14we're now finding that these early immigrants were just the start of a more general movement of animals into cities,
15and of adaptation by these animals to city life.
16And one thing that researchers are finding especially interesting
17is the speed with which they're doing this -
18we're not talking about gradual evolution here -
19these animals are changing fast.
20Let me tell you about some of the studies that have been carried out in this area.
21So, in the University of Minnesota,
22a biologist called Emilie Snell-Rood and her colleagues
23looked at specimens of urbanised small mammals such as mice and gophers
24that had been collected in Minnesota, and that are now kept in museums there.
25And she looked at specimens that had been collected over the last hundred years,
26which is a very short time in evolutionary terms.
27And she found that during that time,
28these small mammals had experienced a jump in brain size when compared to rural mammals.
29Now, we can't be sure this means they're more intelligent,
30but since the sizes of other parts of the body didn't change,
31it does suggest that something cognitive was going on.
32And Snell-Rood thinks that this change might reflect the cognitive demands of adjusting to city life -
33having to look in different places to find food, for example,
34and coping with a whole new set of dangers.
35Then over in Germany at the Max Planck Institute,
36there's another biologist called Catarina Miranda
37who's done some experiments with blackbirds living in urban and rural areas.
38And she's been looking not at their anatomy but at their behaviour.
39So as you might expect, she's found that the urban blackbirds tend to be quite bold -
40they're prepared to face up to a lot of threats that would frighten away their country counterparts.
41But there's one type of situation that does seem to frighten the urban blackbirds,
42and that's anything new - anything they haven't experienced before.
43And if you think about it, that's quite sensible for a bird living in the city.
44Jonathan Atwell, in Indiana University,
45is looking at how a range of animals respond to urban environments.
46He's found that when they're under stress,
47their endocrine systems react by reducing the amount of hormones such as corticosterone into their blood.
48It's a sensible-seeming adaptation.
49A rat that gets scared every time a subway train rolls past won't be very successful.
50There's just one more study I'd like to mention which is by Sarah Partan and her team,
51and they've been looking at how squirrels communicate in an urban environment,
52and they've found that a routine part of their communication is carried out by waving their tails.
53You do also see this in the country, but it's much more prevalent in cities,
54possibly because it's effective in a noisy environment.
55So what are the long-term implications of this?
56One possibility is that we may see completely new species developing in cities.
57But on the other hand, it's possible that not all of these adaptations will be permanent.
58Once the animal's got accustomed to its new environment,
59it may no longer need the features it's developed.
60So, now we've had a look...