common bird, but didn’t realise there were so many types.

Adam:
I found an interesting new study on the Australian Crested Pigeon. It makes a special sound to warn the rest of the flock of danger.

Jennifer:
But a lot of birds use calls or songs to find a mate or to sound the alarm. What’s special about this one?

Adam:
Well, it uses its wings.

Jennifer:
Really?

Adam:
Yes. If the pigeon is startled, it makes a whistling sound when it flies off. This sound warns other pigeons in the flock that there’s danger.

Jennifer:
Interesting. I found a lot of stuff on the rock pigeons — they’re the ones with the widest distribution of all the pigeon species. They’ve been the most successful at adapting to different environments, haven’t they?

Adam:
In contrast to the rock pigeon, there’s a pigeon in the north of Australia, the black-banded pigeon, which is restricted to one very small patch of forest. Another interesting thing about it is that, unlike the typical pigeons we see on pavements and roads, it stays way up in the trees in the rainforest.

Jennifer:
That’s unusual.

Adam:
They’re varied in terms of diet as well. The Galapagos pigeon, for example, gets all its nutrients from this one kind of cactus that grows on the island where it lives.

Jennifer:
Really? So is there anything that pigeons can’t eat?

Adam:
Yes actually, they should stay away from meat because it contains bacteria that is dangerous to them.

Jennifer:
Oh right. You know, I thought pigeons all looked the same, but their plumage is really variable too. The Nicobar pigeon from Indonesia is very attractive — it has beautiful metallic green feathers.

Adam:
They’re not hunted.

Jennifer:
Now, in the second part of our presentation, we plan to look at why pigeons are seen as pests nowadays and what is being done to control them. A lot of people in the city like to feed pigeons, don’t they?

Adam:
Yes, some people think that it’s kind, but in fact it’s not a good idea.

Jennifer:
I suppose human food isn’t very healthy for birds, especially fast food.

Adam:
Actually, because the pigeons don’t have to spend time looking for food, they have more time to mate and reproduce.

Jennifer:
And so it results in a population explosion.

Adam:
I see. So the city becomes absolutely overrun by pigeons.

Jennifer:
That’s bad for the city and for the pigeons. Now I read that here in Melbourne we have a pigeon problem in the centre of the city and the city council is trying to deal with it.

Adam:
Yes, they’ve built some special nesting places in one of the parks in the city centre. They’re designed to house pigeons so they stop creating nests on buildings.

Jennifer:
But isn’t that just changing the location of the problem?

Adam:
Well, that’s just the first step. In the second stage of the council scheme, they exchange pigeon eggs for dummy eggs.

Jennifer:
It’s like a form of birth control.

Adam:
A very elaborate one — someone would have to go in and replace those eggs by hand.

Jennifer:
Well yes, the program does work as a means of controlling the population, but the financial burden on the taxpayer is quite high.

Adam:
Yes, I imagine it would be. The most successful pigeon control program in recent times was in Basel in Switzerland.

Jennifer:
And what did they do?

Adam:
Well, the City Council found that teaching the public about the negative effects of feeding pigeons was more effective than trapping the pigeons, or providing alternative nesting sites for them. These were both methods they had tried previously.

Jennifer:
Really? We’ll have to include that finding. Do you think we’ve got enough for our presentation, or should we do more research?

Adam:
Well, I was thinking that we should also make it clear to the audience why pigeons and cities are undesirable.

Jennifer:
Yes, we haven’t really done that yet.

Adam:
Right, I’ve got some information on the damage their droppings do to buildings.

Jennifer:
I’ve got something related to that on how their feathers can block gutters and pipes, causing water damage. But I haven’t found anything yet on the health risks to humans that urban pigeons pose.

Adam:
Neither have I. Let’s look for some information about that and add it.

Jennifer:
Okay, can we meet again tomorrow in the computer lab too?