From the BBC:
5 August 2013 Last updated at 16:52 GMT
A pair of swallows have raised four chicks in a nest built in the roof of a Land Rover at a Norfolk nature reserve.
The mud and twig nest was created in the roof of the Pensthorpe Nature Reserve vehicle, used to carry visitors around the 800-acre (324 hectare) site.
Warden Darren Williams, 45, said he felt like a “surrogate father” and was convinced the “hot air” from his tour commentary helped incubate the eggs.
Two chicks fledged on Sunday and now follow the vehicle around the reserve.
The other two chicks remain in the nest at the reserve in the Wensum valley, which hosted the BBC’s Springwatch programme for three years.
Mr Williams said: “Two of them fledged yesterday, but they’re still hanging around because as far as the birds are concerned the back of the Land Rover is home.
“I feel like a surrogate father and I’m sure all the hot air from my tour patter was keeping them warm.
“The nest is just on top of a speaker and we’ve rigged up a swallow hammock from a little bit of netting in case they fell out as we bounced over the rough terrain.”
The nest was initially removed from the vehicle to discourage the birds nesting so close to the public, but the adult swallows began to build again as soon as it was removed.
Mr Williams said: “This is uncharted territory for us.
“Initially we were concerned the birds might not incubate the eggs as they’d be scared off by our passengers, but they insisted on building the nest and there was little we could do about it.
“With a nest comes the added chore of cleaning up after the babies, but the passengers have just been enamoured with them.
“It’s very unusual to be able get that close to them in the wild.”
More about swallows
Swallows are migratory and flock in large numbers in September ready to fly to Africa, south of the Sahara
In early April, they return to the UK often roosting communally in reed beds
Agile in flight, they are insectivorous, plucking insects from the air
To rehydrate while flying they skim the surface of a body of water
Source: BBC Nature