http://news.bbc.co.uk/2/hi/science/nature/3621605.stm
Wednesday, 14 April, 2004, 10:01 GMT 11:01 UK
Nasa helps its feathered friends
By Alex Kirby
BBC News Online environment correspondent
US ornithologists have begun working with the American space agency
Nasa to study bird migration in greater detail.
The Nature Conservancy is paying for the use of one of the agency's
hi-tech radars, which allows it to follow the movements of neotropical
songbirds.
The radar, sited on the western shore of Chesapeake Bay in Virginia, is
one of only two in the whole of the US.
The conservancy says the work will help it to identify vital feeding
areas on the birds' southerly migration routes.
Weather studies
Barry Truitt of the conservancy said radar ornithology began almost 60
years ago, but took off in the US only with the use of "nexrad" systems
- next generation weather surveillance radars.
The system Nasa is renting to the conservancy is a polymetric radar,
used normally to study rainfall.
Barry Truitt told BBC News Online: "They were explaining to me the
physics of a falling raindrop, and how this radar let them look at it
horizontally, vertically, from above and from below, and even determine
the size of it.
"So I asked whether they could see birds with it. And they said: 'Oh
sure, but we turn on all these filters to get rid of the birds'. And I
said: 'Well, can you turn the filters off?' They said: 'Yeah, no
problem'.
"Now Nasa collects rainfall data when it's raining, and I get access to
the radar when it's not. This is really pioneering work."
High mortality
The neotropical songbirds hatch in Canada and the north-eastern US and
winter in the Caribbean, central and South America. They use the area
around Chesapeake Bay as a staging post, and the radar is revealing the
flightpaths and the feeding sites they use.
Mr Truitt said: "Work's been done on where they breed and where they
winter, but this is the first study on a landscape scale of an area
they migrate through.
"Apart from something like 10-12 million short-distance migrants, it's
estimated 5-6 million neotropical birds go through here, and 80% of the
young of each year die on their first migration.
"If the habitat isn't there for the survivors to replenish their fat
reserves, they won't have the energy to go any further."
Unidentifiable flying objects
Barry Truitt said the information the conservancy is gaining from using
Nasa's radar would enable it to help the migrants.
He said: "It will help us to identify what habitats they're using, and
to prioritise how we spend our money, for instance what kinds of trees
we should be protecting.
"But there's still a problem with calibrating the data. Radar data is
no good without verification.
"You have to have someone out there on the ground who can tell you
these really are birds, and not insects for instance - dragonflies show
up on the radar just like birds."
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