Only 9 per cent of migratory birds have adequately protected habitat across their range, a new study has found.
The findings, reported today in the journal Science, help explain why migratory bird numbers are declining despite global efforts to protect them, said researchers who are calling for a greater focus on the needs of migratory species in global conservation planning.
"Migratory species rely on a chain of good quality habitat all the way along their migratory route," said senior author Associate Professor Richard Fuller, a biologist from the University of Queensland.
"If links in that chain are not well protected then some species might not be able to complete their lifecycle."
Migratory birds travel over vast distances each year.
"Some migratory birds are flying to the distance to the Moon and back - not once, not twice, but three times during the course of their life," Dr Fuller said.
He said migration enabled the birds to find the best seasonal feeding and breeding places, and places to fuel up for their journey along the way.
"Often young birds only eat certain types of food and their parents need to be in particular places at the right time to get that food."
Dr Fuller and his colleagues, including PhD student Claire Runge, looked at how well the needs of the world's 1451 species of migratory birds are covered by protected areas.
The researchers collected information on the movement of all migratory birds species at different times of the year, and compared this with maps of protect areas, such as national parks, in different habitat types, including wetlands, Arctic tundra, desert environments, savannas and forests.
"We overlaid those two things on top of each other and asked how well protected each migratory species was across its whole annual cycle," Dr Fuller said.
"We found that more than 90 per cent of species have one or more parts of their lifecycle poorly protected."
For example, the bar-tailed godwit breeds in Alaska, flies across the Pacific to Australia, then north through the Yellow Sea back up to the Arctic, travelling over 10,000 kilometres in one go.
The researchers found that while there was adequate protection of its breeding habitat, the bar-tailed godwit has suffered a loss of intertidal habitats, which it needs for stopovers to fuel its migration.
Evidence suggests this is mainly because of land reclamation activities in the Yellow Sea for urban, industrial and agricultural expansion, the researchers said.
"Migratory bird species are slipping through the net in various countries all around the world and the maps in our paper point to where some of those gaps might be," Dr Fuller said.
Dr Fuller said only 3 per cent of threatened migratory species - those on the verge of extinction - have adequately protected habitat.
"One might hope that they're better protected than non-threatened species," he said. "That turns out sadly not to be true for migratory species."
By comparison, the researchers found 45 per cent of non-migratory birds were protected.