Migratory connectivity studies can link breeding and nonbreeding grounds while illustrating potential interactions among populations that may spread diseases.
Thus, migratory connectivity studies of birds can be used to define important migratory pathways and identify the population of origin of individuals at all stages of the annual cycle (Webster et al. 2002).
"It is quiet now in terms of cases, which is contrary to what many people had expected," said Ward Hagemeijer, a bird flu specialist with Wetlands International, an environmental group based in the Netherlands that studies migratory birds.
David Melville, a New Zealand-based ornithologist not affiliated with any research institute who studies migratory bird routes in Asia, says there is now a real possibility that these birds could carry the virus to their wintering grounds in India and Bangladesh, where there are no confirmed findings of H5N1.
Due to the difficulty of tracking passerines accurately over entire migratory stages, experimental studies have not been able to reveal the consequences of maintaining constant headings through the night.
While there is still a lack of systematic monitoring of migratory flows, existing studies show that a global market for health professionals has developed, leading to a global increase of doctors and nurses migrating to other countries.
In two recent studies, migratory females had either a higher calving success than residents (in reindeers Rangifer tarandus[ 17]) or a higher fecundity and calf weight (in elk Cervus elaphus[ 18]).
While it is difficult to provide a precise picture of global migratory flows, various studies indicate a pattern that is characterized by migration from low- and middle-income countries (LMICs) to high-income countries (HICs) in North America and Western Europe (3– 6).
With limited money, Dr. Runstadler could not mount his own bird-catching efforts, but university ornithologists and dedicated amateurs who study migratory patterns run what he called "ring and fling" leg-banding operations.
Until March 24, that is, when a researcher studying migratory birds, Laura Cárdenas, caught one in a mist net, banded it and took its picture before releasing it.
