According to the annual ‘State of the Birds’ report recently released by the US Interior Department, the condition of the country’s migratory birds, which are already facing a threat from environmental factors, has become increasingly disquieting due to the changes in global climate.

The report, which indicates that climate changes are taking their toll on the migratory birds, shows that almost one-third of the 800 bird species in the US fall in the category of endangered, threatened or experiencing population decline.

Adding climate change to the list of factors – like damaged habitats, pesticides, hunting, invasive species and loss of wetlands - that threaten bird population, the Interior Department report notes that the birds most exposed to the risks of climate change include oceanic and shore birds, who are combating the fast-changing marine ecosystems as well as the ever-rising sea levels.

Meanwhile, in a related study pertaining to affect of climate change on birds, researchers – including Dr Josh Van Buskirk of the University of Zurich, Switzerland, and colleagues Robert Mulvihill and Robert Leberman of the Carnegie Museum of Natural History in Rector, Pennsylvania, US – the songbirds in the US are shrinking in size.

The study, which observed nearly half a million birds, from over 100 species, found that within the last five decades many of the country’s songbirds have gradually become lighter, and have started growing shorter wings, because of warmer temperatures.