The bird population along the Mura, Drava and Danube rivers has been stabilised to some extent in the last ten years, however, a long-term falling trend in bird numbers is noticeable, especially when it comes to the sand martin, a migratory passerine bird in the swallow family, whose population has been reduced by 75% over the last 30 years, according to estimates of the World Wide Fund for Nature and the "Drava" nature society.
The World Wide Fund for Nature and the Viirovitica-headquartered society have launched the monitoring of 12 species, including the sand martin, the delichon, the European bee-eater, the river kingfish, three types of terns, the killdeer, the black stork, and the white-tailed sea-eagle.
The WWF Adria organisation says awareness should be raised about the bird populations in the basins of the three rivers.
The Drava is known as home to many bird species, while the Mura can be hit by any loss as this basin is not so rich in bird species, according to those organisations.
The sand martin is listed among vulnerable avian species in Croatia. The monitoring from 2005 to 2016 has shown that their number in Croatia slid from 12,232 to 7,444.