Sightings of the Yangtze River dolphin or baiji

 

( Reuters) geographic range contraction are basic ecological characteristics of a population decline , but the investigation has been done relatively little in view of the general trend of the dynamic nature of the range of ecological collapse . Yangtze River dolphin ( The Yangtze river dolphin ) or baiji ( Lipotes vexillifer ) , perhaps the first large mammal species have become extinct more than 50 years ago , is believed to have suffered a collapse during the span of a progressive decrease through contraction on large -scale and fragmented .

Range -collapse models to analyze new data sets from 406 last baiji sighting records collected from the entire historical range of the baiji during the interview survey Yangtze fishing communities , the researchers reported in the Proceedings of the Royal Society B. Although many areas of Baiji which may vary across the range , review the extensive analysis of the series provide a comprehensive evidence that baiji population decline was not associated with a major contraction in the geographical reach of the Yangtze drainage in the middle and lower reaches of the river , even in the decade before the possibility of global extinction of species .Therefore, the risk of extinction of the baiji does not seem related to the collapse of the reach of proof . Baiji apparently experiencing periodic and seasonal movements on a large scale throughout their range , and the researchers suggest that the various contraction and fragmentation may not be related to the general biogeographic characteristics to decrease the mobility of populations of species in the landscape are connected .