Definition: Generate an appropriate title for the given text. The generated title must be short and include the main topic of the text. The preferred titles are under fifteen words.
Input: It is thought the larger number roosting at Ham Wall nature reserve could be due to colder weather in Russia. Tony Whitehead, from the Royal Society for the Protection of Birds (RSPB) said the number of birds was a record. It is thought the birds group together to deter predators and keep warm. The RSPB said the starling population had fallen by over 80% in recent years and the birds were on the critical list of UK birds most at risk. It believes the decline is caused by the loss of permanent pasture, increased use of farm chemicals and a shortage of food and nesting sites in many parts of the country.

Record starling mumuration on Somerset Levels