 The Zapata rail is restricted to a single area , with an extent of about 1 @,@ 000 km2 ( 400 mi2 ) , and its small population , estimated on the basis of recent surveys and local assessments of population densities at between 250 – 1 @,@ 000 individuals , is assessed as decreasing . In the past , grass @-@ cutting for roof thatch was a cause of extensive loss of breeding habitat , and habitat loss through dry @-@ season burning of the vegetation continues . Predation by introduced small Asian mongooses and rats is a problem and , more recently , introduced African sharptooth catfish ( Clarias gariepinus ) have been identified as major predators of rail chicks . 
