More than 6,400 migratory birds and other animals were killed in Nevada by drinking water in the cyanide-laced ponds produced by gold mining operations.
If a bird drinks cyanide it will die 
cyanide is a poison, the passage says birds drinking cyanide-laced ponds died. There can be no other conclusion except cyanide kills birds if they drink it
( z1 die :ARG1 ( z2 bird ) :condition ( z3 drink :ARG0 z2 :ARG1 ( z4 cyanide ) ) )