Big Cobra at the PCN

I saw a big cobra on the PCN when I cycle this evening.  It is about 6:30pm and the sky was getting dark due to the rain.  I just cycled past the Punggol Point toward the Punggol Seafood.  The lamp position was 266.  I decided to call my friend from NParks to let her know.  I called and she pick up this time.  I sent her pictures of the location.  The cobra is the big about 6 to 7 feet long and quite thick in the body.  As I cycle past, it hurried into a hole in the grass.  This cobra can kill as it is so big.  It is puzzling how the cobra can attain such big size.  There must be enough wildlife for it to grow so big.