Binance was the first to tweet a reduction of bitcoin withdrawal fees by 50% today at 10:00AM on the 1st of March;
#Binance is happy to announce a 50% reduction in $BTC withdrawal fees. Effective immediately, BTC withdrawal fees are only 0.0005 BTC!
On the same day kraken a few hours later tweeted;
Effective immediately, withdrawal fees on Bitcoin (XBT) are reduced to 0.0005, and withdrawal fees on Bitcoin Cash (BCH) are reduced to 0.0001.
This could be because of competition with each other exchanges, both enabling batching of bitcoin transactions and the recent huge drop in bitcoin fees because of Segwit and less load .