The Yorkshireman was England’s second-highest scorer with 52 on a day when only four batsmen got into double figures after the tourists fell for 187.
West Indies closed on 30-0 for as they look to build on last week’s emphatic first-Test win in Antigua.
“It was tough, you could see the variable bounce that we had to contend with,” said Bairstow.
“They put the ball in good areas and made us make decisions on a pitch that was probably bowler friendly, especially in the first couple of sessions this morning.
“There are two different grass types on it. On the outside where the balls were bouncing from, there’s either a ridge there or there’s something to do with the grass. There’s a few variables with that but you have to counter-act them.
“I don’t think you felt in because you always knew there was a ball in there that could bounce or keep low.
“Especially when they have three guys (bowling) there that are well over six foot. It is just a case of understanding the situation when you come in.
“When you come in at six and seven you are against an older ball. Coming in at three you have guys that are fresh with a new ball in their hand potentially, in their first spells on a pitch that is fresh.”
Bairstow believes England’s bowlers can strike back on day two, adding: “We bowled extremely well tonight. I thought we were unlucky not to get a few nicks.
“The boys put the ball in the right area and to be 30 off 21 or 22 overs is testament to the way we bowled.”
“The indecision that has been coming has been coming from that length that is slightly less full.
“You can say you should have gone fuller but at the same time I don’t think that they went overly full all the time. The ball went past the bat many times and on another day, you can nick a few of those.”