Ben Whiteman slotted home from close range in the 94th minute to earn a point for Rovers and continue the impressive run of form which has seen them climb to 11th in League One.
Rovers had looked set to come away empty-handed after struggling to break down a resolute Peterborough side who went ahead on 14 minutes through Danny Lloyd.
But the persistence paid off, to Ferguson's delight.
He said: "We're not getting overexcited by the fact that we've got a point but when you equalise in the 94th minute you take it obviously."
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"I'm just pleased with the performance. It was really good.
"It was quite open but I didn't mind that because I thought if we were good on the ball then we'd cause them problems.
"The players showed great character again.
"We've had a really good Christmas with ten points out of 12 games from some tough games.
"Mentally the players have been very good and they just kept going until we got the wee break."