Yearbury and then Tokoroa's Jake Wightman rounded out the top five riders on the AA course on Saturday.
In terms of the AA championship division, Buxton leads by just four points from Yearbury, with Whanganui's Seth Reardon – who finished sixth on Saturday – third overall for the series thus far, 18 points behind Yearbury.
However, with Buxton and Yearbury both now heading away to events in Romania and Austria, it puts Reardon in a good position to take over the series lead if he performs well again at Round 4, near Martinborough on June 9.
Whangamata's Jason Davis, who finished eighth on Saturday, is just one point behind Reardon in the series standings, so anything is still possible with a long way still to go before the engines are finally shut off after the final round near Hokitika on July 20.
Birch said on Saturday he had entered the Tokoroa round to have some fun.
"It's quite good that there had been a date change with the fixtures [which] allowed me to come and I only realised that last week, so it was a last-minute decision, really, to come and ride here.
"I've raced here many times in the past and I always try to come to the Tokoroa enduro events because they are just so good.
"Sean Clarke and his crew do a wonderful job of running this event.
"I had no dramas at all. I had good pace today, but nothing too crazy.
"These days I always have something or other coming up, so I don't want to injure myself. I wasn't sticking my neck out too far today.
"I got to race at Whangamata and that was good, but I was in Morocco when the Porirua event was on and I'm overseas for the rest of them too, so I won't be a national title contender this year."
Townley, who finished third at Tokoroa, likewise won't do the whole series as he is a "fair weather rider".
"I like race enduros every now and again. This is probably my one for the year. I just don't come out and ride these if it's muddy.
"The bike was awesome, a real weapon. I just put some Pirelli tyres on it, some hand guards from Yamaha and off I went.
"I mucked up a couple of special tests, and I wrecked my gear peg too, but no real moments other than that.
"Next thing for me is to do the last round of the cross-country nationals near Taupo, but I'm not a fan of racing in the winter now."
There is now a break until the fourth round of the series at Martinborough on June 9, which is followed by Bideford near Masterton on June 29.
The series will conclude with back-to-back rounds in Hokitika on July 19-20.