DemographicsBirchs Bay is approximately 7.99 square kilometres. In 2016 the population of Birchs Bay was 93. The population is 53% male and 47% female. On average the monthly mortgage repayments in Birchs Bay are $0 to $299. The most common weekly income bracket is $300 to $399 per week. Weekly rents in the area are on average $0 to $74.