Indeed for the Sydney market, CoreLogic's head of research Tim Lawless called first home buyers the "bright spark."

"First home buyers are probably the bright spark here, and potentially are one of the factors that could be driving the market place going forward," Mr Lawless told a CEDA event this week.

"Better affordability, the fact that we are still seeing mortgages very low and a build up in pent-up demand for first home buyers is probably one of the factors supporting values around that lower end of the marketplace."

CBA senior economist Belinda Allen said rising vacancies in Sydney resulted in falling rents.

“We’ve certainly seen a pick up in rental vacancies in Sydney and as a result we have seen rents start to retreat in Sydney as well."

Ms Allen said the RBA had concerns that an influx of apartments would hit the Sydney market over the next 12 months, which could drive rents down further and send vacancy rates higher.

The quiet month

April is traditionally one of the quietest months for new rental listings and historically overall rental listings are 8 per cent lower in the month. This is primarily due to cyclical factors as the rental market cools down in the wake of a busy December-January period.

“I guess what’s more surprising about the April results for cities like Brisbane, Perth and Hobart, where vacancy rates have been tightening, is that we’ve sort of got this jump in the level of rental supply," Ms Owen said.

Vacancy rates in Brisbane rose to 2.6 per cent from 2.1 per cent in March this year, while rates in Perth hit 3.2 per cent, up from 2.6 per cent in March.

Of the vacancies on the market in April, only only 23.3 per cent of them came to market in that month, with the remaining 76.7 per cent rolled over from the previous month. This suggested slower leasing activity, perhaps due to an extended run of public holidays with ANZAC day and Easter linking up this year, Ms Owen said.