Commercial vacancies declined in Boston in the first quaerter of the year, with absorption of 800,000 square feet dropping the rate 0.3 percent to 16.9 percent from 17.2 percent, according to a new report from commercial brokerage Colliers International.

The first quarter represents the eighth consecutive quarter of positive absorption in the Boston market. The downtown submarket was the tightest space in the city, with a 12.7 percent vacancy rate at year-end. The Financial District was primarily responsible for the solid results with 278,000 square feet of positive absorption, followed by the Seaport at 125,000 square feet.

According to the report, the steady performance in the Boston and Cambridge submarkets is being fueled primarily by small- to mid-sized firms, leasing activity in the suburban markets represented a broad range of industries and sizes.

The overall vacancy rate in the Cambridge office and lab markets dropped to 8.9 percent during the quarter, with over 300,000 square feet of positive absorption.  After a statistically flat 2012, the office market tightened even further and accounted for nearly half of the positive absorption.

The suburban markets report a 20 percent vacancy rate and positive absorption for the quarter of nearly 200,000 square feet. Results were mixed across the submarkets, but there have been more suburban companies expanding and relocating than was evident 12 months ago. Overall, activity in the leasing markets is brisk and momentum is generally positive.