A slight dip in year-over-year May hotel occupancy in Greater Boston was more than offset by gains in average daily room rates (ADR) and revenue per available room (RevPAR) during the month, continuing a strong spring for the area’s hoteliers.

The 78 hotel operators in the PKF Trends sample for the Greater Boston area achieved an average 81.6 percent occupancy at a $191.04 ADR, with a resulting $155.96 RevPAR. These performance levels represented a 0.8 percent occupancy loss, 2.6 percent boost in AD and an overall 1.9 percent rise in RevPAR for May 2011 compared to May 2010, according to a report from Boston-based hotel industry tracker PKF Consulting USA.

The four Boston submarkets of Back Bay, Downtown, Cambridge and Route 128 all achieved occupancies of over 80 percent in May. According to Back Bay-area lodging managers, smaller citywide groups in May this year compared to last, with lower peak room nights, contributed to a decrease in overall occupancy for the submarket for the month of May compared to the same month last year.

The hotels along Route 495 South achieved the greatest percentage increase in occupancy of 11.7 percent, but also started at a much lower baseline with occupancy rates in the mid-50 percent range. For this submarket, area lodging managers reported a pickup in corporate business, more vacation travel and compression from the Boston hotels to be driving their May increases in occupancy.