The aerodynamics and energetics of two large raptors are studied experimentally in free forward flight mode. A great horned owl and a Harris’s hawk were trained to fly in a wind tunnel. A perch-to-perch flight was chosen and multiple flights were conducted. The velocity fields behind the flapping wing of the birds were sampled around the midspan location using time-resolved PIV and the birds’ kinematics were measured using high-speed imaging, simultaneously. From the velocity fields, the lift and drag coefficients have been estimated using the momentum equations. Results show that the lift and drag characteristics of the two birds vary significantly. The owl exhibits higher lift variations over the wingbeat cycle compared to the hawk. These variations are essential for weight support while flying at low speeds. The hawk drag coefficient was ~2 times lower than the owl as the hawk is a high-speed flier. While the steady drag of the owl is positive throughout the wingbeat, negative values over the wingbeat cycle have been observed for the hawk, indicative of efficient flapping mode. Using the experimental data, the energy requirements during flight were estimated for two cases: i) aerodynamic power output during flapping flight and ii) power expenditure in intermittent flight. The owl was 30% heavier and its flight speed owas 20% lower than the hawk. Results show that the aerodynamic power output of the owl is higher than the hawk over the wingbeat cycle. But the estimated specific-power and work done by the flight muscles are lower for the owl. Power expenditure results show that the intermittent flight pattern yields moderate saving of aerodynamic energy requirements and minimizes the total power output for both birds. Yet, the results of the owl show relatively higher benefits from the intermittent flight.