Hunting patterns and success of an osprey (Pandion haliaetus) population at Magdalena Bay, Baja California Sur, Mexico

Abstract

In late autumn 2004 we studied the effect of water surface condition, wind speed, and tidal status on the hunting patterns (flapping, gliding, hovering) and hunting success of the osprey population at Magdalena Bay, Baja California Sur, Mexico. Through focal sightings we obtained the number of hunting dives, hunting length, and the proportion of hunting length invested in each pattern. Hunting success was 61%. Ospreys required an average of 2.4 dives to catch a prey. Hunting lasted 450 seconds on average, with about 50% of this time invested in flapping, 41% in gliding, and 7% in hovering. The average number of dives to catch a prey varied according to the different water surface conditions, wind speed, and tidal status. The probability of catching a prey decreased when wind speed increased and the condition of the water surface deteriorated; however, hunting length was similar in both cases. Ospreys at Magdalena Bay decrease the proportion of flapping and increase gliding when wind speed increases and the condition of the water surface changes from calm to choppy. The change from low to high tide favored an increase in the probability of catching a prey and in the number of dives, but hunting length was not affected. We compared our results with studies from other regions.