Osprey KL9, DAY 4

The migrant Osprey (Pandion haliaetus) marked KL9 was still at the Dos Pinos reservoir this morning, Sep 23, where I observed it from about 10:00-11:00. The bird was seen resting at various points on the upper rim of the reservoir, and made three short flights over the water without attempting to fish. Shortly before 11:00 it flew off in a northeasterly direction, eventually disappearing from sight.

The reservoir is an artificial, irrigation-water storage facility. The water is always clean due to constant refilling and distribution: it is channeled in as ground water, to be led off in various directions along pipelines for irrigating banana plantations. The result is a rather sterile concrete environment with no build-up of aquatic vegetation or algae, and scarce trophic resources for birds.

However, the site does provide a safe haven for a number of species since it is completely fenced-off with no public access. Birding is only possible from a couple of spots along its northeast flank. The inaccessible west side makes a perfect retreat for birds.

There are presently around 20 Grey Herons (Ardea cinerea) and 2 Spoonbills (Platalea leucorodia) using the site as a daytime refuge, and probably as an overnight roost. The herons and spoonbills feed elsewhere in the vicinity, in half-empty irrigation ponds with better food resources, and return to the reservoir by midday. 

Above, KL9 flies past a group of herons

Above, 2 Spoonbills among a group of herons

KL9, who originates from the north of Scotland, could possibly have adopted a similar strategy, having discovered other irrigation ponds offering larger numbers of fish, or easier conditions in which to catch them. It remains to be seen whether KL9 will be found at the Dos Pinos tomorrow morning: if not, the bird may already be heading further south.