RELATIONSHIPS BETWEEN FREQUENCY OF MIXED-SPECIES FLOCKS, WEATHER AND INSECT ACTIVITY IN A MONTANE CLOUD FOREST IN ECUADOR

The frequency of mixed-species flocks of birds, weather and insect act ivity were studied in a high-altitude cloud forest in Ecuador, It is g enerally accepted that participation in mixed-species flocks improves foraging efficiency If this is true, more nock activity may be expecte d when food is less available, which may happen during long-lasting pe riods of rain and otherwise adverse weather conditions, The total numb er and mean size of flying insects decreased as rainfall increased, Th e number of flocks observed increased with decreasing number and bioma ss of insects, Relatively more flocks were seen during rain than durin g dry weather. No flocks stopped foraging during rain, The flock activ ity pattern appeared to be the opposite of that found in humid lowland s, probably because of different weather regimes in the two zones, In the lowlands, heavy rain is typically of short duration, In high-altit ude cloud forest, the rainfall is often less intense but persists for prolonged periods, Hence, from an energy point of view, cloud forest b irds cannot afford to stop foraging during adverse weather conditions when insect availability is low, The results suggest that some mixed f eeding parties have evolved in response to low tropical insect availab ility, necessitating long feeding excursions outside the territory.