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Mixed flocks of the cloud forest

The forest dripped steadily following the morning’s light rain. Luxuriant mosses, bromeliads and orchids decorated the branches. Ferns and other understory plants reached into the muddy trail straining for a little more light. I was in the cloud forest of the Andes in Ecuador and had hiked for more than an hour detecting only a single bird, a small flycatcher high in the canopy. Later, an unseen bird called loudly in the distance. I was told it was a mountain toucan.

I eventually began to feel as much as hear slight high-pitched calls up ahead. Was I imagining the faint noise after so long with only the sound of drips from the vegetation? Suddenly, I was surrounded by a blizzard of swirling color, including mountain caciques, crimson-mantled woodpeckers, dusky pihas and turquoise jays. Many were high in the canopy plucking small fruits. Others were in the understory seeking insects. But the real stars were the colorful tanagers. There was the flame-faced tanager with a teal green body and a boldly marked face of orange, yellow and black. A beryl-spangled tanager landed on a rare sunlit perch with its black body heavily speckled with the most beautiful shade of blue. Next a saffron-cowled tanager came into view followed by a blue-winged mountain tanager. Then as suddenly as it had begun, silence. The flock seemed to evaporate. This is birding in the cloud forest.

In the Rogue Valley we also have mixed-species flocks cruising the forests in winter. A flock may contain more than 30 individuals. Families of golden-crowned kinglets or chestnut-backed chickadees form the core of these flocks, with a few attendant brown creepers, red-breasted nuthatches and even a Hutton’s vireo, hairy woodpecker or Townsend’s warbler on occasion.

Flocks in the cloud forest differ. They, too, often exceed 30 individuals, but there are seldom more than three or four individuals of any one species. There are no core species. Also, each flock includes many more species, sometimes more than 15, and many of these are stunning tanagers.

Flocks in both places maintain integrity with the same soft, high-pitched calls. High frequency sounds travel a relatively short distance before being absorbed by the vegetation. This makes it difficult for a forest hawk to detect the flock.

I understand flocks in the cloud forest persist year round. It leaves me wondering how the birds rear young. Nests are in a fixed place but not flocks. Does a pair temporarily abandon the flock while caring for young, or do they commute to and from the flock? If so, how do they relocate the roving group? So many questions.

I tallied 47 species of tanagers while in Ecuador, most a dazzling mix of bright colors. Oregon supports a single species of tanager, the western tanager. I recall many times the intake of breath and exclamations of beauty as a student encountered their first male tanager. With its bright yellow body, bold orange head and black wings and tail that accent the colors, it would fit right in with a flock of cloud forest birds. If our lone tanager leaves you wanting more, grab your binoculars and head for the mountains of Ecuador for a real treat.

Stewart Janes is a biology professor at Southern Oregon University. He can be reached at janes@sou.edu.

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