Hummingbirds and mountain goldenbean in summer

The high meadows around Gunnison hold the longest light of the year. At eight thousand feet, the sun lingers past eight in the evening, and the mountain goldenbean stands tall in the brightness, its yellow flower spikes catching the late rays. If you are walking here now, you are stepping into the peak of the mountain summer, when nectar flows most freely and the air hums with wings.

The broad-tailed hummingbird works these flowers with methodical precision. The male hovers at each bloom cluster, his throat flashing ruby when the light hits it right. Mountain goldenbean grows in dense stands, sometimes covering entire slopes, and each plant sends up multiple flower spikes that open from bottom to top over several weeks. The hummingbird follows this progression, returning to the same plants as new flowers open higher on the stem. His wings beat fifty times per second, creating the high metallic trill that gives him his name. That sound is not a call but the air moving through his specialized outer wing feathers.

This partnership runs deeper than a simple exchange of nectar for pollination. Mountain goldenbean blooms precisely when broad-tailed hummingbirds are feeding their second broods of the season. The female builds her nest in late June, lays two white eggs the size of navy beans, and incubates them for sixteen days while the male defends his territory. The chicks hatch blind and featherless, requiring constant feeding for three weeks. During this intensive period, the mountain goldenbean reaches full bloom, providing a reliable nectar source within the male's defended territory. The plant produces nectar most abundantly in early morning and late afternoon, matching the hummingbird's feeding schedule around the heat of midday. Each flower spike can support a hummingbird for several minutes of feeding, long enough for the bird to transfer pollen between plants as it moves through the meadow.

The mountain goldenbean depends on this relationship as much as the hummingbird does. The plant's flowers are perfectly sized for the hummingbird's bill and positioned to dust pollen onto the bird's head and throat as it feeds. Other pollinators visit these flowers, including bees and butterflies, but the hummingbird's constant movement between widely scattered plants ensures genetic mixing across the meadow. The seeds that result from this cross-pollination will germinate after the snowmelt next spring, when the cycle begins again. Listen now for that metallic wing trill in the distance. The broad-tailed hummingbird may be working a patch of goldenbean just upslope from where you stand, following the nectar from flower to flower in the long mountain light.