On The Trails: Ducks, midges, and flowers

A bumblebee buzzes pollen from a shooting star. (Photo by Bob Armstrong)

By Mary F. Willson

The first little mallard ducklings have been appearing on ponds around town. They are tiny and downy, trailing along with their mother. An important food is the larvae of chironomid midges. That group of aquatic insects contains thousands of species (hundreds in Alaska) and provides a much-used source of food for lots of birds, fish, and invertebrates. The short-lived adult midges of this type don’t bite humans or other animals to feed on blood; they may sip on nectar, honeydew excreted by aphids, and other sugary sources.

All those well-fed ducklings had a lucky mother, who managed to raise her clutch successfully. While those little families are cruising around, other, less lucky females come to my home pond, usually in afternoons or evenings, to get started on a replacement clutch. Although in the mornings, there may be two or three male mallards out there, by afternoon, there is only one, who waits for arriving females, who somehow know where to come. 

Mallards lay large clutches of eggs — up to 13 or so, laying one egg a day; incubation takes about four weeks. That’s roughly 40 days of danger of discovery by nest predators. So lots of females lose their first clutches. Here in Alaska, egg success ranges between 40% and 80%, depending on location and year. Ravens, bears, coyotes, dogs, squirrels, weasels and marten are among the likely kinds of egg predators. After eggs hatch, ducklings gradually get real feathers and can fly in seven or eight weeks, but during that time they are often victims of predators, now including eagles, otters, mink, and owls. Duckling survival in Alaska is usually very low, less than 50%, sometimes as low as 10%. Mortality of adults can be high too, predation by eagles and especially by humans.

One of the things I notice these days, along certain trails and roadsides, is the spectacular show of flowering elderberry bushes. Conspicuous inflorescences are composed of many tiny flowers that are primarily cross-pollinated by various insects (bees, butterflies, small flies). The fruits of our local species are red, and birds love to eat them. Humans are advised not to eat them raw, but cooking is said to detoxify them. 

Tiny downy mallard ducklings swim along with their mother. (Photo by Dave Harris)

Spring beauty/miners’ lettuce blooms along some trails; their flowers are mainly cross-pollinated, mostly by bees and flies. Out in the meadows are more flowers that may self-pollinate a little, but are chiefly cross-pollinated: buttercups, by a variety of insects, and lupine, primarily by bees. Shooting star requires an insect pollinator, usually a bee. The flowers have no nectar; the bees collect pollen by vibrating vigorously and shaking loose the pollen (this is called buzz pollination). 

These early bloomers are out-crossers, mainly — requiring an insect visitor. But the weather so far has been quite cool and wet, which discourages insect activity.  A few days were notable exceptions, however, and on one of those days I saw shooting stars being well attended by small bees. But most of the flowers that opened in late May and early June may not yield offspring for future times.

The ordinary dandelion that is so common in fields and gardens and roadsides does not have such problems. An exotic that originated in the Old World, it produces seed without insect visitation. But it makes pollen and nectar that insects would like — although I have yet to see more than two insects on hundreds of these flowers this spring. They don’t need the insects, but insects could make use of them — if they were out and about, being active.

• Mary F. Willson is a retired professor of ecology. "On The Trails" appears periodically in the Juneau Independent. For a complete archive of Mary Willson’s “On the Trails” essays, go to https://onthetrailsjuneau.wordpress.com