Nature Watch: Bright Competition

Author: Steve Ellis | 05/29/24

About the author: Steve Ellis is a naturalist and Land Trust member who enjoys sharing his love of the natural world. His blog series, “Nature Watch,” will appear each month in “Habitchat,” chronicling native plants and wildlife you can expect to see during that particular time of year. We thank Steve for sharing his passion, illustrating the importance of island conservation.


It’s a jungle out there. Plant species struggle against each other for sunlight, water and room for their root systems. They also vie for the attention of pollinators for which various strategies are deployed in an effort to outdo other blooming species.

Location is important. Twinflower grows to form mats on the shaded forest floor, a habitat where few other wildflower species can thrive. Twinflower attracts flies and tiny solitary bees that prefer the protected forest floor rather than windy open areas.

Massing colorful blossoms together is beneficial to bees that desire maximum nectar with a minimum of effort. Nootka rose and thimbleberry bushes produce multiple blooms that ease the life of bees. Massed colors also attract butterflies.

Many flowers display colorful spots or lines on their petals and other parts to guide pollinators to the prized nectar. Siberian candyflower is a plant with such lines. Some guides fall in the ultraviolet range which aid bumblebees but remain invisible to humans. Nectar guides are analogous to arrows pointing to the drive-up windows at fast food restaurants.

Flower shape can set a species apart from its competitors. An example is the tube-shaped blossoms of the orange honeysuckle vine which are perfect for attracting hummingbirds.

Timing the blooming period can be critical. Those that bloom early such as skunk cabbage, or flowers found in the fall including Puget Sound gumweed have few or no competitors. The former are pollinated by scavenger flies and beetles while the latter rely on the hardiest of bumblebees.

Scents are emitted by some flowers to entice bees and butterflies. Rhododendrons and fireweed are not only showy with mass blooms, but they also appeal to the olfactory senses of insects. Other scented wildflowers include false lily of the valley and pearly everlasting. The latter attracts many  butterflies in late summer.

The strangest strategy might be that of yellow sand verbena, a wildflower that grows on the upper portions of sandy beaches. I’ve witnessed bumblebees and other pollinators bypass the clustered yellow blooms as they search for nectar. This plant releases its aroma at night to entice the sand verbena moth, the only pollinator of this hardy plant.

Visiting a variety of habitats in June should allow a person to observe many of these strategies. This bright competition is a delight to our senses.

Thimbleberry by Martha Ellis.

Flora: Thimbleberry, Rubus parviflorus

The tissue paper-like blooms of thimbleberry are a common sight in June. Thimbleberry grows to a height of 8 feet on thornless stems. Its leaves are 2- 7” long and are shaped like those found on maple trees

The white blooms grow in clusters with each blossom consisting of five petals that measure 1” across. Pollinators include bumblebees and butterflies.

Thimbleberry fruits are dome-shaped and resemble “half raspberries.” They are an important food source for Swainson’s Thrush and other bird species, particularly American Robins attempting to raise a second brood. These birds then spread the tiny seeds. The berries are also eaten by chipmunks.

Deer and rabbits browse the leaves, and the stems form thickets that shelter shrews, deer mice and small birds.

Galls are sometimes found on the stems. These are created by the larva of tiny wasp species and are not detrimental to the bush itself.

Thimbleberry bushes are some of the early pioneers that enter areas after wildfires or other disturbances. They can form thickets as they spread from their rhizome systems. Shade tolerant, they can be found on many Land Trust properties where they favor roadsides and open forests.

Western tiger swallowtail by Martha Ellis.

Fauna: Western Tiger Swallowtail, Papilo rutulus

This handsome insect is the largest and showiest butterfly in our area.

Western tiger swallowtails have a wingspan of 4 inches. Wings are bright yellow with black borders and sport tiger stripes. In addition, there are one or two orange spots and several blue spots on the lower edge of the hindwings.

Adults of this species begin emerging in late May and are common through midsummer. Males patrol energetically for females and may fly back and forth over your house in an activity known as hilltopping.

Both genders take nectar from a variety of blooms. Rhododendrons, yarrow, thimbleberry and columbine are among their favorites. Males will also visit muddy areas to obtain minerals, a habit dubbed puddling.

After mating, females search for host plants to lay their eggs. Alders, willows and bigleaf maples are often selected species. A single green egg is laid on top of a leaf, usually 5 to 8 feet up. The butterfly then flies some distance before laying another egg.

After hatching, the instar (caterpillar) eats the eggshell. In its first stage, the instar resembles bird droppings so it can munch leaves without the threat of being eaten by a predatory bird. As it grows, it becomes green and develops two large eyespots, which serve as another sort of deterrent to birds. Another defense is an organ behind the caterpillar’s head that emits a foul odor if it is threatened.

Western tiger swallowtails are conspicuous and can be found in parks, gardens, along roadsides and in open forests.

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