Neighborhood Naturalist Spring 2018

neighborhood naturalist CORVALLIS, OREGON — SPRING 2018

Henderson’s Shooting Star

article by Don Boucher, photography by Lisa Millbank

A

little more than 20 years ago, I was new to Corvallis and walking through Woodland Meadow Park in the spring. I was surprised to see shooting stars blooming, because this was a plant I’d previously seen only in the mountains. From the field guide, I learned that Henderson’s Shooting Star is most common in lowlands.

I recently visited Woodland Meadow Park again and was delighted to see that there are still some Henderson’s Shooting Stars blooming there. They’re eye-catching and extraordinary among the other flowers in the meadow. The pink flowers can appear in clusters of more than a dozen and rise up to a foot above the low, basal leaves. Not only do the unique blossoms make a memorable impression on the wildflower lover, they are also linked to a dispute in botanical classification.

Shooting star’s swept-back petals look as if the blossoms were falling from the sky. The petals are precisely painted with a white and yellow band at the base, and the anthers are dark purple. To me, a large cluster of blossoms resembles an exploding, aerial firework. Buds and young blossoms emerge upright from the top center, and as they mature, they nod downward and toward the outside and bottom of the cluster.

Henderson’s Shooting Star (Dodecatheon hendersonii) is the most common shooting star in the Willamette Valley.

It’s not widespread, but is locally common in undisturbed prairies, low-elevation forest meadows, and rocky seeps that are wet in the spring but dry out in the summer. Another species, Few-flowered Shooting Star (D. pulchellum), is found only in a few spots in the Willamette Valley, notably

Neighborhood Naturalist, Spring-18 v16#1 • page 1

the Kingston Prairie (owned by the Nature Conservancy) near Stayton. Other shooting star species in Oregon are found in the mountains, the Columbia Gorge, and coastal bogs.

Shooting stars require buzz pollination. The anthers are sealed, except for a small opening on one end, and will only release pollen when vibrated. When a pollinator perches on the flower, it pulsates its wing muscles at a certain frequency to access pollen. Most pollinators, like honey bees, most native bees, hoverflies, beetles, and butterflies, don’t buzz pollinate. Bumblebees, and some species in the Halictidae family, are among the minority of bees that do.

When Henderson’s Shooting Star is in bloom, in early to mid-spring, the most common buzz pollinators are newlyemerged queen bumblebees that have yet to start a colony.

The bumblebee workers emerge later in spring and summer, after the shooting stars are finished blooming.

The shooting star’s flower structure allows the bee to get its body close to the anthers, without petals in the way, and vibrate the pollen loose. The pollen falls into the dense fuzz on the bee’s body, where it can be brushed off and stored on the pollen baskets on the legs. The flower shape is similar to the unrelated plants in the Solanum genus (tomatoes and potatoes are familiar examples) which have co-evolved to favor buzz pollinators.

Shooting stars are in the Dodecatheon genus, and are part of the Primulaceae family, which includes familiar garden plants like primroses and cyclamen. You may have encountered wild plants in the Willamette Valley in the Primulaceae family, such as Western Starflower and the introduced, but cute, Scarlet Pimpernel.

Some botanists want to eliminate the Dodecatheon genus, based on genetics. Long ago, plant classification was based solely on physical characteristics, but there’s a modern trend to favor molecular patterns and DNA for classification, which, in many cases, more accurately represents evolutionary relationships. According to molecular and DNA studies, shooting stars have recently evolved in the Americas from ancestors in the Primula genus. The genus includes the garden primrose, Primula vulgaris. They argue that shooting stars are so genetically similar to plants in the Primula genus, that they should be included. Those who favor keeping the Dodecatheon genus value tradition and the unique adaptations of shooting stars. It should be noted that shooting stars are the only members of the Primulaceae family that are buzz pollinated.

A single plant will have at least three flowers and more than a dozen is possible.

You may find instances of shooting stars listed in the Primula genus, but Dodecatheon is more common.

Someday, the case for Primula may be favored. I might

Neighborhood Naturalist, Spring-18 v16#1 • page 2

The basal leaves of Henderson’s Shooting Star are broad and round.

lament the loss of the name Dodecatheon, due to its colorful etymology. Linnaeus chose the name, knowing shooting stars were closely related to primroses. He was inspired

by Roman naturalist Pliny the Elder, who wrote that the primrose, dodecatheos, was a cure-all. In Greek mythology, Dodekatheon (spelled with a “K”) refers to the 12 superior gods who resided on Mt. Olympus, and the primrose was said to be under the gods’ protection.

The anthers form a dark purple cone in the center. Pollen is only Some local nurseries sell Henderson’s Shooting Star. We have them in our native plant garden. The flat, basal leaves are easily covered up by other vegetation, so it’s best to plant them in a spot where they won’t have competition. You can place them in full sun or partial shade. They need moist soil in the spring and not long after they bloom, they go

Tall Mountain Shooting Star (Dodecatheon jeffreyi) lacks the yellow band at the petal bases, and is found at higher elevations.

released when buzz pollinated by a bumblebee.

dormant. It may seem that the plant dies in mid-summer, but it’s just the natural growth pattern.

I hope you can find some Henderson’s Shooting Star this spring. You have until about mid-May or a little later at mid-elevations, or areas that dry out later in the season.

Whether or not you feel this shooting star deserves its godly place among the 12 Olympians, it will certainly warrant some photos. ó

Although it doesn’t look like it, the common garden primrose (Primula vulgaris) is closely related to shooting stars.

Neighborhood Naturalist, Spring-18 v16#1 • page 3

Tree Swallow article and photography by Lisa Millbank

B

irders welcome the Tree Swallow’s arrival in February As the weather warms and the insect population rises, and March. Clad in glittering steel blue and snowy pairs of Tree Swallows select and defend cavities, with males white, they glide over wetlands and rivers, giving a singing loudly. Woodpecker holes in snags near lakes and rich gurgling song. rivers are their natural nesting sites, but many Tree Swallows use artificial nest boxes today. Competition for cavities is As aerial insectivores, most Tree Swallows spend the fierce, with Tree Swallows battling bluebirds, wrens and winter in warm areas in Mexico and the southernmost other swallows, sometimes knocking one another to the parts of the US, where prey is active year-round. They begin ground. their northbound migration quite early, risking starvation if they’re caught in prolonged bad weather. Perhaps the earlier In our area, Tree Swallows almost always raise just one they arrive, the better the nest sites they can claim. Just a brood. But should their eggs or young be destroyed by a few Tree Swallows remain in our area throughout the winter predator or a competing cavity-nesting species, they’ll try each year; they may not survive unusually cold weather. again. At a public garden, we observed a Tree Swallow pair produce three clutches in a season. House Sparrows killed Flies, beetles, moths, damselflies and other flying insects their first two broods, but their last brood was successful. are the mainstay of the Tree Swallow’s diet. But unlike the other swallows, Tree Swallows are somewhat omnivorous, The female is responsible for almost all of the nestoccasionally eating seeds and berries. The berries of wax building. She looks for pieces of dead grass, and collects myrtles are important for Tree Swallows in some regions; just a few pieces at a time. As she places grasses in the cavity, the ability to digest the energy-rich wax gives them a reliable she forms them into a ring with her feet and by pushing food resource if weather limits the availability of insects. with her breast. Gradually, a cup is formed, which she then lines with feathers. Both male and female Tree Swallows Most adult Tree Swallows are an iridescent blue-green are zealous feather-collectors. They have a preference for above, with pure white below. However, young adult small, curled white feathers, the quills of which they push females are brown with traces of blue iridescence, quite into the grass nest. The ends of the feathers curl over the similar to juveniles. Adult males and older females are cup, and the female may begin laying her pure white eggs almost identical, though males are slightly larger. while still adding feathers.

Neighborhood Naturalist, Spring-18 v16#1 • page 4

It’s been demonstrated that nests with more feathers are more successful, probably due to their insulating properties.

The eggs or young nestlings can stay warmer while their mother is away collecting food, and can put more of their energy into growth, rather than keeping warm. Feathers are so valuable that some Tree Swallows pilfer them from others’ nests. I’ve seen what appeared to be a feather burglar at the nest box in our yard. A nervous-looking female tentatively entered the cavity. She was spotted by the resident female, and as the nest owner swooped toward the box, the trespassing female popped out of the hole, and dropped a white feather as she fled.

Tree Swallows don’t just sneak around stealing feathers, they also seek out other mating opportunities. Up to 90% of nests in some populations have at least one egg fathered by a different male. A female can increase the genetic diversity of her clutch, and a male can father more offspring by engaging in extra-pair matings.

After a two-week incubation, the 4-7 eggs begin to hatch. Most female songbirds lay one egg per day, and begin incubation when the clutch is completed, but Tree Swallows start to incubate soon after laying begins. In Western Bluebirds, for example, the eggs generally hatch within 24 hours of one another. Tree Swallow eggs hatch asynchronously, with some of the nestlings being several days older than their siblings. The smallest nestlings cannot compete with their older siblings, and may starve unless food is abundant. This strategy allows the Tree Swallows to maximize the number of young they can raise in good years, but still ensure that some young will fledge in years when food is scarce. As Tree Swallow landlords, the starvation of the youngest chicks has been difficult to witness and accept; we’ve taken several of these unfortunate chicks to the wildlife rehabilitation center.

Males (the bird on the left) are slightly larger than females.

A mid-air battle between males.

Collecting food for the chicks begins before sunrise and ends as the evening’s last light fades. The parents catch dozens of tiny flying insects and compress them into a ball, called a bolus, that is carried in the throat. Usually, the parent deposits the entire bolus into the gaping mouth of one nestling. Research suggests that about 8,000 tiny prey items may be fed to one brood per day. As the babies get older, parents may deliver large prey, such as a dragonfly.

When almost three weeks have passed, the nestlings weigh as much as their parents and their flight feathers are about 85% of their full length. They look out of the cavity, becoming more curious about the outside world.

The parents seem to tease them by approaching the box as if to deliver food, then suddenly veering away. Calling and fluttering excitedly, the parents eventually coax one of the young swallows to release its grasp on the lip of the hole

The similar-looking Violet-green Swallow has white patches extending onto the flanks and white around the eyes.

Neighborhood Naturalist, Spring-18 v16#1 • page 5

personal catalog of songs is fixed in the brain, and does not change. Exceptions exist, such as parrots and European Starlings, who continue to learn and imitate new sounds as adults. New evidence suggests that throughout their lives, Tree Swallows can learn to imitate the specific gurgling songs of neighboring males at breeding sites.

Even though Tree Swallows are still common birds, their population has been in decline for many years.

Researchers are trying to understand the contributing factors. At Cornell University, an experiment showed that Tree Swallow chicks grew faster when provided with a diet rich in omega-3 fatty acids. Because aquatic insects are richer in omega-3s than terrestrial insects, this may mean that Tree Swallows living close to healthy wetlands Bluebirds and Tree Swallows directly compete for nesting spaces. and rivers have the highest reproductive success. Aquatic This male Western Bluebird has a nest in a nearby box, but he won’t insects are typically sensitive to water quality, so excessive tolerate Tree Swallows nearby. Eventually, the bluebird gave up his sediment runoff, high temperatures, insecticides and other pollutants that contribute to the decline of aquatic insects aggression at this box and let the swallows claim it. could have a direct impact on aerial insectivores like Tree Swallows. The researchers surmised that this may be one Watch a video and listen to the factor in the serious losses in the swallow, nightjar, swift sounds of Tree Swallows and flycatcher populations of North America. www.neighborhood-naturalist.com and take its first flight.

A fledgling’s maiden voyage usually ends when it finds a nearby perch, but occasionally a young bird will just keep flying until it’s out of sight. They instinctively know how to feed themselves, but some Tree Swallow parents provide supplemental feedings to their fledglings for a few days.

Food may be transferred from parent to fledgling while both birds are in flight.

For fledgling males, the song-learning process is just beginning. In most songbirds, a repertoire of songs is learned during a period of neuroplasticity in the first year of life. After this crucial song-learning period, the male’s

The female lines the nest with curled feathers. The effect is a cozy, insulating cup with feathers enclosing the nestlings.

But for Tree Swallows, the lack of natural nesting cavities is also a major factor. For obvious reasons, dead and diseased trees are usually removed from urban areas, and old riparian woodlands and their snags have been lost to agriculture. Fortunately, artificial nest boxes have helped to reverse the declines of many cavity-nesting species, but conserving snags is also crucial for Tree Swallows and other wildlife.

Tree Swallows may be found where there are nest boxes, but the best sites are usually near wetlands or rivers. This spring and summer, look for their flashy blue colors in the sky and listen for that liquid song. ó

Tree Swallows nestlings hatch at different times, leading to some nestlings that are smaller. The tiny chick in the center may starve .

Neighborhood Naturalist, Spring-18 v16#1 • page 6

A parent is removing a nestling’s fecal sac. They stop removing these as the babies get older, and droppings pile up around the nest.

This male Tree Swallow is singing by a nest box. He shows his mate various cavities and sings nearby until she settles on one of them.

Tree Swallow Nest Boxes Like other native cavity-nesting songbirds, Tree Swallow eggs, nestlings and adults are frequently killed by the introduced House Sparrow.

There are effective lethal and non-lethal methods of controlling House Sparrows (see http://www.sialis.org/hosp.htm). If you’re interested in attracting breeding Tree Swallows, and you have House Sparrows in your area, you should think seriously about your willingness to commit to House Sparrow control. It may do more harm to put up a box where House Sparrows are uncontrolled, than to have no box at all.

The ideal Tree Swallow box is roomy, with the floor no smaller than 5” x 5”, preferably larger. When a female is incubating in a small box, her very long primary feathers can be damaged by constantly rubbing against the sides of the box. Nestlings about

to fledge also need the space to flap their long wings vigorously, which prepares them for their first flight out of the box. A larger box also allows the young to spread out and cool themselves in hot weather, and not have to stand in their own droppings.

Because nesting cavities are so scarce, and competition is intense, Tree Swallows will settle for small or low-quality nest boxes out of desperation.

They sometimes choose boxes that allow rain to soak the nest, let predators eat the eggs, or damage their feathers.

Providing a properly-sized, weatherproof box gives young swallows their best chance to grow up healthy and strong.

House Sparrow

This thick-walled cedar box has a roomy floor designed specifically for Tree Swallows. The extra holes are an experimental design and serve as extra feeding ports for older nestlings.

Boxes like this one are more decorative than functional. Sadly, when desperate Tree Swallow pairs use small, inadequate boxes, they may suffer nest failure or feather damage.

Neighborhood Naturalist, Spring-18 v16#1 • page 7

Brown Tree Swallows and Look-Alikes Tree Swallow fledglings are brown, without a trace of blue iridescence. Some youngsters have a light brown breast band, which occasionally leads to confusion with the Bank Swallow (which is rare in our area). The brown fledglings, and the brown young adult females, also resemble the Northern Rough-winged Swallow, but that species has a brownish wash on its throat and chest.

A Tree Swallow fledgling has a clean line separating the brown from the white on its face.

In Violet-green Swallow youngsters, the brown and white pattern on the face is patchy and variable.

The Northern Rough-winged Swallow’s entire face is brown, and the underparts have a brownish wash.

In the year after hatching, a young female Tree Swallow is brown with a little blue iridescence. Here, she’s feeding a nestling.

Neighborhood Naturalist promotes interest about nature in mid-Willamette Valley backyards, neighborhoods, and countryside.

neighborhood naturalist

Subscribe 4 issues per year By mail: $15/year E-mail: free

2855 NE Lancaster St. Corvallis, OR 97330 541-753-7689 donaboucher@gmail.com www.neighborhood-naturalist.com ©2018 Don Boucher and Lisa Millbank

Neighborhood Naturalist, Spring-18 v16#1 • page 8