Habitat Help For Bird Haven

The City of Boise is taking action to improve the habitat in Kathryn Albertson Park, a bird and birder favorite. The City will remove Russian olive trees from 5 acres of the 41-acre park this winter. Golden Eagle Audubon supports the Kathryn Albertson Park Russian Olive Tree Removal Project because it will benefit the birds and insects.

Kathryn Albertson Park was gifted to the City of Boise in 1979 by Joe and Kathryn Albertson. The area had been used as a gravel quarry and horse pasture. The Albertson’s goal was to create a park for wildlife and wildlife enthusiasts different from the common ballfield and playground park.  The quiet park with meandering pathways was a big hit, and visitors enjoy the park year round today.  The park is especially popular with bird watchers and bird photographers because of the many species found there.

In 2021, the City of Boise completed a 2-year renovation that improved the landscaping and irrigation, installed new boardwalks and overlooks, and updated interpretive signs. Some grass areas were transformed into meadows to favor native insects, birds, and small mammals. Read more history of Kathryn Albertson Park.

Hermit Thrush in Kathryn Albertson Park by Ceredig Roberts

Native Vegetation Is Best For Birds

One of the unique features of Kathryn Albertson Park is its mature and diverse vegetation, including many native trees, shrubs, flowers and grasses. The ponds and extensive riparian areas are especially attractive to birds. In the semiarid Intermountain West, riparian areas comprise only a tiny percentage of the landscape but more than 50% of landbirds depend on riparian areas for food, shelter and/or nesting. The most productive riparian areas are dominated by native trees and shrubs like the black cottonwood trees, willows, Oregon grape, snowberry, golden currant, black hawthorne, chokecherry, honeysuckle, and red-osier dogwood found in Kathryn Albertson Park.

Russian Olive Trees Spreading in the Park

Unfortunately, invasive Russian olive trees (Elaeagnus angustifolia) have gained a strong foothold in Kathryn Albertson Park. The southern side of the park is dominated by Russian olive. In the 2024 aerial photo below left, the Russian olive trees are the light silvery-green color. To establish healthier, more diverse habitat, the City is removing Russian olive trees in the southern area of the park. The Russian olive tree removal project map is on the right.

No Room For Company

Russian olive trees displace native vegetation, especially along the edges of ponds and waterways. They can form dense, thorny thickets that quickly shade out native willows and cottonwood along with the shrubs, flowers and grasses. Russian olive trees are a water-thirsty species, and the dense thickets can deplete wetlands and small waterways.

Ruby-crowned Kinglet with bug by Ceredig Roberts

Because Russian olives often form single-species stands like they have in part of Kathryn Albertson Park, the ecosystem lacks a diversity of insects, seeds, fruits, and browse used by a wide variety of animal species, including birds.  Of particular importance to bird-lovers, Russian olive leaves are unpalatable to most insects and don’t support the rich diversity of bugs birds find on native cottonwoods, willows and other plants. Studies have shown that parent birds feed their nestlings hundreds of protein-rich caterpillars a day. Vegetation that supports butterflies and moths and their caterpillars is critical. Insects are a primary food source for many bird species for much of the year.

Aquatic insects are impacted too. Russian olive leaves that fall in the water are ignored by most bugs. That means less food for the fish and for birds like swallows that love aquatic insects.

Too Small For Cavity Nesters

The trees are too short with small diameter trunks and don’t provide nesting sites for cavity nesters like woodpeckers and Western screech owls, colony nesters like Great Blue Herons, or birds that require large branches, such as most raptors. In contrast, native willows and cottonwoods provide abundant insects and large cottonwoods provide nest sites for cavity nesters, colony nesters, and raptors. Some adult  birds will eat Russian olive berries. In Kathryn Albertson Park, American Robins, Cedar Waxwings, and White-crowned Sparrows have been observed eating the berries. Many other trees and shrubs provide berries for birds in the park.

Some impacts aren’t as obvious. The Russian olive tree root system supports nitrogen-fixing bacteria and alters soil chemistry with understudied effects.

Western Screech Owl by Christopher Well

Fire Risk Reduction

Russian olive trees have a lot of dead material in the crowns and  the crowns usually extend to the soil surface. This can be a fire risk when dense stands are present. The alteration of local water availability suggests that Russian olives can increase the general flammability of riparian areas. Riparian areas dominated by cottonwoods and willows generally do not support fire readily given tree architecture and the higher water content of the riparian areas where these two species types are dominant.

Winter Removal Project

The Kathryn Albertson Park Russian Olive Tree Removal Project will be conducted during winter months to minimize disturbance to wildlife and park users.  The park will remain open, although some paths may be closed at times. The project area will be planted with native vegetation following removal of the Russian olive trees. The area will be monitored in subsequent years and Russian olive trees removed as needed.

To share your opinion or get further information please visit the Project Webpage.

Birds of Kathryn Albertson Park

Above: Belted Kingfisher, Black-chinned Hummingbird on native sunflower, and Northern Flicker by Ceredig Roberts. Lesser Goldfinch on native goldenrod by Terry Rich

Below: Cedar Waxwing eating native juniper berries by Ceredig Roberts