Non-native Norway Spruce May Become Essential Bird Habitat

Research Issue

The blackburnian warbler is one of several species that were more abundant in Norway spruce plantations than any of the native forest types we sampled in central Massachusetts.

The composition of many native forests are changing. Sometimes forests are replanted with non-native tree species deemed more commercially valuable. Other times, invasive species or outbreaks of insects or diseases can greatly diminish predominant species across a landscape. As forest types change, the plant and animal communities accustomed to those habitats can potentially be impacted.

In western Massachusetts, non-native Norway spruce (Picea abies) were planted in the early 1900s as a potential commercial species, but now land managers are wondering whether they should retain them to support native wildlife. Native eastern hemlocks (Tsuga canadensis) are in decline from an invasive Asian beetle known as the hemlock wooly adelgid. Norway spruce share characteristics with eastern hemlocks, such as short needles and dense canopy cover, and could possibly serve as surrogate habitat for native wildlife.

Our Research

Researchers with the Northern Research Station and their collaborators surveyed songbird diversity and abundance in eastern hemlock forests and Norway spruce plantations to see if they supported similar species. Other forest types within the region were also surveyed to determine whether the hemlock and Norway spruce stands provided a habitat distinct from neighboring forest types.

Songbirds often serve as indicator species for other wildlife because their presence or absence often corresponds with other wildlife within a habitat. Furthermore, songbirds’ prolific and distinctive calls make them relatively easy to survey compared to other animals.

For two spring breeding seasons, researchers recorded bird calls at 174 research plots within five forest types: eastern hemlock (42 plots), Norway spruce (42 plots), white pine (30 plots), deciduous forests (30 plots), and mixed forests of deciduous and conifer trees (30 plots). During the course of the study, 4,880 birds were recorded, representing 82 different species.

Expected Outcomes

Three bird species were more abundant in Norway spruce than in any of the native cover types: golden-crowned kinglet, red-breasted nuthatch, and blackburnian warbler. Several other species considered to be associated with eastern hemlock (black-throated green warbler, magnolia warbler, and blue-headed vireo) were equally as abundant in Norway spruce as eastern hemlock. These species that were most abundant in Norway spruce and hemlock comprised a bird community distinct from the other, more widespread deciduous, white pine, and mixed forest types.

Researchers theorize that the similar structure and needle length (“architecture”) of Norway spruce to eastern hemlocks allowed the plantations to better mimic hemlock habitat than the other widespread conifer forest type (white pine), which has long needles.

Research Results

Ritter, Calvin. 2020. "The Ecological Value of Spruce Plantations in Massachusetts." Masters theses. 904.

Ritter, C.; King, D.I.; DeStefano, S. 2020. “The Ecological Value of Norway Spruce Plantations in Massachusetts.” Oral Presentation at the 74th Annual Northeast Fish and Wildlife Conference, Groton, CT, April 15-16.

Research Participants

Principal Investigator

  • David King, USDA Forest Service Northern Research Station, Research Wildlife Biologist

Research Partners

  • Last modified: December 7, 2020