By Sonya Daw, Science Communication Specialist for the National Park Service Klamath Inventory & Monitoring Network
This article first appeared in The Klamath Kaleidoscope Spring/Summer 2017 newsletter
People spend a lot of time watching birds, and scientists are no exception. Because birds use such a wide variety of resources and respond quickly to environmental change, they are gold mines of information. Even better, most species are easy to find, especially in the spring when they are singing! Scientists from Klamath Bird Observatory, the Klamath Inventory & Monitoring (I&M) Network and others used a wealth of bird data from the Klamath Ecoregion to understand how birds naturally group themselves across the landscape. Their results were just published in PLOS ONE, “Bird Communities and Environmental Correlates in southern Oregon and northern California, USA.”
The researchers wanted to explore the relationship between bird communities and the highly diverse environment of the Klamath Ecoregion. This 17.5 million hectare ecoregion stretches eastward from the central Pacific coast across several mountain ranges to the Great Basin.
The researchers took a new approach to grouping birds. Managers and scientists typically group birds by taxonomy (genetic relation), behavior (foraging guilds), and habitat (species preferences and needs). However, none of these classifications describes how birds co-occur and interact across broad landscapes. This study looked at how birds naturally group themselves on the landscape, letting the birds define their own communities.
After identifying statistically distinct bird groups, researchers then looked for associated patterns in the environment at three different scales. Understanding this could provide a more nuanced understanding of how birds might respond to management at different landscape scales in the Klamath Ecoregion.
How do birds group themselves across the landscape?
What environmental factors (climate, geography, and vegetation) are associated with those groups at three different spatial scales: (a) Klamath Ecoregion, (b) vegetation formations (agriculture, conifer, mixed conifer/hardwood, and shrubland), and (c) National Park Service units?
How well do the six Klamath Network park units represent bird communities in the broader Klamath Ecoregion?
Data for the study came from 21 years of point count surveys conducted during the breeding season by various agencies and organizations between 1992 and 2013. Point count surveys are conducted in the first few hours after dawn. A surveyor stops at stations along a transect route and records all birds seen or heard for five minutes.
How Birds Grouped Themselves in Relation to Their Environment
Analyses revealed 96 species of songbirds, woodpeckers, and hummingbirds, distributed in 29 distinct groups across the Klamath Ecoregion. These groupings were strongly associated with several environmental conditions at all three spatial scales: (1) Climate: breeding season mean temperature and temperature range, (2) Geography: elevation, and (3) Vegetation: environmental site potential (what the natural, climax community would look like), and existing vegetation formation.
In other words, bird communities tended to separate out along gradients in temperature, elevation, and certain aspects of vegetation. Several other environmental factors, however, varied by scale. For example, disturbance (e.g., wildfire) and distance to stream or lake only appeared to influence the composition of bird communities at the smallest scale analyzed—the National Park Service unit.
How Well National Park Lands Represented Bird Communities
Parks appeared to represent bird communities fairly well across the region. Most of the bird communities occurred within at least one of the park units. Network parks have abundant mature conifer forest and strongly represented bird communities in this habitat type. Interestingly, while forests with a mix of conifer and hardwood—often oak—trees were heavily represented in park units, the bird community associated with oak woodlands was not found in the park units. Oak woodlands do not commonly occur within the elevations and geographic settings of this ecoregion’s parks. Identifying bird communities, like those associated with oak woodlands, not currently protected within park boundaries is an important first step for targeting future lands to protect.
Using long-term monitoring data for research and management achieves an important I&M goal, says Eric Dinger, Network Ecologist, who analyzed the data:
“Using our monitoring and inventory data to better understand the ecology of bird communities and what influences the distribution of species across a landscape lays the foundation for better ecosystem management in the future.”
Specifically, park managers will be able to make more informed management decisions with a better understanding of how their park contributes to bird diversity and conservation in the region. More generally, land managers from any agency in the region will have a better understanding of how environmental factors influence bird communities differently at the three landscape scales analyzed.
PLOS ONE journal article citation:
Stephens, J. L., E. C. Dinger, J. D. Alexander, S. R. Mohren, C. J. Ralph, and D. A. Sarr. 2016. Bird Communities and Environmental Correlates in Southern Oregon and Northern California. PLOS ONE 11(10): e0163906. doi: http://dx.doi. org/10.1371/journal.pone.0163906.