Birds & Insects
Birds and Insects
An important rationale for evaluating the response of birds, ants, and butterflies to treatment is to gain confidence about the patterns of whole system effects. In particular, we hope to understand to what extent other components of the system, not directly related to vegetation management, track the response of the vegetation over time. Understanding these effects will provide managers with much more confidence on how their treatments influence the whole system. If wildlife and invertebrate response is consistently related to vegetation response over time, then managers can argue that the changes they observe in the managed landscape are reflected within.
Demography and Habitat Use of Song Birds
Song birds are of keen interest because sage-obligate species are considered to be especially at risk of habitat loss and subsequent population declines given the rapid habitat changes now occurring in sagebrush steppe ecosystems. Species richness and diversity, and productivity of song birds are being evaluated across a suit of species that breed in habitats along a woodland invasion gradient. Primary questions being addressed are:
- What are the dominant habitat characteristics that determine response in the bird community?
- What spatial and temporal scales are the primary drivers of change in bird assemblages?
- What are the primary mechanisms by which the bird community responds to changes in quantity, composition, and configuration of their habitat? Does productivity at the individual and/or population level change relative to habitat treatments?
Point counts are being conducted twice a year during the breeding season across the SageSTEP woodland network to study species richness and density in relation to the various ecosystems. Response of sagebrush-obligate species (Sage Thrasher, Brewer’s Sparrow, Sage Sparrow, Vesper Sparrow, Black-throated Sparrow, Green-tailed Towhee, and Gray Flycatcher) to management treatments is being studied intensively at the Onaqui, Seven Mile, South Ruby, and Five Creeks woodland study sites. Data collection for intensive study includes delineating territories, mist-netting and color-banding individuals, and assessing nesting success.
Species Richness and Colony Dynamics of Ants
Ants are ecologically dominant arthropods in sagebrush steppe ecosystems. Ants serve as scavengers, predators, symbiotic partners of other invertebrates, predators and dispersers of seeds, and as prey for a wide array of vertebrates, including many sage-obligate birds. We are evaluating species composition and relative abundance of ants, harvester ant colony density, and spatial dynamics of ant foraging systems. Since ant species differ markedly in the ecological roles they play, and these roles are generally well known for sagebrush species, we will be able to understand how management treatments alter the balance between roles over time. Primary questions to be addressed include:
- Does the ratio of seed harvester versus seed disperser change as a result of treatment, and how might this influence the distribution and abundance of plants?
- Do ant communities follow plants in terms of recovery after treatment, or do they precede plant communities?
- Do ants hinder or facilitate recovery of the plant community after treatment?
Ants are being collected throughout the SageSTEP network using pitfall traps, one trap deployed in the center of each of the 1150 sub-plots. Ant community data can then be compared directly to all vegetation, soils, and fuel information collected within each sub-plot.
Species Richness and Foraging Habitats of Butterflies
Butterflies are easy to count and identify on the wing, and so can be sampled with almost no impact. Further, their larvae are intimately linked to native host plants, typically forbs, and so assessing the effects on them will tell us something about effects of treatment on the plant community. Accordingly, we will evaluate the influence of SageSTEP treatments on the species richness and relative abundance of butterflies, at all sites except Scipio where the treatment plots are too small. Primary questions to be addressed include:
- Do treatments cause a divergence in the complexion of butterfly communities over time?
- Do butterfly species continue to use treated plots, even if their larval host plants are eliminated?
- How quickly do butterfly communities change after treatment? How fast do they recover?
Butterflies are surveyed along a 1000 meter transect, within each SageSTEP plot at least twice per year in May and June.
Publications resulting from the wildlife research can be found on our Scientific Publications page.
SageSTEP Project Co-coordinator
Department of Fisheries and Wildlife
Oregon State University
Corvallis, OR 97330