SaP: Songbirds as Pollinators
Songbirds that are not considered nectarivorous, such as Western Tanagers, are often observed probing flowers, coated with pollen, or feeding at hummingbird feeders. Despite these observations, there has been no scientific effort undertaken in North America to understand the potential role of these flower-foraging songbirds in pollen movement.
So, what is the SaP Project?
The SaP Project is a collaborative effort between members of the public, the Institute for Bird Populations (IBP) MAPS (Monitoring Avian Productivity and Survivorship) initiative, individual bird-banders, and Colorado State University to collect pollen samples from songbirds and document flower-foraging behavior. Banders gently wipe the faces and bills of target species when these birds are in the hand. These swabs are specifically designed to pick up small particles, such as pollen. The swab is then snapped into a small, pre-numbered tube, then put into a coin envelope where data can be recorded. Each swab is associated with a single bird, which we can then use to make inferences about plants visited by that individual, and look for patterns across species and genera.
Goals of the SaP Project
By partnering with banding stations and nature enthusiasts, we will collect observations in addition to pollen samples. With the pollen samples we can search for angiosperm DNA; exploring exciting and impactful questions about the relationships between North American songbirds and flowering plants.
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Through the course of this 2 year project we seek to...
1. Understand the which songbirds flower forage and what plants they visit.
On a clear morning in San Diego California’s Balboa Park on March 25th, 1927, Zoologist and Botanist Frank F. Gander observed a flock of Bullocks Orioles and Hooded Orioles displaying a peculiar behavior: inserting their bills deeply into the “…very heart of the flowers” of a Tasmanian Blue Gum tree. The phenomenon of North American songbirds; namely orioles, wood-warblers, and tanagers, probing flowers in trees and shrubs has been well documented through western ornithological history. However, observations of flower-foraging behavior have become less prevalent across academic literature in recent years. Simultaneously, technology that allows birders, botanists, and nature enthusiasts alike to capture images and videos of songbirds flower foraging has only increased. With this increase also comes more public awareness and, for many, an interest in sharing their observations with the world through social media.
The SaP Project seeks to collaborate with members of the public that observe or photograph songbirds flower foraging by providing a space to submit observations. This will allow us the opportunity to expand the scope of the SaP Project beyond a single area and beyond our list of species, and give us a greater understanding of which songbirds flower forage and what plants they visit. By 2025, photos and observations will be organized into a freely available database of avian pollinators as well as into an interactive live map available here.
2. What individual bird characteristics (e.g., sex, age) or environmental factors (e.g., weather, altitude) are associated with the presence of pollen on songbirds
While certain species of songbirds may rely to varying degrees on flowers, particularly during migration, this may differ by characteristics of the individual bird, and/or by the environmental factors associated with the site of capture. Characteristics of the individual bird will include sex, age, body condition. Environmental characteristics will include time of first flowering, site location, altitude, and weather. Through our work, we will use mathematical modeling to understand how these may affect the presence of pollen on a given songbird.
3. Determine what makes a plant attractive to a flower-foraging songbird
A well-established hypothesis in pollination ecology is pollination syndrome: a concept dating back to the 1870s that associates floral traits with a specific group of pollinators, and as such, allows researchers to infer the type of pollinator that will visit a particular plant. Songbirds in North America have been observed on plants with white, radial flowers; red, tube-shaped flowers; and white, brush-like flowers. While these observations may suggest that warblers, tanagers, and orioles visit a wide variety of floral types, they are typically single observations that may not reflect the entire suite of plants even visited by that individual bird. By assessing the shared characteristics of flowers visited by songbirds from pollen samples, researchers at CSU can understand what floral characteristics may predict flower selection.
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4. Explore how pollen profiles of hummingbirds compare to that of songbirds.
In temperate western North America, many species of hummingbirds that are largely considered "generalist" will spend their spring and summer foraging in flowers. Because we are looking at what flower species that songbirds might forage within, we will simultaneously collect pollen from hummingbirds to compare the networks of songbirds to that of hummingbirds from the same sites.
