Pollen Samples From Hummingbirds

Pollen Samples From Hummingbirds

January 27, 2017

Kate Stone and Kerr Rasmussen share results from 38 pollen samples taken from hummingbirds.

Sampling the grains: pollen samples from hummingbirds Kate Stone, Eric Rasmussen

Hummingbirds transmit pollen actively and passively in the course of feeding and other activities. To better document their use of floral resources and role in pollen transfer, we collected 33 samples from hummingbirds with visible pollen and 5 from hummingbirds without visible pollen. We collected pollen from June 16th to July 20th 2017. We collected most samples in June.

We sampled pollen from all three resident hummingbird species: Calliope, Rufus, and Black- Chinned. Most samples came from Calliope Hummingbirds, our most frequently captured species.

Erin Herring, a paleoecology Research Associate at the University of Oregon, identified a wide range of pollens. In many cases, she was only able to identify to broad plant groups (Table 1). She detected more penstemon pollen than any other type. In addition to flower pollen, she also found tree and grass pollen and one fern spore. Based on incidental observations of hummingbird activity, we were surprised that she did not find paintbrush or currant pollen.

Penstemon flowers invite the transfer of pollen and are well known as a hummingbird favorite. We have eight penstemon species on MPG Ranch, including fuzzy tongue penstemon (Penstemon eriantherus) (left) and Wilcox’s penstemon (P. wilcoxii) (right).

Pine pollen (below) blankets all surfaces and clogs the air at certain times in the summer. Hummingbirds may pick up tree and shrub pollen when perching in trees, visiting their nests, or by incidental encounters in the air. Pollen varies in its passive dispersal characteristics; pine and alders disperse widely due to pollen productivity and small grain size, while pollen of Douglas-fir, larch, and true fir do not travel far due to lower productivity and large grain size. Next year we will collect and process more ambient pollen samples to identify what pollens are present in the air.

We found pollen from three plants not occurring on the MPG Ranch: mountain hemlock, western hemlock, and a plant in the genus Sarcobatus. Ambient pollen sampling would help us determine if foreign pollen is present in the air or if hummingbirds may have transported it during migration.

Erin found pollen on one hummingbird when we did not visibly detect it. This finding suggests that visual pollen assessments, part of standard hummingbird processing protocol, misses some pollen. We will test more of these “negative” samples next year.

Future Directions & Acknowledgements

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