Download Rufous Hummingbird Background Info by Rima Givot

Rufous Hummingbird Background
Rima Givot, 4/10/14
Pollinators and Hummingbirds
Pollinators play a critical ecological role in the reproduction of many flowering plants.
Hummingbirds have specialized to feed on nectar and pollinate specific plants, and with decline in
populations due to habitat fragmentation (both physical and chemical), breaks in nectar corridors
along which hummingbirds migrate, and loss of habitat, plant species may be affected (AllenWardell et al., 1998). Hummingbirds help to diversify genetics of local populations because they
travel great distances and so help disperse pollen between distinct plant populations. Such pollen
spreading would not likely happen with other resident pollinators (Arizona-Sonora Desert Museum,
2014).
Rufous Hummingbirds
Rufous Hummingbirds (Selasphorus rufus) are one of the most common and widespread
hummingbirds in North America, but populations have been declining by 3% per year over the last
30 years, and the source of decline is unknown (Bailey, Segelbacher, Healy, Hurly, & Pemberton,
2013; Sauer et al., 2012). Rufous hummingbirds migrate farther than any other bird when relating
size of the bird to distance migrated (Arizona-Sonora Desert Museum, 2014; Moran et al., 2013).
Breeding grounds extend from Northern California to Alaska, and they winter in Central Mexico. In
their wintering grounds of Mexico, Rufous Hummingbirds play a critical role in pollinating many
flowering desert plants, including many of the plants seen in the desert of el Rancho San Gregorio.
Rufous Hummingbirds generally migrate up the western part of the Pacific Northwest, starting in
February, with males being the first to stake territories, and females following. They migrate south
between the Rockies and inland west, with males starting in July. Males do not help with rearing
young. Migration is an elliptical pattern, utilizing flowers that bloom along the way (ArizonaSonora Desert Museum, 2014; Gough, 2003).
Regionally some populations have declined more, while others have stayed more stable.
Populations in the Pacific Northwest have shown more decline than populations associated with the
Basin and Range and Rocky Mountains. Genetic tests on microsatellite markers using DNA from
Rufous Hummingbird tail feathers were conducted to determine if significant genetic variation
exists between populations of different regions (Bailey et al., 2013). Microsatellite markers are
distinct sections of DNA with repeating nucleotides that can be used to compare individuals or
populations. Very small amounts of DNA can be collected, and the specific DNA sequences that
make up the microsatellite marker can be amplified by PCR (polymerase chain reaction) technology
(Selkoe & Toonen, 2006).
It turns out that Rufous Hummingbird populations breeding in four distinct geographic locations
in Canada were very weakly different, but not different enough to claim genetic isolation. Because
the differentiation was weak, most likely there is intermixing in the populations, and populations
are not necessarily separated geographically. This is important in determining why population
numbers of Rufous Hummingbirds are declining in some areas, but not in others (Bailey et al.,
2013).
These genetic microsatellite studies can be used in conjunction with banding to assess
movement of individuals within and between populations. However, banding of juveniles is still
lacking. Most banding is completed on adults, so dispersal at birth has not been documented yet.
(Bailey et al., 2013).
Habitat Fragmentation
Rufous Hummingbirds are facing habitat fragmentation, habitat loss, and change of habitat
along their migration corridors. Because they are such a small bird, about the weight of a penny,
they need to replenish energy reserves frequently (Rufous Hummingbird, n.d., Arizona-Sonora
Desert Museum, 2014; Gough, 2013). They have little room for energy storage, and they use a lot
during migration. Because Rufous Hummingbirds travel such great distances, the nectar corridors
on which they depend are especially critical to their survival. These migration routes are also
susceptible to habitat fragmentation and change. In the southwestern United States and western
Mexico, millions of acres of desert and scrub-land have been converted to agriculture crops with
high chemical exposure, creating vast expanses of 100-200 kilometers with no food stops for the
hummingbirds (Arizona-Sonora Desert Museum, 2014).
In a recent study of habitat fragmentation, it was found that a keystone tropical plant species
(Heliconia tortuosa), produced more seeds and was visited by more pollinators in larger forest
patches. The size of the habitat fragment directly correlated with the number of hummingbirds
present and with the number of seeds produced by the plant. Regardless of how fragmented an area
was, if the area was larger, there were more hummingbirds, most likely resulting in more
pollination and more seed sets per plant (Hadley, Frey, Robinson, Kress, & Betts, in press).
Understanding the Rufous Hummingbird migration routes both north and south, and working to
increase nectar corridor connectivity is critical to the Rufous Hummingbird success (ArizonaSonora Desert Museum, 2014).
Behaviors
Rufous Hummingbirds are very aggressive and can maneuver quickly in the air at high speeds.
In one study conducted on how Rufous Hummingbirds would respond to nectar with different
concentrations of sugar, territories with higher quality of food were given preference by different
species of hummingbirds, and the aggressive Rufous Hummingbirds tended to displace the
subordinate, larger Broad-tailed Hummingbirds (Camfield, 2006). In their natural habitat, Rufous
Hummingbirds spend much of the time perched and defending their territory, generally foraging the
edge of their territory first, at early dawn and dusk, and then working to the center and more dense
food, where they can more easily deter competitors and better defend the high quality food. The
abundance of flowers and other food may determine the size of Rufous Hummingbirds’ territory
(Gough, 2003).
Hummingbirds lose up to 10% of body weight when they sleep. Rufous Hummingbirds go into
a state of torpor at night to conserve energy, and lose 1% instead. They weigh about as much as a
penny and must double in weight before they migrate (Gough, 2003).
Migratory birds and pollinators must adapt to climatic changes and variation in the plants that
are flowering along their migration routes. Understanding their migration requirements can guide in
conservation management strategies (Arizona-Sonora Desert Museum, 2014). The hummingbird
citizen science study will hopefully contribute data to better understand the migration and local
populations of Rufous and other hummingbirds in Sisters, Oregon, furthering the knowledge base
of hummingbird biodiversity in the Pacific Northwest. The hummingbird study was started in 2012,
by an undergraduate student in Matt Betts’ lab at Oregon State University (OSU), in which a
partnership with teachers, undergraduate students and the lab was formed. The study was designed
to engage teachers, students, and undergrads in citizen science data collection, using science inquiry
to address conservation, pollination, and hummingbirds (Greer, 2014).
Rufous Hummingbird Study
The data from 2012, showed an increase in feeder visits and more nectar being consumed in
areas of greater forest cover and less habitat fragmentation (rural vs. urban) in Corvallis, Oregon
and the surrounding area. This led to the current research question: “How does forest cover affect
Rufous and Anna’s Hummingbird presence/abundance?” Other goals of the study include
determining methods that can be used to learn more about why Rufous Hummingbird populations
are declining (per the Breeding Bird Survey), monitoring Rufous Hummingbird populations and
better understanding cause of declining populations, and understanding how declining Rufous
Hummingbird populations affect pollination services for plants and ecosystems (Greer, 2014). The
Sisters High School hummingbird study will lead into a native bird study addressing adaptations of
other local bird species, and the biology students will have an opportunity to present their findings
at a student-led Watershed Summit in May, 2014.
References
Allen-Wardell, G., Bernhardt, P., Bitner, R., Burquez, A., Buchmann, S., Cane, J., Cox, P.A., …
Nabhan, G. P. (1998). The potential consequences of pollinator declines on the conservation
of biodiversity and stability of food crop yields. Conservation Biology, 12(1), 8-17.
Arizona-Sonora Desert Museum. (2014). Rufous Hummingbird (Selasphorus rufus). Migration
Pollinators Program. Retrieved from
https://www.desertmuseum.org/pollination/hummingbirds.php.
Bailey, I., Segelbacher, G., Healy, S., Hurly, T., & Pemberton, J. (2013). Microsatellite variation in
Rufous Hummingbirds (Selasphorus rufus) and evidence for a weakly structured population.
Journal of Ornithology, 154, 1029–1037.
Camfield, A. F. (2006). Resource value affects territorial defense by Broad-tailed and Rufous
hummingbirds. Journal Of Field Ornithology, 77(2), 120-125.
Cornell Lab of Ornithology. (2011). Rufous Hummingbird. All About Birds. Ithica, NY: Cornell
University. Retrieved from http://www.allaboutbirds.org/guide/rufous_hummingbird/id.
Gough, G. ( 2003). The Hummingbird Diet: How To Gain Weight And Keep It. Migratory Bird
Center. Smithsonian National Zoologic Park: Washington, D. C. Retrieved from
http://nationalzoo.si.edu/scbi/migratorybirds/featured_birds/?id=266.
Greer, J. (2014). Hummingbird Citizen Science Project. Unpublished presentation.
Hadley, A., Frey, S., Robinson, W. D., Kress, W. J., & Betts, M. (In press). Tropical forest
fragmentation limits pollination of a keystone understory herb. Ecology. Retrieved from
http://www.esajournals.org/doi/abs/10.1890/13-0929.1.
Moran, J., Wassenaar, L., Finlay, J., Hutcheson, C., Isaac, L., & Wethington, S. (2013) An
exploration of migratory connectivity of the Rufous Hummingbird (Selasphorus rufus),
using feather deuterium. Journal of Ornithology, (154), 423–430.
North American Breeding Bird Survey. (2001). Laurel, MD: USGS. Retrieved from:
http://www.mbr-pwrc.usgs.gov/bbs/
Sauer, J., Hines, J., Fallon, J., Pardieck, K., Ziolkowski, D., Jr., & Link, W. (2012). The North
American Breeding Bird Survey, Results and Analysis 1966 – 2011. Version 12.13.2011.
USGS Patuxent Wildlife Research Center. Laurel, MD. Retrieved from: http://www.mbrpwrc.usgs.gov/cgi-bin/atlasa11.pl?04330&1&11.
Sauer, J., Link, W., Fallon, J., Pardieck, K., & Ziolkowski Jr., D. (2013). The North American
Breeding Bird Survey 1966–2011: Summary Analysis and Species Accounts. North
American Fauna, 79, 1-32.
Selkoe, K., & Toonen, R. (2006). Microsatellites for ecologists: a practical guide to using and
evaluating microsatellite markers. Ecology Letters, 9(5), 615-629.
Ziolkowski, D., Jr., Pardieck, K & Sauer, J. (2010). On the road again for a bird survey that counts!.
Birding, 42(4), 32-40. Retrieved from:
https://www.pwrc.usgs.gov/bbs/bbsnews/Pubs/Birding-Article.pdf.