The Evolutionary Adaptations of Hummingbirds Nicole Eastep, Garrett Edwards, Daniel Ngembus & Rachel Travitz

Hummingbirds are thought to have a long history, but it is hard to determine their exact lineage. Linnaeus Buffon

Hummingbirds eat every 15 to 20 minutes to maintain energy levels. When they are unable to feed due to weather or other reasons, they go into torpor.

Hummingbirds are the overachievers of the avian world. To sustain their hyperactive lifestyle, they eat their own bodyweight in nectar and insects every day.

Does wing pace of hummingbirds have an advantage on the overall fitness of the heart? FEMALES

Hummingbird’s Heart Fairly large organ when compared to the small body and low weight of the bird. Depending on the species: Compared to its own body size:

Heartbeat During flight: A rate of 1260 beats per minute has been recorded. During torpor: The heart rate can drop to per minute.

Torpor Is a mechanism used to preserve energy through a reduction in metabolic rate. What this suggests:

Torpor Contiued Studies show that a portion of the energy consumed during feeding is stored.

When torpor does occur, it drastically lowers the rate of depletion of remaining energy reserves.

Hovering demands an extensive amount of energy. While hovering, oxygen intake, fuel supply and waste removal in hummingbirds are all increased. This is the highest energy expenditure out of all vertebrates.

How this relates to our Question Hummingbirds have a higher wing pace compared to other birds which indicates a higher overall fitness of the heart and the muscle of the bird in general. The wing pace of hummingbirds indicates an overall fitness on the heart and body. It is not simply a reflection of having a small body size.

Was diet or rapid wing movement developed first in hummingbirds? MALES

Case Study Richard S. Miller (1985) performed a study on why hummingbirds hover while feeding from flowers. He wanted to know whether or not these birds actually preferred to hover or if they only hovered because there wasn’t a perch available to utilize while feeding.

Implication: – The relative importance of energy costs versus speed increases with relative body size. Birds that hover while feeding can move quicker from flower to flower than birds that perch. So, hovering is not necessarily preferred by hummingbirds.

Results: – Even the smallest of hummingbirds prefer to perch while feeding if given the opportunity. What This Means

Hovering is most likely the dominant feeding mode for Hummingbirds Some plants have even evolved flowers that tend to exclude bees and attract hummingbirds This suggests that plants, not pollinators, are responsible for this coevolved system The fact that hoverers can move more quickly between flowers may be more beneficial to the plants than the birds, forcing a cost on the birds that is less optimal.

Bird pollination seems to be more beneficial to plants for multiple reasons: To Summarize: Hovering is not necessarily a preferred mode of feeding, but one that cant be avoided.

Two Extreme Forms of Flight Hovering and low-speed flight (figure 8 movement) Fast forward flight (oval movement)

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How this relates to our Question The rapid wing movements(hovering or perching) of Hummingbirds depends on the architecture of the plants(diet). The Diet or structure of the flowers/plants forced the hummingbirds to adjust the necessary rapid wing movements which provided a better chance to obtain the maximum amount of food.

Other interesting facts There are seventeen species of hummingbirds in North America. They have tiny little feet that are only good for perching, scratching or preening. This means if they wish to move, even a few inches, they must fly. Hummers can starve to death in about an hour. They eat every 10 minutes throughout the day. Have very good memories and will even be able to remember where they found food from the previous year. Can fly up to mph. The only bird that has an insect that will eat it. Praying mantis's think they are yummy. Average lifespan is 3-6years. The record is 12 years. They lay two eggs that are about ½ inch long. The eggs hatch in days depending on the species.

Sources Flight of the Hummingbird, Earthwatch Institute Journal, Jun/Jul2003, Vol. 22 Issue 2, p35, 1/2p. Chai, Peng and Robert Dudley. Maximum Flight Performance of Hummingbirds: Capacities, Constraints, and Trade-Offs. The American Naturalist, Vol. 153, Vo. 102, p Miller, Richard S. Why Hummingbirds Hover? The Auk, October 1985, Vol. 102 No 4, p Chambers, Lanny. About Hummingbirds. Hummingbirds.net Hainsworth, F. Reed, Brian G. Collins, and Larry L. Wolf. The Function of Torpor in Hummingbirds. Physiological Zoology. July Vol. 50. No 3. P Hummingbird Anatomy. World of Hummingbirds Gupta, Rachna. Facts About Hummingbirds. the-hummingbirds.html