Riverside Hybrids


Ensifera ensifera | P. mixta & Ensifera ensifera | Ensifera ensifera skeleton |


A female Ruby-throated hummingbird Archilochus colubris on Passiflora sanguinolenta. Image © 2012 Stacy Pugh.


 

Hummingbirds, often known as 'hummers' are pollinators for many plants including Brugmansia, Datura, Fuchsia & Passiflora. There are over 330 species & they are closely related to swifts. They are found only in the Americas, especially up in the Andes & also in the Caribbean.

They have proportionally the largest brains, longest tongues, smallest eggs & largest hearts in birds & although we think of them as being very small some are up to 8'' long. Even in the wild they are thought to live ten years or more. These colourful birds are unique in their ability to hover and fly backwards or even upside down, thus being able to drink nectar & catch insects on the wing.

Hovering is achieved by rotating the wings alternately backwards & forwards so that upward lift & forward thrust are balanced by downward lift & backward thrust. The wings can beat 60 times per second, creating the 'hum'.

Daytime body temperature of 102°F to 108 °F which drops right down at night to near air temperature to conserve energy. At this time heart rate can drop to 50 beats a minute. It can take up to an hour for them to 'get up' in the morning.

They can breathe up to 250 or more times a minute & heart rate varies from 1,260 to 2,000 beats per minute.

Often forked, their very specialized long tongues with many tiny hairs are curled into a tube shape to make use of capillary action. They flick their tongues at high speed repeatedly many times a second into the floral tube to reach the nectar. Those with the longest beaks & tongues can reach down long floral tubes that others cannot & so avoid competition. The tongues, on average, have the ability to extend as far beyond the beak as the beak is long.

Some hummers are "nectar robbers" and enter a hole at the
base of the tube that has been made by bees, wasps, or other insects who are known to use that technique, stealing the nectar without repayment by pollination.

As anyone who has put out feeders for them will know, some are very aggressive, solitary & territorial birds. This is because in the wild nectar sources are always temporary by their nature & must be defended. The iridescent throats of many of the male species are to attract the female & keep other males away. Males will mate with any female & the female brings the offspring up on her own.

Many hummingbirds in North America migrate in winter to Central America, a distance of nearly 2000 miles covered in one to two weeks at up to 25mph when flying.

Nevertheless its not a bad life, Schuchmann 1999 found that 70% of a hummingbird's time is spent doing little else than singing, self-preening, and sunbathing!

Some Passiflora with long floral tubes that do not readily self pollinate have become overdependent on specific hummingbirds to pollinate them. For the best example of this see a paper by Annika Büchert here.