Signs of Spring: Report Your Observations!

Nectar is loaded with sugar--a carbohydrate that provides a lot of energy. But bats cannot live on sugar alone. Nor can you! We all need other nutrients, especially protein. Most of a bat's, and our own, body tissues are made of protein, and so without protein we can't grow. And nursing mothers, be they bats or humans, need lots of protein to produce milk. It has been estimated that the average adult mammal requires 10% protein in the diet; young and growing mammals require 20%.

Nectar-feeding bats get their protein from pollen. The plants upon which these bats depend have on average 15%-30% pollen -- plenty for even the growing youngsters.

Interestingly, when scientists compared plants upon which bats fed and closely related plants that bats did NOT visit, there was a significant difference in sugar and protein content. The bat- visited plants had much more of each. In contrast, hummingbird plants also have high sugar content but not protein. Hummingbirds get their protein from insects, not pollen.

These four bats have pollen on their faces. Photo Copyright by Merlin D. Tuttle

After a bat has visited a flower, it is so covered with pollen that it looks yellow in color, not its natural brown color, because of the dense covering of yellow pollen. The bat will stop foraging for anywhere from several minutes to several hours to lick off the pollen and to rest.

Over the eons, the lives of flowers and their pollinators have evolved together. Compare these lists of their characteristics and note the similarities.

Pollen and nectar produced at night
Strong musty odor
Large and conspicuous flowers
Dull color, often whitish
Flower tubular with anthers protruding or brush-like

Nocturnal foraging
Good sense of smell
Large eyes for orienting
Probably color blind
Approach flower from air
Large body size compared to other pollinators like bees and butterflies
Elongate snout
Protusible tongue for probing deep into flowers
Hairs in neck region rough-textured so as to pick up pollen

Not only do Leptos and other nectar-feeding bats pollinate saguaros, but they also pollinate other culturally important plants such as bananas, avocados, agaves (from which tequila is made), dates, figs, mangoes, and peaches. The wild plants are used for improving the cultivated stock. The fruits of the columnar cacti (such as the giant saguaro seen many cowboy movies) are an important food item for Native Americans.

Try This! Journaling Questions
Think of the ways that bat-pollinated plants are adapted for bats. Think about these:

How might their odor help attract bats?
Why might the flowers be white?
How might the shape of the flowers help the flowers?

Now think of the ways bats are adapted to find and feed from bat-pollinated plants.

Why might their noses be long?
Why might the tongues be so long?
How do their long neck hairs help the bats? How do they help the saguaros?