BATS AND COLUMNAR CACTI

There are 70 species of columnar cacti in Mexico. Two-thirds of those species have blossoms which appeal to foraging bats because of their design, nectar and pollen abundance and nocturnal blooming schedules. Some of the columnar cacti species are bat dependent. Bats share the pollination of others with birds, bees and other insects.

A National Geographic article in 1991, The Cactus Connection, and a number of articles in BATS, the magazine of Bat Conservation International, describe the meticulous research which has established bat-cacti connections in Mexico and Peru. Those articles are listed below in References.

Some of the bats that pollinate columnar cacti and plant their seeds also pollinate and seed-disperse agave plants.

Diving deep; a nectar-drinking bat. A visit can last less than a second.

The pitaya, a bat-pollinated columnar cactus which grows in Mexico and the southwestern United States, is planted in village gardens and is prized for its fruit.

The saguaro cactus, also bat pollinated, grows in Mexico and southwestern Arizona. It is the largest cactus in the United States, reaching 35 to 50 feet in height (10.6 metres to 15.2 metres). It was and is prized by the Papago Indians for its fruit. The fruit was eaten fresh and a syrup was strained from cooked fruit which was stored in clay containers. The fruit was also made into jam, flour, gruel and candy. Fruit pulp was dried. A fermented drink for ceremonial events was made from the fruit.

Lesser long-nosed bat, a columnar cactus blossom pollinator

Clay jars of saguaro fruit syrup and balls of dried fruit pulp were traded by the Papago Indians for pottery and grain.

The saguaro gave much more than fresh fruit and syrup to the Papago Indians. The long ribs of the cactus became part of doors, walls, ceilings, shelves, furniture, cradles, carrying baskets, small animal traps, bird cages and doll houses. A broken bone could be stabilized for healing with a saguaro rib.

Ceremonial drinking and vomiting of a saguaro cactus fruit wine brought rain. Saguaro gruel prompted a mother's milk to flow more readily.

Gary Nabhan, author of The Desert Smells Like Rain, said that the saguaro cacti are still regarded by the Papagos as fellow tribesmen. In tribal stories, lost children live again as saguaros in intricate tales involving the activities of tarantulas, crows, gila monsters, rattlesnakes, eagles, rabbits and Indians. In one legend, the first saguaro sprouted from the buried bones of a child.

Mexican long-nosed bat, a columnar cactus blossom pollinator

The necessary ingredients for photosynthesis in plants are: sunlight, carbon dioxide, water and chlorophyll.

Photosynthesis in most plants takes place in leaves. In the leafless cacti photosynthesis takes place in its green skin where chlorophyll resides. Cacti live in drought conditions and must conserve moisture so their skin pores cannot be open during the day to receive carbon dioxide. Carbon dioxide is admitted into the plant at night when the plant pores open.

There is no sunlight at night and no photosynthesis. This problem is overcome in cacti by the overnight storage of carbon dioxide as crassulacean acid which can be used during the day in place of carbon dioxide.

Pallid bat, a surprise cactus flower pollinator

The pallid bat is an insect-eating bat of the North American desert. It is well-known for its ability to kill and eat poisonous scorpions without being adversely affected. During Theodore Fleming's research in the Sonoran Desert, he mist-netted pallid bats with pollen-frosted faces and conjectured that the bats might be drinking cactus nectar. A sophisticated test using minute bits of pallid bat tissue revealed that Fleming's conjecture was correct.

Greater long-nosed bat, a columnar cacti pollinator

References:

Cruse-Sanders, Jennifer (2005) The Pitaya Connection, BATS, Volume 23, No. 1, Spring

Fleming, Theodore H. (1989) Climb Every Cactus, BATS, Volume 7, No. 3, Fall

Fleming, Theodore H. (1991) Following the Nectar Trail, BATS, Volume 9, No. 4, Winter

Research Reveals Key Ecological Role of Curacao's Nectar Bats (1995) BATS, Volume 13, No. 3, Fall

Sahley, Catherine (1995) Peru's Bat-Cactus Connection, BATS, Volume 13, No. 3, Fall

Tuttle, Merlin, D. (1991) The Cactus Connection, National Geographic Magazine

Valiente-Banuet, Alfonso, et al (1996) Nectar-Feeding Bats in the Columnar Cacti Forests of Central Mexico, BATS, Volume 14, No. 2, Summer

Wild, Peter (1986) The Saguaro Forest, Northland Press, Flagstaff, Arizona

The bat species identified in the above research are:

Lesser long-nosed bat (Leptonycteris curasoae, also known as L. sanborni, L. yerbabuenae)

Greater long-nosed bat (L. nivalis)

Mexican long-tongued bat (Choeronycteris mexicana)

Peruvian long-nosed bat (Platalina genovensium)

Jamaican fruit bat (Artibeus jamacensis)

Pallid bat (Antrozous pallidus)

The columnar cacti identified in the research are:

Organ pipe, cardon, saguaro, pitaya, tetcho, viejo, Stenocereus weberii, S. pruinosus, Neobauxbauinia macrocephala, N. mezcalaensis