Friday, April 5, 2019

Hunting the ancient agave

Agaves spend much of their lives as toothy, spikey plants we avoid while hiking. Most agaves bloom only once, throwing their heart and carbohydrates into raising an exorbitant stalk of fragrant flowers that ripen into dry fruits stacked with flat, black seeds. We're captivated by the transformation from spikey to florescent.

Wendy Hodgson makes agave seeds fly in Cascabel.
However, for over 8,000 years, people have harvested agaves just before flowering, usurping the carbohydrates in the stem for human food and beverage. The leaves also provide fibers for rope, baskets, bags and sandals.

Although people have used agaves continuously in Mexico, the plants' cultivation and culture faded from what is now Arizona by the 16th century. Residents of the Middle San Pedro Valley have periodically wondered if we could grow agave in our area. After all, Sobaipuri Native American agave fields dot our community, and wild agaves grow in the valley.

When this question came up again last winter, we learned that survivors of pre-Columbian cultivated agave had recently been found in our area. Wendy Hodgson and her colleague Andrew Salywon, both with the Desert Botanical Garden, named the new species Agave sanpedroensis. Wendy and Andrew even suggested that this low-water-use crop could be revived to diversify agriculture and stimulate new industries in the U.S. Southwest.

Agave sanpedroensis.
We contacted Wendy, who was as eager as we were to connect. In January 2019, she told a packed Cascabel Community Center about the eight (and counting) species of formerly cultivated agaves she and her colleagues have found. In February, dozens of people braved blustery weather on a follow-up field trip. Wendy explained how she recognizes the different species of agaves and outlined how we can help her survey the plants in our valley.

Wendy and Andrew work with archaeologists, who have documented extensive agave fields at many sites in central and southern Arizona. Rows of rocks along contour lines slowed runoff across the fields and rock mulch piles reduced evaporation. Near the fields, archaeologists find knives used for removing leaves and roasting pits where agave stems, or "heads," were baked to sweetness.

The plants we see today are genetically identical to those the Sobaipuri and other groups developed to suit their needs. Unlike their wild relatives, these cultivated agaves produce little or no seed. Instead, the plants reproduce vegetatively, usually by pupping, to produce offspring identical to the parent. Cultivated agaves are also sweeter than their wild relatives and their leaves are easier to cut.

After surviving drought, insects, and rodents for centuries--or millennia--climate change and development threaten these rare plants. As cultivated crops, they fall into a protection gap: the Endangered Species Act protects only wild species and the Archaeological Resources Protection Act protects only inanimate artifacts.

Wendy fears that these recently discovered, living storehouses of information on people, culture, and plants could be lost. She is helping residents of the Middle San Pedro Valley learn about the ancient agaves in their area and work to protect them.

Wednesday, April 3, 2019

You can help agaves and bats in southern Arizona

Step outdoors on a warm southern Arizona night and you might be swept up in what naturalist Ralph Waldt calls a "bat tornado" of winged mammals. Residents routinely wake to find that the clouds of bats have drained their hummingbird feeders overnight.

Although nectar-feeding bats are most noticeable in the area, only two of the 30 bats native to Arizona feed from flowers; most Arizona bats eat insects. Both nectar-feeders, Choeronycteris mexicana (Mexican long-tongued bat) and Leptonycteris yerbabuenae (lesser long-nosed bat), visit Cascabel during warm months.
World-wide, the more than 1,300 bat species represent almost a fourth of the over 5,400 mammals. Bats have the agility to catch and eat prodigious amounts of night-flying insects and to pollinate night-blooming flowers atop tall agave stalks and columnar cacti.

Agaves and cacti provide bats a nectar meal in exchange for pollen the bats inadvertently carry among plants. The bats move with the blooms, from southern Mexico in winter to the grasslands of northern Mexico and the southern U.S. in summer.

This elegant partnership evolved over millions of years and is crucial to the survival of both partners. Currently, bats and agaves are both threatened by climate change and the loss of agaves to land clearing, development, and the harvest of wild agave for bacanora, the agave liquor of Sonora.

The lesser long-nosed bat is the more imperiled of the two nectar feeders in this area. Although this bat was removed from the endangered species list by the U.S. Fish and Wildlife Service in 2018, these pollinators are still at risk due to the decline of their nectar sources.

The Borderlands Restoration Network (BRN), in Patagonia, Arizona, works with many partners to protect bats by increasing their agave food supply. You can help both agaves and bats by participating in two of these projects.

BRN and volunteers track the effects of climate change on two native agaves in our area through the USA National Phenology Network's Flowers for Bats campaign. Many plants are blooming earlier as our climate warms. If bats migrate from Mexico on their usual schedule, but Agave parryi and Agave palmeri bloom earlier, the bats might arrive to find nothing to eat.

BRN replants agaves lost from the southwest U.S. and northwestern Mexico as part of Bat Conservation International's Agaves for Bats campaign. Each year, BRN collects agave pups and seed to grow thousands of agaves for planting by landowners.

If you haven't experienced a bat tornado, keep your hummingbird feeders full for the night shift, watch when agaves flower in your area, and plant some agaves at your place. Then step outdoors on a warm southern Arizona night and wait for the whirlwind.