Each plant can produce about eight liters of nectar, he added, which explains why the nectar bats rely almost solely on agaves as a source of food.
Nectar bats' dependency on agaves isn't all one-sided. Keeley said the large genetic diversity of agave species is thought to result from pollination by bats across a wide swath extending from central Mexico to the southern United States.
In three days of searching, Keeley's team identified four agave clusters in the Chisos, Davis, Glass, and Chinati mountain ranges of Texas.
"We set up nets around the agaves, and then sleep next to them," Keeley said. "Every few hours we get up to remove the bats and tag them."
However, the team failed to find any roosting sites of the greater long-nosed bats this year. One possible explanation is that the bats don't always return every year to roost in the Chisos Mountains. Keeley hopes to have better luck next year in the three-year study.
"We also didn't have access to the best agave clusters in the Glass and Chinati ranges because these were on private land," he said, adding that next year the team will try to get the landowners' permission to survey and study those areas.
Meanwhile, the team is encouraging that similar surveys and research efforts be conducted in Mexico in the coming winter.
The study is part of Programa Para la Conservacíon de Murciélagos Migratorios (Program for the Conservation of Migratory Bats). The program is a collaborative project by American and Mexican scientists to protect bats that migrate annually between the two countries.
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