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Our wet and mild winter has migratory creatures and seasonal blooms arriving in San Antonio early this year. According to bat, butterfly, bird and bloom specialists, we’re running seven – 10 days ahead of schedule.
Monarch butterflies, which typically start showing up in Texas en masse in late March, have been spotted regularly since early in the month. Over at Bracken Bat Cave, maternal bats who overwinter in Mexico also arrived ahead of schedule.
“This year they were 10 days early,” said Fran Hutchins, Bracken Bat Cave coordinator and a Texas Master Naturalist. Hutchins added that the insect eating mammals began showing up in waves around February 21. “There hasn’t been a lot of research on specific dates of their comings and goings,” said Hutchins, explaining that he inadvertently noticed the increase in bat population while completing an overwintering survey at the Cave.
The pattern holds for wildflowers and birds. “It’s definitely early,” said Andrea Delong-Amaya, director of Horticulture at the Ladybird Johnson Wildflower Center. “But in terms of what’s normal, it’s hard to say. It just hasn’t been as cold.” Reports of the Golden Cheeked Warbler, our local endangered songbird, arriving a bit early have made the rounds at the San Antonio Audubon Society, according to Martin Reid, an avid birder and environmental consultant.
“It’s a mixed bag: some of our resident birds are showing signs of breeding activity slightly earlier than usual–probably related to rain,” he explained. “But it doesn’t seem to have much effect on the wintering birds.”
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Is it the warmth or the wet that drives the timing? Depends on who you ask.
“Pepper weeds, bluebonnets, prickly poppies–those are all early. Not because of temperatures, but because of rain,” said Matt Reidy, Texas Parks and Wildlife Biologist. “When you get the moisture, that’s what determines what you’re gonna get when.”
Many point to climate change for the advance of the season. Interestingly, February 2012’s average high temperature was about the same as–actually .07 degree less than–the historic average of 66 degrees. Yet, the average LOW temperature for the month was 4.5 degrees higher than average.
Minimum temperatures are especially impactful to seed germination and plant growth. Seeds and plants require a certain soil temperature in which to germinate and thrive. Savvy gardeners know to put a heating pad under setting seeds to expedite sprouting. Higher average minimum temperatures translate into faster growth, and an earlier season.
At the Children’s Garden at the San Antonio Botanical Garden, volunteers planted tomatoes the first week in March–“weeks early,” according to David Rodriguez, Horticulture specialist for the Texas Agrilife Extension. Those tomatoes will likely be ready the first week in May. “Everything’s off,” said Rodriguez, referring to Nature’s unpredictable timing.
Earlier this year, the USDA announced changes in plant hardiness zones, moving parts of San Antonio into the same planting zone as Houston and Corpus Christi. Some San Antonio zip codes moved from zone 8b, with annual lows of 15 – 20 degrees, to zone 9a, with annual lows of 20-25 degrees.
The redrawn maps (plug in your zip code and find out your zone here) seem to be telling us something that birds, butterflies and bats have known for awhile: it’s just not as cold as it used to be.