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Low counts worry many after a sparse summer
Through the spring and summer, it’s a question that has worried naturalists and those who just like to see the insects drifting on the breeze. People around Cape May County say they have seen far fewer of the bright green, orange and black caterpillars this year, and the same goes for the distinctive orange and black adult butterflies.
Pat Sutton, a local author and naturalists who teaches courses on creating wildlife-friendly gardens through the Nature Center of Cape May, said she has only seen one caterpillar in her garden this year, and only one or two butterflies.
“That freaks me out,” she said. “Normally I have hundreds.”
It’s not just the low numbers locally that have people worried. This spring, the World Wildlife Fund Mexico reported record low numbers of the butterflies at their winter grounds in the mountains northwest of Mexico City, and monarch watchers nationally have expressed concern about the future of the species. Naturalists are not saying they are close to extinction, but the alarm is consistent and widespread.
Mark Garland, the communications director for the Monarch Monitoring Project in Cape May County, said Tuesday that it’s probably too soon to panic.
“We want people to be concerned, but we don’t want them to give up,” he said.
Continuing into October, monarchs from throughout the Northeast will be funneling through Cape May County on a unique journey that will take them thousands of miles to Mexico. For more than 20 years, the Monarch Monitoring Project has been tracking their numbers during that migration. Data from two weeks this year have been posted on the project’s website. So far the numbers are low – far below last year – but they are still better than the numbers from four other years on record for the same dates.
It’s still very early in the migration, Garland said.
“We’ve been hearing doom and gloom from lots of people,” he said Tuesday. “It’s been a low year, but it’s not by any means the worst ever.”
Garland said people tend to remember the big years, when there are monarchs everywhere, or when they have seen trees coated in butterflies in September. It is so dramatic an image that people often don’t realize how rare an occurrence that is, he said.
His project numbers are more rigorous, he said, and give a clearer picture of the population.
Over nine weeks each year, the monarch monitors keep track of how many butterflies are seen in an hour. The number was 6.95 the first week and 6.21 the second. Last year at this time, those numbers were 16.87 and 141.7, respectively. But last year saw far more monarchs than usual, although it was not a record-breaker. That goes to 1999, according to the project’s posted data, when for nine weeks observers saw an average of 359.8 monarchs an hour. In the fifth week of the migration period of that year, the monitors counted an average of more than 1,536 monarchs an hour.
Last year’s survey was cut short by Hurricane Sandy. Roads used in the census route were closed by the storm.
The project counts the number of monarchs seen around Cape May Point, driving a six-mile route at 20 miles an hour three times a day from Sept. 1 until Oct. 31.
According to a blog kept by the Monarch Monitoring Project, Sept. 15 saw an increase in the number of migrating butterflies seen, up to 12 an hour, and project members are hoping the increase will continue through the season.
Sutton said this week that she has been hearing from people worried about the low monarch numbers in the county and beyond.
There are two populations of monarchs in Cape May County: the resident butterflies that live and breed here during the spring and summer, and the migrating insects that pass through this time of year.
Sutton said there were decidedly fewer resident insects this year; however, some of those resident insects are still laying eggs, trying to fit in another generation before migrating south.
Locals have long heard about the amazing journeys of wildlife migrating through the county – red knots flying from South America to the arctic, or the huge number of hawks that head south in the fall.
But in some respects, the monarch’s journey is unique. Not least of all, the individual insects heading to their winter grounds this year have never been to Mexico. For them, generations have passed over the summer. Usually, it was their great-great-grandparents that made the trip north. There is some biological trigger – Garland said scientists still don’t know exactly what – that tells this generation to head south. Although they have never been there themselves, they return to the same area, within a few hundred yards of where their forbears left the spring before.
The migrating generation also lives a lot longer, not only making it to the Mexican mountains, but also heading back north to breed again.
The butterflies have no protection against freezing temperatures, Garland said. Their winter habitat is similar to a refrigerator – cool and dry, but not freezing, slowing their metabolism so they live through the winter.
Multiple causes of decline
Scientists say all of the butterflies east of the Rocky Mountains head to the same spot, a mountainous area on the border of Michoacán and Mexico state. It’s a preserved area, listed as a World Heritage Site, and seen as vital to the survival of the species, but there are still concerns about illegal logging and encroachment, ironically including from overeager ecotourists.
It was there that wildlife advocates reported the winter numbers were the lowest on record, taking up 2.9 acres in the preserve. At one time the overwintering numbers took up an area 10 times that.
But according to numerous sources, including Garland and Sutton, a more pressing concern for the species is found well to the north, in the American Midwest.
Changing technology and economics mean today’s cornfields and other major crops are far different than they were generations ago. While the image of the family farm remains, with tilled fields separated by scruffy patches of weeds or woods, now more farmland is cultivated as a huge expanse of a single crop, often soybeans or corn.
Monarch butterflies and other species made their living on those scruffy margins, where the milkweed the species depends upon to lay its eggs grew wild.
Meanwhile, demand for corn for ethanol has meant areas that were once grassland or left wild are coming under the plow.
Sutton, Garland and other naturalists throughout the country say a larger problem is genetically manipulated crops that are resistant to herbicides. Once, some milkweed would survive within the corn rows, but today, genetically manipulated crops such as those marked as “Roundup Ready” are not killed by the broad spectrum herbicide glyphosate. That allows a wider use of the chemical by farmers, killing off the competing weeds and ensuring that more fields are monocultures.
A spokesman for Monsanto, the company that manufactures Roundup, told the New York Times in July 2011 that scientists are still learning about how agriculture in Iowa affects the monarch population. In the same story by Andrew Pollack, sources cite the Cape May numbers as evidence that the monarch population is fluctuating rather than declining.
But that story cites a number of scientists who expressed worry about the monarch habitat and the increasing use of genetically engineered crops.
What to do locally
Sutton said she has taught gardening with indigenous plants for 30 years and is not about to give up now. She pointed to the number of lawns given over to close mown grass and non-native trees and shrubs, which offer little or nothing to native birds and insects. Planting some species of milkweed, such as swamp milkweed or butterfly weed, and providing flowers for nectar may not look as manicured, she said, but will be beautiful and inviting to hummingbirds, dragonflies, butterflies and other species.
According to Garland, this year’s weather may be having a considerable impact on the number of butterflies as well. He said the cool, rainy spring and other weather patterns may have meant the monarch generations were off to a slow start.
He said monarch lovers should not give up hope.
“There’s a lot of concern for the population, but like many insects, they can rebound very, very quickly,” Garland said. On a phone interview on a sunny, chilly day, while out in the field in Cape May Point counting monarchs, he suggested that if more people become interested in wildlife gardens, it could provide habitat throughout the United States.
Sutton is more worried.
“So many things are going on right now that are knocking back the monarchs,” she said. “I keep trying. I’m not a pessimist. But I’m really, really upset with what I’m seeing.”
This winter she will present a series of workshops on gardening for wildlife at New Jersey Audubon’s nature center on Route 47 in Middle Township. The first is Saturday, Feb. 28.
In the meantime, counters for the Monarch Monitoring Project will still be slowly driving their route each day and reporting the data.
The Nature Center of Cape May plans to present a program on the monarch butterfly 10:30 a.m.-noon Saturday, Oct. 6 that will include tagging a butterfly as part of the monitoring program. The cost to members is $10 for adults and $5 for children age 3-12; for nonmembers the cost is $15 for adults and $8 for children 3-12. Admission is free for children under 3.