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Art Lander’s Outdoors: An Iconic pollinator, Monarch Butterflies are suffering alarming population decline

This time of year vegetable and flower gardeners are receiving seed catalogs in the mail and planning for the spring planting season.

Across rural Kentucky and in suburban neighborhoods adjacent to farms, woodlands, and overgrown fields, a familiar old friend is growing noticeably absent.

The Monarch Butterfly (Danaus plexippus), whose beauty and agility in flight thrills nature lovers and gardeners alike, is in danger of disappearing. Their numbers have plummeted by about 90 percent over the last 20 years.

Monarch Butterfly (Photo from Flickr Commons)

Loss of breeding habitat, overwintering habitat, intensive mowing, the widespread use of herbicides used in growing no-till corn and soy beans, and other anthropogenic factors are believed to be factors in the decline of the Monarch Butterfly and other pollinators.

Endangered species

Last July, this iconic butterfly was placed on the endangered species list.

The U.S. Fish and Wildlife Service (USFWS) provides national leadership in the recovery and conservation of our nation’s imperiled plant and animal species, working with experts in the scientific community to identify species on the verge of extinction and to build a road to recovery to bring them back.

The USFWS works with public and private partners to protect important habitat, and increase species’ populations and reduce the threats to their survival.

Posted on their website, as of January 3, the USFWS said there were 504 endangered animals in the U.S., including 75 insects. In Kentucky, the Monarch Butterfly is one of 35 endangered animals.

The Monarch Butterfly travels long distances to complete its life cycle. They leave Kentucky and other states in the region in the fall, and head south to wintering grounds.

Huge colonies use air currents to travel as far as 115 miles a day to the Sierra Madre Mountains west of Mexico City where they spend the winter in cool and wet oyamel fir forests, an endangered forest-type, on mountain tops at elevations up to 10,000 feet.

A Monarch Butterfly catepillar (Photo from U.S. Fish and Wildlife Service)

Some butterflies in the eastern population join the south Florida non-migratory population. Others remain in the southern U.S. during the winter months.

While in their wintering grounds the Monarch Butterfly feeds on and reproduces on milkweed plants.

Once the winter breeding season is over in March, the newly-hatched butterflies start the annual migration cycle over again, taking to the air for the long trek back north.

Biologists and citizen scientist volunteers capture and tag the Monarch Butterfly throughout its range. Each tag consists of a small sticker displaying a unique code, which identifies the tagged butterfly and where it originated.

The length of Monarch Butterfly migrations is astounding. In the fall of 2021 the Kentucky Department of Fish and Wildlife Resources (KDFWR) reported that a female Monarch Butterfly tagged at Perryville Battlefield State Historic Site, in western Boyle County, was found months later, 1,600 miles to the south, at the El Rosario Butterfly Preserve.

The Perryville Battlefield State Historic Site is one of several areas in Kentucky where pollinator-friendly habitat restoration programs are underway.

“This is a very rare and exciting occurrence,” said Michaela Rogers, an environmental scientist with KDFWR. “With the help of our partners, we have tagged more than 600 monarch butterflies in the last several years. This is our first recovery.”

The El Rosario Butterfly Preserve is the largest and most visited sanctuary within the 217-square mile Monarch Butterfly Biosphere Reserve. Millions of monarch butterflies from eastern North America overwinter there, clustered together in the high-elevation fir forests.

Life history

Art Lander Jr. is outdoors editor for the Northern Kentucky Tribune. He is a native Kentuckian, a graduate of Western Kentucky University and a life-long hunter, angler, gardener and nature enthusiast. He has worked as a newspaper columnist, magazine journalist and author and is a former staff writer for Kentucky Afield Magazine, editor of the annual Kentucky Hunting & Trapping Guide and Kentucky Spring Hunting Guide, and co-writer of the Kentucky Afield Outdoors newspaper column.

The Monarch Butterfly, a member of family Nymphalidae, with more than 6,000 butterfly species worldwide, may be the most familiar North American butterfly.

Its range includes Hawaii, Australia, New Zealand, Spain, and the Pacific Islands. Six subspecies and two color variations have been identified.

The iconic pollinator species is easily recognizable, with black and orange wings, with a white pattern. Its wingspan is 3 1/2 to 4 inches.

The Monarch Butterfly was originally described by naturalist Carl Linnaeus in 1758.

Its life cycle has four phases: egg, larva, chrysalis (pupa), and adult.

From egg to adult takes 22 to 37 days, depending on the temperature.

Up to four generations are produced in one calendar year, with breeding taking place in its overwintering habitat and the states and Canadian provinces where the eastern population spends the warm months of the year.

The Monarch Butterfly must have access milkweed plants to complete their life cycle. Without them they can’t survive.

So a habitat restoration program must include establishing and encouraging several species of milkweed plants, genus Asclepias.

There are nine species of milkweed plants native to Kentucky, with the most widely distributed and arguably most important, being the Common Milkweed (Asclepias syriaca) and the Butterfly Weed (Asclepias tuberosa).

Females lay eggs on milkweed plants, which are the food source for the caterpillars that emerge from the eggs. Then the caterpillars form a chrysalis where the pupa undergoes its transformation into an adult. Upon emergence, the adults consume nectar for fuel and begin the life cycle all over again.

A tagged Monarch Butterfly (Photo from Monarch Watch)

In eastern North American populations, overall wing size and the dimensions of wings vary. Males tend to have larger wings than females, and are typically heavier than females. Both males and females have similar thoracic dimensions.

Females tend to have thicker wings, which is thought to convey greater tensile strength and reduce the likelihood of being damaged during migration. Additionally, females have lower wing loading than males, which means females require less energy to fly.

The Monarch Butterfly is capable of distinguishing colors based on wavelength only, not intensity. This phenomenon is termed “true color vision.” This is important for seeking nectar for nourishment, choosing a mate, and finding milkweed on which to lay eggs.

Kentucky’s Monarch Butterfly conservation plan

KDFWR and other conservation agencies have responded to the declines with increased efforts at education, research and habitat improvement for pollinators.

Kentucky’s Monarch Butterfly Conservation Plan is a roadmap for helping this species recover. The Kentucky Wild Program of the KDFWR hosts annual events each fall from late August through early October to capture, tag and collect data on the migrating Monarch Butterfly.

At these, and other Kentucky Wild events, volunteers go into the field and work side by side with researchers working to help wildlife that face threats in our state. To learn more about the Kentucky Wild Program, visit fw.ky.gov.

Establishing and encouraging native perennial milkweed plants on your property is a good way to benefit the Monarch Butterfly, and help restore populations of this iconic pollinator.

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