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Posts Tagged ‘Monarch Butterfly’

The Mighty Migration of the Magnificent Monarch

Saturday, November 21st, 2020

by Mary Emich, Assistant Biologist

Monarch butterfly refueling in Cape May as it prepares for fall migration to Mexico.
Photo courtesy of Lindsey Brendel.

Over the last decade, the monarch butterfly, Danaus plexippus, population has declined. Climate change has affected weather conditions, the winters are colder and wetter while the summers are hot and drier. This disturbs their survival rate, especially during their long annual migration. Other factors like pesticides and a loss of habitat to human development further threaten the monarch population.

The monarch butterfly migration is mysterious and magnificent. Every fall season, monarch butterflies travel thousands of miles from their breeding grounds in the United States and Canada to escape the cold winters. Monarchs in Eastern North America spend the winter months in the Transverse Neo-Volcanic Mountain Range in Michoacan, Mexico. To reach their destination, monarch butterflies migrate over 3,000 miles, utilizing the air currents and making many stops along the way.


New Jersey’s Key Role in the Monarch Migration

Tuesday, October 4th, 2016
The Garden State annually hosts swarms of southbound Monarch Butterflies

By: Kendall Miller, Project Coordinator

Monarch butterfly refueling in Cape May as it prepares for fall migration to Mexico. Photo courtesy of Lindsey Brendel.

Monarch butterfly refueling in Cape May as it prepares for fall migration to Mexico. Photo courtesy of Lindsey Brendel.

Monarch has been a conservation buzz-word for the past decade when data revealed that the population had appeared to be on the decline. Then in 2013, the population of wintering monarch butterflies in Mexico reached an all-time low that jolted scientists, environmentalists, and enthusiasts across the nation.

Monarch abundance in wintering grounds is measured as area in hectares. They roost in large colonies in the Transvolcanic Mountains in Mexico. The 2013-2014 overwintering population experienced the lowest recorded area to date, at 0.67 ha. From

Monarch abundance in wintering grounds is measured as area in hectares. They roost in large colonies in the Transvolcanic Mountains in Mexico. The 2013-2014 overwintering population experienced the lowest recorded area to date, at 0.67 ha. From

This marvelous and iconic lepidopteran is found throughout the continental United States. Its 3,000 mile long migration is an amazing natural phenomenon. The news of population declines in Mexican wintering sites inflamed concern and incited action. Many groups have since created partnerships, implemented programs, and conducted research to understand more about this widely known yet still mysterious insect.

The location of wintering monarchs was a complete mystery until 1975 when the remote wintering sites were discovered in transvolcanic mountain ranges in Mexico. Much is still to be discovered about the migration pathways even within the United States, and doing so will answer questions which will inform conservation and management of this species which faces multiple threats during every aspect of its expansive journey.

Glider pilots have observed monarch butterflies at an altitude of 1200 meters (Gibo 1981).  Migratory flights at these altitudes can allow insects to disperse against wind directions found at lower altitudes.

But first, a little bit about biology and the annual life cycle

The monarch’s annual lifecycle is a really marvelous and multifaceted journey – it can be thought of as a multigenerational relay race.

From the Xerces Society. Map depicts the known general migration routes of monarch butterflies.

From the Xerces Society. Map depicts the known general migration routes of monarch butterflies.

Monarch butterflies, just like other lepidopterans, metamorphosis from caterpillar to butterfly. The big thing that sets them apart is the migration they make annually. (Although there are many other species of moths and butterflies, and other insects as well that migrate – the monarch is arguably the most well recognized example

Temporal cues and an innate determination drive these ambitions fliers to travel as far north as the Canadian border. In the search for milkweed and favorable temperatures – possibly to avoid disease pressures – monarchs fly north to reproduce and recolonize across North America each year.

They leave overwintering grounds in Mexico in early spring. Along their route the monarchs will mate and reproduce. Their lives are lived within a short couple weeks, and their offspring will continue the migration northwards in search of food and milkweed.

When the seasons shift in late summer and early fall, the last generation of monarchs will begin a southbound journey, instinctively traveling to wintering sites in Mexico (there are a few populations that overwinter in California and Florida – but the large majority are thought to return to Mexico). This generation will be responsible for making the longest trek of the migration to wintering grounds. These monarchs enter reproductive diapause – the state where the body will temporarily pause reproduction – until the following spring. These monarchs will spend the winter roosting in trees in Mexico until spring when they will take up the first leg of the relay north.

This last generation from the previous year now makes up the first generation of the present year – and will pass the baton on to their offspring as the cycle starts anew.

The role of the Garden State

So what part does New Jersey play in the grand scheme of this massive population?

The Atlantic coast migration was once characterized as “aberrant”, a fluke of sorts – the result of southbound monarchs being blown off course. Research and monitoring conducted in Cape May and published by Walton and Brower (1996) in The Journal of the Lepidopterist’s Society have supported the hypothesis that a migration along the Atlantic coast is part of the monarch’s normal fall migration.

What does a monarch have in common with a hawk?
Walton and Brower (1996) have proposed the idea that monarch butterflies could display similar flight patterns to that of migrating hawks. Utilizing an elliptical flight path during the fall south-bound migration, the model suggests that these birds take advantage of prevailing winds by first traveling east and then west, thus providing a quicker and more energetically-efficient route. Could monarch do the same?

New Jersey – Southern New Jersey and Cape May in particular – is historically recognized as a concentration area for southbound monarchs during the fall migration to wintering grounds. Hamilton (1885) [expressed his wonder of the] characterized the September 1885 monarch migration at Brigantine, New Jersey as “almost past belief … millions is but feebly expressive … miles of them is no exaggeration.” Reports of trees “more orange than green” is no exaggeration, as monarchs congregate en masse in prime roosting spots to warm and rest.

But why is this important? The monarchs migrating through Cape May seem to be representative of the entire North Eastern population – and therefore it offers the opportunity to collect quantitative data on populations in addition to other annual counts. The fourth of July counts focus on quantitatively monitoring the Northeastern population of monarchs as they arrive in the spring and summer. Therefore this data can be used to analyze population trends.

What part can New Jersey residents play?

Monarchs are traveling across New Jersey May through October. There are plenty of simple ways you can help protect this iconic species.

  • Plant native species of flowering plants – monarchs and other insects (like bees) rely on a healthy diversity of nectar sources. Planting a wildflower garden is a quaint, ecological-friendly way to create habitat, and not to mention, make less work watering and money spent purchasing plants. Check out the Native Plant Society or Jersey Friendly Yards to get started.
  • Share this article, talk about environmental issues, and get informed. Show your support and share your concern for the wellbeing of this (and other) species!
  • Rear monarchs. At home or in classrooms, rearing wild monarchs and releasing them is a rewarding and educational way to contribute.
  • Participate in tagging and monitoring projects. Monitoring and tagging projects take place in the summer and fall for New Jersey Monarchs. You can also contribute simply by reporting your sightings on these websites.



From Birds to Butterflies

Tuesday, September 1st, 2015
Why Should We Care About Endangered Species?

by Lindsey Brendel, Technician

Piping plover sheds its breeding plumage as it readies for migration to wintering grounds. Photo courtesy of Northside Jim.

Piping plover sheds its breeding plumage as it readies for migration to wintering grounds. Photo courtesy of Northside Jim.

As summer melds into early autumn, migration comes underway.  The nesting season for beach nesting birds is drawing to a close, and shorebirds can be seen feasting along the beaches as they fuel their bodies for their journey south. This was my first season working with endangered beach nesting birds.  Watching territory disputes and courtship displays early in the spring transitioned into nest searching and anxiously awaiting the hatch dates of our incubating pairs.


I feel an incredible sense of pride in the birds that have survived to fledge. It is impossible not to become attached when you spend weeks closely watching tiny chicks who take a tumble, are then brooded under their parents’ bodies, and finally mature into independent, fully feathered young birds, preparing for their first migration.


The start of fall migration also marks the reason I originally came to New Jersey one year ago, that being to study the monarch butterflies’ southward migration along the Atlantic coast. Last year was my first season as a field technician with the NJAS Monarch Monitoring Project, a research and education program that performs daily censuses of migrating monarchs, public tagging demos, and educational outreach. The project runs from September 1 through the end of October, and I will be back and working with the team again this fall.

Monarch butterfly refueling in Cape May as it prepares for fall migration to Mexico. Photo courtesy of Lindsey Brendel.

Monarch butterfly refueling in Cape May as it prepares for fall migration to Mexico. Photo courtesy of Lindsey Brendel.

For me, I see the monarch butterfly as the perfect gateway animal into the larger world of conservation.  Their widespread range in North America, and easy recognition means that many people are already familiar with this royal insect. Many school age children have learned about their life cycle in school, and may have even raised caterpillars and been witnesses to metamorphosis. Even if you have never learned about monarchs, their bright and bold appearance, sporting the warning coloration of orange and black, make them hard to miss.


That is one of the big differences I see between the beach nesting birds I have grown to love this summer and monarch butterfly. Cryptic and camouflaged are words that describe our beach nesters, specifically the endangered piping plover, who, when standing still, blends in perfectly with the sandy beach landscape. When I talk to people who have gone inside the fenced areas we have on the beaches for the nesting birds, a common response that serves as their rebuttal is that they “didn’t see” any birds, so they thought it would be okay. Situations like this happen frequently, and I have found that teaching, rather than scolding, is a better use of time. I love being able to show people the birds and highlight the fenced off areas as a family zone for our feathered friends; removing any mystery as to why these spaces are off limits.


Coming from a background in the arts, outreach is the arena I feel best suited for. I have had the pleasure of leading the beach nesting bird walks at Cape May Point State Park this summer. I love being able to share with others the life of a beach nesting bird, emphasizing that it really is a family affair, and a difficult one at that. The State Park will serve as a major hub for my work this fall, as that is where the Monarch Monitoring Project holds its butterfly tagging demos, and where we teach the public about the 2500-mile migratory journey the monarch butterfly undertakes to reach its wintering grounds in the mountains of Mexico.


The beach nesting birds I have worked with this summer are endangered. Currently, the monarch butterfly is also under consideration to be listed as an endangered species. One question that comes up at both the bird walks and the butterfly tagging demos is, “Why would it matter if this species was gone?”


Sometimes it is asked with genuine curiosity, and other times it is said as a jab. Either way, it is a difficult question for me to answer, and I have to evaluate why I care. I think and worry a lot about the loss of milkweed, lack of nectar sources, and loss of wintering habitat for the monarchs all the time.  After working with beach nesting birds, I will never be able to enjoy a summer thunderstorm the same way again because I will always be picturing a tiny least tern or plover hunkered down on their nest trying to protect their eggs through the wind and the rain.


We protect things of value, but what value do these birds or this butterfly have? Why should we care about endangered species? One argument often made about rainforest deforestation is that there are possible undiscovered medicinal properties that could be cures for diseases. It is unlikely that piping plovers or monarch butterflies hold untapped medical value. So, why should we worry about their declining numbers?


Lindsey Brendel getting up close and personal with American oystercatcher chick, one of several beach nesting bird species she monitored this summer.

Lindsey Brendel getting up close and personal with American oystercatcher chick, one of several beach nesting bird species she monitored this summer.

For me, my fear is less about losing individual species, and more about the dangers of a widespread ideology where everything is treated as a commodity. I see this as the reason these two species have been pushed to dangerously low numbers and one of the hardest challenges conservation efforts have to face.  We live in a very “me centered” culture, and conservation asks us to acknowledge our place as just one of the many functioning pieces in the world around us. If we are going to be on the beach with our family, we need to understand that the least tern flying with a fish in its mouth is bringing food back for his family on that same beach. If we are going to invest in monoculture farms that heavily rely on herbicide use for our food, then we need to realize that we are taking away the food source for monarchs, and many other insect species.


Do I think compromise between humans and critical habitat for endangered species can be achieved? Absolutely. Indeed, one of my favorite parts about working with endangered species is letting go of my role as Supreme Being, and acknowledging that an insect or bird is doing something that I never could.  When a monarch butterfly emerges in the fall, regardless of the fact that it has never taken a long flight before, it starts off on more than a 2,000 mile journey to a place it has never been, but knows instinctively to navigate to. When an intruder gets too close to a plover’s nest, the adult will flop around pretending to have a broken wing, making himself look like the vulnerable and easy target, all in an effort to protect its eggs. Some of the best examples of determination and selflessness are happening right around us in the natural word, and we all have the invitation to expand, and learn, and watch it take place. That is the marvel. That is the mystery. That is where I feel the real value of protecting endangered species comes from.


Learn more:


Lindsey Brendel is a Technician with the New Jersey Division of Fish and Wildlife, who worked with Todd Pover on our Beach Nesting Bird Project.

Fight for the Flight: Monarch Butterfly Status Under Review

Thursday, January 22nd, 2015

By: Julianne Maksym, Intern 

A monarch butterfly emerges from a chrysalis in the wild. (Courtesy: US Fish & Wildlife Service)

As the summer leaves turn brown and children head back to school, flutters of black and orange wings flitter through the skies over the beaches in Cape May. As part of its yearly migration from Canada to Mexico, the monarch butterfly passes through New Jersey in search of a warmer climate for the blistery cold winter months. Multiple generations make the trek, leaving in the fall and returning in late spring.


During the summer months, the monarch can be found throughout the United States where milkweed, the species’ host plant, is plentiful. Milkweed provides nutrients to hungry caterpillars as well as space for mature females to lay their eggs. Although an adult monarch may lay up to 500 eggs in its lifetime, it has now been discovered fewer and fewer butterflies make the migration each year.


Losses of habitat and milkweed plants, the insect’s sole food source, are having tremendously devastating effects. According to a petition from butterfly advocates, the North American population has declined by more than 90 percent based on comparisons of the most recent population size estimates to the 20-year average. Numbers of monarch butterflies east of the Rockies dropped to the lowest record ever, signifying a decline of more than 90% since 1995. Monarch numbers west of the Rockies showed a similar decline of more than 50% since 1997. These figures suggest a significant predicament as the North American population represents the vast majority of all monarchs in the world. Without it, the entire species is vulnerable to extinction.


On December 29th, 2014, the U.S. Fish and Wildlife Service announced it would be conducting a status review of the monarch butterfly under the Endangered Species Act (ESA). The Service has reason to believe a listing may be necessary due to considerable evidence from a petition submitted by the Center for Biological Diversity, the Center for Food Safety, the Xerces Society for Invertebrate Conservation and Dr. Lincoln Brower. The petition stated that habitat destruction and loss of milkweed due to pesticide use are two of the most contributing factors to the declining monarch population. Other factors include disease and predation, overutilization for commercial purposes, and lack of existing conservation procedures.


To begin the status review, the Service is requesting scientific and commercial data and other information through a 60-day public information period. The Service is specifically seeking information regarding the following:

  • Subspecies’ biology, range and population trends, habitat requirements, genetics and taxonomy
  • Historical and current range, including distribution patterns
  • Historical and current population levels and current and projected trends;
  • Life history or behavior of the monarch butterfly that has not yet been documented
  • Thermo-tolerance range and microclimate requirements of the monarch butterfly
  • Past and ongoing conservation measures for the subspecies, its habitat or both
  • Factors that are the basis for making a listing determination under section 4(a) of the ESA


Starting on December 31, information can be submitted via by entering docket number FWS-R3-ES-2014-0056 in the search box and clicking on “Comment Now!” The information collection period will be open until March 2, 2015.


Until a decision has been made, take a moment to appreciate the beauty that is the monarch butterfly. Consider planting a few milkweed plants in your garden or speaking out against the overuse of pesticides. As much as the monarch butterfly’s migration is a group effort, the conservation of these beautiful creatures is even more so.


Julianne Maksym is a graduate wildlife intern for Conserve Wildlife Foundation of New Jersey.