Butterflies are among our most conspicuous and well-loved pollinators. Learning to identify butterflies is a fun and rewarding undertaking. NH Audubon participates in butterfly conservation through the Motus project tracking migration patterns and by partnering with nonprofit and state conservation organizations in the annual statewide census.
by Lindsay Herlihy, Project Biologist, July 2026
Since 2023, NH Audubon has coordinated the Capitol Area Butterfly Survey as a part of the nationwide, long-term butterfly population monitoring efforts by the North American Butterfly Association. Each year in the last week of July, teams of volunteers disperse across the greater Concord area to identify and count every species of butterfly they encounter. This joyful and fun participatory science initiative generates invaluable data which provides insight into butterfly population trends and how they are affected by habitat alterations and climate change.
Results of the 2025 Capitol Area Butterfly Survey included a total of 482 individual butterflies of 35 species. Highlights from the survey include sighting two Common Sootywing—an uncommon species in New Hampshire because we sit at the northern edge of their range. Survey participants also enjoyed close-up views of the tiny American Copper, Coral Hairstreak, and Least Skipper. The most frequently observed species was the Wild Indigo Duskywing, with 87 total individuals recorded. Among nine observed individuals of the tiger swallowtail species complex, one was identified in-hand as the newly described Midsummer Tiger Swallowtail.
Over the past three years, the total number of butterfly species observed has remained mostly constant (see Figure 1), except for the following taxonomic groups:
Swallowtails – The timing of the annual Capitol Area survey falls at the end of the normal flight period for swallowtail butterflies. Therefore, the absence of Spicebush Swallowtail butterflies in 2025 is not concerning. Giant Swallowtails are gradually increasing the northern extent of their range into NH, so their absence from the 2025 survey is also not cause for concern. A taxonomic re-classification of the Tiger Swallowtail species complex had a benign impact on the number of swallowtail species observed in 2025.
Brushfoots – This group of butterflies includes fritillaries, crescents, and admirals. This year saw a noticeable decrease in both the number of brushfoot species observed and the number of individuals of each species compared to past years.
Grass-skippers – This group of notoriously difficult to identify butterflies has shown a gradual decline in the number of species observed since 2023. With only three consecutive years of survey data, it is difficult to be certain if this decline is a true reflection of population reduction, or if the emerging trend is clouded by species identification challenges.
Survey results from 2025 indicate an alarming decrease in the number of individual butterflies observed across all taxonomic groups (see Figure 2). Many insect populations, including butterflies, experience natural boom-and-bust cycles. For lepidopterans—the order that includes butterflies and moths—this is often controlled by availability of host plant species as well as weather fluctuations. Indeed, butterfly experts suspect that butterfly reproduction in 2025 was likely impacted by the cold, wet spring coupled with the hot, dry summer of 2024. These observations over a relatively short period of time highlight the importance of routine, standardized surveys to track butterfly population trends long-term.
Concern is mounting in the scientific community about the threat of widespread insect decline. Experts note a 22% decline in butterfly populations over the past two decades, while the total population decrease across all insect taxa is currently estimated at 2% global population reduction per year. However, monitoring insect populations presents unique challenges due to their incredible diversity, difficult species identification, and natural, cyclical fluctuations in population size driven by weather conditions and resource availability.
References
De Roller CJ, Wang X, Dupuis JR, & Schmidt BC. 2025. A cryptic new species of tiger swallowtail (Lepidoptera, Papilionidae) from eastern North America. Zookeys,1228: 69-97. DOI: 10.3897/zookeys.1228.142202.
Edwards CB, et al. 2025. Rapid butterfly declines across the United States during the 21st century. Science, 387: 1090-1094. DOI: 10.1126/science.adp4671.
Montgomery GA, Belitz MW, Guralnick RP, & Tingley MW. 2021. Standards and best practices for monitoring and benchmarking insects. Frontiers in Ecology & Evolution, 8:579193. DOI: 10.3389/fevo.2020.579193.
Sanchez-Bayo F & Wychuys KAG. 2019. Worldwide decline of the entomofauna: A review of its drivers. Biological Conservation, 232: 8-27. DOI: https://doi.org/10.1016/j.biocon.2019.01.020.
Motus: The Monarch Projectby Lindsay Herlihy, Project Biologist, July 2026
The Monarch butterfly is a familiar and much-loved species, but its numbers have dropped sharply since the early 1990s. What makes Monarchs especially remarkable is their long-distance migration. No other butterfly in North America makes a journey like it, spanning multiple generations and crossing state and national borders along the way. To help reverse their decline, it’s important to better understand this incredible journey. Since 2022, New Hampshire Audubon biologists have been using the Motus Wildlife Tracking Network to gather detailed information about where Monarchs travel, how fast they fly, and how they behave during migration. Tiny, lightweight radio tags known as NanoPins allow the network’s receiving stations to pick up signals from butterflies as they pass by. This information helps scientists identify important places where Monarchs stop to rest and refuel, guiding conservation efforts and making it easier for groups across different regions to work together to protect this iconic species.
In New England, the peak of Monarch migration typically falls in mid- to late September. During that window in 2025, biologists from New Hampshire Audubon teamed up with volunteers to gently net migrating Monarchs at the Concord Community Gardens and the Massabesic Audubon Center. Each butterfly was carefully weighed on the spot to see if it was big enough to carry a tiny radio tag—Monarchs need to weigh at least 0.50 grams to safely handle one. These tags, called NanoPins, weigh about 0.13 grams, which is a big load for such a small creature. Even though Monarchs are impressively strong for their size, the team takes extra care to make sure the tags don’t interfere with their flight.
Butterflies that weighed less than 0.50 grams weren’t left out. Instead, they were given a much lighter adhesive wing tag, weighing less than 0.01 gram. Volunteer Amira Provost joined the effort this year and brought along these special tags from Monarch Watch, helping ensure even the smallest Monarchs could still be part of the study.
Miniaturizing radio telemetry tags comes at a cost: the tiny NanoPin batteries will only last for 19-21 days. That’s not nearly long enough for a Monarch to complete its incredible 3,000+ mile journey from New Hampshire to its winter home in the Oyamel fir forests. In past years, the furthest signals from tagged butterflies came from places like Virginia, West Virginia, and Maryland. To follow the butterflies farther south, the team partnered with additional researchers in 2025, including Amy O’Donnell in Maryland and Micah Perkins in Kentucky.
Together, they tagged 74 Monarchs during the fall migration—24 in New Hampshire, 25 in Maryland, and 25 in Kentucky. By working across regions, the team is now able to track Monarchs much farther along their journey than ever before, helping paint a clearer picture of how these butterflies travel from their breeding grounds in the eastern U.S. all the way to their winter refuge in Mexico.
Tracking data collected between 2022 and 2025 suggest that Monarchs generally take one of two main paths during their fall migration:
Coastal route—follows the Atlantic seaboard south before cutting west at an undetermined latitude to avoid crossing open water on their way to Mexico.
Inland route—follows the Appalachian Mountains south and slightly west; these butterflies would also need to take a westerly turn to avoid the Gulf of Mexico.
For Monarchs starting out in the Northeast, that westward turn is a key part of the journey. Early data hints that this shift may begin around the latitude of Maryland and Virginia. For instance, one butterfly tagged on Poplar Island, Maryland in late September was detected in Shannondale, Missouri just 12 days later. Another Monarch tagged in Kentucky showed a similar westward move into Missouri around the same time. As more detections come in through the Motus Wildlife Tracking Network, researchers are hoping to better understand exactly how Monarchs navigate this critical stretch of their journey.
By linking together these detection points, scientists are also starting to see where Monarchs pause along the way to rest and refuel. Many of these stopover spots are in or near large natural areas, like the Jamaica Bay Wildlife Refuge in New York and the Blackwater National Wildlife Refuge in Maryland. These places cover thousands of acres and provide plenty of nectar-rich flowers to fuel migrating butterflies. Other detection sites tend to be on fairly large properties too, typically over 500 acres in size.
But not every stretch of the journey is so welcoming. Monarchs traveling along the coast pass through some of the most developed parts of the Northeast and mid-Atlantic, where cities and suburbs have replaced much of the natural habitat they rely on. Without enough safe places to stop and find food, it becomes much harder for them to complete their long trip to Mexico.
To help fill in those gaps, New Hampshire Audubon is working with partners along the migration route to create and improve Monarch-friendly habitat. This includes teaming up with ReWild Long Island in New York and the Lower Shore Land Trust in Maryland to plant native, fall-blooming flowers that provide essential food for migrating Monarchs. These projects also give local communities a chance to get involved and learn more about conservation.
As these new habitat patches take root—especially in more developed areas—researchers will be watching to see if Monarchs begin using smaller, scattered sites as stopover spots. This “patchwork” approach could turn out to be one of the most practical ways to support Monarchs along the Atlantic coast, where large natural areas are limited. Stay tuned as this work continues into 2026 and beyond, and as we learn more about how Monarchs respond to these efforts!
As tracking technology gets smaller and more advanced, it’s becoming easier to follow the movements of even the tiniest wildlife—but it’s also important to compare new tools with tried-and-true ones to see what really works best. For years, a company named Lotek has been a leader in creating lightweight tracking devices. This includes the NanoPin, the lightest VHF radio tag available, which NH Audubon has been using to track migrating Monarchs since 2022. Two years after the release of Lotek’s NanoPins, Cellular Tracking Technologies developed its own ultra-light tag, the BluMorpho, first used on Monarchs in 2023. Early results from a 2025 collaboration with Project Monarch suggest this newer tag could offer detailed insights into the butterflies’ full southbound journey.
In the fall of 2026, New Hampshire Audubon plans to test these two tiny tracking tools side by side during Monarch migration. By placing both types of tags on butterflies under the same conditions, researchers hope to see how they compare in real-world use—looking at things like how easy they are to attach, how long they last, and how often tagged butterflies are detected or spotted again. They’ll also compare what each tag reveals about the journey itself, such as how far the butterflies travel, where they stop to rest along the way, and how long they stay at these stopover areas. Ultimately, the goal is to figure out which tool does the best job of helping us understand Monarch migration across the eastern U.S.—from their routes and travel speeds to the habitats they depend on. These insights can then be used to support conservation efforts, improve habitat, and inspire more people to connect with and protect these remarkable insects.
Monarch population decline is a complex issue spanning both state and national borders. This means that conserving these incredible butterflies will be most effective if all members of the community take action to support all parts of the Monarch life cycle. You can help monitor and conserve Monarchs in the following ways:
PLANT NATIVE
Monarchs have evolved intrinsic ties to native plant species over millions of years of side-by-side evolution. Native milkweed varieties, such as Common Milkweed (Asclepias syriaca) and Swamp Milkweed (Asclepias incarnata), are a crucial food source for Monarch larva. Fall-blooming wildflowers, particularly asters and goldenrods, are vital for migrating adults. Cultivating these native wildflower species will also benefit a wide variety of other native pollinators.
REDUCE OR ELIMINATE PESTICIDE USE
Pesticides used for controlling household and garden pests are nonspecific toxins that also harm beneficial insects, birds, and other creatures. Scientific research shows that even slight residues of past pesticide application can harm Monarchs and likely other insect pollinators. Instead, consider increasing the diversity of plant species in your yard (this increase in biodiversity often helps to naturally reduce pest populations) and/or using native natural enemies of pest species as biocontrol.
PARTICIPATORY SCIENCE
Community participation is an invaluable tool for scientists to monitor insect populations in the long term. NH Audubon always is happy to welcome new volunteers to our annual butterfly surveys and Monarch tagging efforts! Additionally, the new BluMorpho tags rely on Bluetooth detections as well as the Motus network. This means that your smartphone can detect tagged Monarchs! There is even a free app called “Project Monarch Science” you can download to follow the progress of migrating Monarchs.
ADVOCATE FOR POLLINATOR-FRIENDLY PRACTICES
Encourage local nurseries, neighboring landowners, and homeowners’ associations to prioritize the cultivation of native plants and the creation of Monarch-friendly habitats.
Learn more about pollinator conservation on our Pollinator page.
Visit our Motus page to learn more about the Motus wildlife tracking system.
See NH Butterfly Monitoring Network website and learn more about the annual butterfly census.
Video posted January 2023, NH Fish & Game
Learn about new technology that is helping biologists understand more about Monarch butterflies, where they travel, and what can be done to help protect this declining species.
(by Lindsay Herlihy) The Monarch butterfly is a beautiful, charismatic species that is well-recognized by its bold black-and-orange coloration. Unfortunately, Monarchs have seen dramatic population declines since the early 1990s,
(Photos and story by Lindsay Herlihy) Monarchs are one of the most recognizable butterfly species in North America due to their large size and striking coloration. They are also unique
(by Lindsay Herlihy) On July 26, 32 volunteers divided into 5 teams and surveyed 14 sites across the Capitol Area as a part of a nationwide effort coordinated by the
July 26, 9am-4pm (McLane Center in Concord) Join NH Audubon and fellow butterfly enthusiasts to help survey butterflies in the capital area! Whether you’re an expert or just curious, there’s
New Hampshire Audubon is grateful for generous grants recently awarded from the following charitable supporters: NH Audubon received grants from the Butler Foundation and the Davis Conservation Foundation to support
(by Diane De Luca) A groundbreaking study analyzing 12.6 million butterfly sightings reveals a disturbing reality: 22% Decline in butterfly numbers across the U.S. since 2000 – an alarming rate
Photos, from the top: American Copper, by Kate Osgood; butterfly identification in the field, by Kate Osgood, Monarch with new nanotag, by Lindsay Herlihy.
