Rapid Butterfly Declines Across the United States

© Steven J. Cary, March 8, 2025

Before we dive into that timely, if heavy, topic, I have some lighter reports:

First, Spring is happening, ready or not. (I am very ready!) If you have been out looking, you have probably seen an adult hibernator or two: Mourning Cloaks have been most numerous, but Commas, Question Marks, and other tortoiseshells (California and Milbert’s) also have been seen in NM. Other early spring flyers actually overwinter as pupae, but adults pop out pretty quickly in spring so their eggs can be placed on early spring host plants. Thanks to Gordon Berman, we have new early flight dates (February!) for Southwestern Orangetips, Desert Orangetips, and Desert Marbles, all in the Las Cruces area. And please check out friendly blog posts from Joe Schelling (Natural Moments | Nature photography, birds, butterflies and travel) and Lisa Tannenbaum (https://everydaymagic.substack.com/) to see some very early Sandia Hairstreaks, our State Butterfly!

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Second, we have a story by Jim Von Loh based on his work last October in Hidalgo County. Butterfly and Moth Species and Habitats in Alkali Flats Part of Lordsburg Playa, by James Von Loh. Hi Everyone. Last year I volunteered to photo-document shrimp and Odonate species using aquatic habitats of the Alkali Flats area (where I could access public land in the complicated ownership pattern). Since I was there anyway, I also recorded all vertebrate and invertebrate species I encountered over 12 visits during and after monsoon rainfall events from August 1 through November 20, 2024, and prepared an illustrated summary. For purposes of disseminating this information, Steve requested, and I gave him permission, to condense my three-part report into a more concise blog post, which you are now reading.

Most of the 31 butterfly species I photo-documented are routinely present across the southern desert of NM and adjacent AZ. The most abundant butterfly species were: Western Pygmy Blue (Brephidium exilis), American Snout (Libytheana carinenta), Sleepy Orange (Abaeis nicippe), Orange Sulphur (Colias eurytheme), and Variegated Fritillary (Euptoieta claudia). The more important species to consider, IMO, are: Mexican Fritillary, Tiny Checkerspot, and the various color forms of Marcellina Sulphur. These three are all presented below in further detail.

Marcellina Sulphur (Phoebis marcellina Cramer, 1779). Marcellina Sulphur males are large, bright yellow, and with few markings while the females observed were either light yellow or albinic (white) and with prominent and distinct markings; they were frequently observed during September, and several were photographed puddling and nectaring from Aster flowers.

Mexican Fritillary (Euptoieta hegesia meridiana (Stichel, 1938)). One Mexican Fritillary was photo-documented perching behind clumps of Alkali Sacaton (Sporobolus airoides (Torr.) Torr.) tallgrass to avoid wind gusts on a cool morning. It perched on sun-warmed gravel along the edge of the parking area used by birders viewing the South Alkali Flats Duckpond site. This fritillary is further warmed by spreading its wings fully to expose the dorsal surface and long hairs to the sun’s rays.

Mexican Fritillary frequently moved from perch-to-perch within the tall bunchgrass stand during several minutes of observation, likely frightened by the crunching sound (me stepping on small gravel) and my motion while positioning for photograph angles. It would have been easy for me to pay little attention to this flighty fritillary because Variegated Fritillaries were foraging among Aster flowers in the vicinity and were easier to approach; sometimes both tenacity and luck pay dividends when conducting camera work in the field.

[SJC: Jim, what a terrific sighting and great photos! We have a slim handful of records for NM, so this is a great addition to our knowledge.]

Tiny Checkerspot (Microtia dymas chara W. H. Edwards, 1884). A single Tiny Checkerspot was photo-documented perching on sun-warmed sand on the bank of New Tank near the Arizona/New Mexico border. Seedling Common Purslane (Portulaca oleracea Linnaeus) are the weedy annuals, emerging from this sandy surface which is continually broken and turned by the hooves of watering cattle. 

Anyone interested in butterfly species within Hidalgo County is encouraged to review the highly informative and regularly updated website, Butterflies of New Mexico (https://peecnature.org/butterflies-of-new-mexico/, which Steve Cary and Mike Toliver curate. 

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Last, but not least, a major scientific article (Rapid Butterfly Declines Across the United States During the 21st Century) was recently published in Science magazine by a large group of highly respected researchers and authors headed by Collin B. Edwards. Here is the link: https://www.science.org/doi/10.1126/science.adp4671. Here is the abstract:

Numerous declines have been documented across insect groups, and the potential consequences of insect losses are dire. Butterflies are the most surveyed insect taxa, yet analyses have been limited in geographic scale or rely on data from a single monitoring program. Using records of 12.6 million individual butterflies from >76,000 surveys across 35 monitoring programs, we characterized overall and species-specific butterfly abundance trends across the contiguous United States. Between 2000 and 2020, total butterfly abundance fell by 22% across the 554 recorded species. Species-level declines were widespread, with 13 times as many species declining as increasing. The prevalence of declines throughout all regions in the United States highlights an urgent need to protect butterflies from further losses.

I have read the article but have not studied it in great detail. This monster statistical effort uses existing studies and monitoring efforts around the US to try to quantify what many are seeing, namely declining numbers of many butterfly species. Although it is easy to point out shortcomings with the data, it is difficult to overlook the consistent results produced across the entire country. New Mexicans know that our contributions to the data may be geographically spotty, of brief duration, and of irregular quality. Yet many of us also generally think/feel/believe that many of our species, at least in some areas, seem to be scarce compared to the “old days.” We also can feel the intensifying dryness and the lengthening of our growing season, while wondering how butterflies (and everything else) will respond to these big changes. I am generally loath to generalize about any group as complex as “butterflies,” but this study/report takes a major step toward quantifying what we are seeing. It also underscores the need to know more about our particular butterflies, each of them, if for no reason other than to enjoy them, but also to monitor how they react to changes that are underway.

How do we do that? I’m thrilled you asked! I encourage all of us to participate more fully in available citizen science efforts to document butterflies in New Mexico. If you already post photographic observations to online platforms such as butterfliesandmoths.org, iNaturalist or BugGuide.net, then THANK YOU! It is a terrific way to get help with identifications while also giving your images scientific value. You also could sign up to do a transect for the New Mexico Butterfly Monitoring Network (Home | New Mexico Butterfly Monitoring Network).

A third option is to get involved in ad hoc monitoring efforts as they come up. This year, for example, I will participate in efforts to get better data for several of our rarest native, breeding butterfly species. In its latest State Wildlife Action Plan (SWAP), the NM Department of Game and Fish listed more than 30 of our butterflies as Species of Greatest Conservation Need (SGCN). I recommend you dig up the SWAP and check out the list of SGCN butterflies. Do any live near where you live? If so, you might think about investigating that species and sharing what you learn. If you like, I can help you think about how to do that.

New Mexico has at least two regions of endemism which are high on my personal list to do something about. First, several SGCN butterfly species are restricted to the Raton Mesa Volcanic Field in Colfax and Union counties (also Las Animas County, CO). Second, almost a dozen other SGCNs are known only from the complex of uplands that include the Capitans, Sacramentos and Sierra Blanca. Therefore, I plan to spend most of my 2024 field time in those areas trying to ascertain if those geographically localized species are still there, and if so, how widespread and abundant they may be. Do you care to be part of either effort? If so, send an email to sjcary1@outlook.com. Of course, you can contribute without coordinating with me or anyone else. Just get out there and take photos, then share the photos. Pretty simple, eh? Thanks in advance for anything you are able to do.

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