Diario del proyecto Butterflies of New York County (Manhattan)

12 de mayo de 2020

May butterflies in Manhattan

In May, butterfly flights begin in earnest in our region. The swallowtails and some of the skippers begin to appear, and several brush-foots are on the wing. Red Admirals become common, and the first of two American Lady broods is on the wing. The American Lady butterflies we are seeing this month (like the one shown above) are individuals that have either overwintered here as adults or have moved north from more southern areas. They will mate and lay eggs and begin to die, so we'll see fewer of them in June and July until the second generation takes to the wing in mid-summer.

Here are some things to look for this month:

  1. Look for Juvenal's Duskywing (https://nhpbs.org/wild/juvenalsduskywing.asp) in May. This oak-loving duskywing appears to be very rare in Manhattan -- there are actually no records in iNaturalist so far. It's a single-brooded butterfly that flies in May, before most of our other duskywings appear. Inwood Hill Park and Central Park, given their forest cover, would be good places to look. An important field mark for this species is two pale spots on the ventral side (underside) of each hind wing.
  2. The Eurasian ornamental shrub Prunus laurocerasus (cherry laurel) is a butterfly magnet in May. The American Lady in the photo above is nectaring on the sweet-scented flower spikes of this species. The peak bloom is starting to fade now, but keep an eye on plantings of this shrub for nectaring butterflies as long as the flowers last.
  3. Look for Celastrina azures. My current hypothesis is that only Summer Azure (Celastrina neglecta) occurs in Manhattan and that adults begin to emerge in late May after overwintering as pupae. But if we did have any Cherry Gall Azures (Celastrina serotina) in the city, we should see them now. I've been checking Black Cherry trees in my neighborhood with no luck so far. Here's an article on this topic: https://www.inaturalist.org/projects/butterflies-of-new-york-county-manhattan/journal/31861

Have fun and stay safe during these challenging times.

Ingresado el 12 de mayo de 2020 por djringer djringer | 0 comentarios | Deja un comentario

27 de marzo de 2020

Stuck inside? ID some NYC butterflies!

We should all be staying at home and away from other people to limit the spread of COVID-19. So if you have a few minutes this evening, why not get a little nature fix by identifying some NYC butterflies?

Here are the New York County butterfly observations that still need ID confirmation (and I've broken out various groups in more detail below): https://www.inaturalist.org/observations/identify?verifiable=any&project_id=49510&place_id=any (note: You can tick the "reviewed" checkbox to the right of the filter bar if you want to revisit observations you'd already seen in the past). Don't follow the herd, of course -- make the IDs in which you are personally confident.

For reference, here's the work-in-progress Manhattan Butterfly List (using a lot of Research Grade data from iNaturalist): https://docs.google.com/spreadsheets/d/1Y2mNKMNXqtk4Ms820YvKXaaTySSYoxtcGlq7znoCjtY/edit?usp=sharing

Some groups to explore for those of you who specialize:

Below: a female sulphur butterfly that I observed last summer in Hudson River Park. I think she is a white form Clouded Sulphur (Colias philodice) based on the narrow black border on the dorsal hindwing that does not fully enclose pale spots, and only small spots in the dark forewing margin, but she is one of many butterfly observations in the city that still lacks ID confirmation.

Tagging some top identifiers -- thanks for all you do! @nycbirder @wayne_fidler @nlblock @greengenes @kdstutzman @sadawolk @maractwin @susanhewitt

Ingresado el 27 de marzo de 2020 por djringer djringer | 1 comentarios | Deja un comentario

19 de marzo de 2020

Celastrina Azures in Manhattan: What Do We Know?

This lovely shot by @ansel_oommen depicts a Summer Azure (Celastrina neglecta) during July in Central Park, with a characteristically pale, whitish underside; small, fine dark markings; no strong marginal markings on the hindwing; and a white, unmarked fringe on the hindwing.


Celastrina is a genus of small gossamer-winged butterflies (family Lycaenidae) with species distributed across North America, the Palearctic, and tropical Asia through Wallacea to New Guinea. In North America, Celastrina species are generally called azures.

Eastern North America holds quite a complex tapestry of similar-looking azure species. These species differ in timing of flights, number of broods, and host plant choices, and locality matters a lot -- what's true in one place may not be in another. Flight dates, number of broods, and host plant choice can all vary across a species’ range, and appearance can vary seasonally, all greatly complicating identification. This recent paper from @bryanpfeiffer summarizes several of the issues with this group: https://bryanpfeiffer.com/wp-content/uploads/2018/04/Getting-the-Blues-Celastrina-2Apr2018.pdf.

What About Manhattan?

Several Celastrina azure species fly within 50 miles of Central Park, but which azures occur specifically in Manhattan's urban parks and small islands? It currently appears that only the Summer Azure (Celastrina neglecta) occurs in New York County, flying from late May to mid-October. The species’ peak abundance appears to occur in June and July, and it appears to utilize a variety of host plants in Manhattan.

How do we arrive at this hypothesis?

First, here are the currently accepted species (following Pelham 2020 with iNaturalist’s common names) that occur in the tri-state area (NY-CT-NJ), arranged in rough order of flight times at our latitude and with a few notes relevant to our region:

  • Celastrina lucia (Lucia Azure). Flight: March-April, and possibly later. Broods: 1-2+. Range: High latitudes and elevations across North America, nearing southern limit of its range in the greater NYC area. Appearance: Often dark grayish below and heavily marked, but variable. Notes: Recently shown to have both spring and summer flights in southern Ontario: https://zookeys.pensoft.net/article/7882/.
  • Celastrina ladon (Spring Azure). Flight: March-April/early May. Broods: 1. Range: Widespread in eastern U.S. but range not fully understood. Appearance: Often lighter than C. lucia but with somewhat dark ventral hindwing margin. Crucially, males have a distinctive dorsal wing scale morphology visible under magnification. Notes: See notes on distribution, wing scales, and introgression with C. lucia and C. neglecta which can cause males of those two species to show the distinctive C. ladon male wing scale morphology here: https://www.researchgate.net/publication/331939185_New_thoughts_on_Celastrina_in_Florida)
  • Celastrina idella (Holly Azure). Flight: Spring. Notes: Occurs south of NYC, from central New Jersey along the Atlantic Coastal plain, utilizing native hollies as host plants. Described in 1999: https://leplog.files.wordpress.com/2011/03/pavulaan-wright-1999-taxonomic-rpt-on-c-idella3.pdf
  • Celastrina serotina (Cherry Gall Azure). Flight: May-June. Broods: 1. Range: Northeastern U.S. Appearance: Whitish below often with fairly bold dark markings and fairly white hindwing fringe. Notes: Uses mite galls on native Prunus cherry leaves as larval food (https://www.flickr.com/photos/mcrainey/4680056033/), but will use other host plants too (and C. lucia larva recently shown also to use cherry galls in paper linked above). Described in 2005: https://leplog.files.wordpress.com/2014/04/pavulaan-wright-2005-c-serotina.pdf.
  • Celastrina neglecta (Summer Azure). Flight: late May-October. Broods: Multiple. Range: Widespread east of the Great Plains. Appearance: Whitish underside with reduced markings and white hindwing fringe. Notes: Uses a variety of host plants and has multiple broods annually.
  • Celastrina neglectamajor (Appalachian Azure). Flight: Overlaps with C. neglecta. Broods: 1. Range: Appalachian Mountains and nearby areas where its host plant grows. Appearance: Very similar to C. neglecta. Notes: Only one host plant: Actaea racemosa (Black Cohosh).

When we examine iNaturalist reports for Celastrina azures in New York County, New York (and iNaturalist provides by far the most abundant publicly available data on this question), we see that there are currently zero Celastrina records in Manhattan in March or April. In fact, the first report across any year is not until May 23. This is particularly noteworthy because the City Nature Challenge in late April results in a large number of observations submitted to iNaturalist, relative to other months. As of March 2020, there are approximately 23,400 iNaturalist observations of all taxa in April (all years combined) vs. 14,500 in May and 12,700 in June. However, there are zero Celastrina observations in April, a handful in May, and nearly 30 in June. If azures were regularly flying by late April in Manhattan, it seems likely that someone would have reported one. After a sporadic showing in late May, azures peak in Manhattan in June and July and taper off through August, September, and into October, according to iNaturalist reports.

The absence of March, April, or early to mid-May azure reports argues strongly that neither C. lucia nor C. ladon have populations in Manhattan. Even if C. lucia has a second, summer-flying brood in our broader region, there is no evidence of a spring brood in Manhattan, so there would be no summer brood.

The late-May start date for our azure flight (and the visual appearance of those May individuals, with very light markings on their ventral hindwings) also seems likely to rule out C. serotina, though more careful observation might be worthwhile. Late May is when the first C. neglecta would be expected to emerge, and C. neglecta is known to have multiple broods through the summer, which tracks the distribution curve present in iNaturalist data so far.

What of C. neglectamajor? The Appalachian Azure is very similar to the Summer Azure, but it uses only one host plant: Actaea racemosa (Black Cohosh), at a specific stage of flower bud development. There are likely no wild stands of the plant in Manhattan, and though it is cultivated in Central Park and probably other parks, its presence there is strongly isolated from native stands, probably making a population of this specialist butterfly unlikely. (Note that Summer Azure will also use Black Cohosh as a host plant: https://groups.google.com/forum/#!searchin/nyleps/appalachian$20azure%7Csort:date/nyleps/oOFQyzKGDy4/nerW9rrEBQAJ)

It is not clear exactly why C. lucia, C. ladon, and C. serotina should not occur in Manhattan. Some of their host plants grow prolifically in our parks and between the cracks of civilization. Perhaps habitat fragmentation or urban pressures are too intense for them. Or perhaps we need to pay more attention.

Harry Pavulaan is one of the people who has contributed most to our understanding of azure ecology and taxonomy in the last 30 years (describing, with David Wright, both C. idella and C. serotina). So, I asked him this month what he knew about azure distribution in Manhattan. Citing New York City Butterfly Club data, he agreed that C. neglecta is likely our only azure.

Further Research: How You Can Help

Is this the last word on Celastrina in Manhattan? I hope not! If there's one thing we know about Celastrina azures, it's that they're full of secrets and surprises. They reward careful and patient observation.

Other azure species do occasionally turn up in NYC's outer boroughs. For example @cesarcastillo photographed this individual in mid-March in Alley Park, Queens, a couple of years ago: https://www.inaturalist.org/observations/15392436. A similar-looking individual was photographed at Wave Hill in The Bronx last week: https://www.inaturalist.org/observations/39879555. And @christophereliot photographed this very dark individual in Prospect Park, Brooklyn, on May 1 two years ago: https://www.inaturalist.org/observations/12006196.

Could there be other azures showing up around the edges of Manhattan, at Inwood Hill Park, or on Randalls or Governors islands? Maybe, and now is the time to start looking, as we officially mark the arrival of spring after a historically mild winter.

If you did find an early azure, and it were a male, high-magnification photographs of the upper wing surface showing the details of the scales would be extremely useful.

Connecting azures to host plants in Manhattan would be another useful line of exploration. Right now, iNaturalist has two records of female Summer Azures ovipositing on flower buds: this one from @kasimac (on Salvia) and this one from @filiperibeiro, apparently on some sort of shrubby Cornus -- can anyone ID that plant?

If you can catch azures ovipositing (or in their tiny, obscure larval form) and document the plant, that could be very interesting information. And as May and June unfold, keep an eye on cherry leaf galls and young Black Cohosh flower spikes if you want to be the first to document C. serotina or C. neglectamajor in Manhattan. Are they here and just overlooked? Or do they truly not occur in an area of such human density? Right now, all we know for sure is that they haven't been documented yet.

Two general reminders: Butterflies of Manhattan project is here: https://www.inaturalist.org/projects/butterflies-of-new-york-county-manhattan, and checklist-in-progress with monthly abundance graphs is here: https://docs.google.com/spreadsheets/d/1Y2mNKMNXqtk4Ms820YvKXaaTySSYoxtcGlq7znoCjtY/edit?usp=sharing.

Joyous Vernal Equinox, and thanks to Harry Pavulaan and all of you who contribute your observations and expertise. Be healthy and well.

Tagging some of you who contribute a lot of butterfly observations and/or IDs in New York as an FYI: @blkvulture @cathyweiner @craghorne @danielatha @greengenes @kdstutzman @kenchaya @klodonnell @maractwin @nlblock @nycbirder @nycnatureobserver @pawelp @sadawolk @spritelink @steven-cyclist @susanhewitt @wayne_fidler @zahnerphoto

Ingresado el 19 de marzo de 2020 por djringer djringer | 6 comentarios | Deja un comentario

08 de marzo de 2020

March Manhattan butterflies

After a historically warm winter, butterflies are already on the wing in New York, with recent reports of Mourning Cloak, Eastern Comma, and Cabbage White in the city. Mourning Cloaks and Eastern Commas overwinter as adults (so do Question Marks) and emerge on warm days; Cabbage White overwinters in pupal form. American Lady is also possible in March, though whether they are individuals that overwintered or migrated from the south is apparently unclear.

Remarkably, an American Snout was photographed in Prospect Park, Brooklyn, on March 2: https://www.inaturalist.org/observations/39470345

Keep your eyes peeled for early sightings of these species, especially as temperatures reach 50s and 60s in the city over the next few days.

And watch for any Celastrina azures -- so far, there are no iNaturalist records of this complex in March in Manhattan. If you come across one, try to get photographs showing as much detail of the wings as possible.

Here's @kasimac's photo of an Eastern Comma from Central Park on March 4, when temperatures hit 57 degrees:

Manhattan butterfly project is here https://www.inaturalist.org/projects/butterflies-of-new-york-county-manhattan, and checklist-in-progress is here: https://docs.google.com/spreadsheets/d/1Y2mNKMNXqtk4Ms820YvKXaaTySSYoxtcGlq7znoCjtY/edit?usp=sharing

@kasimac @kenchaya @nycnatureobserver @nycbirder @pawelp @susanhewitt @spritelink

Ingresado el 08 de marzo de 2020 por djringer djringer | 4 comentarios | Deja un comentario

14 de octubre de 2019

Outstanding October butterflies in Manhattan

Though we are now well into autumn, butterfly season is not over in Manhattan, and a few finds in particular so far this month demonstrate the value of staying alert.

1. Funereal Duskywing

On Oct. 10, @kasimac took a photo of an unusual-looking butterfly that turned out to be New York state's first record of Funereal Duskywing (Erynnis funerealis), a southern species that is known to wander widely: https://www.inaturalist.org/observations/34169876

2. Harvester

Early this month @spritelink photographed a Harvester (Feniseca tarquinius) in Central Park: https://www.inaturalist.org/observations/33778666. This species is the only U.S. butterfly with a carnivorous larval stage; the caterpillars eat aphids. Apparently there have been only two other sightings in Central Park in the last 25 years or so.

3. Horace's Duskywing

Not on par with the previous two observations but apparently rather rare nonetheless was a duskywing I photographed in Central Park, now identified as Horace's Duskywing (Erynnis horatius): https://www.inaturalist.org/observations/33932164.

Have fun out there!

Ingresado el 14 de octubre de 2019 por djringer djringer | 0 comentarios | Deja un comentario

27 de septiembre de 2019

The Butterflies of Manhattan: Building a List

Which butterfly species occur in Manhattan? I discovered that this seemingly straightforward question does not have a particularly clear answer, so I started compiling information from publicly available sources in an effort to assemble a list, which is accessible here as a work in progress: https://docs.google.com/spreadsheets/d/1Y2mNKMNXqtk4Ms820YvKXaaTySSYoxtcGlq7znoCjtY/edit?usp=sharing.

The Challenge

Observations documented here on iNaturalist provide a helpful starting point but not a complete picture. Not all species are fully or correctly identified, and Inwood Hill Park, which could have more species than anywhere else on the island of Manhattan because of its remnant forest and marsh habitats, has only a few dozen observations recorded on iNaturalist, out of nearly 5,000 observations for the whole borough. This may mean that some species are not yet documented from the island on iNaturalist. Furthermore, some rare occasional vagrants like Long-tailed Skipper have not been recorded yet on iNaturalist.

As far as other data sources, eButterfly is barely used in New York; there appear to be only four checklists submitted from the entirety of Manhattan. A group of enthusiasts compiled a list of species seen within 50 miles of New York in the 1990s, and Nick Wagerik kept a list for Central Park up until at least 2007. Butterflies and Moths of North America has a number of historical records (without dates or locations) and some contemporary reports from New York County. And periodic reports are submitted to North American Butterfly Association's sightings log.

A small network of knowledgeable observers seems to keep detailed records privately, and occasionally post anecdotal reports on the New York Leps Google Group, but as far as I know no contemporary compilations of this data are published publicly.

The List

I created a spreadsheet attempting to compile data from as many of these sources as possible in order to begin creating a relatively well-rounded and view of species reported from Manhattan historically and, especially, since 2010.

You can view that document here: https://docs.google.com/spreadsheets/d/1Y2mNKMNXqtk4Ms820YvKXaaTySSYoxtcGlq7znoCjtY/edit?usp=sharing -- and the second tab of the spreadsheet contains an explanation of the fields and data, including links to the various data sources and lists referenced.

The results so far include reports of 81 species from Manhattan through time, and 51 species since 2010, with several more reported in the greater New York City region but not necessarily from Manhattan. The reliability of some of these reports or identifications may be questionable, especially for difficult genera, but a picture does begin to emerge when all these data sources are considered together.

It's clear even from this rudimentary effort that some species have become rarer over the last 30 years, or may have even become locally extirpated. On the other hand, some southern species are increasing in frequency and abundance -- for example, Sachems and and even more recently, Eastern Giant Swallowtails.

The Geography

The borough of Manhattan and the county of New York include of course the island of Manhattan, several smaller islands (including Randalls and Wards, Roosevelt, and Governors), and a sliver of the mainland.

Interestingly, some designations also currently include the piers of Brooklyn Bridge Park, apparently because the county line was drawn along the Brooklyn shoreline, but the piers jut out into the East River, over the historical county line. So a search on iNaturalist today for New York County includes observations from the Brooklyn Bridge Park piers.

Some Questions I Encountered While Compiling the List

  • What is the status of Celastrina azures in Manhattan?
  • What is the status of Northern Crescent, Phyciodes cocyta, in Manhattan?
  • Does Columbine Duskywing occur in Manhattan?
  • Have several species of skippers, hairstreaks, and satyrids been extirpated from Manhattan in the last 20 years, or are they simply underreported?

The Project

I've created an iNaturalist project to start tracking things more closely -- please join if you want to keep a closer eye on Manhattan butterflies: https://www.inaturalist.org/projects/butterflies-of-new-york-county-manhattan


Tagging a few folks who might be interested: @ansel_oommen @blkvulture @cathyweiner @cesarcastillo @conuropsis @craghorne @danielatha @d2b @elevine @ginsengandsoon @kasimac @kdstutzman @kenchaya @maractwin @nlblock @nycbirder @pawelp @sadawolk @spritelink @susanhewitt @wayne_fidler @zahnerphoto @zihaowang

Ingresado el 27 de septiembre de 2019 por djringer djringer | 2 comentarios | Deja un comentario