Posts Tagged 'dragonflies'

Late Odonata

Dragonfly eating damselfly.
Eastern Pondhawk female gobbling up one of the bluets.
Familiar Bluet ungobbled.
Common Green Darner male.
Autumn Meadowhawk female.
Autumn Meadowhawk male (probably). As their name suggests, these Sympetrum genus meadowhawks are one of the last species to fly during the Odonata year.

BioBlitz Notes

Birds are hard to capture with phone cameras, the standard way people enter information on iNaturalist. I led two bird groups of Macualay Honors College students on the BioBlitz Saturday. This is the only picture of a bird I put into iNaturalist. We tallied birds seen the old fashioned way, with paper and pencil.

Macaulay the honors program at CUNY. They do a BioBlitz every year for their sophomores. This started in 2012 when the in-coming dean, a primatologist, was dismayed to see the one science course sparsely attended. A BioBlitz is a survey of lifeforms over a specific time-span. Every year the blitz has been in a different location in the city. Up to five hundred students take part. The data they help collect is used throughout the year in their classes. Here’s what we found.

This year they divided the blitz between Green-Wood and the Gowanus Canal area. In one of these things, volunteers, or in this case students, accompany educators, naturalists, etc., to search and record. You’ve seen some of the moths I photographed during the night component; there was another moth unit and a bat team that night as well.

The students were not particularly familiar with the common birds, although they all knew what a pigeon was. We had good views of a Great Blue Heron and Red-tailed Hawks, both the perching one pictured and another flying a few minutes earlier. There were lots of warblers out and about, especially American Redstarts. A northeast wind bought a fallout of migrants to town. Following these through binoculars takes some practice. The sight of a Belted Kingfisher bought a real smile of joy to the face of one young woman, an Indian-American — a dozen species of kingfishers are found in India.

My 3pm group was a quartet of the most insect-phobic humans I’ve ever seen. They were terrified of flying things, doused themselves in citronella, and one even jumped away when I pulled a cicada exuvia off a tree. It wasn’t a surprise: knowing how jumpy they were, I announced that it was coming — a hollowed out exoskeleton, lifeless, harmless — but no matter. (I was nervous around bees until after graduate school, so there is hope.)
While looking for birds, the motion of large dragonfly can easily catch the eye. This looks like a Shadow Darner, a species I’ve never seen in Brooklyn before.
***

On the absolute necessity of cities for biodiversity.

Paulson on the Odonata


Dennis Paulson’s new Dragonflies and Damselflies: A Natural History‘s is a great introduction to odonating.

Paulson has written the standard field guides to American/Canadian odes as well as dozens of journal papers on odonates. The pictures in his field guides are too small; that’s these guide’ principal fault. But consider: there are 461 species to be covered in the US and Canada. There is strong sexual dimorphism in odonates, meaning at least two images for each species. Some damselfly species have four or five color forms. Dragonflies and Damselflies of the East is 519 pages long, not including glossary and index. Gotta be some hard calls for the author and publisher in this field of field guide publishing.

This new book, however, is coffee table format. It’s aimed for a popular readership. While there is a Further Resources appendix, I note the absence of a real bibliography. There’s a lot of scientific literature out there; touching base with it would have been a good thing, especially with our unparallelled ability to pull up scientific literature on the ‘net (if not full text than at least the abstract).

Chapters on natural history alternate with two-page spreads on individual species from around the world. At the time of publication, there were 6,299 described odonate species. That number is sure to change. Nearly two hundred of these were first described between 2015-2017. Only a small sample are included here, obviously, representing the great range and diversity of this order of insects.

News to me: the Common Winter Damsel (Sympecma fusca), found in southern and central Europe east to central Asia, stays dormant through the winder. They grab hold of something and sit out the winter in dormancy. The two other species in this genus are the only overwintering adult Odonates we know of. Advantage: very early start to reproduction, before predatory migratory birds show up. Disadvantage: they suffer “moderately high mortality from rodent predation” in winter. A frosted-over damselfly is still fresh meat, after all.

On the Azores, the population of Citrine Forktails (Ischnura hastata) is all female. They’re the only ode that manifests parthenogenesis. With so many species, there are many strategies and adaptations and habitats. The basic plane is the same, but the differences are what fascinates.
The Eastern Pondhawk (Erythemis simplicicollis) rates an entry because it is one of the few species in the world that seems to be increasing its numbers, going against the general decline brought about by… us. I photographed this one in Brooklyn. They thrive in any kind of fresh water; many other species have rather more specific requirements: gravel bottoms, slow moving streams, fast moving streams, muddy bottoms, etc.

What else? Much else. Up to 60% of the weight of a dragonfly is muscle used to power their four wings. “Although they operate independently, the fore- and hindwings interact with one another. The hindwings suffer slightly increased drag owing to the turbulence created in front of them by the forewings, but the positive pressure generated by the hindwings actually decreases drag on the forewings.”

There are even some numbers on flight speed: average speed of a moderate sized dragonfly: 4.5 mph. The largest dragonflies, the darners, can hit bursts of 34mph!
Sweetflag Spreadwing (Lestes forcipatus) female. Photographed in Alley Pond Park in Queens, on the same day as this
Slender Spreadwing (Lestes rectangularis). These are now the only Queens records for Lestes genus spreadwings at Odonata Central. iNaturalist has one more, seen in 2016, but nobody could get it down to species level. I have a similar problem with the third spreadwing I photographed in Ally Pond Park that day. Without the specimen in hand, identification can be impossible, but I’d rather see them flying than tucked into someone’s drawer. Brooklyn, by the way, has only one record of a spreadwing, but here too the picture is too obscure for species-level.

The Better To See You With

You may have noticed the long antennae of butterflies, or the sometimes very elaborate and feathery antenna of certain moths.
Male moths especially, like this Chickweed Geometer (Haematopis grataria), pick up the scent of female pheromones from great distances. Some beetles also have long antenna; c.f. the “long-horned beetles.”
But note how minor a dragonfly’s antenna are.
This is a Blue Dasher male. Blue Dashers are the most common dragonfly species in NYC. And yes, they definitely see you coming.
Here’s a female Great Blue Skimmer.
It’s only recently that Odonata antennae have been shown to have olfactory sensory pits on them. But a dragonfly’s main sensory receptors are its eyes. We humans, who bleat on and on how we are the top a-number-one Americans of the animal world, have three color-sensing proteins in our eyes. Dragonflies have from eleven to thirty, depending on the species (and for some, age). They see in “ultra-colour” as New Scientist puts it. There are as many as 30,000 facets on their compound eyes — along with bees, they have the largest eyes in the insect world — which can see in all directions at once.

Except obviously, their blind spot, which is behind and below. “They see the sky as a very bright background against which flying insects [their prey] stand out dramatically,” Dennis Paulson writes in his new natural history of odonates, which I will give more attention to shortly.

Robber Flies & Dragonflies

A Holcocephala genus gnat ogre. Hey, I don’t make these names up, I just report them. Like the examples below, these are robber flies. Ommatius genus. Robber flies hunt and kill “insects of many orders” according to bugguide.net. In this case, a fly victim.Genus Efferia. Another captive fly.Here, the prey looks like a tiny wasp.

And now for some dragonflies. These are Great Blue Skimmers mating.Female Great Blue Skimmer.One of the meadowhawks.Female Carolina Saddlebags.Spot-winged Glider. It’s rare to find these perched. They seem tireless when flying, patrolling meadows and lawns for prey. This is one of the migratory species: the late summer generation will head south. Like with its Pantala genus-mate, the Wandering Glider, their hindwings are wider than other species of dragonfly, better adapted for frequent flying.
***

The Republican assault on America comes in many blows. Trump’s environment-rapists are attempting to undercut public control of public lands. The Forest Service wants to revise its rules to bypass environmental impact studies for the benefit of loggers and miners. They are, of course, bullshitting about the intent of their sneak attack. Comments on this proposed rule change are due by Monday.

I excerpted this from a recent comment because I thought it was so spot on: “I am opposed to the U.S. Forest Services proposal to cut out public participation from the vast majority of its decisions. I want to have the ability to comment on decisions affecting places I care about in the future. The current proposal would fundamentally change the relationship between the U.S. Forest Service and the public, cutting our voices entirely out of how to manage these special places.”

Of Wings and Stigmata

Found the remains of a dragonfly on a Brooklyn sidewalk recently. Possibly a Common Green Darner, one of our most common species. One of the hind wings was still in pretty good shape.Pretty good, but at 40X showing some wear and tear. These two shots are hand-held through the microscope, so not as great as I’d like them, but certainly passable. And the leading edge. I was surprised to see how rough it looks, with regularly spaced thorn-like structures. But I shouldn’t have been. We think of the aerodynamic as streamlined, but this is old school thinking, from the Art Deco in Space, a.k.a. Jetsons, Era. We now know, from things like bird feathers, that a rough surface actually works better for flight.

The dark yellowish bit here the pterostigma, sometimes called simply the stigma, and yes, stigmata in the plural. (See first image for location: on front edge of the upper left). This is a thickened, pigmented cell. A number of other insects have these, but they are most obvious on dragonflies, some of our biggest-winged insects. The stigmata have greater mass than similar-sized sections of the wing. They seem to be a kind of ballast, helping with flight stabilization. Odonates are extraordinary fliers. See here for more detail: “By passive, inertial, pitch angle control, the pterostigma probably makes the wing beat more efficient in slow and hovering flight of small insects, while its raising of the critical flight speeds probably is of more importance to larger insects.”

Exuviae

Wait… what? This Rambur’s Forktail damselfly is perched on the exuviae of a dragonfly.Another view of the male Rambur’s green-blue color pattern. Dragon- and damselfly eggs are laid on or near water. The larval stage is aquatic. After a season, or a year (or more depending on species and location), the aquatic nymph crawls out of the water, onto a twig, stone, etc. A floating leaf in this case. The adults emerge from these, with wings! The remaining husks of exosleton are called exuviae. These were left by dragonflies: the short wing-like gill structures on the back tell you this. This is what’s left of an aquatic damselfly. The gills are at the end of the abdomen. This is about an inch-long and quite hard to see from up above. There were a lot of dragonfly exuviae around the Sylvan Water the other day, presumably from Eastern Amberwings, which were all over the place. This was the only damselfly exuvia I found, even though there were several adult damselflies flying.And mating…

More Insects

The Common Sootywing. The Kaufman guide says “flight is slow and close to the ground” but I beg to differ with the first characterization. This was about the tenth I’ve seen in various places before I could get a photo.Black Swallowtail, another mover, if not shaker.This is a Great Blue Skimmer, another case where the description of the adult male gives us the common name. This is the female. This photo makes her look smaller than in real life. The larval Asian Ladybug (they seem to have dropped the “multicolored” in the common name; what’s distinguishing about them is that they are variably spotted in the adult form).

No photo, but on 6/2 I spotted a Two-spotted Ladybug in the same Brooklyn Bridge Park patch I first found them in in 2012. I also wrote about them for Humans & Nature.

Odes

Spot-winged Glider, in a rare perch. They can spend hours in the air.Blue Dasher male, quite common and frequently perched.Eastern Pondhawk male.Male Painted SkimmerThis damselfly is peculiar. I can find no matching ID for it, and both iNaturalist and bugguide.net remain silent to my queries. I think it may be a maturing andromorph (that is, male-like) female Eastern Forktail. Lam illustrates six forms of Ischnura verticalis; Paulson pictures five forms. None of their examples are quite this one, though, Bar-winged Skimmer male. A new species for me.

All spotted in either Brooklyn or the Bronx recently. A quick reminder: males are usually patrolling water bodies, which females only visit for mating purposes.And here’s a female Common Whitetail, away from the water…

Darning (?)

Common Green Darner dragonflies (Anax junius).
This is a migratory species, one of the first seen in the spring and one of the last seen in the fall as they move up and down North America. Male is grasping the female as she oviposits, laying her eggs in the lake in Woodlawn Cemetery. Not all Odonata do it this way: in some species, the female will be on her own; in some, the male will be patrolling nearby; and, in some species, as these, the male will continue to stay attached after fertilization.

So far, the only other Odonata action I’ve seen in NYC this season have been a couple of big blue darners of some kind patrolling a sunny path filled with Diptera at Jamaica Bay. They did not pause for photographs. Word on the street is that there are an extraordinary number of dragonflies around the NYC metropolitan area; evidently northwest winds created an unusual fallout situation yesterday. I’ll to keep my eyes open today.

***
Going to use my pulpit here to print this NYC City Council Resolution (No. 864). Wordy, aspirational (what the last sentence actually means isn’t addressed), but this gives a good sense of the interconnected challenges largely going unmet here in the wealthiest city in the country, not to mention the rest of the nation. Contact your council member to get it passed.

Resolution declaring a climate emergency and calling for an immediate emergency mobilization to restore a safe climate.

By Council Members Kallos and Constantinides

Whereas, On April 22, 2016, world leaders from 174 countries and the European Union recognized the threat of climate change and the urgent need to combat it by signing the Paris Agreement, agreeing to keep warming well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C; and

Whereas, On October 8, 2018, the United Nations International Panel on Climate Change (“IPCC”) released a special report, which projected that limiting warming to the 1.5°C target this century will require an unprecedented transformation of every sector of the global economy over the next 12 years; and

Whereas, On November 23, 2018, the United States Fourth National Climate Assessment (“NCA4”) was released and details the massive threat that climate change poses to the American economy, our environment and climate stability, and underscores the need for immediate climate emergency action at all levels of government; and

Whereas, According to the National Aeronautics and Space Administration (NASA)’s Goddard Institute for Space Studies (GISS), global temperatures in 2018 were .83°C (1.5°F) warmer than the 1951 to 1980 mean, and the past five years are collectively the warmest in modern history; and

The death and destruction already wrought by climate change demonstrates that the Earth is already too hot for safety, as attested by increased and intensifying wildfires, floods, rising seas, diseases, droughts and extreme weather; and
Whereas, World Wildlife Fund’s 2018 Living Planet report finds that there has been 60% decline in global wildlife populations between 1970 and 2014, with causes including overfishing, pollution and climate change;

Whereas, According to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, human activity has already severely altered 40% of the marine environment, 50% of inland waterways, and 75% of the planet’s land, and it is projected that half-to-one million species are threatened with extinction, many within the next few decades; and

Whereas, The United States of America has disproportionately contributed to the climate and extinction emergencies and has repeatedly obstructed global efforts to transition toward a green economy, and thus bears an extraordinary responsibility to rapidly address these existential threats; and

Whereas, Restoring a safe and stable climate requires transformative societal and economic change on a scale not seen since World War II to reach net zero greenhouse gas emissions across all sectors, to rapidly and safely drawdown or remove all the excess carbon from the atmosphere, to end the 6th mass extinction of species, and to implement measures to protect all people and species from the increasingly severe consequences of climate change; and
Whereas, A sweeping overhaul of the economy that centers on equity and justice in its solutions is vital to our future and must include the following goals: dramatically expand existing renewable power sources and deploy new production capacity with the goal of meeting 100% of national power demand through renewable sources; build a national, energy-efficient, “smart” grid; upgrade every residential and industrial building for state-of-the-art energy efficiency, comfort and safety; eliminate greenhouse gas emissions from manufacturing, agricultural and other industries, including by investing in local-scale agriculture in communities across the country; repair and improve transportation and other infrastructure, and upgrade water infrastructure to ensure universal access to clean water; fund massive investment in the drawdown of greenhouse gases; make “green” technology, industry, expertise, products and services a major export of the United States, with the aim of becoming the international leader in helping other countries become greenhouse gas neutral economies and bringing about a global transition; and

Whereas, Marginalized populations in New York City and worldwide, including people of color, immigrants, indigenous communities, low-income individuals, people with disabilities, and the unhoused are already disproportionately affected by climate change, and will continue to bear an excess burden as temperatures increase, oceans rise, and disasters worsen; and
Whereas, Addressing climate change fairly requires a “Just Transition” from fossil fuels to clean, renewable energy that is ecologically sustainable and equitable for all people, especially those most impacted by climate change already and those who will be most impacted in the future; and

Whereas, Core to a Just Transition is equity, self-determination, culture, tradition, deep democracy, and the belief that people around the world have a fundamental human right to clean, healthy and adequate air, water, land, food, education, healthcare, and shelter; and
Whereas, Just Transition strategies were first forged by a “blue-green” alliance of labor unions and environmental justice groups who saw the need to phase out the industries that were harming workers, community health, and the planet, while also providing just pathways for workers into new livelihoods; and

Whereas, Just Transition initiatives shift the economy from dirty energy that benefits fossil fuel companies to energy democracy that benefits our people, environment and a clean, renewable energy economy, from funding new highways to expanding public transit, from incinerators and landfills to zero waste products, from industrial food systems to food sovereignty, from car-dependent sprawl and destructive unbridled growth to smart urban development without displacement, and from destructive over-development to habitat and ecosystem restoration; and

Whereas, Building a society that is resilient to the current, expected, and potential effects of climate change will protect health, lives, ecosystems, and economies, and such resilience efforts will have the greatest positive impact if the most dramatic potential consequences of climate change are taken into account; and

Whereas, Climate justice calls for climate resilience planning that addresses the specific experiences, vulnerabilities, and needs of marginalized communities within our jurisdiction, who must be included and supported in actively engaging in climate resilience planning, policy, and actions; and

Whereas, Actions to eliminate greenhouse gas emissions and/or drawdown greenhouse gases may be taken in ways that also improve resilience to the effects of climate change, and vice versa; and

Whereas, Climate justice requires that frontline communities, which have historically borne the brunt of the extractive fossil-fuel economy, participate actively in the planning and implementation of this mobilization effort at all levels of government and that they benefit first from the transition to a renewable energy economy; and

Whereas, Fairness demands the protection and expansion of workers’ right to organize as well as a guarantee of high-paying, high-quality jobs with comprehensive benefits for all as the mobilization to restore a safe climate is launched; and

Whereas, Common sense demands that this unprecedented mobilization effort address the full suite of existential ecological threats facing humanity in a comprehensive, integrated and timely fashion; and

Whereas, Nearly 400 cities, districts and counties across the world representing over 34 million people collectively have recently declared or officially acknowledged the existence of a global climate emergency, including Hoboken, Berkeley, Los Angeles, Montgomery County, Oakland, Richmond, and Santa Cruz in the United States, Bristol and London in the United Kingdom and many cities in Australia, Canada, and Switzerland; and

Whereas, New York City, as the largest city in the United States, can act as a global leader by both converting to an ecologically, socially, and economically regenerative economy at emergency speed, and by rapidly organizing a regional just transition and climate emergency mobilization effort; now, therefore, be it

Resolved, The City Council declares a climate emergency and calls for an immediate emergency mobilization to restore a safe climate.


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