A firefly that doesn't light up, Ellychnia corrusca

Winter Firefly (Ellychnia corrusca) hiding in the bark of a
maple tree.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

As I catalogue each species of animal that I find living in my yard, I include quick facts about each animal. Things like: Where does it go in the winter? For one entry, the banded net-wing, I told you that it hides in crevices in the bark of trees during the winter. Given this bit of information, and the fact that I hear woodpeckers digging bugs out of trees every morning around my yard, I thought it might be interesting to look under the bark of a maple tree to see what I might find.
Within seconds, I spotted three specimens of an insect that bears some similarity to the banded net-wing, but which had quite different coloration. Having grown-up in New England chasing bugs very much like these, I had a suspicion about what they were. If I hadn't known, then I would have been able to start with the similarity to the banded net-wing and work backward through taxonomy using the handy tools at bugguide.net to identify it.
How to identify insect species

This is the same Ellychnia corrusca in the above and below
photos, but with it's head clearly extending beyond the
pronotum, which goes counter to species descriptions.
The other photos all show the head tucked and hidden,
so it seems that position is preferred, but a matter of
behavior rather than basic body architecture.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

Starting from the banded net-wing page, we can click on the taxonomy links at the top of the entry. First, we click the Genus Calopteron and scan the pics. They all appear to be bicolored with a different wing-shape than the specimens I found today. Continuing back, we don't see anything close in appearance to our specimens until we get to the Superfamily Elateroidea which is comprised of click beetles, fireflies, and soldier beetles.
Even then, I don't see a picture that closely matches what I've found, but there is enough diversity here that it might be included and I don't want to have to go further up the chain into much broader beetle categories until I have exhausted possible candidates at the Family level. Within the Superfamily Elateroidea, there are twelve Families. I can immediately rule out click-beetles which tend to have a hard, chitinous outer wing cover (elytra). I can rule out borers and Texas beetles.

From there, it's a process of elimination. I choose one family, enter it into the search box at the top of the page and look for a close match to what I've found. I started with Lampyridae (Fireflies) and quickly found that the images of various species in this group look very much like our mystery bug. From there, we have another process of elimination. There are a handful of subfamilies, and then tribes within the subfamilies, but clicking on an image that looks almost exactly like our subject, I find the species Ellychnia corrusca. Ellychnia corrusca is sometimes commonly called the winter firefly.

The body length of 14mm is the surest clue to the exact
species once it's been narrowed down to the Genus
Ellychnia.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

That gives me a strawman that I then try to rule out.

• Size of my specimen: 14mm, reported size of Ellychnia corrusca 10-14mm. Check. 
• Complete lack of bioluminescent organs at tip of abdomen? Check.
• Pronotum shape and markings, check.
• Elytra details, check. 
• Antenna segment details? check.
• Range? Northeast United States, check.
• Habitat? check.
• Behavior: overwinters as adults in tree bark? Check.
• Behavior: adults known to feed on maple sap in early spring? These specimens were found on a maple tree on March 15th, check.
• Head hidden by pronotum when viewed from above? Uh-oh. No. In an ID photo I took, the head is clearly visible from above. Let's dig deeper.

I search the web for other photos and descriptions (from reputable sources) of Ellychnia corrusca and find some showing the head visible as in my photo. I then go back out to the tree where I found this insect and look for others. They have their heads "tucked" under the pronotum.

In reviewing the photos I took of the original specimen in situ, I see it similarly posed, with head tucked and not visible from above. Apparently, this identification key listed by bugguide.net refers to certain postures and is not absolute for this species.

Ellychnia corrusca with pronotum angled down and head
hidden from view from above as in most species accounts.
This is the same specimen as in the photo to the above-right.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

When I can't rule out Ellychnia corrusca, I see if I can rule in any other species. Every resource I can find tells me that although there are three known species of non-luminescent lightning bugs in New England. Only one is larger than 7.5 millimeters in length, which rules out all the others as this is clearly a lightning bug. So there we have it. Ellychnia corrusca, a lightning bug or firefly that doesn't ever light up and is active in the daytime instead of the night.

Undiscovered new sub-species?

What's particularly interesting is that the University of Alberta suggests that the insects currently identified as Ellychnia corrusca as "possibly consisting of several species, but not sufficiently studied or understood to differentiate between them." This is based on observed differences between specimens identified in different regions of their accepted range.

UA suggestion is correct) currently classified as Ellychnia corrusca. Thesis material, anyone?

Given the tremendous complexity of the wild forest biosphere, I've often thought that there are surely species of plants and animals (particularly arthropods), even in well settled areas like my own backyard, that have not yet been discovered or identified. Do the various sub-species of Ellychnia corrusca qualify? Because the differences may occur geographically, it's unlikely that I would be able to find more than one of the proposed sub-species (if such exist) in my yard, nevertheless, I will keep a specimen preserved and compare it against future finds to look for inconsistencies. I will certainly never look at a lightning bug in my yard the same way again knowing it might be an unrecognized sub-species!

Quick facts about the Ellychnia corrusca:

Lifespan of the winter firefly: about one year

Life Cycle: Ellychnia corrusca, according to the University of Alberta's E.H. Strickland Entomology Museum, spends the winter in the crevices of tree bark, moving very little and never leaving the tree until March. In March, it begins flying again. mating season is April and May. The adults die in late spring, sometimes prematurely by drowning in the sap collection buckets of those tapping maple trees. The larvae of Ellychnia corrusca, says the E.H. Strickland Entomology Museum, live in rotting wood and are predators, likely eating grubs and slugs that are also found in or on rotting wood.

Diet: Adults live on plant liquids such as maple sap, maple flower nectar, and possibly fluids from flowers during the fall before they find a winter hiding place, according to the E.H. Strickland Museum.

Range: Bugguide.net credits researchers Downie and Arnett with stating that the winter firefly lives in the eastern United States, from Maine to Wisconsin and as far south as Maryland. Populations are also found on the western coast of the Untied states into Colorado and Arizona. In Canada they are found in the east and in British Columbia.

Where does it go in winter? The winter firefly stays hidden in the folds of tree bark in the winter, although it may move a few inches from one place to another, it otherwise stays put during the cold months.

Notes: Most people think that all lightning bugs or fireflies light up and come out at night, but Ellychnia corrusca does not possess bio-luminescent organs and is diurnal. Most (if not all) northern, luminescent fireflies overwinter in larval form inside rotting wood. Ellychnia corrusca, however, pupates before the winter snow and overwinters in adult form.

Ellychnia corrusca taxonomy:

Kingdom: Animalia (Animals)
Phylum: Arthropoda (Arthropods)
Class: Insecta (Insects)
Order: Coleoptera (Beetles)
          Suborder: Polyphaga (Water beetles, Rove beetles, Longhorn beetles, Leaf beetles, 
          Snout beetles, and Scarabs)
Superfamily: Elateroidea (Click beetles, fireflies, and Soldier beetles)
          Family: Lampyridae (Fireflies)
                    Subfamily: Lampyrinae
                             Tribe: Photinini
Genus: Ellychnia
Species: Ellychnia corrusca

Pine Siskin (Carduelis pinus), an irruptive visitor

Pine Siskins at a thistle feeder. March, 2012.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

Living in the northeast United States and having thistle feeders out during the winter months, I expect to see large numbers of American goldfinches, which I do, and I also expect to see pine siskins on occasion. Until this year, however, I had not seen a single pine siskin on our property, despite living here during the 2008-2009 pine siskin irruption documented by the Cornell lab of Ornithology's Project Feeder Watch. This year, beginning in early March, we finally have pine siskins at the thistle feeder on our back deck.

Irruptive Migrants

Pine siskins fall into the group of birds known as irruptive migrants. That means that they may or may not migrate for the winter depending upon local conditions. These types of birds often form small flocks during the winter and move from food source to food source. When there is plenty of food in their usual summer territories during the winter, they may not move far at all. When this happens relatively few pine siskins will be seen in the southern reaches of their winter range although there are usually still some that make the trip. In other years, if food is scarce in their summer range during the winter months, pine siskins or other irruptive migrants may come south in great numbers and be widely seen over a much broader range.

While I haven't seen great numbers of reports that would suggest that this winter (2011-2012) has seen a large irruptive influx of pine siskins, there is an ordinary number of reports of pine siskin sightings throughout New Hampshire and we are lucky enough to have spotted them for the first time in our yard.

Similar to American Goldfinch

Pine Siskin (Carduelis pinus) in profile.
Photo by Brad Sylvester. Copyright 2012.

Pine siskins enjoy thistle seed as do American goldfinches. They are often seen together, with one or more pine siskins mixed in with a larger group of goldfinches. When this happens, they can be easy to miss unless one looks closely. Pine siskins look a bit like goldfinches when the latter is in its winter drab colors. Indeed, they are from the same taxonomic genus as the goldfinch: Carduelis. They are a similar size and shape, behave similarly at the feeder, may show a bit of yellow coloring when the wings are folded, and even have wing bars that can resemble those of goldfinches when they are mixed together and swarming a bird feeder.

Upon closer examination though, they are easy to differentiate. Most notably, the pine siskin has prominent streaking on its underside. The American goldfinch's underside is a nearly uniform pale olive-yellow during the winter months. Likewise, the pine siskin's head shows streaking as opposed to the solid yellow-drab of the winter goldfinch (although males may also show the beginnings of the black forehead and crown they'll wear in the summer). The pine siskin will have a relatively bright yellow patch visible on the lower part of its folded wing.

When the wings are extended, the yellow patch of the wings and another on each side of the base of the tail become more visible. The pine siskin is also decidedly more brown in color than the American goldfinch and can sometimes be mistaken for  female house finches or female purple finches until the yellow markings on the tail and wings are spotted.

Attracting Pine Siskins to your Yard

Pine siskin (Carduelis pinus) looking at the camera.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

Your best bet for attracting pine siskins in the winter in the United States is to put up thistle feeders like one of these. If you are getting American Goldfinches in the winter, then you've done all you can to also attract irruptive pine siskins. To encourage them to breed, well, either you've got an established coniferous forest, or you don't.

Quick facts about the Pine Siskin (Carduelis pinus):

What do Pine Siskins Eat? Pine siskins eat small seeds such as thistle seeds,dandelion, and pine seeds, and many others. They also eat small insects and the small buds of trees such as birch and maple.The Cornell Lab of Ornithology says they also may be attracted to mineral deposits like road salt, ashes, or fresh cement.

Range: In the summer, the pine siskin lives mainly in Canada and the extreme northern United States, but can also be found throughout the Rocky Mountains and in parts of California. Sometimes, after a particularly irruptive winter, a few pine siskins will stay in the southern winter range to nest. I'm hopeful that some of those visiting us this month will remain to breed here as we have many large, established evergreen trees in our backyard forest.

Where does it go in winter? As irruptive migrants, pine siskins generally do move south for the winter, but the distance and degree to which they migrate depends upon local food conditions. Movement is generally done is short flights over a period of time. In some winters, they may be found all over the continental United States in good numbers, in others, they may be much more sparse throughout the United States and absent in many regions.

Lifespan: Unavailable

Nesting: According to the Cornell Lab of Ornithology's All About Birds site, nests are built toward the end of the branch of an evergreen tree, well-hidden by the needles. 3-5 greenish-blue eggs with brown or reddish-brown spots are laid in a shallow nest made of twigs, grasses and other fibrous plant material, lined with feathers, thistle-down or other softer material to cushion and insulate the eggs against cold temperatures in the northern nesting range. The eggs take 13 days to hatch.

IUCN Red List Status: Species of least concern. Large population over a wide range.

Pine Siskin Taxonomy:

Kingdom: Animalia

Phylum: Chordata

Class: Aves

Order: Passeriformes

Family: Fringillidae

Genus: Carduelis

Species: Carduelis pinus

Red-tailed hawk (Buteo jamaicensis) riding a thermal



Hawk flying over my yard on March 7, 2012. This is
 a juvenile red-tailed hawk.
Photo by Brad Sylveser. Copyright 2012.
Do not copy.

 For the purposes of this blog, I will count the skies overhead as a part of my yard. If I spot a bird flying overhead and it can be identified, I'll list it here. This morning I happened to look out my window and spy a hawk flying overhead. At first it seemed to be hunting, actively flying in a stright line, then hovering in place with quick wing beats as it focused on some object below.

It did not dive after whatver it spotted and instead began to circle lazily. Riding an uplifting thermal current to gain elevation. Hawks will sometimes ride these thermals all the way up to and even past cloud level. This particular hawk was quite high up by the time I got outside with my older camera. They look like they are just circling, but the rising air carries them quickly upward.

My camera has an autofocus feature and an infinite focus landscape setting. Depending on the height of the hawk, I might use either to catch a soaring bird. If the autofocus can get a good lock on the bird, that is the best option for my camera. Otherwise, using the infinite focus yields acceptable results for ID photos, if not nearly professional caliber. This particular camera has a 10X optical zoom. At any rate, the photo is good enough for an ID. The observed hovering behavior in a Buteo also suggests a red-tailed hawk, although it is not definitive.

Red-tailed Hawk hovering.
Photo by Brad Sylvester. Copyright 2012

 This hawk is definitely a member of the Buteo genus which can be differentiated by the length of the tail relative to the wings. Longer tails are found in Accipiters and shorter tails like this one, in Buteos. One of my favorite resources for identifying hawks is Hawks at a Distance. This book offers 3-4 pages of photos of each raptor and a separate page with dozens of silhouettes of each species to help make identifications under less than optimal conditions.

New Hampshire falls within the northeast migration corridor for a huge number of raptors that head south in the fall and come back in the spring. Some hawk watch station may see thousands of hawks ina single day during the annual migrations.

The red-tailed hawk, however, can be found in New Hampshire all year round, with Canadian birds coming down ffrom the north in the winter. When hawks migrate, they will usually ride thermals high into the sky and then glide for long distances preserving as much energy as possible.

When not migrating, they can often be spotted in trees at the road's edge along highways. This is a great vantage point from which to spot small animals darting out across the road. Unfortunately, this results is a relatively high number of red-tailed hawks being killed by vehicles as well. Despite this, they remain a very common New England hawk.

Quick facts about the Red-Tailed Hawk:

What do red-tailed hawks eat? Red-tailed hawks are carnivores and active hunters. The eat small mammals like squirrels and mice, but, according to the National Geographic Field Guide to the Birds of North America, they are not above taking reptiles, amphibians and birds as well. In New England, reptiles and amphibians would be snakes and frogs. Red-tailed hawks are not nearly as agile bird hunters as the Cooper's or sharp-shinned hawks, but will take birds if they have the opportunity for an easy strike.

Where do red-tailed hawks live: Red-tailed hawks live throughout North America up to the Arctic Circle and down to Central America.

What kind of habitat do red-tailed hawks prefer? Red-tailed hawks live in a wide variety of habitats. They often sit overlooking open grassland to scan for prey. They primarily hunt open spaces, but may also live in forests if there are nearby hunting grounds.

What eats red-tailed hawks? Not much eats red-tailed hawks with any regularity, but if caught on the ground, coyotes and other larger terrestrial predators will take them from time to time.

When is it here? Red-tailed hawks are found in New Hampshire all year round.

Where does it go in winter? Red-tailed hawks migrate south in the winter, but New Hampshire is still within the winter range for Canadian hawks and the summer range for more southern red-tailed hawks.

What's the life span of a red-tailed hawk? Nat Geo Wild puts the average lifespan of a red-tailed hawk in the wild at 21 years.

Nesting: Females lay 1-5 eggs in stick nests high off the ground according to Nat Geo Wild. The eggs take 4-5 weeks to hatch. Both parents care for the eggs and the young hatchlings.

Notes: Although most often identified by their prominent rusty red tails, not all red-tailed hawks have red tails.

Red-tailed hawk taxonomy:
Kingdom: Animalia (Animals)
Phylum: Chordata
Class: Aves (birds)
Order: Accipitriformes (formerly Falconiformes)
Family: Accipitridae
Genus: Buteo
Species: Buteo jamaicensis

Porcupines, Field Observations

As I've mentioned in previous posts, I have several co-located porcupine dens in my yard. There are several dens with active porcupines within the space of 25 feet or so. They may be connected underground, or not. I really can't tell. At any rate, knowing the locations of these dens gives me an opportunity to learn more about these porcupines first-hand.

Despite several freezes and thaws, the well-used path
depression leading from the porcupine dens is easy to find
and follow. Not single set of tracks diverged from the path.
Photo by Brad Sylvester. Do not copy.

I've set up both still picture and video trail cams and recorded some good footage and pictures which seem to show at least three different individuals, although I suspect there are more. Despite being generally solitary creatures, porcupines do sometimes form communal dens in the winter. Although they are well insulated with thick fur and quills, each porcupine throws off body heat. Have several of these living heaters in a single den means the air temperature inside the den will be higher and each individual will need to burn fewer calories to stay warm. It also lowers the chance of freezing to death if the weather turns very, very cold.

Since the snow around the dens is tracked with mud from inside the dens, we can determine that either the dens go down deeper than the frost line into unfrozen ground, or the animals' body heat inside the den is sufficient to melt the frozen ground inside the den.

Fresh snowfall also gives me the opportunity to follow the nightly routes travelled by the porcupines. Today, I did just that to find out exactly where they go and what they eat. We know that porcupines eat small tender twigs and the inner bark of trees, especially during the winter, but what species do they prefer? How big is their range? And how many trees does it take to support them?

We had a significant snowfall here five days ago on top of bare ground. That means that for five days, the porcupines from these dens have been laying down tracks and trails. From previous experience, I know that porcupines (at least in winter) tend to be creatures of habit and follow set patterns. That means that rather than dozens of trails radiating out from the dens in all directions, we'd expect one or possibly two frequently used trails going to specific destinations repeatedly.

Figure 1: Sketch of the path leading from the porcupine
dens in my yard. Not to scale.
Drawing by Brad Sylvester. Do not copy.

The sketch labelled figure 1 shows what I found. It's not to scale but shows the well-worn trail laid down by the porcupines from these dens. As I would have bet, there is a single trail leading from Den #1 directly to Den #2 and from there to a beech tree then on to a hemlock tree. From there, the porcupines (since they were not still in the trees) used the same route to return back to their dens. In the five days since the most recent snow at least, the porcupine or porcupines from these dens visited only two trees.

The last time I set out trail cams to view the nocturnal porcupines was earlier this winter. There could be fewer or more living in the dens now than there were then. Although I could see three that looked different enough in the previous pictures for me to believe they were distinct individuals, that is by no means an accurate population count of the dens at the time.

Examining the trees to which the porcupine trails lead gives us more information about them. Although there is inner bark available at the base of the tree, these porcupines climb high into the tree and its smaller branches to eat. Fresh scars left by their gnawing can be seen no lower than about 15 feet up. I can think of three main reasons or theories about why the porcupine should eat only the inner bark from high in the tree even though it takes more energy to climb the tree than to eat from ground level.

Beech tree gnawed by a porcupine. The inner bark has
been stripped, girdling the upper trunk. This part of the
tree will die as a result of porcupine feeding.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

The first is that the porcupine is safer from potential predators while high up in the tree than it would be on the ground. Under this theory, those with a predilection for climbing before eating would fall victim to predation less often and have an evolutionary survival advantage over porcupines that stayed on the ground to eat. The porcupine in a high tree would certainly be protected from predators like coyotes which cannot climb at all. Although some porcupine predators can climb trees quite well, the backside of a porcupine climbing a tree is pretty well defended. On the other hand, once it is out on a narrow branch, the porcupine's undefended underside might be exposed. This theory is pretty difficult to prove.

A second possibility is that the outer bark is thicker at the base of the trees than it is higher up on the thinner branches, so it is more difficult for a porcupine (with relatively short chisel-shaped incisors) to gnaw through to the inner bark around the tree's base. It might wear out the rodent's teeth too fast. Most animals tend to select food that offers the highest nutrition for a given amount of effort. For this theory to be workable, the lesser chewing and digestion effort or the lower rate of tooth wear of eating thin upper bark, instead of thicker lower bark would have to outweigh the effort of climbing the tree. Difficult to prove outside a lab setting.

Photo by Brad Sylvester. Copyright 2012.

The third choice is similar to the second. There might be a difference in the nutritional content of the upper tree bark compared to the lower tree bark. Its composition might be different so that it contains nutrients not found in the lower bark in sufficient density to support the porcupine's health. Although this is easier to test, we'd still need a lab to analyze bark samples.

Finally, of course, it could be a combination of any of those theories, or something else entirely.

What did we learn?

What we do know is that porcupines eat the inner bark of beech trees and hemlock trees when there is thick snow cover on the ground. We know they chew through the small twigs, near the main branch dropping the twig ends to the forest floor below. They do not appear to eat these small twigs from the forest floor once they have fallen (unless they carry them back to the den, a possibility for which I found no evidence).

We know they visit a small number of trees when there is heavy snow cover, only two in this case over a period of five days. The entire length of the slightly winding trail used by these porcupines extends perhaps 100-175 feet in length. We know they do significant damage to the trees from which they eat during the winter, with the inner bark completely stripped from large sections of the upper trunk and branches, likely killing branches and perhaps even the top of the tree.

Hemlock twigs littering the forest floor are a sing of
porcupine feeding.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

From previous experience, I know that a littering of fresh hemlock twig ends on the forest floor is a sure sign of the presence of porcupines all year round, so we know porcupines include hemlock in their diet all year round. I have also seen porcupines, especially very young porcupines, eating clover and grass in the summer.

What we still don't know

What we don't know from the above-reported observations is whether the porcupine's diet or habits change when there is not a thick snow cover. We don't know whether the small twigs are removed because they get in the way of stripping the bark off larger branches, or if the ends simply fall when they are eaten through. We don't know if porcupines eat other tree species. We don't know how many porcupines might eat from a tree at one time, how much time they spend eating, or how long it might take them to strip a tree to the point where diminishing returns necessitate finding a new tree from which to eat. We don't know if their range increases when there is less snow and travelling is easier. We don't know how many porcupines share these communal dens, the familial relationship, if any, between the members of this seasonal group, or their ages.

We don't know if a winter communal group stays in the same group or den all winter or if individuals might leave and move into other dens within a single season. We don't know much, if anything about their behavior within the den. We don't know whether one individual might stay in the same den throughout the following summer or if they all split up to find new dens. While we might find the answers to some of these questions in existing literature about the porcupine, I'd like to do some non-invasive observations of my own to learn about my own resident porcupines directly. I think I'll start by putting a trail cam high in a tree to observe the animals as they eat.

---

Update: My new YouTube channel: @WhatLivesinmyYard talks about the porcupine in Episode 1.