Tuesday, June 28, 2016

MD Herps - Copperhead (Agkistrodon contortrix)

The copperhead (Agkistrodon contortrix) is one of Maryland's most notorious snakes.  Like most venomous snakes, it is both widely feared and misunderstood. This, unfortunately, not only causes the unnecessary death of copperheads, but also a variety of other snakes that are misidentified as such.  In this post, we'll get to know this infamous snake, and learn methods of living alongside these maligned reptiles.

A copperhead snake. Notice the dark hourglass patterns with their "waists" over the spine. 
COPPERHEAD ID CHECKLIST:

  • colored in shades of reddish-brown and tan, bearing a striking resemblance to fallen leaves
  • patterned in dark hourglass-like bands with the skinny "waist" of the hourglass over the spine
  • scales are keeled and not shiny
  • head is broad, with the "cheeks" being very distinctively wider than the "neck"
  • no rattle (though will sometimes shake the tip of its tail)
  • vertical pupils
  • relatively stocky, fat body

NATURAL HISTORY

Of the 27 different species and subspecies of snakes in Maryland, only two are venomous to humans - the copperhead and the state-rare timber rattlesnake (Crotalus horridus). Both the copperhead and the rattlesnake are pit vipers, a group of venomous snakes that have a heat-sensing pit between their nostril and eye on either side of their head.  In general, this feature gives this group an exceptional ability to hunt warm-blooded prey at night.  Overnight, the plants, stones, and soil cool down without the heat of the sun, but warm-blooded animals, such as rodents, remain hot.  The pits are sensitive to the infrared light emanating from warm objects, essentially highlighting mammals in in the darkness.

Notice the pit between the eye and the nostril of this copperhead. 
While adult copperheads take a large number of rodents as part of their diet, juvenile copperheads have an additional adaptation - the tips of their tails are a striking yellow-green.  The young copperheads will lay camouflaged in the leaves and wiggle their tails like a squirming grub.  This acts as a lure, which attracts lizards and frogs as prey for the small snakes.  This diet high in cold-blooded prey is fairly unusual among pit vipers. As the copperheads mature, their tails darken, and they turn to a diet mainly of mice and voles, though they will continue to eat amphibians and reptiles when available.  They have even been known to eat birds, smaller snakes, and large insects, such as cicadas! Like all of Maryland's snakes, however, children, dogs, and cats are far too large to eat, and are off the menu.

File:Juvenile copperhead snake.jpg
A juvenile copperhead, wiggling its yellow-green tail. Image public domain via Wikimedia Commons
Copperheads hunt by using their keen sense of smell to locate areas where prey frequent, then set up camp, lying motionless in the leaf litter for days, or weeks, until food comes within striking range. Prey is subdued by a hemolytic venomous bite that destroys red blood cells.  While dangerous to small animals, the venom of copperheads is actually weak among vipers, and is typically not fatal to humans.  Regardless, all bites should receive medical attention to treat pain and prevent damaging complications due to swelling or secondary infections.  While adult humans generally experience non-fatal, though unpleasant, effects of copperhead bites, such as pain and nausea, they can be more dangerous to children and pets due to their smaller body size.

Bites from copperheads, however, are fairly rare.  The copperhead's venom has evolved to allow it to capture prey, not fend off large animals.  Its main defense against disturbance by humans is to sit motionless and allow its near-perfect camouflage to render it invisible.  If further provoked, it will often try to slither away, rather than bite.  Most bites occur when they are accidentally stepped on, or when humans are trying to handle or kill them.  One of the best ways to prevent copperhead bites is to not try to kill copperheads!

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A copperhead's camouflage is near-perfect!  Image public domain via Wikimedia Commons.
Another common misconception about copperheads involves their habitat.  Folk knowledge places copperheads near bodies of water, but copperheads are just as likely to occupy wet habitats as they are dry environs. The association of copperheads and water possibly stems from confusion between copperheads and water snakes and water moccasins, both of which prefer wet habitats.  Water moccasins are not found in Maryland, but are close relatives of copperheads.  In fact, in the southern states, copperheads are sometimes called "highland moccasins" or "dry-land moccasins" due to their habit of living in much dryer areas than their cousin.

In truth, copperheads are not particularly picky about their habitat type - they can be found along rivers, in wetlands, on dry slopes and ridges, sandy woodlands, and hilly forest.  While many of these habitats tend to have a water source nearby, it isn't a always a requirement for copperheads. Copperhead habitats commonly feature rocky areas or dense woodpiles that can can provide shelter throughout the year or hibernation dens during the cold months. Good hibernacula can be few-and-far-between in some areas, and copperheads tend to hibernate together and with other species of snakes, including rattlesnakes and rat snakes.

Rocky areas, like this in the Catoctin Mountains, make good snake habitat. 
In spring, after emerging from hibernation, copperheads tend to bask around their winter dens before dispersing, sometimes long distances, in search of feeding grounds.  This is also the start of their first breeding season, the second breeding season beginning in fall.  Females who mate in the spring will give birth that season, but those who mate in fall will store the sperm and give birth the following year.

Mother copperheads show a remarkable amount of parental care for their young.  They do not lay eggs, but rather, carry their developing young inside them for several months, then give birth to fully-developed young snakes.  This allows the female to provide better protection and thermoregulation of her young than she would be able to provide for a batch of eggs. After they are born, the young stay with their mother until their first shed, giving them additional protection and a head-start to life.

Young copperheads are at risk from a large number of predators, including a variety of predatory birds, larger snakes, cats, opossums, and even large bullfrogs!  Many copperheads will die before they reach maturity at 2-4 years.  The oldest recorded wild copperhead was 18 years old, but they can live almost 30 years in captivity if provided good care.  Copperheads are sometimes cared for by educational, conservation, and research institutions, and their venom may have anti-cancer properties which are being explored.  As venomous snakes, they are not legal to keep as personal pets in Maryland.

COPPERHEADS IN MARYLAND

In Maryland, we have two distinctive populations of copperheads.  The northern copperhead (A. c. mokasen) is found throughout the state, except for the Delmarva peninsula. Its numbers are highest in western Maryland and decline eastward toward the coastal plain.  The second group of copperheads are an intergrade population between the southern copperhead (A. c. contortrix) and the northern copperhead.  They are found on the southern portion of the Delmarva peninsula.  Northern copperheads are generally darker than their southern cousins, and often have dark blotches between their hourglass markings, while southern copperheads tend to be lighter and without excess blotches. Intergrade copperheads have characteristics of both subspecies, being somewhat lighter and less blotched than northern copperheads, but darker and more spotted than true southerns.  Copperheads are rare to non-existent on the northernmost portion of the Delmarva peninsula.

File:Agkistrodon contortrix mokasen CDC.png
A typical northern copperhead (A. c. mokasen). Image public domain via Wikimedia Commons.
File:Agkistrodon contortrix contortrix CDC-a.png
A typical southern copperhead (A. c. contortrix). Image public domain via Wikimedia Commons.
LIVING WITH COPPERHEADS

Copperheads spend most of their time hidden from sight, either within rock crevices, under brush, or by sitting perfectly still and camouflaged.  Copperhead bites can be prevented in a few ways:

  • Take care when walking through brush, over logs, and in rocky areas, particularly if you are not using established trails, as copperheads can be very difficult to spot in undisturbed leaf litter
  • Check hand- and foot-holds carefully when rock climbing
  • Wear long pants when hiking, and wear protective clothing when moving brush or clearing debris in natural areas
  • Never try to handle or kill a copperhead if you find one
  • Carefully monitor pets and children when playing or traveling in areas where copperheads are suspected of living
  • Avoid known hibernation sites
What should you do if you find a copperhead?
  • In most cases, all you need to do is leave it alone and appreciate the opportunity to view one of Maryland's most cryptic snakes - don't try to touch or scare it, just let it do its thing. 
  • If the snake is in a location that requires it to be moved (in a home, garage, in a busy path, etc.) contact the Maryland DNR or visit this site to find a licensed wildlife control officer.  Do NOT try to handle or kill it. 
  • Sometimes snakes appear dead when they are sick or injured.  Even if a copperhead appears dead, do not attempt to handle or move it, and instead contact your county's Animal Control service for dead animal pick-up.  If you suspect the animal is sick or injured, contact a licensed wildlife rehabilitator.
  • In the case of a copperhead bite, seek medical attention immediately!  Even though copperhead venom is relatively weak and rarely fatal, it can cause medically significant symptoms and lead to potentially dangerous complications if untreated. Animals suspected of being bitten should receive immediate veterinary care. 
SIMILAR SPECIES

Many Maryland snake species are frequently confused for copperheads.  Copperheads and rattlesnakes are pit vipers, and have several features unlike Maryland's non-venomous snakes. 

MARYLAND VENOMOUS SNAKES
  • Heads are very distinct from body, with their fat "cheeks" much wider than their "necks"
  • Relatively thick, stocky bodies
  • Vertical, cat-like pupils
MARYLAND NON-VENOMOUS SNAKES
  • Heads are rounded, like polished stones, and are indistinct, with their necks only slightly thinner than their heads
  • Most are long and skinny
  • Round pupils
A copperhead next to a timber rattlesnake.  Notice the distinctly wide head that is characteristic of vipers. Also notice the difference in pattern between the copperhead and rattlesnake.
Copperheads can also be easily distinguished from rattlesnakes as follows:

COPPERHEAD:
  • Distinct hourglass-shaped bands that are thinnest over the spine
  • Colored and patterned like crisp, fallen leaves
  • No rattle
  • Our most common venomous snake
TIMBER RATTLESNAKE:
  • Dark, tiger-stripe or zig-zagged bands that are widest over the spine
  • Typically gray or tan with dark bands, like strips of tree bark
  • Rattle on tip of tail
  • State-rare
A adult copperhead tail (no rattle) next to a timber rattlesnake tail (rattle). The body of the timber rattlesnake is in the background. 
The most common snakes confused for copperheads are northern water snakes, possibly because copperheads are strongly, but somewhat erroneously, associated with bodies of water. Corn snakes and milk snakes are also frequently mislabeled as copperheads because of their reddish coloring.  Water snakes, corn snakes, and milk snakes all have round pupils, heads that are only slightly wider than their necks, and dark blotches/bands of color that are widest over their spines. 

A northern water snake, frequently mistaken for a copperhead. 

REFERENCES:

Animal Diversity Web, University of Michigan

Maryland Biodiversity Project

Maryland Department of Natural Resources, "Snakes in Maryland."

Maryland Department of Natural Resources, "Field Guide to Maryland Snakes: Northern Copperhead."

Smithsonian National Zoological Park, "Fact Sheet: Northern Copperhead"


Friday, June 24, 2016

Maryland: Weird and Wonderful - The Mystery of The Dead Shrews

Anyone who spends time outdoors in Maryland is bound to come across dead animals from time to time.  After all, one of the tragic but necessary qualities of life is that which lives also dies. With nature being the harsh mistress that she is, many animals fall victim to predation, starvation, disease, competition, and natural disasters.  It is not unusual to find the remains of wildlife past as we explore our parks, gardens, and neighborhoods.

However, one diminutive creature's remains hold an air of mystique to those who find them.  The bodies of shrews are often found completely untouched in the middle of trails and walkways. It's as if in the midst of crossing, the small animals simply dropped dead.  Often mistaken for mice or voles by those who find them, shrews are not rodents, but are more closely related to hedgehogs and moles.  Shrews can easily be told from mice and voles by their exceptionally pointed snouts and sharp, red teeth.

A dead, yet untouched, shrew. 
Shrews' lives can be claimed in many ways.  Being small but active animals, they have a high metabolism and need a steady supply of food to drive it.  During population bursts, it is possible that some shrews may starve for lack of food.  Fights with rivals in order to secure good feeding and breeding grounds may also take their toll. It is even possible that the furiously whirring organs of shrews cannot handle excess stress, and they may die if overly exerted. Further, shrews have remarkably short natural life spans, only 1-3 years.  Factor in parasites and disease, and it seems the Grim Reaper is constantly nipping at shrews' tiny heels.

However, shrews who meet their ends in these ways typically die where they live - beneath the cover of overgrowth and leaf litter, not out in the middle of trails and sidewalks. What is compelling shrews to keel over in such unusual, exposed places?

The answer lies in the shrews' defense mechanism. Many shrews, including our most common shrew, the northern short-tailed shrew (Blarina brevicauda), have a secret weapon - an unpalatable stench and taste exuded from glands on their bellies and sides.  This makes them exceptionally distasteful to scent-oriented predators, such as foxes, weasels, and roaming cats. The shrews' frantic scurrying beneath the leaves is irresistible to such predators, who probably mistake the small mammal for something tasty, like a mouse or vole. Once caught and killed with a bite or shake, it becomes apparent that this little creature is absolutely foul, and its virtually unscathed body is discarded.

Foxes and cats may not like shrews, but scavengers, such as flies and beetles, don't mind the smell!
Foxes and cats often use established trails, including human pathways, as it is easier than bushwhacking and it gives them the best opportunity to smell the markings left by animal and human traffic through the day.  The unwanted bodies of shrews are left by the wayside of these predator highways, some even surrounded by scrape marks or feces, essentially "put out with the trash." Domestic cats who are allowed to roam may leave shrews as "gifts" for their owners (or other friends), in which case, they are often left in conspicuous places, such as doorsteps or even their humans' beds!

Shrews do have predators that eat them, namely owls, which do not seem bothered by their noxious smell.  However, owls tend to swallow their prey whole and leave no carcass, which adds to the rarity of half-eaten or badly mauled shrews.

If you find a dead shrew on your property, take it as a bit of useful information! Here are a few things you can surmise:

  • You have shrew food on your property, which may include worms, beetles, slugs, mice, and small snakes.
  • If you don't like worms, beetles, slugs, mice, or small snakes, you are in luck! You have shrews eating them.
  • You have predators that don't like to eat shrews on your property, probably foxes or domestic cats.
  • You have good shrew habitat, including leaf litter and overgrowth, which is also great habitat for many other creatures, such as frogs and fireflies.
  • You may also have moles, since shrews frequently use old mole tunnels as they forage. 

So what can you do with this information?

  • For starters, don't let your cats outside! Shrews eat pest animals and owls love to eat shrews.  You can help feed owls and control pests by keeping cats away from shrews. Also, cats allowed to roam outside are at higher risk of killing other beneficial wildlife, as well as getting killed themselves!
  • You are doing a good job at creating good wildlife habitat on your property - keep it up! Replace some of your lawn with gardens, and don't worry too much about those mole hills. 

REFERENCES:

Animal Diversity Web, University of Michigan
http://animaldiversity.org/

Internet Center for Wildlife Damage Management, "Shrews"
http://icwdm.org/handbook/mammals/shrews.asp

Maryland Biodiversity Project
http://www.marylandbiodiversity.com/


Saturday, June 18, 2016

Fathead Minnow - The Perfect Backyard Pond Fish

Backyard ponds are wonderful additions to wildlife gardens!  They are magnets for birds, who use them to bathe, drink, and cool down in the summer heat.  They provide habitat for amphibians, dragonflies, and other aquatic animals.  Not to mention the beauty and serenity they bring to a backyard getaway!

However, backyard ponds have a nasty problem - mosquitoes!  Even in ponds with fast-moving water, mosquito larvae will find small pockets of still water in which to thrive. Many pond-owners turn to chemical additives and Bti to control mosquitoes, which can also affect some beneficial insects, including craneflies, whose larvae feed on mosquitoes. Others turn to goldfish, which are effective mosquito predators when small and young, but inevitably grow large enough that they begin to feed on important native species, including dragonfly larvae, amphibian eggs, tadpoles, and smaller fish!

Goldfish are popular pond fish, but unfortunately prey on native wildlife, such as frogs, dragonflies, and other fish. 
Another fish species commonly used to control mosquitoes is the mosquitofish (Gambusia), so named to market it towards mosquito control.  However, most mosquitofish available in pond supply stores or pet shops are western mosquitofish (Gambusia affinis), which are not native to Maryland and have a detrimental effect on native fishes when they are accidentally transferred to natural streams and ponds.  Further, while they eat mosquito larvae, their preferred prey are other beneficial aquatic insects and other fishes' fry!

File:Mosquitofish.jpg
The western mosquitofish unfortunately prefers other insects and fish fry over mosquitoes.
Image public domain via Wikimedia Commons
So what is a conscientious pond-owner to do? Many mosquito control options can actually harm native wildlife in some form or another! Fortunately, Maryland has a perfect, native solution - the fathead minnow (Pimephales promelas)!

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The star of this post, the fathead minnow!
Image public domain via Wikimedia Commons
Fathead minnows are native to most of the central United States, with the Appalachian Mountain range creating a natural barrier to their eastward spread.  They naturally occur in Maryland at the extreme western edge of the panhandle, before the start of the Chesapeake Bay drainage system. However, they are a popular bait fish, and have been introduced into freshwater areas across the state by anglers dumping their unused live bait.  NEVER release live bait into a native ecosystem, as introduced species can become invasive or carry disease to native fish populations.  Fortunately, fathead minnows set up breeding populations east of the mountains with little to no adverse effect on the native wildlife.  While every effort should be made NOT to introduce bait or pets to new habitats, the fathead minnow seems to be a relatively innocuous species, and accidental introductions have been fairly harmless, unlike those of goldfish and western mosquitofish.  I'd wager that if the mountains weren't in the way, the fathead minnow would have been a natural member of most of Maryland's freshwater ecosystems.

So we know that fathead minnows are a gentler, more wildlife-savvy option than most other pondfish, but their appeal doesn't stop there!  Many of their natural attributes make them well suited to backyard ponds.  Their popularity as bait fish and as feeder fish comes from the fact that they are readily consumed by a large number of predatory fish.  This means that their preferred habitats are pretty much anywhere the large predators are NOT. Because of this, they are not particularly picky about habitat conditions, and are tolerant of a wide range of water conditions that might be unfavorable by predators.  This includes shallow pools, turbid water, water with high acidity or pollutants, low oxygen, and quick and frequent changes in water quality. Anglers sometimes call fathead minnows "tuffies" due to their ability to "tough out" the experience of being kept in an unregulated bait bucket for the entire day.

While you should always strive to make a good, healthy home for your fish, the fatheads' tolerance for poor water conditions also makes them tolerant to human mistakes when regulating an artificial pool.  Algal blooms, drops in oxygen, pump and filtration problems, and other surprise pond problems are less likely to adversely affect fathead minnows than they are many more sensitive fish.

A fathead minnow hunts for mosquito larvae along the edge of a pond. 
Because they are often found in murky water, fathead minnows have many wonderful adaptations to help them thrive in poor visibility. Like most members of the carp/minnow family (Cyprinidae), fathead minnows have excellent hearing. A series of bones connects their swimbladder to their inner ear, amplifying sounds and making them exceptionally sensitive to vibrations in the water.

They also use a variety of chemical cues to communicate, such as releasing pheromones when breeding or alarmed.  Using their chemical scents, they are even able to discern individuals they have met before from strangers!  During breeding, males develop sensitive tubercles on their heads that help them sense females, rival males, and eggs, as well as select and maintain breeding sites.  The large heads of the males that accommodate these tubercles give rise to the species' common name of "fathead" minnow.

Like many true minnows (Leuciscinae), fathead minnows tend to be small (about 3in at the largest) and silvery in color.  Females and juveniles have silver sides, a pale belly, and a brownish back, with a dark line running the length of their sides. Mature males have large black heads and a dark body with one or two pale bands. Fathead minnows have short lifespans, living only about 1-3 years. Because of this, they are eager breeders, since many may only survive for one breeding season.

Fathead minnows begin to breed when water temperatures are above 60F (15C) and continue to reproduce throughout the warm months (typically May-September). Males who are ready to breed find and maintain nesting sites in small "caves" under horizontal surfaces, such as flat rocks, logs, and water lily leaves.  Pond-owners can create these nesting sites with landscaping rocks, cored cinder blocks and broken pottery.  Many locally-run garden centers will give away broken pots for free!  The Loading Dock in Baltimore City often has free ceramic tiles available on their lot, as well.

File:Pimephales promelas Fathead.jpg
A male fathead minnow, showing its large head and tubercles on its snout.
Image public domain via Wikimedia Commons
Once a male has set up his site, he vigorously defends it against all intruders - even females that do not seem ready to breed, as they may eat other females' eggs. Females "shop" for males and seem to prefer large males who already have eggs. Once a female has selected a male and is ready to lay, the pair remains in almost constant contact inside their little cave. When the female releases her eggs, they float upwards and stick to the roof of the nest site with a natural adhesive.  The female then leaves, but the male stays and dotes on the eggs, cleaning them, wafting them with fresh, oxygenated water, and defending them from predators.

Several females may lay in the male's nest, and as long as there are eggs to care for, the male will not leave them to eat.  He primarily uses his energy reserves to sustain himself during his parental duties, but if he comes close to starving, he will eat some of the eggs. The eggs typically hatch within a week, but because he may continue accepting females during this time, the male may be rearing broods non-stop during the breeding season.  Many males die towards the end of the season due to the extreme energy depletion involved with caring for the eggs.

Upon hatching, the minnow fry are extremely tiny, only about 1.5mm (0.06in) in length.  They spend about 1-2 days living off of the nutrients in their yolk sacs, then become active and eager little feeders!  Fathead minnows eat minute food - algae, bites of vegetation, and tiny invertebrates, like mosquito larva.  They rarely, if ever, feed on fish fry, and amphibian eggs and tadpoles are simply too large for them.  My fatheads are well-fed on the natural bounty of my pond, though I net a few out every week to judge body condition.  If your fathead minnows are thin or are not able to find enough food in your pond alone, they can be fed bloodworms, brine shrimp, small goldfish pellets, and even betta pellets.

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The "rosy red" or xanthic color phase of the fathead minnow, male in foreground and female in back
Image public domain via Wikimedia Commons
One downside to typical fathead minnows is that they can be difficult to see and enjoy, not only for their camouflaging coloring, but also because of their habit of lurking under rocks at the bottom of the pond when they are not hunting.  However, a selectively-bred color mutation helps correct this aesthetic problem.

These fish, called "rosy red minnows" have a simple mutation that makes them lack melanin.  They are essentially albinos, but because fish produce more pigments than simply melanin, they are not pure white.  Instead, lovely yellow and orange (xanthic) pigments are revealed, making the minnows bear a striking resemblance to small goldfish.  Because there is no dark pigment to mask the blood vessels beneath their skin, they are also rosy-pink in some areas of their body, such as around their gills and along their lateral line, hence the name "rosy red."

"Rosy red" is also the common name given to both dark and xanthic fathead minnows in pet shops, as it is sounds more attractive than "fathead."  The mutation is also known as "golden" or "pink" in other species.  Some fathead minnows are even "pied," exhibiting spots of normal dark color on an otherwise xanthic fish. If you like the look of goldfish, but not their size or voracious appetites, rosy red minnows are for you!

A rosy red fathead minnow does a convincing impression of a small goldfish. 
Fathead minnows are readily available from bait shops and pet stores, where they are sold as feeder fish for less than a quarter a piece. Since they are normally sold to be fed to larger animals, they often do not receive particularly attentive care and are frequently underfed or ill.  NEVER release fish from bait shops or pet stores into natural ponds or streams, as they can introduce illness to the native populations.  If you are adding newly purchased fish to an artificial pond that already contains fish, it is prudent to keep the new fish in a separate quarantine tank for 14-30 days while they receive preventative treatments.  Work with your vet to determine what treatments may be reasonable for your fish before adding them to your pond.

To learn more about fathead minnows, check out Robyn's Rosy Red and Fathead Minnow Page on fishpondinfo.com. It is an excellent site with a wealth of information on their care and rearing.

RESOURCES:

Montana Field Guide, "Fathead Minnow - Pimephales promelas"
http://fieldguide.mt.gov/speciesDetail.aspx?elcode=afcjb32020

Animal Diversity Web, University of Michigan
http://animaldiversity.org/

Thursday, June 16, 2016

Maryland: Weird and Wonderful - The Ghost Plant

"Maryland: Weird and Wonderful" is a WMD101 series showcasing specific natural phenomena occurring in Maryland that are particularly interesting or unusual.

Called ghost plant, corpse plant, and Indian pipe, Monotropa uniflora, lives up to its many names. It rises seemingly overnight from the damp forest soil in sparse clusters.  Its pale, translucent flesh and nodding floral heads give it the appearance of both a pipe and a mournful spirit.


INDIAN PIPE ID CHECKLIST

  • typically less than a foot tall
  • color ranges from gray to white to pink, often with black spots
  • resembles a smoking pipe, each stem bearing a single, nodding flower
  • begins appearing in June, often during warm, wet weather
  • typically found in forests with beech trees and rotting wood
  • prefers shady, moist conditions

Its waxy, pallid color and lack of identifiable leaves gives it the look of a fungus, but Indian pipe is, in fact, a plant - a very special one!  It does not photosynthesize, hence the lack of green clorophyll and its insignificant leaves.  Instead, it has a complex relationship with both the fungi and the trees in its habitat.


Many trees have a symbiotic, mutualistic relationship with fungi, often "mushroom" fungi.  When they aren't producing mushrooms, these fungi exist as a network of tiny, threadlike structures below the ground.  These mycelia interact with the roots of trees, exchanging nutrients and allowing both to benefit.

A miniature forest of Indian pipes. 
Indian pipe is typically found growing within the mycelia of brittlegill or milk-cap fungi. The plant taps into the fungus's resources, leeching off its nutrients. It is able to absorb nutrients from both the fungus, and from the tree with which the fungus has partnered. In this sense, it is a parasite of the fungus - and indirectly, the tree - and is known as a mycoheterotroph. Its preferred fungi tend to form relationships with the roots of pines and beeches, and therefore, Indian pipes are typically found along the root systems of these trees.

Notice how the Indian pipes follow the roots of this beech tree. 
It's bell-shaped flowers point downward while they wait to be pollinated by passing bumblebees.  This keeps rainwater from filling the heads and depleting the pollen.  Once polinated, the flowerheads darken and point straight up, and the plant forms a dry seed capsule. The seeds are small and may be dispersed by the wind.
This flower has been pollinated and is starting to turn upward. 
Look for Indian pipe in rich, moist forest that has beech and/or pine and plenty of shade. Indian pipes typically first appear in June in Maryland.  They regularly appear in Oregon Ridge Park in Baltimore County in late spring/early summer.  Be sure to marvel at their ghostly beauty without trying to take them home.  Not only do they do poorly as a picked flower, their complex relationship with the forest community makes them difficult to transplant.  And as always, respect parks and natural areas by leaving nature where you find it.

RESOURCES:

Botanical Society of America
http://botany.org/Parasitic_Plants/Monotropa_uniflora.php

Faifax County Public Schools ecology pages
http://www.fcps.edu/islandcreekes/ecology/indian_pipe.htm

Maryland Biodiversity Project
http://www.marylandbiodiversity.com/

USDA Forest Service, "Monotropa uniflora - Ghost Plant, Indian Pipe"
http://www.fs.fed.us/wildflowers/beauty/mycotrophic/monotropa_uniflora.shtml

Maryland: Weird and Wonderful - Millipedes, Mycosis, and Mind-Control

"Maryland: Weird and Wonderful" is a WMD101 series showcasing specific natural phenomena occurring in Maryland that are particularly interesting or unusual.

An infectious pathogen slowly takes hold of its unfortunately victim.  Doomed to die, its host mindlessly crawls upward. No longer in control of its own body, its only mission is to infect other members of its species. 

It sounds like the plot of a zombie movie, but this same story plays out on a much smaller scale within the forests of Maryland. In this case, the hapless victims are flat-backed millipedes (Apheloria virginiensis corrugata) and the deadly pathogen is a entomopathogenic fungus called Batkoa. 


Dead flat-backed millipedes cling atop the branch they were compelled to climb.
Harmless to humans and most other animals, this fungus species does little to affect its millipede host until it is a sufficiently-sized adult.  When the temperature and humidity is just right, the fungus releases chemicals that compel the millipede to leave its safe habitat beneath the leaf litter, climb atop fallen logs and branches, and grasp these perches tightly.  The fungus then consumes the internal organs of the millipede and pushes through the creases of its exoskeleton, releasing its spores into the air.  Carried by the breeze that hits the top of the logs, the spores disperse over a large distance. Having landed, the spores lie dormant in the leaf litter, waiting to be accidentally ingested by another millipede. 

Notice the puffy whitish fungus emerging between creases in its exoskeleton. 
The purpose of Batkoa's "mind-control" is clear - if the millipede were to stay beneath the leaves, the spores would be trapped in a small area.  Many entomopathogenic fungi use this strategy of compelling their hosts to climb to conspicuous locations during their spore-bearing phase.  It's so common, the behavior even has its own name - "summit disease" - for the tendency of the dying arthropods to seek out the summits of rocks, logs, and plants so the spores may catch the wind. 

Despite their life-like poses, these millipedes are quite dead - they are even hollow inside!
If you are hiking in the spring or fall, be on the look-out for precariously perched creepy-crawlies - you may find the victim of a morbidly fascinating fungus!


RESOURCES:

BugGuide

Cornell University Plant Pathology Photo Lab

Herlocker, David

Maryland Biodiversity Project




Sunday, March 20, 2016

Amazing Maryland Bugs: Allegheny Mound Ant (Formica exsectoides)

"Amazing Maryland Bugs" is a WMD101 series showcasing a variety of Maryland's fascinating terrestrial invertebrates, including insects, centipedes and millipedes, isopods, and others. Butterflies and moths, and spiders are featured in their own series: "Maryland Butterflies and Moths" and "Maryland Spiders."

Ants are well-known for exhibiting some of the most complex social structures in the animal world.  Allegheny mound ants (Formica exsectoides) are a native Maryland ant species whose fascinating adaptations and behavior is more than worthy of a closer look.

ALLEGHENY MOUND ANT ID CHECKLIST
  • large size
  • red-orange head and thorax, black gaster (abdomen)
  • head is distinctly concave between the eyes
  • creates large thatched mounds in sunny areas
  • during the warm months, the mounds are crawling with busy workers (during the cold months, the overwintering queen and workers rest deep below the mound)
A hard-working Allegheny mound ant - notice the strongly concave head shape.
Despite their common name suggesting a montane habitat range, Allegheny mound ants are actually very widespread and are among the most common ants along the eastern coast of North America.  They are a member of the Formica genus of ants, and like most members of this group, they are large in size, highly predatory, active during the day, and known for secreting formic acid.

A colony of Allegheny mound ants starts like many ant colonies - with a new queen looking for a place to raise her young.  However, an Allegheny mound ant queen is not capable of raising a brood herself - she needs workers to help care for her eggs and larva.  To accomplish this, she infiltrates a colony of a closely related Formica ant, typically the silky field ant (Formica subsericea).  This infiltration is risky business - many invading queens are likely killed by workers before they have the chance to reach the colony's resident queen.  But those that do, will subsequently kill the resident queen and take over the colony.  The dead queen's workers feed the impostor queen and rear her brood until they die of old age and are completely replaced by the new queen's daughters and the colony takeover is complete.  This style of colony establishment is known as temporary social parasitism

An entrance into the mound.
Once an Allegheny mound ant colony is established, it may have more than one queen operating within a supercolony of many mounds, chambers, and networks of tunnels.  A particularly large colony may fragment into several individual colonies, similar to honeybees. Evidence of mound ant colonies are distinctive - open, sunny spaces marked with several mounds of thatched grasses, dirt and wood fragments.  These mounds are seething with workers as they maintain the mound, remove detritus, and return to the colony with food.  

The mounds are solar incubators for the colony's brood, warming the eggs and pupae as they develop.  Shade is the Achilles' heel of the mound ant colony - without the warming sun, the colony will fail as the next generation struggles to reach maturity. Nature, however, abhors a vacuum, and sunny habitats often succeed into woodlands and eventually shady forest.  Allegheny mound ants have a unique method of insuring their sunny paradises are not overshadowed.  When tall vegetation sprouts up around their mounds, workers bite the stems of the plants, then inject formic acid into the wound, gradually killing the plant.  

A mound made by Allegheny mound ants. 
Growers of plants are generally split in their opinion of mound ants as pests or beneficial insects - while their activity will kill plants immediately around the mound, their voracious predatory nature acts as highly efficient pest control over a wide area around the colony. These ants are ecologically significant, maintaining sunny clearings in areas that would have otherwise succeeded to woodland.  Some birds, butterflies, and other animals who prefer open habitats may be able to thrive in areas cleared by mound ants in the midst of less suitable habitat.  It has even been suggested that these ants could be used to help clear areas of invasive plants.

While the dietary needs of an ant colony are complex, the most important food sources fall into two broad categories: proteins and sugar.  Allegheny mound ants obtain most of their protein by predating a wide variety of other insects and spiders, with their large size and numbers allowing them to overpower even very formidable prey.  They are adept at killing caterpillars, a major pest of gardens and crops.  It is fascinating to watch a mound ant colony as workers parade through with bits and bodies of an assortment of local insects.  However, many members of the returning foraging party do not carry prey. Rather, their abdomens are swollen with fluid.  These ants are carrying the second most important food source - sugars - in the form of nectar and honeydew.  Mound ants can often be seen tending and protecting aphids and leafhoppers in return for the honeydew they secrete. 

A habitat maintained by Allegheny mound ants - notice the two mounds and lack of tall vegetation in their vicinity.
The activity of mound ants change throughout the year. In early spring, workers begin to care for the brood at the surface of the colony structure, but not in the mound itself, which is still too cold and exposed to be used as an incubator.  By the summer, brood production is in full swing, with the queen producing many eggs, and the brood is cared for in the mound, which is now warmed by the summer sun.  Workers move the brood up and down the mound to ideal development temperatures and humidity. Winged males and new queens are produced mid-summer, when they mate outside the colony and the males die shortly after. Not every nest produces reproductives each year, and each nest that does seems to invest in either males or reproductive females. Early season queens may return to their original hive to reproduce or parasitize a related species.  Late-season queens may return to the hive to await dispersal the next spring. By fall, egg production stops, and workers prepare themselves and the queens to overwinter.  Through the winter, the colony is torpid, lying in wait for the coming spring. 

Because Allegheny mound ants are common and very conspicuous, they are typically not hard to find and observe.  Colonies can be observed in Soldiers Delight's serpentine barren savanna, but mounds can also be easily spotted and identified from a moving vehicle on the edges of highways!

RESOURCES:

Bristow, C. M.; Cappaert, D.; Campbell, N. J.; Heise, A.; (1992). "Nest structure and colony cycle of the Allegheny mound ant, Formica exsectoides Forel (Hymenoptera: Formicidae)." Insectes Sociaux 39(4): 385-402. 


Michigan State University Extension: Mound Ants

University of Maine Cooperative Extension: Insects - 195-Beneficial Insect Series 1: Allegheny Mound Ant

Thursday, October 9, 2014

Maryland Naturalist's Notes: Understanding Breeds, Species, and Domestication

How is a breed different from a species?  What makes an animal domesticated instead of tame? What makes an introduced plant invasive?

If you have trouble answering these questions, you are not alone!  As humans have bred, altered, and transported plants and animals around the globe, the relationship between their new and natural forms has been muddled and blurred.  Below is a little chart and glossary of terms to help you better define and understand how humans have changed the creatures who share our lives. 

A handy chart!  Click to view larger.

Species: Broadly speaking, a species is a population of organisms that shares a great deal of genetic similarity. Modern determinations of species typically use genetic material, occupation of specific niches, and evolutionary history as the primarily factors defining a species.

Examples of species: tiger, Grevy's zebra, African gray parrot, gray wolf, white oak, lowbush blueberry, scarlet beebalm
     
The Canada goose is a species of goose. 

Subspecies:  Subspecies are subgroups within species.  Typically, subspecies are capable of interbreeding with other members of their species to produce healthy, fertile offspring, but are prevented from doing so by factors such as geographic isolation or resource specialization. A similar designation often used with plants is a variety.

Examples of subspecies: Siberian tiger, grizzly bear, eastern milk snake, Hers maple, Rolfs milkweed

The eastern milk snake is a subspecies of milk snake.

Domesticated: Domesticated animals or plants have been artificially selected (bred) by humans over many generations to be physically and genetically different from their ancestral species.  For instance, domestic dogs are domesticated wolves, domestic horses are domesticated tarpans, and broccoli is a domesticated form of wild mustard.

More examples of domesticated organisms: domestic rat, housecat, dairy cow, chicken, American budgerigar, domestic honey bee, mustard, tomato, zucchini 

Moonbeam is a domesticated African pygmy goat.
Her wild ancestors were Eurasian wild goats.

Tamed: Tamed animals are behaviorally different from their naturally occurring forms in that they are well-acclimated human interaction or presence and are generally non-threatening to humans. The term "tamed" is considered archaic by many animal professionals, who often prefer to refer to these animals as socialized or habituated to humans.  Tamed animals are not significantly physically or genetically different from their wild ancestors - their tame behavior is the result of behavioral conditioning, not artificial selection. Therefore, "tame" wild animals are not domesticated.

Examples of tamed animals: a circus lion, a falconer's hawk, a pet macaw, a wolf used in educational programs, dolphins at a marine park
This box turtle used in educational programs is so well-socialized to humans,
it does not pull into its shell when picked up.  


Feral: Feral animals are domesticated animals who are not socialized or habituated to humans (in other words, they are not "tame"). The domesticated ancestors of feral animals were once used by humans, but due to escape, release, or simply a lack of conditioning, these animals do not willingly interact with humans.  Common examples of feral animals include the mustangs of North America, stray dogs and cats who are stressed by human presence, and your typical city pigeons.

More examples of feral animals: feral cats roaming neighborhoods, goats on Galapagos, Assateague Island ponies, Australian water buffalo, city pigeons, North American wild boar

A common sight in cities, pigeons are feral animals who originally descended from domestic homing pigeons.

Breed:  Breeds are a subgroup of a domesticated animal. Breeds have been artificially selected by humans to create distinctive forms of a domesticated animal that can by recognized by their physical appearance, behavior tendencies, and pedigree. Not all domesticated animals have breeds, but many of the earliest domesticated animals do, including dogs, cats, rabbits, horses, cows, chickens, sheep, goats, pigs, and even pigeons.

Examples of breeds: German shepherd, Persian cat, thoroughbred, Rhode Island red, Hereford cow

A pair of Indian runner ducks, one of many domestic duck breeds. 
Cultivar: Cultivar is short for "cultivated variety" and is essentially the plant version of an animal breed. As with breeds, cultivars are subgroups of plant species or varieties that are distinctive in appearance or habit, and reproduce true when propagated.

Examples of cultivars: Kwanzan cherry tree, Celebrity tomato, John Cline scarlet beebalm, Little Lanterns eastern red columbine

The 'Emerald Blue' cultivar of creeping phlox
Landrace: A landrace is a subgroup of a domesticated animal or plant that has not developed due to formal and directed selection by humans (as in a breed or cultivar) but due to isolation within a regional area.  Landraces develop due to the unique climatic and ecological factors within their region, and due to genetic isolation from other members of their species.  A landrace may develop entirely without any human selection, or with very low, informal selection by the humans in their locality.  Eventually, humans may establish standardized, formally managed breeds from their original landraces - these are sometimes called natural breeds.

Examples of landraces: Van cat, Florida cracker cattle, Assateague Island pony, Spanish goat, Gerdeh rice
Examples of natural breeds: Turkish Van cat, Egyptian Mau, Carolina dog, Shetland pony, many heirloom tomato cultivars
An Assateague Island pony
Ecovar: Among plants, an ecovar is created through the original selection of a wide variety of wild specimens.  Ecovars, while less genetically diverse than a wild population, are more diverse than most cultivars.  Ecovars can come from stock selected only within certain regions, allowing each ecovar to reflect the genetic traits found in certain ecological areas.  Ecovars are sometimes seen as intermediates between cultivars and wild species. Ecovars are typically named for the areas their original stock was harvested.

Examples of ecovars: Bad River blue grama, Itasca little bluestem

Little bluestem is a grass species often collected to develop ecovars.
Image public domain by Paul Fusco via PublicDomainFiles.com.

Native species: A native species is naturally found within a certain region, or has shifted or expanded its range due to natural influences or factors. Another term used to describe a species native to a region is indigenous. A species found naturally in one location and nowhere else is known as endemic.

Examples of native species: American bison in Montana, cheetahs in Namibia, redwoods in California, black cherry trees in Maryland, false monkey puzzle tree in Queensland

The New Zealand pigeon is endemic to New Zealand.

Introduced, or non-native, species: Introduced species have been relocated by humans to a region outside of their natural range, either intentionally or accidentally. They are also known as exotic, alien, or non-indigenous species. Once a species has spread outside of the confines of human care, it is known as an adventive non-native species.  If that adventive species then establishes self-sustainable populations, it can be said to be naturalized. Non-native species may or may not have adverse effects on the ecosystem in which they are introduced.

Examples of introduced species: dandelions in North America, camels in Australia, muskrat in Europe, monk parakeets in New York City

Chinese mantises have been introduced in North America to control garden pests. 
Invasive species: Invasive species are introduced species that have adverse effects on the ecosystem to which they have been introduced. Often, the designation of "invasive" is made by governing agencies, based on many factors, such as the species' ability to outcompete native species, disrupt natural food webs or population cycles, and affect the physical features of the geographical area.

Examples of invasive species: kudzu in North America, cane toads in Australia, black rats in New Zealand, domestic cats over much of the world

Free-roaming domestic cats can have devastating effects on native wildlife. 
Pests and noxious weeds: Pests and noxious weeds are animals and plants which adversely affect agriculture, horticulture, livestock, or humans.  Pests and noxious weeds are often introduced and invasive species, but native plants and animals can also be classified as pests or noxious weeds.  Sometimes, the classification of native animals or plants as pests drives them to endangerment or extinction.

Examples of pests and noxious weeds: poison ivy, gypsy moth, black rats, mosquitoes, common ragwort


Japanese beetles are common garden pests. 
EXAMPLES OF INCORRECT USAGE

INCORRECT: "The Siberian tiger is the largest breed of big cat."
CORRECT: Only domestic animals have breeds.  Siberian tigers are a subspecies of tiger, and tigers are a species of big cat. 

INCORRECT: "Poison ivy has become invasive in the backyards of many Marylanders"
CORRECT: Only exotic species can be designated as invasive.  Vigorous spreading is simply part of the natural history of some native plants.  Poison ivy, however, could be considered a pest or noxious weed, even though it is native, because it impacts human activity. 

INCORRECT: "We went to the circus and saw domesticated bears!"
CORRECT: Bears have not been altered significantly from their wild ancestors by human breeding and selection.  Even though some bears may be well-socialized to humans under captive care, they cannot be considered domesticated, but rather, could be called "tame" or habituated/socialized to humans. 

INCORRECT: "After being widely planted, English ivy has become native over much of Maryland."
CORRECT: Because English ivy was introduced to North America by humans, it is not a native plant. It has escaped human care and can live in a variety of conditions without human intervention, so it could be considered naturalized.  However, naturalized species can also be invasive if they negatively impact the natural ecosystem. 

INCORRECT: "I let my cat outdoors to roam because it is more natural."
CORRECT:  There is nothing natural about allowing domestic cats to roam around Maryland habitats and communities. Domestic cats are a domesticated from of the African wild cat, which is not native to Maryland.  Further, the activities of domestic cats negatively impact wildlife and natural communities, making them an invasive, introduced species. 

Friday, January 17, 2014

Maryland: Weird and Wonderful - Piebald Deer

"Maryland: Weird and Wonderful" is a WMD101 series showcasing specific natural phenomena occurring in Maryland that are particularly interesting or unusual. 


Between the brown trunks and dappled shadows of trees, a ghostly white shape steps quietly.  Its snowy coat and delicate movements are reminiscent of a heraldic unicorn. But this striking animal is no mythical creature - it's a piebald white-tailed deer!

A piebald white-tailed deer with normally-pigmented companions.
Image public domain by the U. S. Fish and Wildlife Service via Wikimedia Commons.
White-tailed deer are normally brown in color, with white on their throats, undersides, insides of their legs, and of course, under their tails.  They vary their color by season, being gray-brown in the winter and red-brown in the summer.

Piebald deer, however, have a genetic mutation that causes pigmentless, white patches throughout their coat. The skin beneath these patches is also pigmentless, appearing pink. The effect is similar to white spotting patterns in horses or rabbits.

Piebald is a broad "catch-all" term for animals with unusual pigmentless patches on their bodies. It is also known as "white-spotting," "pied," "partial-leucism," "partial-albinism," or "part-colored."

Because "piebald" describes only the appearance of an animal, but not the specific underlying condition, the cause of piebaldism varies greatly by species and within species. Piebald coloration can be caused by genetic mutations, developmental abnormalities, injury, disease, and even nutritional deficiencies. Horses, for instance, display over five different forms of piebaldism, all under the influence of different genetic and developmental mechanisms.

A piebald deer sighted in VA. Image public domain via Wikimedia Commons
While piebaldism may at first seem like random white spattering, the pigmentless areas actually follow a pattern, with some areas of the body more likely to be white than others.  Below is a rough chart showing three types of piebaldism in deer and their patterns.  These different types of piebaldism are likely the result of different genetic mutations.

A chart showing three patterns of piebaldism in white-tailed deer.
Many wild piebald deer show the Type 1 pattern, whereas many piebald deer bred on deer farms show the Type 3 pattern.
Image copyright Jane Marlow. 
Piebaldism in deer is commonly thought to be the product of a recessive gene or genes. Because recessive genetic traits are more likely to physically appear when inbreeding occurs, piebald deer may be more likely to occur in inbred or isolated deer populations, such as those in habitats surrounded by a tall fence or by urban development.  Piebald deer are also credited as being more likely to show other unusual traits, such as unusually curved spines and short legs, than normally-pigmented deer.

Piebald deer have been sighted throughout Maryland, even in Baltimore City!  While Maryland's DNR website states that around 1% of deer are piebald, this percentage may be higher in local or isolated populations.

Two piebald deer. Image public domain by the U.S. Fish and Wildlife Service via Wikimedia Commons.
Piebaldism is generally seen as a disadvantage for many wild animals. It can interfere with the camouflage of both predators and prey, and can make prey animals more easily targeted in a group.  Because the skin under the white fur or feathers of piebald animals lacks pigment, it has limited protection against UV rays and can be prone to sunburn.  Further, piebaldism is sometimes linked to other traits that lower physical fitness, such as the curved spines seen in many piebald deer.  Under natural circumstances, it is likely that piebald animals do not survive or reproduce as well as their normally-pigmented brethren, making them more rare.

Despite the disadvantages of piebaldism that may occur in the wild, humans have long considered piebaldism an aesthetically appealing trait and have selected for it in domestic animals.  The vast majority of domesticated species are commonly found in piebald patterns, including cows, goats, sheep, horses, dogs, cats, pigs, alpacas, ferrets, chickens, ducks, pigeons, finches, and even domestic parrots, such as cockatiels.

Ancient Egyptian art depicting domesticated cattle with piebald patterns.
Image public domain via Wikimedia Commons.
Piebaldism has also been spotted in several other wild animals in Maryland, including American robins, dark-eyed juncos, and gray squirrels.

So next time you see a flash of white among the shadowy hues of the forest, look closely!  You may catch a glimpse of a rare piebald animal!

REFERENCES:

Diseases and Parasites of White-tailed Deer: Piebald Anomaly. Maryland Department of Natural Resources. Web. 17 Jan. 2014. <http://www.dnr.state.md.us/wildlife/Hunt_Trap/deer/disease/ddpbald.asp>.