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Articles in the category Ecological Features

May 18, 2021 By crm

By Karen Anderson, Master Naturalist/ACLT Guest Blogger

The North American river otter (Lontra canadensis) is one of 13 species of otters worldwide and is the one species that is found in our area. While some are lucky to actually spot an otter or group of otters, the most likely way you will know they are around is by finding their signs – tracks, slides, or their latrine areas.

Otters are found in most aquatic habitats around the world, except for Australia, Antarctica, and the northern parts of the Arctic.

North American river otters are found throughout most of the United States and Canada, except for arid portions of the southwest. As a semi-aquatic mammal, they are found along most types of waterways and coasts – including fresh, brackish, and marine water. In our area, they are found in rivers and streams, and along the Chesapeake Bay coast and make their dens in embankments along the waterways.

Before European settlers came to North American, river otters were common throughout the continent. Over harvesting for their fur, loss of their habitats by filling of wetlands, along with pollution caused many populations to disappear. By the 1970s, State wildlife agencies had concerns about otter populations and began reintroduction programs. Since 1976 over 4,000 otters have been reintroduced among 21 states (IUCN website). With improved water quality, and a decrease in the loss of wetlands, otters have rebounded in many states. Today, oil spills, runoff from mining, and continued land development can still affect otters in localized areas.

Although otters are present here in Calvert County and on ACLT property, you may not see them often as they tend to be shy of people and are most active from dusk into the night. In fact, usually the way people know they are around is by spotting their scat or latrine areas which may be on a dock, a particular rock, or other prominent area. These communal latrines are used by a family group, in part, to communicate with other otters.

You may also spot their tracks in snow or on a sandy beach or muddy bank, or find their slides – which might be easy to spot after a snow. Another way you might know an otter has been around is by their strong musky smell – they use the scent glands near their tails to advertise that they have been at a particular site within their home range by rubbing on vegetation. Otters will also communicate with each other using squeaks, whistles, twitters, chirps, and growls.

Built for aquatic life, otters have dense fur which they need to keep groomed to maintain water repellency. Otters have long tapered tail which helps propel them in water; small ears, and vision adapted for underwater (so near-sighted out of water), along with short legs and fully webbed feet bearing non-retractable claws. Adult otters weigh from 10 to 33 pounds and are about 2.5 to 5 feet long. Females are roughly a third the size of males.

Otters feed opportunistically but consume primarily fish. They also eat crustaceans, mollusks, amphibians, insects, and even occasionally birds. Otters have a high metabolism and feed throughout their active hours. Being at the top of the aquatic food chain, contaminants such as heavy metals and other pollutants can bioaccumulate in the food they consume and may affect their health.

River otters form family groups and the young stay with their mother for about eight months after they are born, typically in April-May; they leave when the mother gives birth to another litter. Like most mammals, young otters spend time playing with each other learning skills they will need when they venture out on their own. Some studies on river otters indicate that they mate for life, while other studies seem to indicate that the male only stays with the female for a few months during the breeding season.

Otters have been spotted only rarely on one of ACLT’s trail cameras (see video below).

If you want to see live river otters, you could visit the Calvert Marine Museum in Solomons, the Baltimore Zoo, or National Zoo – check their websites for current visiting protocols.

You may also enjoy watching otter videos on the Smithsonian Environmental Research Center’s Facebook page.

Links with additional otter information and otter cams:

Chesapeake Bay Otter Alliance | Smithsonian Environmental Research Center (si.edu)

Information Sources:

https://www.otterspecialistgroup.org/osg-newsite/

https://www.iucnredlist.org/species/12302/21936349

North American river otter | Smithsonian’s National Zoo (si.edu)

May 7, 2021 By crm

Syrphid Flies: "Have you Hugged a Flower Fly Today?"

By Judy Ferris, ACLT Guest Blogger

As springtime bursts into bloom, you may have noticed tiny bee-like insects hovering amongst your flowers. Many of these little insects wear convincing yellow and black bee costumes. You may wonder “What are they?” And more importantly “Do they sting?”

In fact, these gentle creatures are Syrphid Flies [pronounced SUR-fid, as in the Beach Boys’ smash hit “Syrphid USA”]. Also called Flower Flies. Their colors alone scream “I’m bad! Very bad!”. But their bee-like disguise is all a bluff. Flower flies have no stinger, no venom, and cannot bite. Any bird that has been stung by a wasp or a bee is likely to avoid repeating that mistake. Thus, the yellow and black warning colors of Flower Flies scare predators into leaving them alone. Flower flies, then, operate under the radar and get a free pass from many predators in your garden!

Adult Flower Flies range in size from 1/3 to 1 inch. They are often called Hover Flies for their ability to hover in place and even fly backwards! Both are rare skills in the insect world. Thus, hovering itself is a clue to Syrphid fly identification. Adult Syrphids feed on nectar for energy and pollen for protein. They are excellent pollinators; in some crops even out-performing bees! Their attention, however, is focused on mating and egg-laying. Female Flower Flies lay tiny, white, football-shaped eggs near thriving aphid colonies. (I can just hear you groaning “Oh no! Here we go again with those poor aphids!”) Some evidence suggests that female Flower Flies can actually dole out the proper amount of eggs proportionate to an aphid population. Just enough larvae will hatch to control the aphid outbreak. Wow! Flies that can do math!

Eggs hatch in about a week and the leech-like larvae set to work. Syrphid fly larvae are nocturnal predators of small insect pests. They snooze by day, then awaken after dark to wreak havoc on aphids, thrips, scales, and caterpillars of both butterflies and moths. Blind and legless, the larvae stumble in the darkness until they bump into something edible. The mouth of the larvae is equipped with an efficient hook, typical of many fly maggots, which is used to grab prey. The hapless victim is thus lifted overhead and held up off the surface as it is gulped from the hook.

According to Michael Raupp of the University of Maryland, a single Syrphid fly larvae can eat more than 25 aphids per day and an estimated 200 aphids in the course of their development. With a healthy balance of maggots and aphids, 75% to 100% of the aphids can be controlled. For a fascinating 2-minute video of a Flower Fly larva chowing down on aphids, click on the link below. Keep your eye on the lower left corner of the video for clueless aphids.

How do you get this aphid-chomping action in your garden? To attract Flower Flies, grow the plants they love! Composite blooms – Yarrow, Queen Anne’s Lace, cornflowers, parsley, carrots, coriander, dill, and fennel are Flower Fly favorites. Syrphids are particularly attracted to white and yellow flowers.

The fortuitous combination of pollinator and pest-remover make the gentle Flower Fly your ideal garden companion! Look for these small visitors where flowers bloom. With luck, you may spot more than one species of flower fly; each identifiable by its unique color pattern. It almost goes without saying; if you see aphids, skip the pesticides and allow Mother Nature to work her magic instead. And don’t forget to hug a Flower Fly today!

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April 19, 2021 By crm

Lacewings: Beauties & Beastly Babies

By Judy Ferris, ACLT Guest Blogger

Lacewings are an insect we may have heard of but perhaps never seen. Adult Lacewings get their names from the delicate network of ‘veins‘ which characterize their wings.

Unfortunately, we see Lacewing adults only rarely because they are nocturnal. Yet, adult Lacewings are the miniature fairy princesses of the crepuscular world. Measuring about ¾ of an inch long, they have bright green bodies and golden eyes. Gowned in lacy, diaphanous wings which almost glow, they flutter in the darkness on a nightly quest for nectar, pollen, and honeydew.

Hungry bats also roam the darkness, using their sonar to detect delicate fairy princesses in flight. Amazingly, Lacewings have specialized veins in their wings that sense the ultrasonic sounds made by hunting bats. Alerted to danger, a flying Lacewing takes evasive action. It closes its wings, making a smaller sonar image, and sinks to the ground out of danger.

During her lifetime, which may last 4-6 weeks, a female Lacewing lays up to 200 eggs. They are placed on the undersides of leaves, preferably near a burgeoning colony of aphids or other soft, yummy pests.

Each egg is cleverly placed at the end of a slender stalk which is coated with ant repellent. The stalks may also prevent newly hatched lacewing larvae from eating their unhatched siblings!

While adult lacewings are gentle and fairy-like, Lacewing larvae are the exact opposite! Known as Aphid Lions due to their voracious feeding habits, Lacewing larvae are shaped rather like alligators.

The feisty babies are about ½” long. Note the no-nonsense feeding apparatus on the head. The large, curving mouth parts (known as maxillae) have hollow grooves which serve as fluid conduits. Although Aphid Lions have eyes, their senses are very weak. Instead of spotting prey visually, they swing their upper bodies back and forth like a rampaging Attila the Hun, until they crash into something edible. Grasping the unsuspecting victim with their maxillae, they inject potent toxins into its body. So powerful are these chemicals, that they can dissolve the insides of an aphid in 90 seconds! Let the feasting begin! Body fluids from the aphid are sucked out via the maxillae. As the withered husk of the aphid runs out of fluid, let there be no doubt, they are good to the last drop! The Aphid Lion, with prey gripped in its curving ‘jaws‘, tilts its head back and shakes the carcass to savor every ounce of sugary goodness.

But wait! There‘s more to this story! An Aphid Lion, alone and unprotected, is a juicy target for insect or bird predators. Thus, as soon as they leave the egg, some Lacewing larvae begin collecting items to form a shield‘ on their backs. This protective cover may consist of spent egg cases, the shed skins of molting larva, or the withered bodies of the Aphid Lion‘s victims. Over time a significant pile of detritus accumulates atop the larva; the perfect camouflage for a tiny, but fearsome predator.

Once the larvae matures, it spins a cocoon; incorporating a shield of dead insects and other debris. Here in Maryland, Lacewings overwinter in these cozy cocoons; surrounded by molted body parts of relatives and the empty husks of victims. In spring, a fully formed-adult Lacewing with translucent wings emerges. A beastly baby no more!

For a fascinating peek into the lives of adult Lacewings and Aphid Lions in action, be sure to check out the short video below.

Aphid Lions typically eat about 200 aphids or other pests per week during their 2-3 week developmental cycle. In addition to aphids, the larvae also eat mites, insect eggs, and fearlessly wade in to attack much larger prey such as caterpillars as well. They are valuable additions to any garden and are even used for large-scale pest control of some crops. Lacewing eggs, larvae, and adults are all available for purchase online for use as biological pest control. Gardeners can attract Lacewings by using certain plants and tolerating beneficial weeds; Asters, Cosmos, Sunflowers, Dill, and Dandelions.

My magnifying glass is at the ready as I almost look forward to discovering aphids in my garden this spring. Can‘t wait to see what sort of insect mayhem transpires!

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April 16, 2021 By crm

By: Nicole Stevens, Chesapeake Conservation Corps Member

A long-drawn-out and tolling cry,
That drifts above the chorus
Of shriller voices from the marsh
That April nights send o’er us;
A tender monotone of song
With vernal longings blending,
That rises from the ponds and pools,
And seems at times unending

~ John Burroughs, “The Song of the Toad”

This is the second in a series of monthly blogs that will showcase progress on ACLT’s conservation and research efforts as well as highlight currently-active frog species. Stay tuned to receive updates! Read Frog Blog #1 here. You may also wish to subscribe to our blog here: www.acltweb.org

Spring has sprung! Over the past few weeks, the weather has warmed, birds have sung, flowers have bloomed, and more and more frogs have left hibernation to serenade listeners with jubilant nighttime song. At ACLT, wood frog and spotted salamander eggs have appeared in our vernal pools and recent evenings and cloudy days have been filled with the croaks and peeps of thousands of singing frogs.

The prevalence of these wonderful animals is great news for the Parkers Creek watershed! Not only do they take care of bothersome insects, but frogs are also considered indicator species, so their presence “indicates” the health of an ecosystem. While they have lungs, frogs can also breathe through their skin (and therefore breathe while underwater), allowing them to have added protection from terrestrial predators and to hibernate undisturbed in aquatic environments. However, breathing through their skin also makes frogs especially susceptible to harmful pollutants since they may also absorb unwanted chemicals or diseases. The Parkers Creek watershed appears quite healthy since our frog populations are not suffering from contaminants and are instead thriving and growing!

More precise information about the type of species and number of individuals present at ACLT is being gathered through my capstone project. University of Maryland scientist Dr. Christopher Rowe, dedicated volunteer Kevin Donahue, and I set up several drift fences along an existing vernal pool on the PF2Bay trail and along one of the two new vernal pools installed last month. These fences, made from aluminum sheeting and tobacco stakes, are about 12 feet long and prevent amphibians from walking (or hopping) directly into the vernal pools. Instead the fences guide the amphibians into buried coffee cans where they are trapped for a short period of time until volunteers come to documents and release them. Volunteers will monitor these cans daily for two weeks each month from April to June and count and identify the species present. When there are multiple days in a row when monitoring cannot take place, the cans are covered and amphibians can freely move around the fences.

Frog call surveys are also being conducted periodically in the evenings. These require someone (myself or one of ACLT’s fantastic volunteers) to stand by the vernal pools at night and record which species of frogs they can hear and the intensity of their song. This data allows us to know what species are active at ACLT and get a rough idea of the number of individuals, even if we cannot see the animals. Data is also reported to FrogWatch USA, a program run by the Association of Zoos and Aquariums, where it joins a national database and can be used for larger science and conservation projects.

Through these monitoring efforts and from periodic visual observation (including the amazing Master Naturalist herp hunt on March 24^th), we have seen a lot of species in ACLT’s vernal pools. Spring peepers, wood frogs, green frogs, and southern leopard frogs have been out and about, as have other amphibians like spotted salamanders and eastern newts! While the two manmade vernal pools I constructed last month (with LOTS of help from some amazing volunteers) have yet to have any breeding amphibians, recent rains filled the pools, and some insects and a spring peeper have moved in. Soon, these pools should be teeming with life, just like nearby natural areas!

Last month, I highlighted some of the frog species that may be active the earliest: spring peepers (Pseudacris crucifer), wood frogs (Lithobates sylvaticus), upland chorus frogs (Pseudacris feriarum), pickerel frogs (Lithobates palustris), and American toads (Anaxyrus americanus). These species will likely all still be calling throughout April, except for the wood frogs which complete their breeding season within just a few days. This month, many more species will emerge (or already have emerged) from their hiding places underground to join in the raucous evening symphony. Some of these species include the southern leopard frog (Lithobates sphenocephalus), the gray treefrog (Hyla versicolor), Cope’s gray treefrog (Hyla chrysoscelis), the Fowler’s toad (Anaxyrus fowleri), and the green frog (Lithobates clamitans). More information about these wonderful species and links to hear their calls can be found below!

Additional Southern Maryland Frog Species Active During April

Southern Leopard Frog (Lithobates sphenocephalus)
The southern leopard frog is the most common true frog species in the Coastal Plain, often found around backyard ponds and vernal pools (seasonal wetlands that only fill with water for part of the year). They have dark, roundish spots on their backs (hence the name leopard frogs), range in color from green to brown, generally grow to about 2-3.5 inches, and have two lighter-colored dorsolateral folds (raised lines) running down the edges of their backs. They greatly resemble the related pickerel frog, though their spots are less square and more uneven, and they lack the pickerel frog’s distinctive yellow patch on the inside of their thighs. Southern leopard frogs are great swimmers and may use their powerful back legs to jump into your local waterways! They are not very particular in the types of wetlands they occupy and may even be found in brackish (slightly salty) water. Listen for their chuckle-like call in the evenings or on cloudy days: Southern Leopard Frog Call

Gray Treefrog (Hyla versicolor) & Cope’s Gray Treefrog (Hyla chrysoscelis)
The gray treefrog and the Cope’s gray treefrog look identical to the naked eye and can only be differentiated through genetic analysis or by call by a trained listener. Both species are generally gray or green (and can change color in a few hours depending on their environment) with darker blotches on their backs. They are fairly small and generally only grow to 1-2 inches in length. Like all treefrogs, (Cope’s) gray treefrogs have slimy skin and large toe pads to facilitate climbing, though their skin is rougher than most other treefrog species. Since the two species resemble each other so closely, researchers are unsure how much the ranges of gray and Cope’s gray treefrogs overlap, but the two species together inhabit much of the central and Eastern US. Look for them in trees or even on manmade structures like your fences or deck. Both of their calls sound like fast, high-pitched trills, though the Cope’s gray treefrog’s call is a bit higher and faster. You may hear them singing in the evenings near vernal pools which are their favorite breeding areas: Gray Treefrog Call and Cope’s Gray Treefrog Call.

Fowler’s Toad (Anaxyrus fowleri)
Fowler’s toad is one of the two true toad species found in Maryland, the other is the American toad. Like the American toad, Fowler’s toads are usually brown with short back legs for hopping and glands on the side of their heads that excrete toxins. These toxins aren’t particularly dangerous to humans, though you may not want to rub your eye after picking up a toad. The easiest way to differentiate Fowler’s toads from American toads is by the density of bumps (or “warts”) on their bodies. Fowler’s toads usually have 3-4 bumps per dark brown patch, while American toads generally only have 1-2. Fowler’s toads are usually 2-3 inches long and breed in a variety of wetlands, especially those that are shallow and have sandy bottoms. You may see them hopping through forests or meadows or hear their calls that sound a bit like a sheep saying “baaaa” or a series of short, repeated yells: Fowler’s Toad Call

Green Frog (Lithobates clamitans)
The green frog is usually brown in color (confusing, I know), though often has green markings above its snout that resemble a mustache. They are a fairly large species growing to 3.5 inches in length and are often confused with small bullfrogs. Like bullfrogs, green frogs have a circular tympanum, or external ear, which is larger than the eye in male frogs and the same size as or smaller than the eye in female frogs. To differentiate between a green frog and a small bullfrog, look at the arch that comes out from the eye. If it curves around the tympanum, you have a bullfrog and if the arch continues down the side of the animal’s back, you have a green frog! The green frog generally likes to breed in permanent ponds, though I have spotted some in vernal pools and in small roadside ditches as well. Green frogs usually remain within 1 meter of water as adults (except on rainy nights), so wetlands are a great place to look for or hear this species! If you hear a deep groaning call in early spring, chances are it’s a green frog: Green Frog Call

I hope you enjoyed this month’s Frog Blog! If you are interested in learning more about these animals or want to get involved with amphibian monitoring efforts, please email me at nicole@acltweb.org.

Click to Read Frog Blog #3

April 9, 2021 By crm

Aphids: Life at the Base of the Food Chain

By Judy Ferris, ACLT Guest Blogger

This is the first in a series of blog posts providing a glimpse into the secret lives of insects that live among us – some friends, some foes. The author, Judy Ferris, describes herself as a born nature-girl, a gardener since the age of 10, and a birder for 45 years. Judy volunteers at ACLT’s Double Oak Farm as a ‘Flower Girl’ – a small team that manages several Flower Gardens. According to Judy, “It’s hard to be around flowers without noticing the insects they attract!” Hence the recent dive into the world of insects. Though still an amateur, Judy delights in learning about insects and sharing with others, the stories of these fascinating and vital creatures.

Let’s start our exploration of the insect world at the base of the food chain – with aphids! As we know, aphids are sucking insects, with specialized mouthparts to access sugary sap in the phloem (vascular tissue) of plants. To our eyes, aphids are rather featureless; like miniature balloons of sugar water with legs.

To would-be predators, however, each plump, hapless aphid is a hit of sugar in an easy-to-open container – soft and rubbery on the outside, juicy and irresistibly succulent within.

Aphids have been on earth since before the age of dinosaurs and are still going strong. How have these walking sugar-blobs survived so long while other, mightier species died out forever? Turns out that these tiny bugs have quite a few tricks up their skinny little sleeves.

Here in Aphid World, we are at the bottom of the food chain. If you are an aphid, you are a featured item on the menu of many insect species. Thus, there is one thing you need to do really well; reproduce quickly! Aphids have made rapid reproduction into an art form. How do they do this? The solution is unconventional, yet its simplicity harkens back to the aphid’s ancient origin; cloning!

Here’s how it works. In spring, aphids emerge from over-wintering eggs. All are females. These original females generate more female offspring asexually, giving birth to live young rather than laying eggs. Why wait around for eggs to hatch when you can pop out babies right away? Second-generation aphids are also females and may even be pregnant with a third generation of daughters before they themselves are born! Yes, that’s right – mothers giving birth to daughters and granddaughters!

With this ‘telescoping’ of multiple generations, aphids can multiply exponentially. It is estimated that under ideal conditions, with no predators, pathogens, or parasites, a single female aphid could produce 600 billion sap-sucking descendants in a single season!

Another unique aphid talent is their ability to poop sugar water (also known as ‘honeydew’)! Yes, aphid poop is the basis for the famous win-win relationship between aphids and ants.

Aphids poop honeydew for sugar-loving ants. Ants, in turn, may serve as soldiers to protect their coveted aphid herd from predators. Through adaptations like cloned babies and pooping sugar, aphids have survived on earth for 280 million years and will likely be here long after we humans have vanished.

Lest you are now having nightmares about planet Earth inundated with aphids… Not to worry! There are plenty of insect predators who relish a sweet aphid feast; Lady Beetles, Flower Fly larvae, parasitic wasps, aphid midges, and even ‘aphid lions’ (the larvae of Lacewings). We will meet some of these predators in the coming weeks. Fasten your seatbelts. It may be a wild ride!

Now available! Read the next installment in The Secret Lives of Insects – “Lacewings: Beauty and the Beastly Babies”!