Saturday, 14 March 2015

Mallard Ducks - Interesting, Attractive and Entertaining Birds

The mallard duck is an old friend of mine. It was the first duck that I learned to identify as a child and has been part of my life ever since. The bird's confidence around humans and its relative abundance compared to other ducks attracted me both in Britain, where I grew up, and in Canada, where I live now.

Today I always stop to say hello when I find mallards on my walks. Like the pair in my photo below, they don't seem to be too impressed with my greeting, although they tolerate my presence. I never feed them, which I'm sure is the reason for their lack of enthusiasm.

Identifying a Mallard

A male and female mallard that I met on a walk
Photo by Linda Crampton
The male mallard is a handsome fellow when he's wearing his breeding plumage. His head is a rich and iridescent green and his bill is yellow. The white neck ring above a beautiful chestnut brown chest and the silver sides add to his attractiveness. He also has a black curl on his "tail".

The female mallard is attractive too, although her mottled brown coloration and orange and brown bill are less impressive than the male's. Both birds have a blue patch on their wings called a speculum. The speculum is sometimes visible when the wings are folded.

Mallards hydridize readily with other ducks, so some birds are hard to identify. In addition, after the breeding season has finished, mallards lose their bright colour and the ability to fly for a few weeks as they molt. The effect is most noticeable in the males. At this stage the ducks are said to be in their eclipse phase. This is a dangerous time for the ducks, since it's harder for them to escape from predators. They tend to stay hidden from view during this phase and are seen less often.

Mallard Habitat and Diet

It's not hard to find mallards, at least where I live. Ponds and lakes in nature reserves, wild areas, parks and golf courses are good places to look for the ducks. They can also be found in marshes, streams, temporary wetlands on farms, roadside ditches, reservoirs and estuaries. 

An upended male mallard feeding
Photo by David Wagner via
Mallards are dabbling ducks, which means that they feed by upending their body and dipping their head into the water to find food. They rarely dive but do so occasionally. They also feed on land. Mallards are omnivores and eat aquatic and land vegetation, seeds, grain, insect larvae, shrimp, snails and even earthworms.They are often more than willing to accept handouts from humans.

There are many potential problems caused by humans feeding waterfowl. It's best not to feed the birds, but it's an enjoyable activity, expecially for children. Please give a healthy handout if you decide to feed ducks or any other birds. Grain intended for wild birds is good; bread isn't. Both supermarkets and pet stores sell grain for wild birds. Try to buy the freshest grain possible.

Courtship Displays

A female mallard with her speculum visible
Photo by Antranias via
I always enjoy watching mallards. Their behaviour is very interesting, particularly when they start performing their mating displays in the spring. Recording and analyzing this behaviour is a good project for beginning naturalists because it's easily observed. It's also entertaining for everyone.

Mallard courtship is easiest to observe in open areas that have a group of ducks. Luckily, the birds aren't shy about performing in public. When many birds are present, the ducks can get very excited and often put on a great show.

Some More Mallard Facts

  • Only the female mallard quacks. The male makes rasping sounds instead. He also emits a whistle during the mating display.
  • All domestic ducks - except for the Muscovy duck - evolved from mallards.
  • The mallard"s natural range is the northern hemisphere, but it's been introduced to the southern hemisphere as well.
  • According to the Cornell Lab of Ornithology, mallards can fly up to an estimated 55 mph.
  • The longest known lifespan of a mallard duck is 27 years. Most wild ducks live for a much shorter time, however.

Sunday, 18 January 2015

Angelica - An Interesting and Useful Culinary Herb

Angelica is an aromatic culinary herb that is also used in folk medicine. The herb has the intriguing scientific name of Angelica archangelica, which reflects one of two traditions. One is that the herb blooms on the feast day of Archangel Michael, or Michaelmas, which falls on September 29th in the modern calendar. Another is that the Archangel first informed humanity about the plant's medicinal uses.

Most people that have heard of angelica probably think of it in the form of candied stems, which are used as cake and pudding decorations. The plant can also be used as a vegetable and as a flavouring agent. Its pleasant scent and flavour are very nice additions to food.

The Angelica Plant
Angelica archangelica
Photo by Christian Fischer,
CC BY-SA 3.0

Angelica belongs to the Apiaceae family, which also contains parsley, dill, fennel, carrot and celery. Chinese angelica or dong quai belongs to the same family. 

Angelica is a tall plant that can reach a height of six feet or more - sometimes much more. Its stem is hollow and ridged. The plant has compound leaves with toothed leaflets. The leaves are bright green and shiny.

The small yellow, white or pale green flowers of angelica are born in a structure called an umbel. In an umbel, the flowers are located on the ends of short stalks (or pedicels) that all branch from the same point on the flower stem. The pedicels look rather like the ribs of an umbrella that has been turned upside down. The fruits of angelica are small, yellow-green and oblong.

Angelica is native to Northern and Central Europe and to Asia but has been introduced to other areas. It grows in both a wild and a cultivated form and requires moist soil. The plant is a biennial and flowers in its second year.

Culinary Uses of Angelica 

The roots, stems, leaves, flowers and seeds of angelica are all edible. Of course, it's vital to be absolutely certain of a plant's identity when foraging for wild plants. This is very important when a person is searching for wild angelica. The Apiaceae family contains poisonous plants as well as edible ones. 

Angelica leaves
Photo by Doronenko,
CC CY 2.5
Fresh angelica is used as a raw salad green or as a cooked vegetable. The leaves are added to fish, poultry, savoury stews and soups. They are also added to stewed fruit dishes, such as those containing plums, rhubarb or gooseberries, where they reduce tartness and the need for sugar. The oil in the roots and seeds is used to flavour liqueurs, jams and jellies. The stem is boiled with sugar to make a candied cake decoration or a sweet treat.

Health Effects of Angelica

Angelica was once used as a protection against harmful spells and as a cure-all for disease. Today a tea made from the plant's leaves is said to relieve digestive upset. This claim hasn't been scientifically proven, although there are suggestions that it may be correct. It's important that anyone who wants to eat an edible herb in more than food quantities checks with their doctor first, however. Some plants contain chemicals that interfere with certain medications or aren't suitable for people with certain medical conditions.

Another thing to watch out for with plants belonging to the genus Angelica is that they contain chemicals called furocoumarins. These chemicals increase the sensitivity of the skin to sun damage when they come into contact with the skin and may cause dermatitis at the same time.

Even when it's not being used medicinally, angelica is a very nice herb for a garden or a kitchen. Herbs can add interest and flavour to foods and may have health benefits, too. I love adding them to my food.

Tuesday, 4 November 2014

Deadly Salamander Fungus Could Spread to North America

A deadly fungal disease has spread from Asia to Europe, killing large numbers of salamanders. The disease could easily spread to North America via the pet trade. Amphibians already have to contend with the fungus Batrachochytrium dendrobatidis, also known as Bd, which is having a devastating effect on amphibians around the world. This fungus has caused some species of amphibians to become extinct. Now salamanders are being attacked by a related fungus, which researchers have named Batrachochytrium salamandrivorans.

A fire salamander; photo by Didier Descouens,
CC BY-SA 3.0 License
The newly discovered fungus gained attention when it devastated the population of wild fire salamanders (Salamandra salamandra) in the Netherlands. Facts about the fungal infection known so far include the following:
  • Salamanders in Asia that are infected by the fungus don't appear to be suffering any ill effects and have likely developed some degree of resistance to the fungus.
  • Lab tests have shown that the fungus affects salamanders and newts but not frogs or toads.
  • No North American animals have been shown to be infected by the fungus at the moment. 
  • Given the large number of pet salamanders and newts transported into North America, some researchers think that the fungus is likely already present on the continent. 
  • In lab tests, all specimens of a newt commonly kept as a pet in North America died when exposed to the fungus.
  • The same observation was made in relation to a wild newt with a widespread distribution in North America.
B. salamadrivorans grows in a salamander's skin. It's not known how it kills the salamander, but it may work by a similar mechanism to B. dendrobatidis. Many (but not all) amphibians have lungs, but these aren't very efficient. Much of an amphibian's oxygen is obtained through its skin. B. dendrobatidis interferes with respiration and the uptake of water and minerals. The presence of the new fungus in North America could be very bad news indeed.

Sunday, 26 October 2014

The Many Uses of Fungi

One pleasure of fall in my area is the large number of wild mushrooms that emerge from the soil. Nature walks are very interesting at this time of year. There's a certain sadness in seeing leaves dying and falling from the trees, but there's also joy in seeing the aerial parts of fungi and remembering that life is still present, even if it's hidden from view.

The body of a fungus is made of thread-like structures called hyphae. These form a branching tangle known as a mycelium. The mycelium of a fungus is located in the medium that is providing food for the fungus. Examples of this medium include soil, decaying wood and human food.

A mushroom seen and photographed on one of my walks
Unlike green plants, fungi are heterotrophic. This means they have to obtain food from their environment instead of making it inside their body. Unlike animals, however, fungi don't eat food and then digest it within their bodies. Instead, they release digestive enzymes into their food and then absorb the digested food.

A mushroom is made of compacted hyphae. Its function is to produce and distribute the reproductive spores of the fungus. Mushrooms have a wide variety of shapes, forms, sizes and colours and are interesting to observe.

Mushrooms are popular as food. This is definitely a great benefit of fungi, as long as the mushrooms are edible and not poisonous. There are many other ways in which fungi help us, however. Some of these are listed below.
  • Penicillium chrysogenum and other fungi produce penicillin, an antibiotic that fights bacteria that make us sick.
  • Cephalosporins are also antibiotics produced by fungi.
  • Cyclosporine A is a fungal chemical that acts as an immunosuppressant in humans. This substance is useful in situations such as organ transplants where doctors want to stop the patient's immune system from destroying the donated organ or tissue.
  • Ergot alkaloids constrict blood vessels, which can help to relieve migraine pain. These chemicals have to be used carefully, however, because they are potentially dangerous.
  • Aspergillus terreus produces lovastatin, which lowers high blood cholesterol.
  • Some species of Penicillium are added to blue cheese. The fungi produce blue-green veins in the cheese and add a distinctive flavour. 
  • Miso is made of soybeans fermented by a fungus called Aspergillus oryzae.
  • Yeasts are used to make bread rise. Unlike other fungi, yeasts generally consist of single cells instead of hyphae.
  • Kombucha is made of tea fermented by yeast and bacteria.
Another important use of fungi is their ability to act as decay organisms. Along with other organisms, such as bacteria, some fungi decompose animal wastes and dead bodies, releasing nutrients into the soil. Fungi can be great recyclers!

Saturday, 11 October 2014

Garden Sorrel Uses and Precautions

Sorrel is a garden or pot herb that has much to recommend it, although precautions may be needed when using the plant for food. The leaves are juicy and have a sharp, tangy taste. The tangy sensation is created by the presence of oxalic acid. The young leaves have a mild lemony flavour and are very appealing. They have been appreciated since ancient times.

The garden sorrel is also known as spinach dock, common sorrel or sorrel. Its scientific name is Rumex acetosa. It's both a wild plant that grows on grasslands and a cultivated one that grows in gardens or in containers indoors. Sorrel is native to Europe and Asia but has been introduced to North America.

Garden sorrel
Burschik, CC BY-SA 3.0 License
The garden sorrel has a red-green stem and green, elliptical or arrow-shaped leaves. The lower leaves are attached to the stem via a stalk, or petiole, while the upper leaves generally have no petiole. The leaves are rich in potassium, magnesium, vitamin C and beta carotene, which is converted to vitamin A in our body.

The flowering stems of garden sorrel are tall and bear small red flowers. In places where sorrel grows abundantly, a field may look red during the flowering season due to the presence of numerous sorrels in bloom.

Sorrel leaves are used in many ways. They are eaten raw in salads, steamed or boiled to use as a vegetable and pureed to make a soup or a sauce. The leaves are also added to stews, pies, mashed potatoes and sandwiches. They are a great seasoning for egg, fish, poultry and meat dishes.

Flowering sorrel
Ivar Leidus, CC BY-SA 3.0 License
Oxalic acid is poisonous in excess. This is why rhubarb stems are edible but rhubarb leaves aren't. The leaves contain too much oxalic acid to be safe. Whether or not oxalic acid in other plants should be restricted in the diet is a controversial topic.

Oxalic acid isn't poisonous in plants such as sorrel. However, questions have been raised about whether people with a tendency to develop calcium oxalate kidney stones should eat foods high in oxalic acid or a closely related chemical called oxalate. (Oxalic acid and oxalate are interconvertible). The question isn't easy to answer, because foods high in oxalic acid or oxalate don't necessarily increase the level of oxalate in the body or urine. Another problem is that other factors in the diet beside the ingestion of foods high in oxalic acid are known to affect the body's oxalate level.

Steaming or boiling leaves reduces their oxalic acid content.  Younger leaves generally have less oxalic acid than older ones. Of course, a person should follow their doctor's advice if he or she recommends that they reduce the amount of oxalic acid and oxalate that they eat. For many people, though, sorrel leaves in small to moderate quantities are a lovely addition to the diet.

Tuesday, 30 September 2014

Dolphins Can Detect Magnetism and Magnetic Fields

For some time it's been suspected that wild cetaceans (whales, dolphins and porpoises) can detect the Earth's magnetic field and use it to help them navigate. In fact, one theory for why cetaceans sometimes swim on to a beach and strand themselves is that a nearby source of magnetism is confusing their navigation system.  Now researchers in France have discovered that captive bottlenose dolphins behave differently when they are near a magnet compared to their behaviour when no magnet is nearby, which adds support to the idea that cetaceans are magnetosensitive.

Researchers at a university in Rennes placed a block inside a barrel and placed the barrel in the water of a dolphin tank. The block was either unmagnetized or strongly magnetized. All the barrels used in the experiment had the same density and would have given the same information to the dolphins as they explored them by echolocation. Echolocation is the system in which cetaceans release sound waves that bounce off an object and return, giving the animal detailed information about the object.

The dolphin habitat consisted of four connected pools. The six animals were free to move in or out of the pool containing the barrel as they wished. Their reaction to the barrel was observed and recorded.

Neither the person who put the barrel in the water nor the person who analyzed the videos showing the dolphins' behaviour knew whether the block in the barrel was magnetized or unmagnetized. This precaution was taken to prevent people from giving accidental signals to the dolphins as they approached the barrels. It also prevented the person analyzing the video from unconsciously interpreting the animals' behaviour in a way that supported their preferred outcome.

The researchers found that the dolphins approached the barrels with a magnetized block much faster than the ones containing an unmagnetized block. This suggested that they detected something different about the magnetized barrels and that this difference attracted them. The dolphins didn't interact with the blocks differently, though. Still, the evidence suggests that bottlenose dolphins are another animal to add to the growing list of magnetosensitive organisms.

Friday, 25 July 2014

Why Do Whales, Dolphins and Porpoises Beach or Strand Themselves?

Whales and their relatives are intelligent animals. Many use echolocation (the emission of sound waves and the analysis of the reflected sound) to enable them to navigate even when the visibility in the ocean is poor. It's therefore very puzzling that whales, dolphins and porpoises sometimes swim on to a beach and strand themselves. The urge to reach the beach is so strong that if the animals are moved into the water, they often head back to the beach to face almost certain death. Although cetaceans are mammals and breathe air like us, their bodies are damaged without the buoyancy of water to support them. Starvation and dehydration also contribute to their death on land.

A killer whale and a calf - photo by Christopher Michel,
CC BY-2.0 License

Beaching of cetaceans (whales, dolphins and porpoises) has occurred since at least the time of Aristotle, so it's probably a natural part of their biology. It's possible that human activity is increasing the incidence of beaching today, though, which is one reason why it's important to know the causes. It's heartrending to see sentient animals in distress and dying on a beach. In addition, if a large group of animals beach themselves, or if beaching occurs frequently, the animal's population size may be adversely affected.

Beaching of single animals is generally due to the fact that the animal is sick and can longer swim or because a baby has lost its mother and is too weak to fight ocean currents. Mass beachings or strandings are harder to explain.

In many cases today, investigators never discover why a group of cetaceans beach. Sometimes there are clues, however. Occasionally the animals' bodies show injuries that suggest that they have recently been attacked by sharks or other cetaceans. They may be trying to escape the danger. In other cases, tests show that the whales are infected by parasites or viruses, which may affect their navigation system and cause them to become disoriented, Many cetaceans are very social animals and have close bonds with other members of their group. If one or more animals in a group beach, the others may follow because they don't want to be separated from their companions or their leader.

Beached false killer whales - photo by Bahnfrend,
CC BY-SA 3.0 License
There have been suggestions that military sonar interferes with the navigation system of cetaceans and causes beaching. High intensity sonar has been found to cause bleeding in the brains of cetaceans. Another suggestion is that beached cetaceans have been confused by magnetic field anomolies. There is no direct evidence for this, but a substance called biomagnetite has been found in the brains of some whales. It's known that some animals use this substance to detect the Earth's magnetic field and to navigate. However, we have biomagnetite in our body, too. The role of biomagnetite in whales and in humans is far from clear.

If one cetacean beaches and if that animal is small or is a youngster of a big species, it may be possible to save the animal if a rescue facility is nearby. When a big animal or many animals are stranded, it's harder to help them. It's sometimes possible to move stranded animals back into the water if they're not too big, but they may beach themselves again. One argument against moving the animals into the water is that if they've beached themselves because they're sick, when they're back in the ocean they may infect other animals. We really need to discover the causes of beaching for the sake of the world's cetaceans.