General: The Mute Swan was introduced to the United States in the late 19th century (1), primarily for its ornamental value. Like many such actions, it has manifested into unintended consequences and has become viewed by many as an invasive species due to its increasing population and aggressive behavior. Mute Swans have affected not only native bird species by displacing them but also aquatic animals due to their feeding on large amounts of aquatic vegetation used by fish and invertebrates.
Growing up on Long Island, NY, I had plenty of opportunities to view these birds. They can be very aggressive – I have watched Mute Swans chase dogs, geese and people not only from their nests but just because their “space” was invaded. These are easy birds to observe since they are use to people – yet they need their space. Even if you are motionless a bird that approaches should be treated with a lot of respect.
The male Mute Swan is known as a “cob” while the female is known as a “pen”.
Mute swans become sexually mature when they are two years old, but often will not begin breeding until they are three, four, or even five years old.
The Mute Swan is reported to mate for life. However, changing of mates does occur infrequently, and swans will remate if their partner dies. If a male loses his mate and pairs with a young female, she joins him on his territory. If he mates with an older female, they go to hers. If a female loses her mate, she remates quickly and usually chooses a younger male. (3)
In spring Mute Swans build nests that look like large mounds with waterside vegetation. Female Mute Swans lay an average of 6 off-white to pale green eggs but can produce as many as 11 (2). Incubation takes about 35 days. The hatchlings are called “cygnets”. Within a few days they leave the nest and are able to feed themselves. They stay with the parents for a few months. Cygnets can fly at about 4-5 months of age and are considered “juveniles” at that time.
Identification: Mute Swans are unmistakable; there is really no bird in the eastern US that look like it. They are the largest birds on the water measuring 50”–60” long with a wingspan that is between 80”-94” long (over 7’). They are also heavy weighing between 12 – 30 lbs. The coloration of a mature bird is all-white with an orange bill (with some scant black markings) and a black front to their face. Their legs are black. They have a black “knob” on the top of their bill.
Immature mute swans can be dirty gray or white. Their legs are gray to pink. The bill is gray or tan
Habitat: Lakes, Ponds, shallow coastal ponds, estuaries, ponds, bogs, and streams flowing into lakes.
Territory: The natural range of the Mute Swan is in temperate areas of Europe across western Asia.
Migration: In its natural range, Mute Swans do migrate to a point.
Food: Mute Swans feed on a wide range of vegetation, both submerged aquatic plants and grasses and grains such as wheat.
(1) Audubon Society Field Guide to North American Birds
The first time I watched laughing gulls in any great number my family was vacationing at the outer banks in North Carolina. It was early June and they were the predominate gull species. Their call sounds just like a laugh, at least one a gull would have. Continue reading Laughing Gull information indentification→
Recently, on a visit to Long Island, NY, I sat in a kitchen listening to what seemed like a flock of different song birds singing away right outside a window in a holly bush. It was no surprise to walk outside and see a Northern Mockingbird sitting on the top of the bush switching its tune over and over.
The northern mockingbird is a medium-sized songbird, a bit more slender than a thrush with a longer tail. Mockingbirds have small heads, a long, thin dark bill with a downward curve at the tip and long legs. Their wings are short, rounded, and broad, making the tail seem particularly long in flight. Both males and females look alike.
The Mockingbird is overall gray-brown, paler on the breast and belly. As the picture indicates, mockingbirds have two white wingbars on each wing. A white patch in each wing is often visible on perched birds, and in flight these become large white flashes. The white outer tail feathers are clear when the birds are in flight.
Mockingbirds are approximately 8.3” – 10.2” long with a wingspan of 12.2” – 13.8”. They weigh about 1.6 – 2 oz. As a comparison, northern mockingbirds are slightly smaller than a common grackle
The northern mockingbird can be found in towns, suburbs, backyards, parks, forest edges, and open land at low elevations. They usually reside in fields and forest edges, usually seen in farmlands, roadsides, city parks, suburban areas, and open grassy areas with thickets and brushy deserts
The northern mockingbird is an omnivore. They eat mainly insects in summer but switch to eating mostly fruit in fall and winter. Among their animal prey are beetles, earthworms, moths, butterflies, ants, bees, wasps, grasshoppers, and small lizards. They eat a wide variety of berries and fruits. They’ve been seen drinking sap from the cuts on recently pruned trees.
The mockingbirds’ breeding range is from Maritime provinces of Canada westwards to British Columbia, practically the entire Continental United States, and the majority of Mexico to eastern Oaxaca and Veracruz. The mockingbird is generally a year-round resident of its range, but the birds that live in the northern portion of its range have been noted further south during the winter season. The bird can most frequently be found in the Southern United States
The fisher (Martes pennanti,) is a medium sized member of the weasel family (Mustelidae,) native only to North America. They are striking with their slender bodies and soft dark coats but are increasingly becoming a problem in certain geographic zones where populations are expanding into suburban areas.
Male fishers tend to be larger than females, reaching a mature length of 50” to 63” and mature weight of 7.5 lbs. to 11 lbs. by one year old. Females measure 41” to 51” and weigh between 4.5 lbs. and 5.5 lbs. by 5.5 months old. Their long, thick, bushy tails account for approximately 1/3 their total length. Fishers have long bodies, broad heads with short pointed muzzles, and short legs. Round ears are located on the sides on the head. They have five long, retractable claws on both their front and hind feet.
Fishers have soft coats that are medium to dark brown and frosted on the head, neck, and shoulders. Their coats are accented by black on the legs and tail and white patches (that may occur on the chest, genital area, and underarms.) Their coloration may vary due to sex and season (they tend to be darker in the winter.)
Fishers are solitary animals that are active during the day and night. Although they spend much of their time alone, they may be found together during the mating season. Male fishers are known to show aggression towards each other. Fishers are shy around humans but are beginning to show more and more comfort near human populations as their ranges expand in certain geographic areas.
Fishers create dens and “resting sites”1 for year-round use in hollow logs, trees, brush, ground burrows, or crevices. They show preference for tree nests in the spring and fall, while in the winter they tend to use ground burrows or snow dens (burrows in the snow accessed by long, narrow tunnels.)
Fishers establish home ranges that are 5.8 to 13.5 square miles in size. Males’ ranges are typically larger than females’ ranges and tend to overlap with them; however, a male’s range will never overlap with that of another male.2 Fishers mark their territory using scent and travel within it using established trails on the ground and in the trees.3 They navigate their environments using keen senses of smell, sight, and hearing. Although they are agile climbers and swimmers, fishers are usually found on the ground.
In the wild, fishers can live up to 10 years.
Fishers may be found in mixed, coniferous, and deciduous forests. They prefer habitats that offer den sites (including hollow trees,) access to prey, and high canopy enclosures. They tend to avoid deep snow in the winter.
Within their habitats, juvenile fishers are at risk of predation by hawks and other birds of prey, bobcats, lynx, and red foxes.
Fisher populations can be found across Canada and the United States (from the Sierra Nevada in California to the Appalachian Mountains in Virginia.) They no not live in prairie habitats or the southern United States. North America is the only continent on which fisher populations occur.
Fishers are solitary hunters whose diets consist mainly of small herbivores (such as rodents, birds, and shrews.) Their diets may also include fruit, berries, and carrion. Although they usually prey on animals smaller than themselves, fishers have been known to take on larger prey. They are also one of the only predators that can effectively attack a porcupine (this is done by repeatedly attacking from the front until the porcupine tires, then flipping it on its back and attacking its unprotected stomach.)
Fishers are agile hunters in trees and are capable of elongating their bodies to hunt their prey in ground burrows and narrow spaces.
Fishers breed once a year between March and May. Copulation lasts for several hours. Once the embryos have been fertilized, they remain in a suspended state of development for the first 10 to 11 months of an 11 to 12 month gestation period. Embryos only develop during the last 1 to 2 months of gestation.
Females choose den sites that are high off the ground in hollow trees. The site of the den may be moved several times if the nest is disturbed.
Litters contain 1 to 6 young (on average 3,) that are born blind and naked, each weighing less than one-tenth of a pound. The young, known as kits, are completely dependent on their mothers after birth (males provide no parental support.) Their eyes open around 7 weeks old, and they are weaned by 8 to 10 weeks old (although, some kits continue to nurse occasionally until they are 4 months old.) By four months old, young fishers can hunt for themselves and start to disperse by 5 months old. Fishers establish home ranges by the time they are a year old.
Females experience a postpartum estrus and mate again shortly after giving birth.
Females reach sexual maturity by one year old and breed once a year after that. Males reach sexual maturity by 2 years old.4
Notes of Interest
Fishers are also referred to as: Pekans, Fisher Cats, Black Cats, Wejacks, and American Sables.5
There has been limited success trying to breed fishers in captivity.
In the past, fisher populations were severely impacted by the fur trade. However, the demand for their pelts has decreased and populations have been recovering (particularly in New York and southern Ontario, where populations are expanding into suburban areas.) Due to range expansion, there have been reports of fisher attacks on domestic animals and children, attracted to human-inhabited areas by food and garbage. Fishers are known to react aggressively toward threats or when startled and caution should be exercised in the presence of this species.
Certain fisher populations have been considered for protection under the Endangered Species Act, such as those living in southern zones of the Sierra Nevada.6
The Nutria Rat (Myocastor coypus,) of the order rodentia, is a large, semi-aquatic rodent native to southern South America. It has been described as “a cross between a beaver and a New York sewer rat.”1 Now found on 4 continents, and recognized as an invasive wildlife species in the United States (present in 22 states,) measures are being taken to control populations and manage the devastation this species is wreaking on coastal ecosystems.
Nutria rats are large, robust rodents that are well equipped for an aquatic life. They are sometimes mistaken for beavers or muskrats due to similar physical traits, but are approximately 1/3 the size of beavers and larger than muskrats. Their small ears, eyes, and nostrils are situated high on their large heads and remain above water during swimming.2 Valves located in their mouths and nostrils prevent water intake when submerged. Nutria rats have a total of 20 teeth, including 4 large yellow/orange incisors that protrude from the front of their mouths. Their white whiskers are 3” to 5” long. Glands located at the corners of the mouth produce oils that are combed through the fur to provide waterproofing.3 Nutria rats have partially webbed back feet (all back toes are connected by webbing except one that is used much like a thumb.) The front feet, which are smaller and not webbed, have 4 toes that are similar and one toe that is smaller and functions similar to a thumb.4 Nutria rats have stout bodies that appear hump-backed when not in the water. They reach a mature weight of 15 lbs. to 22 lbs. (males tending to be larger,) and a mature length of 27” to 41” (including the tail, which tends to make-up over half of the overall length.) Their tails are thick, round and scaly, with sparse bristly hairs. When swimming, the tail glides smoothly through the water behind the body. Because of a lack of insulation on their tails, Nutria rats living in northern climates tend to loose portions of their tails to frostbite during hard winters.5
Their coats are made of a coarse outer layer comprised of yellow to dark brown shaggy hairs and a lush undercoat (called nutria,) that is soft and grey. It is the undercoat that is sought by trappers. Their muzzles and chins are white. Although uncommon, albino Nutria rats have been observed in the wild.
Nutria rats are strong swimmers and spend the majority of their time in the water (since they are more agile in the water than on land.) They see well underwater and can stay submerged for up to five minutes.
Nutria rats are shy and nocturnal so they are not often seen in the wild. However, they are social within their species and live in large colonies.
On average, Nutria rats live for 8 to 10 years.
Nutria rats have adapted to a variety of habitats but always maintain a close proximity to fresh or brackish water. They may be found along riverbanks, lakeshores or coastlands, in wetlands, farm ponds, drainage systems, canals, bayous, swamps, marshes, overgrown lots, or even in cities beneath buildings. They build burrows near water in low vegetation or root systems. The inner chambers of their dens are lined with grasses and located above the water line but are accessed by entrances that are up to 24” in diameter and 12” to 24” below the surface of the water. In marshes, Nutria rats build flat platforms of dead vegetation for feeding, birthing, or grooming purposes.6
Within their habitats, Nutria rats are vulnerable to alligators, large snakes, birds of prey, and turtles.7
Nutria rats are only native to southern South America. However, because of both accidental and intentional introduction, they can now be found in Canada and 22 of the United States (most highly concentrated along the Gulf Coast, but also found in eastern and northwestern coastal regions,) Europe, and Asia. Louisiana has an estimated population of 5 million Nutria rats.8 The fur of this species was once popular in the fur trade and Nutria rats were domesticated around the world on fur farms (the first recorded domestication in the U.S. was in1889.) Wild populations that were started by farm escapees exploded in size when the nutria fur trade collapsed (during the 1940’s in the U.S.,) forcing farmers to release their rats into the wild because they could no longer afford to keep them. Wild populations were intentionally expanded by wildlife agencies and private companies who attempted to use the rats to control invasive or noxious weeds.9
Nutria rats are omnivorous surface eaters who often over-harvest their dietary staple, aquatic vegetation (including the roots, stems, leaves, and bark.) They do not eat vegetation in the water, but rather swim with it or carry it back to their platforms to feed. Their diets also include small animals, such as snails and mussels. Nutria rats are capable of consuming 25% of their own body weight every day.10 Their eating habits have proven detrimental to coastal ecosystems, destroying vegetation that is important in the prevention of soil erosion. They are also troublesome to farmers, devouring crops such as rice, corn, alfalfa, wheat, oats, barley, sugarcane, peanuts, and vegetables.11
Nutria rats are prolific reproducers. Typically, a male will live in the same burrow as several females and breed throughout the year. Each female has, on average, 2 to 3 litters a year, each consisting of 1 to 11 young (but usually 4 to 6.) It has been observed that litter sizes are cyclical, with a large litter of 4 to 6 young followed by a small littler of 2 to 4, and so on.12 Gestation lasts slightly longer than 4 months and the young reach sexual maturity in 4 to 8 months, leaving their mother after only 1 to 2 months. Females’ teats are situated high on their backs so the young may feed while she is swimming. Females are ready to breed within days of birthing a litter.13
Notes of Interest
Common names of the Nutria rat include coypu, coypu rat, swamp beaver, and nutria.14
The aquatic diet of the Nutria rat is partially to blame for an increased rate of coastal erosion. In Louisiana, with a population estimated to be around 5 million, the nutria rat is responsible for a rate of erosion of 40 square miles per year. This species damages and destroys vegetation that is necessary for anchoring soil, turning marshes and wetland environments into open water. Additionally, Nutria rats have been known to undermine levees, dams, buildings and roadbeds. Nutria rats have also negatively affected agricultural resources and are responsible for disease transmission. They may carry tuberculosis, septicemia, blood flukes, tapeworms, liver flukes, and a type of nematode that causes “nutria itch,” a rash that is spread through water contaminated by feces and urine.
Federal, state, and local governments are working closely with wildlife agencies to manage Nutria rat populations and protect native vegetation and resources.15
The North American Porcupine (Erethizon dorsatum,) is the largest species of porcupine and the only one that can be found in the United States and Canada. Within their range, they are the second largest species of rodent, aside from the beaver. Although not an aggressive animal, porcupines are equipped with a coat of sharp defensive quills that makes them easily identifiable. This species faces no risk and enjoys an extensive geographic range.
The North American Porcupine is easily identifiable by their stout lumbering bodies and spiny coats. NAP’s reach a mature length of 33” to 46” (the tail comprises approximately 1/3 of that length.) Adults weigh between 12 to 35 lbs. (males tend to be the larger sex.)1 NAP’s have small ears, small heads, and large front teeth that aid in consuming wood. There is a prominent diastema between the front teeth that allows them to draw in their lips while gnawing. Their skulls exhibit a lack of canines. Like other hystricomorphs, they have unique chewing muscles.
The name porcupine is derived from the Latin for “quill pig.” Their coats are comprised of three types of hair: a soft, dense woolly undercoat, long, course, brownish-yellow to black guard hairs, and quills. There are 24 species of porcupines that have coats made of more than 30,000 quills that act as sharp defense mechanisms. These tubular quills are filled with a spongy matrix (making them rigid but light,)2 and cover a porcupine’s head, back, sides and tail. The longest quills are found on the rear and may be up to 12” long, while the shortest quills are on the cheeks.3 The quills located within a central black line on their lower backs and tails are accented with white. This contrast appears on porcupines by three months old and acts as a preliminary warning to approaching predators (many being color blind.)4 Porcupines are non-aggressive mammals that only attack if they are unable to escape a threat. Typically, their quills lay flat but in defense, these quills become erect to fend-off predators. If an attack occurs, the porcupine lashes out at the predator, and the quills detach from the porcupine’s body (despite popular belief, porcupines cannot throw their quills.) The quills have sharp tips and barbs that embed into the predator’s body. The predator’s body heat causes the barbs to expand and muscle movements push the quills further into the predator’s skin. Embedded quills may cause infection or death.5 Growing new quills is possible but difficult for porcupines. To avoid losing quills, porcupines exhibit several warning behaviors to fend off predators before an attack ensues. These include visual cues (contrasting warning colors and erected quills,) acoustic clues (teeth chattering,) and chemical clues (porcupine’s emit a strong chemical odor when threatened.)
Porcupines are well suited for climbing and spend much of their time in trees. Different trees are chosen for feeding and resting. Their feet feature specific adaptations that allow them to grip surfaces and brace themselves high off the ground. They have four long claws on their front feet in addition to a vestigial thumb, and five long claws on the back feet. The palms and soles of their feet are hairless and have pebbly surfaces that create friction with surfaces. Porcupines often secure themselves when climbing with their hind feet and grasp food with their front feet. The quills are also useful climbing implements. Quills located on the tail are thrust into the tree to help stabilize the porcupine and prevent downward sliding. Porcupines are known to spend the majority of time in trees; however, this behavior is directly related to the amount of ground cover available and the types of predators within a habitat. If appropriate ground cover exists, a porcupine will tend to forage and take cover on the ground more often. NAP’s are also good swimmers, aided by their lightweight quills that help keep them afloat.
They are solitary animals but are known to den and forage with other porcupines during the winter, most likely for protection from predators. These groups do not tend to reflect mating preferences. They build their dens in hollow trees, rock piles or caves. These dens are not used for hibernation, rather sporadically throughout the winter during severe weather.
Both males and females establish and defend territories. Males establish territories that overlap those of several females, but never that of another dominant male. Females’ territories tend to be consistent in size but the size of a male’s territory reflects his age and dominance. Juvenile males settle and establish their initial territories within their birth territories. As males mature, their territories increase in size. Juvenile females part from their birth territories and establish new territories before they reach maturity.6
Porcupines use several methods of communication with other members of their species and with predators. They are vocal animals, creating sounds that include moans, grunts, coughs, wails, whines, shrieks and tooth chattering (used to warn predators.)7 NAP’s also emit chemical signals and display the white/black markings on their quills when confronted by a threat. Their padded palms and soles provide them with a keen sense of touch.
Porcupines in the wild may live up to 18 years. It has been observed that a porcupine’s life expectancy is proportionate to the health and longevity of their grinding teeth. By 12 years of age, these teeth begin to show wear, resulting in a diminished diet and, therefore, a diminished body mass.
NAP’s have adapted to many types of climates due to their extensive range that includes a variety of elevations and geographic locations. They may be found living in coniferous or deciduous forests, savannahs, grasslands, mountains, or open tundra. Their behaviors are impacted by their habitat. In the Pacific Northwest, porcupines tend to be more ground dwelling, while populations in New York are primarily arboreal.
Within their habitats, porcupines have many predators, despite their weaponry. These include bobcats, coyotes, wolves, lynx, mountain lions, fishers, wolverines, and birds of prey. These predators have adapted to the porcupine’s weaponry, attacking from the front and flipping the porcupine over exposing its vulnerable stomach.
The NAP has the most northern geographic range of all porcupine species. Their range includes most of North America, spanning from the Arctic Ocean to northern parts of Mexico.
Porcupines have herbivorous diets that vary seasonally. During the spring and summer, their feeding rates decrease due to the increased availability of and their preference for high protein foods. Their diets include leaves, clover, twigs, bark, grasses, flowering herbs, and fruit (especially apples.) The herbivorous nature of their diets affects their sodium metabolism, causing porcupines to crave salt. As a result, they are driven to chew on wooden implements, structures, vehicles, and other items with residual salt. They are generally nocturnal foragers.
They breed once a year, between late summer and early fall. Females secrete chemicals, make high-pitched vocalizations, and mark with urine to alert males of their 8 to 12 hour estrous period that occurs prior to ovulation. Sexually mature males fight to establish sexual dominance, using loud vocalizations, biting, and erect quills. The dominant, and often largest, male establishes a breeding territory (which he may use for up to three seasons,) and wins breeding rights (and must defend the pre-estrous female for 1 to 4 days until copulation.) The dominant male performs a peculiar mating dance, which includes spraying the female’s head with urine. This display will continue until the female becomes receptive to the dance and mating. A male may mate with several consenting females.
Copulation takes place on the ground and may last for several hours. Mating ends when a vaginal plug is formed by an enzymatic action that occurs in the semen. The plug prevents other males from mating with the female.
After a gestational period of 210 days, the female gives birth to a single baby. The newborn has soft quills (which harden an hour after birth,) and weighs between .9 to 1.2 lbs.
The mother nurses her young for approximately 130 days, although young porcupines can eat solid food within a few days of birth. For the first 6 weeks, the baby remains close to its mother. The female sleeps and feeds in trees during the day (leaving her baby hidden on the ground nearby,) and returns to her baby at night.
By six weeks old, the baby begins following its mother to feeding trees, remaining at the base while she feeds. Over the next few months, the distance between the mother and her offspring increases during foraging trips and by 5 months old, the juvenile is independent (left by its mother to survive alone during the upcoming winter.)
Female reach sexual maturity by 25 months old. Males do not reach sexual maturity until 29 months old.
Notes of Interest
While quills are obviously dangerous for predators, they pose some risk to porcupines as well. Porcupines can fall out of trees, resulting in self-impalement. Additionally, the force it takes to impale a predator with quills might exceed the weight of the porcupine, resulting in a difficult or impossible separation of quills from the porcupine.
Native Americans once revered the porcupine for its meat and quills (which were used as decoration and to establish status.)
NAP’s are considered a pest by the timber industry. Their tendency to feed on bark and twigs leaves trees stunted or deformed and unsuitable to be turned into lumber.8