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
Read more about animals at: www.grizzlyrun.com
The Purple Gallinule (Porphyrio martinica) sometimes referred to as a ‘swamp hen,’ is a brightly colored bird that can be found gracefully walking across floating vegetation in southern and tropical marshlands.
Purple Gallinules are chicken-sized birds that reach a mature length of approximately 14”, with a wingspan of 20” to 24”, and a mature weight of 7.3 oz. to 10.2 oz. They have red eyes, a short, triangular red bill with a yellow tip, and a light blu
e or white frontal shield (located on the forehead.) Some of their most unique features are their tall, thin yellow legs and long toes (used to navigate across floating vegetation.) PG’s are perhaps best known for their striking coloration. Purple-blue plumage covers the head, neck, breast, short tail, and underside. The back and wings are green-blue and their undertail coverts are white. Chicks are born covered in black down. Juveniles are buff to brown in color, with some green on their backs, yellow legs, and dull facial features.
Purple Gallinule movements on land have been likened to those of a chicken while in the water, they’re said to move like a duck. Their long toes enable then to gracefully move across floating vegetation, but make it difficult for them to clamber through dense shrubs.1 While walking or swimming, they move their head and tail in a constant jerking motion. The flight of the PG has been described as labored and slow, with dangling legs. Despite this, PG’s have been known to fly great distances from their home ranges and have been sighted as far north as southern Canada and Maine.
Purple Gallinules are vocal and make squawking, cackling, and guttural grunting noises.
PG’s can be found in freshwater marshes, wetlands, lakes, waterways, or bayous where there is a presence of floating vegetation (such as lily pads.)
They are year round residents of northern, central, and eastern-central South America, parts of Central America, southern Florida, and the Caribbean. Breeding ranges reach northward to Texas, Arkansas, the Carolinas, and the Gulf Coast. Some populations migrate short distances and winter along the Gulf Coast of the United States and in Central America.2 Although the PG is not a graceful flier, there have been sightings far from this species normal range (in the northern United States, southern Canada, Europe, and South Africa.)3
They are ground foragers whose diets consist of aquatic vegetation, grasses, seeds, fruit, water hyacinth flowers, grains, insects, and some invertebrates. They gather plant material while standing atop floating vegetation, climb brush for seeds or fruit, and collect insects off the bottom of lily pads (by rolling the edge over and holding it in place with their foot while collecting the insects with their bill.) Insects are fed to the chicks. PG’s are able to use their feet to hold food while eating.
Purple Gallinules breed between April and September. Nests are built using grasses and other aquatic vegetation and are attached to either a floating mat or a thicket of vegetation. Between 6 to 10 eggs are laid -one per day- that are creamy to buff with small irregular brown spots. Both the male and female incubate the eggs for 18 to 20 days. The chicks hatch over the course of 3 to 4 days, covered in black down. The chicks generally remain in the nest until all the eggs have hatched, but are able to leave the nest within a day of hatching if disturbed (already capable of swimming, diving, and running.) The chicks are fed by both parents for 8 to 9 weeks. By 7 weeks old, the chicks are capable of short flights and by 10 weeks old, they can make sustained flights (by this time the chicks have reached 1/3 their mature size.)4
There is a hunting season for PG’s in the United States; however, they are not a common game bird and by the time the season opens, local Purple Gallinule populations have often already started migrating south. For example, the hunting season in Arkansas includes a daily limit of 15 birds and lasts from September 1st through November 15th.5
1. http://www.allaboutbirds.org/guide/Purple_Gallinule/id
2. http://birds.audubon.org/birds/purple-gallinule
3. http://www.allaboutbirds.org/guide/Purple_Gallinule/id
4. http://txtbba.tamu.edu/species-accounts/purple-gallinule/
5. http://thecabin.net/sports/outdoors/2009-08-16/
http://www.allaboutbirds.org/guide/Purple_Gallinule/id
http://birds.audubon.org/birds/purple-gallinule
http://txtbba.tamu.edu/species-accounts/purple-gallinule/
http://thecabin.net/sports/outdoors/2009-08-16/
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The Ruby-Throated Hummingbird (Archilochus colubris,) is one of my favorite backyard sightings, due to its brilliant plumage and spirited behavior. Before you can catch a glance, this acrobatic and energetic bird is usually on its way to the next blossom. This hummingbird has the greatest breeding range of all hummingbirds in North America and occupies much of the eastern United States and Canada during the spring and summer months. By providing the right vegetation and features in your backyard, you may be lucky enough to share your yard with this lovely species.
The Ruby-Throated Hummingbird is named for the metallic ruby-red throat patch found on the throat of the male hummin
gbirds. Both sexes have iridescent green plumage on their backs and heads and white undersides. This species of hummingbird has the lowest number of feathers ever found on any bird1. Females may be distinguished from males by their dull gray throats. The tails also differ between sexes, with forked tails
present on males and white-tipped square tails on females. Young Ruby-Throated Hummingbirds are similar in appearance to adults, except for fewer red feathers on the throats of adolescent males.
Adult hummingbirds reach 3” to 4” in size, averaging 3.5 grams in weight2. Ruby-Throated Hummingbirds have long bills and tongues, used to drink nectar at an average of 13 licks a second. The tongues are grooved to aid in nectar collection and have fringed edges to help collect insects. This acrobatic flyer has short legs relative to their body length, making walking and hopping difficult and inefficient. Possibly the most unique physical attributes of the Ruby-Throated Hummingbird, besides for the red plumage on the males, are the wings. These tiny and delicate appendages are able to beat an average of 53 times per second, creating this bird’s distinctive “humming” noise. During flight the number of beats per second may be 78 times a
second and as high as 200 times a second during a dive (a display used in mating)3. Because of these extreme levels of activity and the tendency to ‘hover’ while eating, Ruby-Throated Hummingbirds have very high metabolic rates. The metabolic rate of these birds at rest is estimated to be 20.6 calories per gram per hour. In addition to their signature hovering, these petite birds are able to fly upside-down and backward.
On average, adult male hummingbirds live to 5 years of age and females live to 9 years in the wild. This species experiences a high mortality rate possibly because of the extreme energy demands of behaviors including breeding displays, migration, and defense of territory, leading to extensive weight loss4.
Ruby-Throated Hummingbird is a solitary species and typically only interact for breeding or territorial purposes. Male hummingbirds are territorial, using vocalizations to ward off intruders. If an intruder enters another male’s territory, the defend
ing male will make a single note, repeating at higher and higher volumes until the intruder retreats. If the vocal warning is not successful, male hummingbirds are known to chase and physically attract other males (using their beaks and feet.)5 In addition to vocalizations, male and female Ruby-Throated Hummingbirds may communicate with and understand olfactory and visual cues. These birds can see the visible light spectrum as well as the blue-violet range. Developed vision along with their sense of smell helps these hummingbirds identify food sources.
Ruby-Throated Hummingbirds are diurnal, most active during the day. When temperatures drop below optimal levels, hummingbirds enter hypothermic torpor in order to conserve energy. Hypothermic torpor is a state similar to hibernation, allowing a hummingbird to conserve energy through a lowered body temperature and slowed body functions6.
Populations of Ruby-Throated Hummingbirds are wide spread and numerous, with an estimated 7.3 million birds worldwide. This species has never experienced any serious threats and is protected under the Migratory Bird Treaty between the U.S. and Canada. As with all hummingbird species, the Ruby-Throated Hummingbird is part of Appendix II of the Convention on International Trade in Endangered Species7.
Ruby-Throated Hummingbirds fulfill an important role in their habitats, pollinating flowers, shrubs and vines. This symbiotic relationship is so strong that some species of plants have adapted to cater specifically to these small birds. Ruby-Throated Hummingbirds are migratory, inhabiting northern habitats during their summer breeding season and tropical habitats after migrating south for the winter. Preferred habitats include deciduous and pine forests, mixed woodlands, orchards, flowering gardens, parks, overgrown pastures, and citrus groves. The Ruby-Throated Hummingbird selects habitats that are close in proximity to water sources such as marshes or streams, to ensure abundant insect supplies8.
Males establish territories that offer food supplies, protection and mating opportunities. Some males have been known to establish a breeding territory distinct from their primary territory when food sources in the primary territory were not sufficient to support mating activities. These separate areas may be as far as two miles apart. Males are defensive of their territories and typically locate their territory at least 50’ away from a territory of another male Ruby-Throated Hummingbird. Territories of Ruby-Throated Hummingbirds may overlap with those of other hummingbird species. In these instances, the male Ruby-Throated Hummingbird will become submissive9.
Within their habitats, Ruby-Throated Hummingbirds are vulnerable to birds-of-prey (including blue jays which feed on nestlings) and, most often, house cats.
Ruby-Throated Hummingbirds are a migratory species. Between February and May these petite birds fly north to their breeding grounds located across the eastern United States and Canada, east of the 100th meridian. Between July and October Ruby-Throated Hummingbirds embark on a southern migration to their winter grounds that extend from southern Florida south to Panama and the West Indies. This species primarily winters in Central America. Ruby-Throated Hummingbirds are capable of a nonstop, 500-mile flight across the Gulf of Mexico and may go so far as to double their body weight in preparation. The migration of this species coordinates with the blooming schedules of flowers.
Ruby-Throated Hummingbirds are omnivorous, feeding on flowers and nectar as well as insects. Adult hummingbirds require an immense amount of calories to support their behaviors and must consume approximately twice their body weight a day. They are most often spotted hovering over flowers as they lick the nectar, consuming approximately half their body weight in sugar a day, spread between five to eight feedings10. Preference has been shown for red flowers, but hummingbirds consume a variety of other flowers and nectar from wildflowers and flowers from shrubs and vines, as well as tree sap (collected from wells excavated by tree-boring bird species.) Insects are collected from sap wells and vegetation and include mosquitoes, small bees, gnats, small flies, aphids, spiders, caterpillars and insect eggs11.
If you are looking to attract hummingbirds to your garden, here is a variety of plantings you may consider:
Flowers:
Begonia, Century Plant, Butterfly Weed, Columbine, Delphinium, Fox Glove, Dahlia, Geranium, Impatients, Lilly, Petunia, Phlox, Snapdragons, Verbena, Sweet William
Vines, Trees, Shrubs:
Honeysuckle, Trumpet Vine, Morning Glory, Butterfly Bush, Rose of Sharon, rosemary, Tulip Poplar
Hanging a hummingbird feeder is also a great way to attract these beautiful birds. Fill your feeder with a concentrated sugar solution (roughly 4 parts sugar to 1 part water.) Boil the mixture until the sugar is fully dissolved. Remember to clean your feeder often, especially during extreme heat. The sugar solution should be changed every few days, especially during high temperatures because heat can cause this solution to spoil.
*Do not use artificial sweetener or honey in your feeder. Honey can ferment and cause hummingbirds to become sick and sweeteners contain no nutritional value13.
Ruby-Throated Hummingbirds breed while in their northern habitats between March and July, the height of breeding occurring in mid-May. This species inhabits a larger breeding range than all other hummingbird species in North America and is the only species of hummingbird that breeds east of the Mississippi14.
Both male and female Ruby-Throated Hummingbirds take several breeding partners during a given season, although no long-term breeding pairs are established. After copulation pairs separate and females assume all parental duties.
Male Ruby-Throated Hummingbirds return to breeding areas in the spring to establish their territories prior to females’ arrivals. Upon entering a male’s territory, a female will be courted with an acrobatic display: a showy display of red throat plumage and diving displays with males flying in loops above the females. If a female shows interest by perching, the male will proceed by flying in fast horizontal arcs just feet in front of the female. Females may give their final consent by emitting a “mew” and displaying a posture of cocked tail feathers and lowered wings15.
Females are solely responsible for selecting the site for and building a nest. Nests are typically attached to a down-sloping branch by pine resin, below a shelter of leaves, 5’ to 20’ off the ground or a stream. Common trees to find hummingbird nests in are oak, maple, poplar, birch, beech, spruce and pine. Nests are constructed of thistle, ferns, young leaves, moss, dandelion and milkweed down, spider and caterpillar webs, and bud scales and decorated on the exterior with lichen (possibly to provide camouflage.)
Females lay, on average, 1 to 3 small white eggs. After two weeks of incubation, the young birds are born and will be fed by their mothers in the nest for approximately 3 weeks. The chicks leave the nest about 20 days after hatching and reach sexual maturity at 1 year of age. In a single breeding season a female may have several broods.
Notes of Interest:
While hummingbirds don’t require a source of water for drinking, providing a water feature in your garden may help attract these beautiful birds. Including a fountain, pond, birdbath, waterfall or mister in your garden may increase insect populations and make your space more attractive.
Ruby-Throated Hummingbirds were a prized specimen in the nineteenth century due to their beautiful plumage. Although these birds were commonly hunted and a coveted prize, this species never became threatened and numbers stayed strong and stable16.
Footnotes
1. http://animaldiversity.ummz.umich.edu/accounts/Archilochus_colubris/
2. http://plants.usda.gov/pollinators/Ruby-throated_hummingbird.pdf
3. http://www.wvu.edu/~agexten/wildlife/hummer.htm
4. http://animaldiversity.ummz.umich.edu/accounts/Archilochus_colubris/
5. http://animaldiversity.ummz.umich.edu/accounts/Archilochus_colubris/
6. http://animaldiversity.ummz.umich.edu/accounts/Archilochus_colubris/
7. http://animaldiversity.ummz.umich.edu/accounts/Archilochus_colubris/
8. http://plants.usda.gov/pollinators/Ruby-throated_hummingbird.pdf
9. http://plants.usda.gov/pollinators/Ruby-throated_hummingbird.pdf
10. http://www.wvu.edu/~agexten/wildlife/hummer.htm
11. http://plants.usda.gov/pollinators/Ruby-throated_hummingbird.pdf
12. http://www.wvu.edu/~agexten/wildlife/hummer.htm
13. http://www.wvu.edu/~agexten/wildlife/hummer.htm
14. http://plants.usda.gov/pollinators/Ruby-throated_hummingbird.pdf
15. http://animaldiversity.ummz.umich.edu/accounts/Archilochus_colubris/
16. http://animaldiversity.ummz.umich.edu/accounts/Archilochus_colubris/
http://animals.nationalgeographic.com/animals/birds/ruby-throat-hummingbird/
http://plants.usda.gov/pollinators/Ruby-throated_hummingbird.pdf
http://www.wvu.edu/~agexten/wildlife/hummer.htm
http://animaldiversity.ummz.umich.edu/accounts/Archiloch
The House Sparrow (Passer domesticus) is one of the most common bird species in North America, although it is a non-native species. These sociable and tame birds can be spotted in backyards hopping along the ground pecking at seed as well as on city streets feeding on crumbs. This species has a long running relationship with humans and has come to rely heavily on human populations for survival. House Sparrows have healthy and stable populations across a wide geographic range and are listed as Least Concern on the IUCN Red List.
House Sparrows are generally tame and sociable birds, within their flocks and with people, especially during the winter. Because these birds live in social communities, methods of communication have been developed to relay dominance, submissiveness, nervousness, courting and aggression. They often feed together to minimize predation and their flocks have social structures that are similar to that of chickens. Male House Sparrows with larger black throat 
patches tend to be dominant over males with smaller bibs. During the courting and breeding season females tend to be more assertive, but males are the dominant sex in the flock throughout the rest of the year. Nervousness is indicated by a flick of the tail. Aggression is communicated by a crouched posture with thrust-forward head, spread wings, erect tails and ruffled feathers (in extreme situations.) In a courting display, a male will puff up his chest and open his wings and tail, hopping stiffly and bowing up and down in front of the female4. In addition to social dominance and behavioral communication, House Sparrows are a noisy species that uses a number of simple vocalizations to verbalize warnings, threats and defense, or to attract a mate. The most common sounds include a chatter (often used by females toward her mate or to chase away competing females,) a cheep (used in a series to attract mates and in a flock to communicate submissiveness,) wheezy calls, and chirps.
House Sparrows tend to have more direct and higher flight than native species of sparrows. Their flight is continuous and lacks periods of gliding5. Because of their stature and short legs, House Sparrows can most often be seen hopping on the ground rather than walking.
House Sparrows tend to have life spans of just a few years. However, there are recorded instances of wild individuals living as long as 13 to 15 years.
House Sparrows are unrelated to other species of sparrows that are native to North America, such as the white-crowned sparrow, and therefore, differ in appearance. They may be identified by their shorter, stockier appearances, accentuated by full chests, shorter tails and legs, large round heads and shorter, thicker beaks. House Sparrows reach a mature size of 5.9” to 6.7” in length and 27g to 29g in weight. Their wingspan, when full grown, is 7.5” to 9.8”1. Geographic variations exist due to the House Sparrows immense range. Colder climates tend to produce larger birds with shorter wings and legs, whereas populations with darker plumage tend to be found in humid climates2.
Coloration may differ between sexes and during different seasons. Both sexes generally have buff, brown and black stripes on their backs, although males tend to be more brightly colored, with gray heads, black patches or “bibs” on their necks and white cheeks. Females are generally dull tan-gray, with gray undersides, buff eye-stripes, and a bill that is more yellow than males. During the summer, breeding males will display a black bill, mask, throat and chest, a gray cap, and a white stripe on their shoulders. Their main coloring is a reddish-brown with black streaks. Non-breeding males lack the vibrant reddish-brown coloration because those feathers become obscured by gray feather tips. Non-breeding males also have less black on their throats and chests, and yellow at the base of their bills3. This seasonal variation is due to an annual molt. Juveniles are plain in color, in appearance to females.
House Sparrows tend to be found in areas inhabited or affected by humans, including cities, towns, suburbs, farms, and parks. Because of their dependency on humans, House Sparrows are unable to survive in areas such as uninhabited woodlands, alpine forests, grasslands, or deserts. In extreme climates House Sparrows must maintain a close proximity to human populations for survival.
In their habitats House Sparrows (and their eggs and young) are vulnerable to a number of predators, such as hawks, owls, cats, dogs, raccoons and snakes. Their tendency to forage in flocks increases their awareness and survival rates.
They are year round residents of their native environments of Eurasia and North Africa. Introduced, invasive populations are also non-migratory and thrive in South Africa, South America, New Zealand, Australia, and North America. Their lack of migration increases survival rates because of a diminished demand for energy and exposure to predators.
The House Sparrow was introduced to Brooklyn, New York in 1851, when 100 birds from England were released. This may have been done to control certain insect populations or to make the area more familiar to European immigrants. By the turn of the century, their populations had spread to the Rocky Mountains. Additional populations were released in San Francisco and Salt Lake City in the 1870’s, expanding this species range across North America (excluding Alaska and northern parts of Canada6.)
The house sparrow is an omnivorous ground forager that spends much of its time hopping along the ground pecking at food. They have also been known to steal food from larger species of birds and drink nectar from flowers. Their diets consist mainly of grain and seed (corn, oats, sorghum, wheat,) crumbs and food waste, ragweed, grasses, buckwheat, commercial birdseed, and insects.
House Sparrows are monogamous and form breeding pairs each season, with nesting beginning in late winter and courtship occurring in early spring. Nesting may begin only a few days before the first egg is laid. They prefer to build their nests in man made structures such as the walls of buildings, on streetlights, in nest boxes or in the eaves of houses. They have been known to evict other birds from their nests, destroying existing eggs and physically attacking the opposing birds. House Sparrows tend to reuse their nests. And have been known to aggressively defend their nesting areas.
Both males and females construct the nests by stuffing their nesting cavities with dry vegetation until the hole is nearly full and then lining the interior with softer materials such as string, paper, and feathers. House Sparrows often nest in close proximity to each other, the nests sometimes sharing a common wall.
A House Sparrow may lay up to 4 broods in a year, each containing between 1 and 8 white/light-green/blue-white eggs, speckled with gray or brown and approximately 7/8” in length. Parents alternate incubating the eggs for a period of 10 to 14 days. Young chicks are born naked and uncoordinated, with closed eyes. During the nestling period of 10 to 14 days both parents feed the chicks through regurgitation. House Sparrows reach sexual maturity by around 9 months of age.
Notes of Interest:
House Sparrows enjoy dust baths and can often be spotted coating their bodies with dust and dirt. They also take baths in puddles or shallow water, using a similar flicking motion to coat their feathers.
Because the house sparrow is so numerous and tame, they are often the subject of avian biological studies and have been the subject of nearly 5,000 scientific papers7.
Although House Sparrows are common and numbers are stable, some populations have experienced a sharp decline, possibly due to farming practices, and changes in land-use. Despite this, they are not considered threatened and are not protected under any laws or regulations.
Footnotes
1. http://www.allaboutbirds.org/guide/house_sparrow/id
2. http://animals.nationalgeographic.com/animals/birding/house-sparrow/
3. http://www.allaboutbirds.org/guide/house_sparrow/id
4. http://www.allaboutbirds.org/guide/house_sparrow/id
5. http://animaldiversity.ummz.umich.edu/accounts/Passer_domesticus/
6. http://www.allaboutbirds.org/guide/house_sparrow/id
7. http://www.allaboutbirds.org/guide/house_sparrow/id
http://www.allaboutbirds.org/guide/house_sparrow/id
http://animals.nationalgeographic.com/animals/birding/house-sparrow/
http://animaldiversity.ummz.umich.edu/accounts/Passer_domesticus/
http://www.thepoultrysite.com/articles/848/understanding-and-control-of-house-sparrows
General: The Great Blue Heron (Ardea herodias) is the largest and most common heron in North America. These wading birds are skilled fishers, thriving in a variety of geographic locations and climates. This species is protected by the United States Migratory Bird Treaty Act despite healthy numbers and stable populations, listed as Least Concern on the IUCN Red List.
Description: As the largest of the North American herons, the Great Blue Heron may reach an adult size of 4.5’ tall but only 4.5 to 7.5 lbs, due in part to their hollow bones. Their rounded wings span 5.5’ to 6.5’ in width. Males reach an adult size that is approximately 10% greater than females1. In addition to their overall size, Great Blue Herons may be identified by their long necks, long, tapered yellow bills and long, thin legs that are dull green in color. Their legs terminate in narrow, wide-set toes that allow these birds to walk on soft ground. Great Blue Herons have an overall dull blue-gray coloration, with white, black and brown streaking along the neck. Their white faces and white head-caps are accented with black eye-stripes that merge with black plumes on the back of the heads. Additional features include a shaggy grey ruff on the back of the neck, short tails, and tan feathers on the thighs. Juveniles are similar in color, but lack the plumes and shaggy feathers of adults. A juvenile may also be identified by its dark crown and mottled neck2. There may be as many as seven subspecies of Great Blue Herons, distinguished by size, color, and geographic location.
During flight, a Great Blue Heron will fold its neck and slowly beat its wings, reaching speeds of 20 to 30 mph3.
On average, a Great Blue Heron will live to 15 years of age in the wild. The oldest known Great Blue Heron lived to be 23 years old. Like many species, Great Blue Herons experience a high mortality rate in the first year of life, losing over half of juveniles to predation and starvation. Great Blue Herons are generally a solitary species and typically forage along. However, this species does nest in single-species colonies that may contain up to several hundred nests. Great Blue Herons are most active in the morning and at dusk to maximize fishing success. During the day they are inactive, sleeping with single-species flocks of up to 100 individuals. Great Blue Herons are a territorial species and have been known to be aggressively defensive.
Great Blue Herons are capable of producing seven distinct noises but relative to other species, they are fairly quiet. Sounds are made in response to disturbances or threats and to greet other herons. They also use physical gestures to communicate during courtship4.
Habitat: Great Blue Herons live in a variety of temperate and tropical habitats located in close proximity to water, often seen wading in marshes, sheltered bays and inlets, streams, ponds, swamps, wet meadows, along saltwater coastlines and at the edges of rivers and lakes. They may be found in fresh, salt or brackish water. East coast populations typically avoid shores, preferring to live inland5. Great Blue Herons tend to locate their nesting colonies away from human disturbances, in quiet areas including mature forests and islands.
Within their habitats Great Blue Herons are efficient at controlling insect and fish populations. These habitats place eggs and chicks at risk of predation by crows, ravens, eagles, bears, cultures, hawks, and raccoons. Adults may fall prey to larger predators. If a juvenile or adult is killed in close proximity to a colony, the colony will be abandoned. Great Blue Herons face other threats within their habitats, include collisions with wires, and loss of habitat due to land development and forestry.
Location: Great Blue Herons inhabit nearctic and neotropical regions. During the spring and summer, breeding colonies may be found across North and Central America, the Caribbean and the Galapagos Islands. Populations living in extreme northern climates may migrate south in the winter to Central and South America in search of food supplies. These migratory populations do not breed in their winter habitats. However, this species is highly adaptable (more so than other species of herons) and populations have been known to winter in environments as far north as British Columbia, the Alaskan coast, and New England.
Diet: Great Blue Herons are carnivorous. They usually hunt alone, seeking a variable diet of fish (making up the majority of their diet,) small mammals, insects, crustaceans, and reptiles, such as frogs and salamanders. They wade slowly or stand still, waiting for their prey to come within reach of their long necks and bills. They attack fast, grab their prey with their bills, and swallow their meals whole, causing some herons to choke to death if the prey is too large for their slender throats. In deep water environments, Great Blue Herons exhibit a variety of methods to locate and catch food. They may hover above the water, swim, or dive below the surface in pursuit of food.
Reproduction: Great Blue Herons form mating pairs that last for the duration of one breeding season. Northern populations breed between March and May and southern populations breed between November and April. Each season new pairs will form. Great Blue Herons nest in single-species breeding colonies containing from several to several-hundred breeding pairs. Isolated breeding and nesting is very rare for this species. Nesting begins in February when males choose a site and begin an elaborate display of courtship including flight, stretching, twig shaking, and physical shows. Great Blue Herons prefer to nest in tall trees but will also select locations in shrubs or on the ground as long as there is a nearby source of water. Colonies are usually situated in undisturbed wetlands, far from human activity and roads, at elevations up to 4900’6. Males collect the materials for the nest, constructed of sticks and lined with bark, pine needles, and small sticks. Females lay anywhere from two to seven pale blue-green eggs that are incubated for an average of 28 days by both parents. Females in northern environments tend to lay more eggs. In the event that a nest is destroyed or abandoned (adults may abandon a nest due to human intrusion or extreme noise,) a female may lay a second clutch. Both parents feed chicks by regurgitating food, showing preference for the largest chick. After two months the chicks reach fledging age, able to fly and survive on their own. However, fledglings will continue to return to the nest to be fed by their parents for several additional weeks. Male chicks generally experience faster growth rates, reaching a fledgling size up to 13% larger than females7. Great Blue Herons reach sexual maturity at 22 months old.
Notes of Interest: A subspecies of the Great Blue Heron living in southern Florida and the Caribbean is often mistakenly called a Great White Heron because of a color mutation resulting in pure white plumage8.
In 1999, Great Blue Heron colonies in Seattle, WA experienced a 40% abandonment rate in the middle of the breeding season. Experts now believe this exodus resulted from an increased presence of Bald Eagles in the area, known to harass herons and feed on their young. Crows may have also contributed, known to feed on nests after Bald Eagles.
In recent years, breeding colonies in Washington State were once again impacted by threats. Colonies that numbered in the hundreds were replaced with colonies containing only 30 to 40 nests. In addition to the presence of predators, forestry, land development, and the associated noises are believed to have contributed to this decline9.
Footnotes
1. http://www.arkive.org/great-blue-heron/ardea-herodias/
2. http://www.birdweb.org/birdweb/bird/great_blue_heron
3. http://animals.nationalgeographic.com/animals/birds/great-blue-heron/
4. http://animaldiversity.ummz.umich.edu/accounts/Ardea_herodias/
5. http://animaldiversity.ummz.umich.edu/accounts/Ardea_herodias/
6. http://animaldiversity.ummz.umich.edu/accounts/Ardea_herodias/
7. http://www.sms.si.edu/irlspec/Ardea_herodi.htm
8. http://animals.nationalgeographic.com/animals/birds/great-blue-heron/
9. http://www.birdweb.org/birdweb/bird/great_blue_heron
http://animals.nationalgeographic.com/animals/birds/great-blue-heron/
http://animaldiversity.ummz.umich.edu/accounts/Ardea_herodias/
http://www.fcps.edu/islandcreekes/ecology/great_blue_heron.htm
http://www.birdweb.org/birdweb/bird/great_blue_heron
http://www.sms.si.edu/irlspec/Ardea_herodi.htm
http://www.arkive.org/great-blue-heron/ardea-herodias/