The Little Blue Heron is sometimes referred to as the blue crane, levee walker, or little blue crane.
They have a commensal relationship with White Ibises (Eudocimus albus). The ibises stir up food as they walk, increasing the number of prey available to the Little Blue Herons. The herons benefit, while the ibises are unaffected. (Riegner 1998, Terres 1980)
Perception Channels: visual ; tactile ; acoustic ; chemical
The major problem facing these birds is the loss of their wetland habitats. Little Blue Herons need clean, undisturbed wetlands for feeding and breeding. Colonies are being lost because of clear cutting of forests, and draining of ponds, lakes, and wetlands. The use of pesticides has also caused eggshell thinning. The population has been decreasing and the Little Blue Heron is considered threatened and of special concern in some coastal areas. (Katusic 1998, Riegner 1998)
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
The Little Blue Heron has no negative affect on humans.
The Little Blue Heron is enjoyable to watch and helps control insect populations. (Riegner 1998)
Egretta caerulea feed mainly during the daylight hours. They are carnivorous, with their diet consisting of fish, frogs, lizards, snakes, turtles, and crustaceans such as fiddler crabs, crayfish and shrimp. They also eat aquatic insects and spiders. When swamps and marshes become dry, they live on grasshhoppers, crickets, beetles and other grassland insects.
The Little Blue Heron's long legs enable it to wade into the water, where it walks slowly along an area in order to locate prey, often retracing its steps or standing motionless. They sometimes rake the ground with their foot to disturb prey into movement and stretch their long necks to peer into the water. Their long beak is used to jab and eat the prey. Extensive studies found the heron's prey capture success rate to be about 60 percent. (Terres 1980, Riegner 1998)
The Little Blue Heron is found along the Atlantic coast from Massachusetts to Florida, but is most abundant along the Gulf of Mexico. It also nests in the West Indies, and along both Mexican coasts through Central America and into South America. Its range can also extend into the Amazon Basin, the Caribbean, and the more northern regions of North America. (Riegner 1998)
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Although Egretta caerulea often lives near saltwater, it is mainly an inland bird. They prefer freshwater areas such as ponds, lakes, marshes, swamps, and lagoons, but also sometimes occupy flooded and dry grasslands, or marine coastlines. (Riegner 1998, Terres 1980, Tarski 2001)
Terrestrial Biomes: forest ; rainforest ; scrub forest
Average lifespan
Status: wild: 167 months.
The Little Blue Heron is a small, dark bird that ranges from 63-74 centimeters in length. It can have a wingspread of up to 1.04 meters. The sexes look similar, but the young look very different from the adults. An adult can be recognized by its purple-maroon head and neck. The rest of the plumage is slate gray. The long neck is usually held in an "S" shaped curve while the bird is at rest or in flight. The heron's long, slender bill curves slightly downward, and is also dark gray but has a black tip. The eyes are yellow and the legs and feet are dark. The young are unlike any other heron because they have all white body plumage. They have a blue bill with a black tip and dull green legs. They stay white through their first summer, fall, and into winter, but start molting in February into the dark color of an adult. (Terres 1980; Tarski 2001)
Average mass: 396 g.
Other Physical Features: endothermic ; bilateral symmetry
Average mass: 215.6 g.
The pale, blue-green eggs of the Little Blue Heron are laid in April. They can lay from 3-5 eggs, but on average lay 4-5. This process takes 5-8 days, with one egg being laid every other day. Both sexes incubate the eggs until they hatch in 22-24 days, and then quickly remove the eggshells from the nest. It may take about 5 days for all of the chicks to emerge. Although the young can raise their heads, they spend most of their time lying on the nest floor. Both parents feed them by dropping food into the nest and later placing it directly into the chicks' mouths. In about 3 weeks, the young are ready to leave the nest for short trips along surrounding branches. When they are 30 days old, they are able to fly and periodically leave the nest area. Soon after, at 42-49 days, the young are on their own. Little Blue Herons can breed when they are one year old. They have been recorded as living more than 7 years in the wild. (Riegner 1998, Terres 1980, Katusic 1998)
Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Average time to hatching: 23 days.
Average eggs per season: 4.
A medium-sized (24 inches) wader, the Little Blue Heron is most easily identified by its size, blue body, purplish neck, and gray bill tipped with black. Other field marks include dull yellow-green legs, dark eyes, and (unlike most herons) a lack of ornamental breeding plumes during the breeding season. Immature birds are all white, but may be separated from other white herons and egrets by their yellow legs and gray bill. Male and female Little Blue Herons are similar to one another in all seasons. The Little Blue Heron breeds in the southeastern United States and along the Atlantic Coast of the U.S. north to Maine. Birds breeding in the interior spend the winter from southern California south to Panama. Coastal populations south of New Jersey, as well as those in the West Indies, are non-migratory. Little Blue Herons breed in colonies along shallow bodies of water, including marshes, lakes, and estuaries. Nests are usually built in the branches of trees above the water. Wintering birds generally utilize similar habitats as in summer. Little Blue Herons primarily eat small fish. Little Blue Herons may be best observed wading in shallow water, where they may be seen plunging their bills into the water to catch fish. It is also possible to see Little Blue Herons at their rookeries, especially when they return to roost at sunset, or while flying with their feet extended and their necks pulled in. Little Blue Herons are primarily active during the day.
A medium-sized (24 inches) wader, the Little Blue Heron is most easily identified by its size, blue body, purplish neck, and gray bill tipped with black. Other field marks include dull yellow-green legs, dark eyes, and (unlike most herons) a lack of ornamental breeding plumes during the breeding season. Immature birds are all white, but may be separated from other white herons and egrets by their yellow legs and gray bill. Male and female Little Blue Herons are similar to one another in all seasons. The Little Blue Heron breeds in the southeastern United States and along the Atlantic Coast of the U.S. north to Maine. Birds breeding in the interior spend the winter from southern California south to Panama. Coastal populations south of New Jersey, as well as those in the West Indies, are non-migratory. Little Blue Herons breed in colonies along shallow bodies of water, including marshes, lakes, and estuaries. Nests are usually built in the branches of trees above the water. Wintering birds generally utilize similar habitats as in summer. Little Blue Herons primarily eat small fish. Little Blue Herons may be best observed wading in shallow water, where they may be seen plunging their bills into the water to catch fish. It is also possible to see Little Blue Herons at their rookeries, especially when they return to roost at sunset, or while flying with their feet extended and their necks pulled in. Little Blue Herons are primarily active during the day.
The little blue heron[note 1] (Egretta caerulea) is a small heron of the genus Egretta. It is a small, darkly colored heron with a two-toned bill. Juveniles are entirely white, bearing resemblance to the snowy egret. During the breeding season, adults develop different coloration on the head, legs, and feet.
They have a range that encompasses much of the Americas, from the United States to northern South America. Some populations are migratory. Climate change will probably cause their distribution to spread north. They can be found in both saltwater and freshwater ecosystems. Their preference for either one depends on where they live.
Nesting behaviors are documented by numerous sources. The adults build nests in trees, in colonies with other bird species. The number of eggs laid varies from place to place. The young mature quickly, requiring little attention from adults after about nineteen days of age. Both young and adults are sometimes preyed on by other species. Adults hunt fish, crabs, and other small animals. As with clutch sizes, diet can vary regionally.
The population of E. caerulea is declining. Many possible reasons for this have been proposed. Exposure to heavy metals has been found to have detrimental effects on young birds.
The little blue heron is part of the family Ardeidae, a group whose members can be found throughout much of the world, including the Americas, Africa, Asia, and Oceania.[3] It was first described as Ardea caerulea by Carl Linnaeus in his 10th edition of Systema Naturae.[4] It is now a member of the genus Egretta.[3] It may be closely related to the snowy egret, another member of its genus, which it greatly resembles when young.[5] Variations of the name include Ardea coerulea, Florida caerulea, and Hydranassa caerulea.[2]
Young birds found in a little blue heron nest in North Dakota, at a site heavily populated by cattle egrets (Bubulcus ibis), which displayed traits of both the former and latter, are believed to be an example of hybridization between the two species.[6] Other species they are known to hybridize with include the tricolored heron, little egret, snowy egret, and black-crowned night heron. Of these four, only the black-crowned night heron is not a member of Egretta.[2]
_juvenile.jpg)
Males and females have the same coloration. The adults are darkly colored, with purple-maroon heads and blue bodies. During the breeding season, their heads turn dark red. They have two-toned bills, which are a light blue at the base, with black tips. Their eyes are yellow and their legs are greenish. Juveniles are almost completely white, although the upper primaries are somewhat dark in color. Like adults, their bills are two-toned. Immature birds transitioning from the juvenile to adult phase have a combination of light and dark feathers. Both sexes are about 56–74 centimetres (22–29 in), with a wingspan of 100–105 centimetres (39–41 in). They weigh about 397 grams (14.0 oz).[7][8]
The lores, which are normally a dull green become a shade of turquoise. They also develop long plumes on the crest and back, which can stretch 20–30 centimetres (7.9–11.8 in) past the tail. The legs and feet become black.[9] The eggs are typically smooth, light blue, and unmarked. In size, they are about 31.7–43.2 millimetres (1.25–1.70 in), with a weight of around 23.1 grams (0.81 oz).[10]
Egretta caerulea can be found regularly in the United States, Mexico, Central America, northern South America (including Venezuela, Colombia, and Peru), and numerous Caribbean islands (including Cuba, Jamaica, and Hispaniola). They have been recorded as a vagrant (a species that appears far outside its natural range) in Greenland, Portugal, and South Africa. Whether or not their range is declining is unknown.[1] In the United States, they can be found from Missouri to Virginia to Florida. They are more common in peninsular Florida than the Florida Panhandle.[7] They can occasionally roam as far north as Canada.[3]
Individuals in central Alabama tend to migrate towards South America and the Caribbean, while those from the Mississippi River west travel to Mexico and Central America.[3] One study found that of seven migratory wading bird species, the little blue heron had the greatest mean dispersal distance, of 1,148 kilometres (713 mi).[11]
Future climate change is projected to increase its overall range. If global warming continues at its current rate, by the year 2080, its summer range will have increased by 87%. Of its current range, it is expected to lose only 1%. These gains would spread its summer distribution well into more northern parts of the US, such as Michigan and Minnesota, and even into southern Canada.[5]
The little blue heron can be found in freshwater and marine environments. These include mangrove forests, bogs, swamps, salt marshes, tidal flats, estuaries, streams, and flooded fields.[1][8] They are usually found at low elevations, but can be seen at heights of 3,700 metres (12,100 ft) in the Andes.[9]
In North America, they tend to favor freshwater habitats, while in the Caribbean, they are more often found in saltwater.[5] Towards the southern extent of their range, in Brazil, they are found almost exclusively along the coast, rarely venturing inland at all.[10]
Juveniles in San Blas, in the Mexican state of Nayarit have an atypical color-scheme. In these birds, the top of the head is chestnut colored and the wings tips are much darker. Initially, it was suggested that they may be hybrids, however further study concluded they were most likely a natural variation.[12] No other geographic varieties have been observed.[9]
Little blue herons prefer to stand still and wait when hunting, rather than chase after prey. They walk slowly and search for fish and other prey items, flying to different spots if needed. They tend to move slower than other related species, which can help distinguish them. They are not usually found in large numbers at any body of water. Occasionally, however, they will gather with other herons, especially if they have found a school of fish trapped in shallow water.[8] They sometimes also feeds in grassy fields.[5]
During courtship, both males and females practice bill-nibling. Males also use a neck-stretch to attract mates.[13]
Little blue herons typically nest in trees alongside other roosting birds.[8] They are colonial nesters (nesting in groups). Examples of species they may nest alongside include the scarlet ibis, yellow-crowned night heron, great egret, black-crowned night heron, and snowy egret.[10]
During nest construction, males bring twigs to females, who use them to build the nest. Both males and females help incubate their clutch.[13] They begin incubation after two eggs have been laid, which will cause any later eggs to hatch out of sync. The chicks that hatch later tend to not receive as much food as early-hatching ones, which limits their growth.[14] Clutch sizes vary significantly throughout their range. In Trinidad, there are usually 2–5 eggs, while in Costa Rica, only 2–4 are laid on average. In North America, the mean is 2.67–4.4. The very lowest values are seen in southeastern Brazil and the US states Florida and Georgia, where no more than three are generally laid.[10]
Young herons are able to start climbing around the branches by their nests at 15 days old.[10] Due to the young age at which they develop motor skills in their legs, the young do not rely on their parents for anything besides feeding after 19 days, at which point the adults begin foraging away from the nest.[14] By 20–25 days, they can climb to the very top of the tree their nest is built on, or even into other trees. They can fly short distances at around 30 days of age (some take 35–38), but will still be dependent on adults for about two weeks after that.[10] It is in their second year of life that juveniles begin to lose their white feathers.[9]
There is circumstantial evidence that young black-crowned night herons and crab-eating raccoons prey on nestling little blue herons. Adults have been observed driving a yellow-headed caracara away from their nests. In the presence of a Harris' hawk, however, the little blue herons fled.[10]
Twenty-four different species of parasitic worms were found on 33 of 35 little blue herons examined in South Florida. These included trematodes, nematodes, acanthocephalans, and one cestode. The most common trematode was Posthodiplostomum macrocotyle, and the most common nematodes were Contracaecum multipapillatum and Contracaecum microcephalum. The acanthocephalan and cestode species could not be identified (in the latter, neither could the genus).[15]
On the eastern coast of North America, little blue herons primarily feed on fish, however their diet varies significantly throughout their range.[9] In a study of individuals in mangrove forests in southeastern Brazil, 80% of their diet during the breeding season was found to consist of crabs. Compared to the scarlet ibis, the herons preferred arboreal or semi-arboreal species, such as Aratus pisonii and Metasesarma rubripes, while the former preferred to take burrowing species. This demonstrates their different feeding strategies—scarlet ibises being foragers who hunt using their sense of touch and little blue herons being visual hunters.[16] In another mangrove forest in southwestern Puerto Rico, the entire diet was found to consist of fiddler crabs.[17]
The little blue heron is listed as a least-concern species by the International Union for the Conservation of Nature, although its numbers are decreasing.[1] Historically, they were not hunted for their feathers as much as other heron species due to their lack of visually attractive plumes.[8]
The dangers faced by Egretta caerulea are not well researched. They could include development along coastlines, habitat disturbance, predators, pesticide exposure, and parasites.[7] The metals cadmium and lead have been found to lead to slower growth rates and higher death rates, respectively, of young birds.[18] In Sepetiba Bay, Rio de Janeiro, Brazil, little blue herons were found to have relatively high levels of metal contamination in the liver and kidneys.[19]
In areas with cattle egrets, little blue herons have been found to nest for shorter amounts of time, and produce fewer young that survive to adulthood. Cattle egrets only begin pairing when most little blue herons already have eggs or live young in their nests. The former species has been observed stealing twigs from nests of the latter. This behavior sometimes leads to the young falling out of the nest or the cattle egrets removing them.[20]
Little blue heron The little blue heron (Egretta caerulea) is a small heron of the genus Egretta. It is a small, darkly colored heron with a two-toned bill. Juveniles are entirely white, bearing resemblance to the snowy egret. During the breeding season, adults develop different coloration on the head, legs, and feet.
They have a range that encompasses much of the Americas, from the United States to northern South America. Some populations are migratory. Climate change will probably cause their distribution to spread north. They can be found in both saltwater and freshwater ecosystems. Their preference for either one depends on where they live.
Nesting behaviors are documented by numerous sources. The adults build nests in trees, in colonies with other bird species. The number of eggs laid varies from place to place. The young mature quickly, requiring little attention from adults after about nineteen days of age. Both young and adults are sometimes preyed on by other species. Adults hunt fish, crabs, and other small animals. As with clutch sizes, diet can vary regionally.
The population of E. caerulea is declining. Many possible reasons for this have been proposed. Exposure to heavy metals has been found to have detrimental effects on young birds.
