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7 Fascinating Facts About the Bare-throated Tiger-Heron

Bird: Bare-throated Tiger-Heron,Tigrisoma mexicanumThe Bare-throated Tiger-Heron, scientifically known as Tigrisoma mexicanum, is a waterbird that belongs to the family Ardeidae. It is native to the lowlands and wetlands of Central and South America and has been sighted in several locations with adequate water supply such as Costa Rica, Nicaragua, and Honduras.

The Bare-throated Tiger-Heron is known for its unique appearance, making it easily distinguishable from other herons. In this article, we will delve into the identification, plumages and molts of this fascinating bird species.

Identification

Field Identification

Identifying the Bare-throated Tiger-Heron in the field can be quite easy for experienced birders, whilst beginners may find it challenging. The bird is about 66-76 cm in length, with a wingspan of 114-127 cm and a weight of about 1-1.5 kg.

The species’ name, ‘Bare-throated,’ is derived from its distinctive and bare neck. It also has a distinctive, bulky body, with long, thick legs that help it wade in shallow water.

The bird also has a short, thick, and curved bill that is grey in color.

Similar Species

It is easy to confuse the Bare-throated Tiger-Heron with the Rufescent Tiger-Heron, which is also found in Central and South America. The Rufescent Tiger-Heron, however, has a heavier bill and a more rufous back, while the Bare-throated Tiger-Heron has a glossy black back.

Plumages

The Bare-throated Tiger-Heron has distinct plumages that can be classified into juvenile, adult and breeding plumages. The juvenile plumage is characterized by a rufous-brown back, a grey neck and wings and a buff-colored breast.

This plumage is usually replaced by the adult plumage at around six months of age. The adult plumage is entirely black with the colorful bare, blue to greenish-blue skin around the eyes and neck that stands out.

The bill is usually black with a slight down-curved tip. During breeding seasons, Bare-throated Tiger-Herons change into breeding plumage characterized by plumes on their lower back and chest that they raise when showing off to potential mates.

Molts

Bare-throated Tiger-Herons undergo two major molting patterns in a year; pre-basic molt and pre-alternate molt. The pre-basic molt occurs during non-breeding seasons, usually in February and is when adult plumage is replaced.

On the other hand, pre-alternate molt follows the breeding season’s end, in October and November, where different body feathers are replaced. These molts are an essential aspect of feather maintenance, and the old feathers must be replaced to keep the birds’ feathers and body contour in good shape.

In conclusion, the Bare-throated Tiger-Heron is a fascinating bird famous for its distinct appearance and unique plumages. Experienced birders can easily identify and differentiate it from other herons, while beginners can refer to the various field guides available.

Understanding the molting patterns of this species is crucial in learning how they maintain healthy and vibrant feathering. Next time you come across this bird species, you can confidently identify it and hopefully get to see it in its breeding plumage.

Systematics History

The systematics history of the Bare-throated Tiger-Heron, Tigrisoma mexicanum, can be traced back to the early 19th century when ornithologists, such as Johann Friedrich Gmelin and Charles Lucien Bonaparte, first described the species. Over the years, researchers have studied the birds different morphological features, sounds, and DNA to better understand the relationships and evolutionary history of this species.

Geographic Variation

The Bare-throated Tiger-Heron has distinct geographic variations, with differences in the size and coloration of their plumage. These variations occur within populations that are geographically isolated, as a result of distinct environments and varying selective pressures.

Subspecies

Currently, there are three recognized subspecies of the Bare-throated Tiger-Heron, Tigrisoma mexicanum mexicanum, T. m.

chiapensis, and T. m.

pallescens. The subspecies T.

m. mexicanum is found primarily in southern Mexico and northern Central America, while T.

m. chiapensis is found in southwestern Mexico.

T. m.

pallescens is the most widespread subspecies and is found in Central and South America. These subspecies differ in body size and coloration, with T.

m. mexicanum being the largest and darkest subspecies, while T.

m. chiapensis is smaller and has a more chestnut-colored back.

Related Species

Bare-throated Tiger-Herons closest relatives are the Fasciated Tiger-Heron (Tigrisoma fasciatum) and the Agami Heron (Agamia agami). These species belong to the same family, Ardeidae, and have similar features, such as bare skin around the eyes and neck, and a bulky body.

Nevertheless, they differ in terms of plumage coloration and morphology.

Historical Changes to Distribution

The Bare-throated Tiger-Herons historical range has undergone significant changes over the years due to human activities and environmental factors. Historically, the species was found across most of Central and South America, including Argentina, Brazil, Colombia, Costa Rica, and Panama, among others.

However, due to habitat loss and deforestation as a result of human activities, the Bare-throated Tiger-Heron’s range has shrunk significantly. The species has become rare or extinct in some areas, such as in El Salvador and Honduras.

In certain countries where it was once common, such as Costa Rica, the species’ population has also declined significantly, with only a few known breeding sites left in the country. Despite these changes, several conservation measures are being taken to protect the Bare-throated Tiger-Heron, such as creating protected areas and implementing habitat restoration programs.

Research on the ecology of the species, including foraging and nesting habits, is also being carried out to better understand its needs. Additionally, efforts are being made to reduce the impact of human activities, such as deforestation and pollution, on the species’ habitat.

Overall, the systematics history of the Bare-Throated Tiger-Heron is a rich and fascinating topic that continues to be studied by ornithologists and researchers. The geographic variation, subspecies, and related species help to provide valuable insights into the evolutionary history of this species.

With increased research and conservation efforts, there is hope that the Bare-throated Tiger-Heron’s range will expand, and its populations will recover.

Habitat

The Bare-throated Tiger-Heron is primarily a habitat specialist that requires specific environmental conditions to thrive. It is found in lowland tropical forests, mangrove swamps, and freshwater wetlands along the Pacific and Atlantic coasts of Central and South America.

They prefer areas with slow-moving streams and rivers, lagoons, and swamps with aquatic vegetation, but can also be found along coastal areas and in shallow saltwater lagoons. The Bare-throated Tiger-Heron is known to be highly adaptable to changes in its habitat.

Despite the extensive loss of wetlands and forests in Central and South America, the species is still able to survive in a variety of modified habitats, including rice paddies, agricultural fields, and suburban areas.

Movements and Migration

Bare-throated Tiger-Herons are mainly sedentary, meaning that they do not undertake long-distance movements or migrations. However, they may move to new areas in search of food or to establish breeding territories.

Juveniles may also disperse to different areas once they reach sexual maturity.

Breeding movements are common among the species. During the breeding season, male Bare-throated Tiger-Herons establish territories that they defend vigorously against other males.

Females also visit different territories to assess the quality of the potential mates’ territories before selecting their mates. Once the pair-bond is established, they construct a nest together and engage in courtship displays.

Bare-throated Tiger-Herons engage in non-breeding movements as well. During non-breeding seasons, the species may move towards flooded areas where they can find more food.

The movements may be relatively short, and frequently occur within the species’ habitat range. Nonetheless, some individuals may move to other areas in search of better feeding grounds.

The Bare-throated Tiger-Herons may also engage in seasonal movements, where they move between breeding and non-breeding sites. During the breeding season, they may move from their non-breeding sites to establish territories in more appropriate breeding grounds.

Similarly, after the breeding season, they may move back to their non-breeding sites to look for food and to rest. Overall, while the Bare-throated Tiger-Heron is primarily sedentary, the species engages in some kinds of movements to cope with changes in their environment, breeding, and feeding requirements.

The movements have different ranges and lengths, depending on individual needs and tendencies. Understanding their movements is crucial in their conservation and management, as it helps ensure that their habitats are protected and free from disruptions.

Diet and Foraging

Feeding

The Bare-throated Tiger-Heron is a carnivorous bird that feeds on a variety of prey species. They are solitary hunters that employ a sit-and-wait strategy where they remain motionless, waiting for prey to come within striking distance.

Once the prey is close enough, they ambush it, using their long, sharp bill to catch and kill their prey.

Diet

The Bare-throated Tiger-Heron has a varied diet, which includes fish, crustaceans, insects, amphibians, and reptiles. Insects, mainly beetles and caterpillars, form the bulk of their diet.

They also feed on small amphibians such as tadpoles, small fish, and crustaceans such as crayfish. They are known to forage both on the water and along the shoreline, probing the mud with their bills and stomping the ground to flush out potential prey.

Metabolism and Temperature Regulation

Bare-throated Tiger-Herons are poikilothermic animals, meaning their body temperature is regulated by external factors such as the temperature of their environment. Therefore, their metabolism is highly dependent on environment temperature, with higher metabolism at higher temperatures and lower metabolism at lower temperatures.

The species’ foraging behavior, particularly in relation to water bodies, is linked to the regulation of their body temperature. During hot temperatures, individuals often stand in the water to cool off and conserve energy.

Sounds and Vocal Behavior

Vocalization

Bare-throated Tiger-Herons are relatively silent compared to other heron species. They produce a range of vocalizations, ranging from soft “woiks,” “growls,” and “grunts” to harsh woofs and rattles.

The vocalizations are usually heard during courtship displays and territorial disputes between males.

Males frequently engage in mutual calling during the breeding season, with each male responding to the call of its neighbor.

The calls may help to deter other males from approaching the territory or may serve as a way for the males to know the proximity of other males within the range. Furthermore, the Bare-throated Tiger Heron’s calls have also been observed to occur in a chorus with other birds in the same vicinity, most commonly with Anhinga anhinga and Cochlearius cochlearius, in what has been termed as a mixed-species heronry.

The behavior of the mixed-species breeding heronry is known as heterospecific nest guarding and has been suggested to increase the chances of detecting predator attacks. In conclusion, the Bare-throated Tiger-Heron is a diurnal heron that feeds on a variety of prey species, with insects and crustaceans forming the bulk of their diet.

The species employs a sitting and waiting strategy, ambushing prey when they get within striking distance. The bird is relatively silent but produces a range of vocalizations that are heard mainly during courtship displays and territorial disputes.

Their foraging behavior and metabolism are also linked to their environmental temperature, with the species engaging different behaviors to regulate their body temperature.

Behavior

Locomotion

The Bare-throated Tiger-Heron is a versatile bird that can move both on land and in the water. They have thick and muscular legs that help them move through shallow water and thick vegetation.

The bird is adept at navigating around obstacles, jumping, and balancing on branches, and is known for its agility and balance. They are also skilled fliers, with broad wings that help them gain altitude and cover a significant distance in a short time.

Self-Maintenance

Bare-throated Tiger-Herons engage in various self-maintenance activities, such as preening and feather cleaning. Preening helps to keep the feathers in good condition, ensuring that they remain waterproof and insulated.

The species may also bathe in water bodies to clean its feathers, which can improve the quality of their plumage and reduce the parasites that infest their feathers.

Agonistic Behavior

Bare-throated Tiger-Herons are solitary birds that are territorial, particularly during breeding seasons. Males establish their territories and defend them against other males, using a variety of display behaviors, such as wing-flicking and bill-snapping, to discourage rivals.

Females may also engage in displays to protect their eggs and young, using bill-clattering and hissing to scare off predators.

Sexual Behavior

During the breeding season, males engage in courtship displays such as erecting their feathers and performing different wing stretches to attract females. The male and female may also engage in mutual calling, touching bills and feeding each other during breeding activities.

After the pair bond is established, the male will help the female build a nest and incubate the eggs until hatching.

Breeding

The Bare-throated Tiger-Heron breeding season varies depending on its location, climate, and the availability of food. In some regions, the breeding season occurs during the rainy season, while in other regions, it occurs during the dry season.

The breeding season generally lasts between February and August. Bare-throated Tiger-Herons usually breed in monogamous pairs and construct their nests in trees, bushes, or rocky outcrops.

The nest is built by the male and female together, and is made of sticks, twigs, and other materials. The pair will typically lay between two and four eggs, which are incubated for between 27 and 30 days.

After hatching, the young are cared for by both parents. They are fed regurgitated food until they are old enough to leave the nest, which is usually at around six to seven weeks with a lack of flying capacity.

Young birds will remain in the vicinity of the nest for some time after leaving the nest, seeking food and parental care.

Demography and Populations

The Bare-throated Tiger-Heron is suspected to have a stable population globally, with a population size of between 10,000 and 20,000 individuals. Nonetheless, the species occurs in relatively low numbers and is considered rare or threatened in some areas due to habitat loss, deforestation, and wetland degradation.

The species is legally protected in many countries, and efforts are being made to preserve and manage their habitats.

Habitat restoration programs, education programs, and research on the species’ ecology and behavior have proven beneficial in conserving the species.

In conclusion, the Bare-throated Tiger-Heron exhibits myriad behavioral patterns, including versatile movements on land and water, self-maintenance activities such as preening, wing-flicking, and mutual bill-touching during breeding activities. The bird also demonstrates classic territorial and mating behaviors, erecting their feathers, and engaging in mutual calling during breeding season, with the male and female constructing the nest together and laying between two to four eggs.

Nonetheless, the species requires different conservation measures, including habitat restoration programs, legal protection, education programs, and ecosystem research to ensure their populations remain stable and their habitats restored. The Bare-throated Tiger-Heron is a fascinating bird species that exhibits a wide range of behaviors and natural tendencies.

From their feeding habits to their locomotion, self-maintenance, and territorial behavior, the species is an excellent example of nature’s diversity and adaptability. With various conservation measures, including habitat restoration programs, legal protection, education programs, and ecosystem research, the Bare-throated Tiger-Heron’s populations remain stable, ensuring that these birds remain an essential part of Central and South America’s biodiversity.

Understanding the Bare-throated Tiger-Heron’s ecology, behavior, and habitat requirements can provide valuable insights into the conservation and management of other bird species and their ecosystems.

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