AnimaliaHighest rank in taxonomy. Groups all life into domains: Animalia, Plantae, Fungi, etc.IUCN LCInternational Union for Conservation of Nature — the world authority on species extinction risk, using standardized criteria. — Least Concern — widespread and abundant; not at immediate risk of extinction.In ProgressCurrent stage of this record in the editorial review workflow. Recent Sighting
Nyctanassa violacea
Yellow-crowned Night-Heron
(Linnaeus, 1758)
Detailed Texts Multi-lang
A stocky, medium-sized heron with a distinctive and boldly patterned head. Adults display a soft blue-grey body plumage with dark streaks on the back, contrasted by a black head featuring a stark creamy-white to pale yellow crown stripe and a prominent white patch below the eye. They possess a remarkably thick, heavy, jet-black bill and large, piercing orange to deep red eyes. The legs are relatively long and greenish-yellow, turning bright coral-pink during courtship. In flight, their feet and a small portion of the tarsi extend well past the tail tip.
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Julia Trouin
TaxonomyBiological classification ranks placing this species within the tree of life, from Kingdom down to Genus.
PhylumRank below Kingdom. Groups organisms sharing a fundamental body plan (e.g., Chordata = vertebrates and some invertebrates).Chordata
ClassRank below Phylum. Subdivides by structural traits (e.g., Mammalia, Aves, Reptilia, Insecta).Aves
OrderRank below Class. Groups related families sharing common ancestry (e.g., Carnivora, Primates).Pelecaniformes
FamilyRank below Order. Groups closely related genera (e.g., Felidae = cats, Canidae = dogs).Ardeidae
GenusRank just above Species. The first word in the two-part binomial scientific name.Nyctanassa
Taxonomic AuthorityThe scientist who first formally described and published this species, followed by the year of publication.(Linnaeus, 1758)
Record Completeness
95%Coming soon
Ecology & StatusHow this species lives: habitat preferences, diet, behavior, population status, and role in its ecosystem.
OriginWhether the species is native (evolved here), endemic (found only here), or introduced by human activity.
Native
Population TrendDirection of change in population size over time: increasing, stable, decreasing, or unknown.
Stable
Breeding SeasonTime of year when this species typically reproduces or flowers.
Year Round
Trophic RolePosition in the food chain: producer, herbivore, carnivore, omnivore, decomposer, or parasite.
Carnivore
Recent SightingsWhether this species has been observed in the wild in Costa Rica within recent years.
Yes
Habitat SummaryOverview of the specific ecosystems and environments where this species is found in Costa Rica. Multi-lang
Primarily associates with coastal brackish and marine ecosystems, with a strict affinity for coastal mangrove swamps, tidal mudflats, salt marshes, and forested estuarine edges. While they occasionally wander inland to freshwater swamps and wet bottomland forests, they remain heavily concentrated near coastal zones where crustacean prey is abundant.BehaviourDaily activity patterns, movement, territory use, foraging style, and seasonal behavioral changes. Multi-lang
A patient, stalk-and-wait predator that moves with deliberate, slow-motion steps through mangrove roots or along mudflat edges. Upon spotting a crab, it freezes into a rigid crouch before delivering a lightning-fast forward strike. It displays strong site fidelity, maintaining precise feeding territories that it defends against conspecifics.Social ActivitySocial structure: whether the species is solitary, paired, or colonial; hierarchy and communication. Multi-lang
Distinctly less colonial and more solitary than most other heron species. They typically forage alone and maintain solitary feeding strategies during the day. However, they nest either in isolated single pairs or in small, loose, widely spaced clusters within multi-species heronries to minimize direct competition.Feeding GuildWhat the species eats, how it forages or hunts, and its role as a consumer in the food web. Multi-lang
Carnivore (crustaceanovore; high-specialization predator focused almost exclusively on brachyuran crabs and freshwater decapods).Trophic Chain DetailsSpecific interactions in local food webs: prey species, predators, competitors, and scavengers. Multi-lang
Serves as an apex microcarnivore in coastal intertidal communities. Its specialized diet is overwhelmingly dominated by crustaceans (fiddler crabs, marsh crabs, land crabs, and blue crabs), supplemented by small fish, marine worms, and snails. Eggs and chicks are preyed upon by raccoons, crows, and gulls, while adults are occasionally taken by large raptors or alligators.Reproductive BehaviourMating strategies, courtship displays, nesting or spawning behavior, and parental care. Multi-lang
Forms socially monogamous pairs. They construct a sturdy, relatively flat platform nest composed of thick sticks, lined with finer twigs, roots, and dry moss. Nests are built in tree forks, frequently in red or black mangroves, or low coastal shrubs overhanging the water. The female lays 2 to 4 pale blue-green, unspotted eggs. Both parents actively share incubation duties for 21 to 25 days and cooperatively feed the young via regurgitation.Physical Measures
Length (cm)
55.0 - 70.0 cm
Weight (Grams)
600 g - 850 g
Offspring per cycleTypical number of young (live births, eggs, or seeds) produced by one adult in a single reproductive event or breeding season.2 - 4
Sexual DimorphismObservable physical differences between males and females of the same species (e.g., size, coloration, features).No
Lifespan
Sexual MaturityAge at which the individual becomes capable of reproducing for the first time.
2 - 3 Years
Gestation / IncubationDuration from fertilization to birth (mammals) or to hatching (egg-laying species).
21 - 25
Lifespan EstimatedExpected duration of life from birth to natural death under wild conditions.
Males8 - 12 Years
Females8 - 12 Years
Evolutionary AdaptationsInherited traits and behaviors that improve the species' survival and reproduction in its specific environment. Multi-lang
The exceptionally stout, heavy, and chisel-like bill is a specialized trophic adaptation designed specifically to exert massive crushing force, easily cracking open the hard exoskeletons of crabs and crayfish.
Possesses large eyes with a highly developed retina rich in rod cells, granting superior visual acuity under low-light conditions to successfully hunt nocturnal crabs during low tides at night.
Main ThreatsDocumented pressures reducing the population: habitat loss, hunting, disease, climate change, and invasive species. Multi-lang
Vulnerable to coastal habitat destruction from infrastructure development, logging of mangroves, and water pollution via oil spills or chemical pesticide runoff that decimates regional crustacean populations.
Interesting FactsSurprising or notable facts that highlight what makes this species unique or ecologically important. Multi-lang
They are meticulous diners; when a Yellow-crowned Night-Heron catches a large crab, it does not swallow it whole. Instead, it systematically shakes or violently hammers the prey against rocks to break off the defensive pincers and legs before consuming the body.
While classified as a 'night-heron', its activity patterns are actually governed more by the moon and ocean tides than by the sun. If low tide occurs during midday, they will forage extensively under bright sunlight to exploit exposed mudflats.