Ardeola grayii (Sykes, 1832)

Scientific Name and General Morphology

Indian pond herons, with the scientific name Ardeola grayii (Sykes, 1832), are stocky herons with short necks, short thick bills, and buff-brown backs.

Breeding Plumage Traits

During summer, adult individuals develop long neck feathers.

Flight Appearance

When they take flight, their appearance changes dramatically: their dull non-flight plumage is replaced by prominent bright white on their wings that stands out clearly.

Similar Species Comparison

They are very similar to squacco herons (Ardeola ralloides), but have darker backs than this species.

Range Replacement

To the east of the Indian pond heron’s range, the species is replaced by the Chinese pond heron (Ardeola bacchus).

Unusual Leg Coloration

During the breeding season, some individuals have been recorded with red legs.

Hypothesis for Red Legs

The number of observed individuals with this trait does not indicate that it is a normal breeding-season change for adults, and some researchers have suggested it may be the result of genetic variants.

Plumage Aberrations

Erythristic plumage has also been noted in this species.

Proposed Subspecies

A subspecies named phillipsi has been proposed for populations found in the Maldives, but this proposed classification has not received much acceptance.

Superspecies Complex

This species forms a superspecies with the closely related Chinese pond heron, Javan pond heron, and Madagascar pond heron.

Vocalizations

Indian pond herons are usually silent, but may produce a harsh croak as an alarm call when they are flushed or near their nests.

Taxonomic Naming History

This bird was first formally described by Colonel W. H. Sykes in 1832, and its scientific name was chosen to honor John Edward Gray.

Karyology

Karyology studies have found that pond herons of this species have 68 chromosomes (2N).

Regional Commonness

In terms of behaviour and ecology, Indian pond herons are very common in India.

Foraging Group Dynamics

They are usually solitary foragers, but multiple individuals may sometimes feed in close proximity during the dry season, when small wetlands have a high concentration of prey.

Breeding and Foraging Locations

They are semi-colonial breeders, and may also forage at garbage heaps.

Dry Season Foraging Habitats

During dry seasons, they sometimes forage on well-watered lawns, and even in dry grassland.

Foraging Tolerance to Disturbance

While foraging, they allow people and other potential threats to approach closely, and only flush away when the threat is near.

Roosting Behavior

They sometimes form communal roosts, often in avenue trees above busy urban areas.

General Feeding Habitat

The feeding habitat of the Indian pond heron is marshy wetlands.

Foraging on Floating Vegetation

They usually feed along the edges of ponds, but make extensive use of floating vegetation such as water hyacinth to reach deeper water.

Aquatic Foraging Behaviors

On occasion, they may also swim on the water surface, or fish from the air before landing in deeper water.

Prey Capture in Flight

They have been observed flying to capture fish that are leaping out of the water.

Prey Herding Behavior

Sometimes, they fly low over the water to drive frogs and fish toward the shore before settling along the shoreline.

Baiting Behavior

They have also been recorded picking up crumbs of bread and dropping them onto the water surface to bait fish.

Wetland Diet

The primary food of Indian pond herons includes crustaceans, aquatic insects, fish, tadpoles, and sometimes leeches of the genus Herpobdelloides.

Non-Wetland Diet

Outside of wetlands, these herons feed on insects including crickets, dragonflies, and bees, fish (one study in Chandigarh noted that Barilius fish are an important food item here), and amphibians.