The black-crowned night heron (Nycticorax nycticorax) is a medium-sized heron found across much of the world. In India, it is a widespread resident bird found in a variety of wetland habitats. However, its populations have declined in recent decades leading some to question whether it is becoming rare in parts of its Indian range.
In this article, we will examine the evidence on the abundance and distribution of the black-crowned night heron in India. Key questions include:
- What is the global and Indian range of the black-crowned night heron?
- What are the population sizes and trends of this species in India?
- Is it endangered or threatened in India?
- In which parts of India is it most common or rare?
- What are the main threats facing this species in India?
Analysis of up-to-date data on this species can help determine whether the black-crowned night heron deserves conservation attention in India and shed light on its current rarity status.
Global and Indian Range
The black-crowned night heron has an extremely widespread global distribution across most of North America, Europe, Africa, Asia, Australia and parts of South America. Its total global population is estimated at 3.1-3.2 million mature individuals.
In India, it is found across much of the country from the Himalayas to the southern tip of the subcontinent. Its recorded range includes:
- Northern India from Jammu & Kashmir to Assam
- Eastern India from West Bengal to Arunachal Pradesh
- Central India including Madhya Pradesh, Chhattisgarh and Odisha
- Western India across Rajasthan, Gujarat and Maharashtra
- Southern India encompassing Karnataka, Kerala, Tamil Nadu and Andhra Pradesh
The black-crowned night heron occupies a variety of wetland habitats across its Indian range including marshes, ponds, lakes, rivers, flooded fields and mangroves. It is found from sea level up to elevations of 2500 m in the Himalayas.
This wide distribution and habitat use indicates that the black-crowned night heron has an extensive range across India and is not restricted to small isolated pockets.
Population Sizes and Trends in India
It is difficult to accurately survey population numbers of the black-crowned night heron across its vast Indian range. However, some estimates can shed light on its abundance:
- Its global population is estimated at 3.1-3.2 million mature individuals. What proportion of this is found in India is unclear.
- Important Bird Areas (IBAs) that are internationally recognized for supporting significant populations of key bird species have recorded up to 2500 black-crowned night herons at some sites.
- In surveys of wetlands in northern India, densities up to 16 birds per km2 have been recorded.
- Single wetlands may support hundreds of these herons, indicating concentrated populations at favorable sites.
These numbers hint at a large cumulative population across India, albeit scattered across many small subpopulations. However, most data indicates that populations are declining:
- It is classified as “Decreasing” on the IUCN Red List of Threatened Species.
- Monitoring has shown declines in Indian IBAs and decreases in density in parts of its range.
- Breeding populations have disappeared from some historical breeding sites.
- Wetland habitat loss is likely causing population reductions.
So while still widespread, the black-crowned night heron appears to be declining in India, though not to the point of endangerment.
Conservation Status in India
The black-crowned night heron is classified as “Least Concern” on the IUCN Red List both globally and in India. Some other assessments of its conservation status include:
- It is not listed as Threatened on Schedule I of the Indian Wildlife Protection Act 1972.
- Categorized as “Common” in the Bombay Natural History Society’s review of the status of Indian birds.
- Not currently flagged as requiring special conservation actions under India’s National Wildlife Action Plan.
These assessments indicate that while the black-crowned night heron has suffered some declines in India, they have not yet been severe enough to warrant listing it as nationally Threatened or Endangered. The species is still common and widespread in suitable habitat across most of its range. Targeted local conservation efforts may be needed at key sites but nationwide measures are likely not required at this point.
Distribution Across India
Looking more closely at the black-crowned night heron’s abundance across different parts of India can reveal where it remains most common versus where declines may be causing it to become rare:
- It remains “fairly common” across its range in the Himalayan region from Jammu & Kashmir to Arunachal Pradesh.
- Still reported to be “common” in the wetlands of Assam, West Bengal, Odisha and Chhattisgarh.
- Considered a “common resident” in Andhra Pradesh and Telangana.
- Reported as “uncommon” now in parts of the Western Ghats and Northeast India.
- Has “declined sharply” in recent decades in Kerala.
- Disappeared from many historical nesting sites in Bihar.
This indicates that while still widespread, the black-crowned night heron may be becoming locally rare or uncommon in some parts of India, particularly the southwestern coastal belt and northeast. Targeted surveys are needed to better quantify distribution changes. But it remains common across much of northern, central and eastern India.
Threats and Causes of Decline in India
What are the major threats contributing to the black-crowned night heron’s population declines in India?
- Wetland habitat loss and degradation due to drainage, land conversion, pollution and human disturbance.
- Overexploitation of wetland fish stocks, reducing food availability.
- Increasingly erratic monsoons and droughts due to climate change.
- Hunting and egg collection at some sites.
- Predation by feral cats and dogs around breeding colonies.
Wetland conservation efforts, pollution control, sustainable fisheries management, public awareness campaigns, and active protection of key breeding sites will be needed to stabilize and restore black-crowned night heron populations in India.
Conclusion
The black-crowned night heron has a widespread distribution across India but has suffered population declines in recent decades leading to local rarity and disappearance from some areas, especially in the south and northeast. However, it remains common and resilient across much of its northern, central and eastern Indian range and is not currently considered Threatened or Endangered nationally. Targeted conservation efforts at key wetlands can help halt declines before more severe threats emerge. Careful monitoring of populations and wetland health will be crucial going forward. This iconic wetland bird highlights the importance of protecting India’s aquatic ecosystems and their services to both wildlife and people.