With a fast-changing landscape and loss of tree cover for infrastructure development, Goa’s corvine ecology is taking a beating for sure
Dr Manoj Sumati R Borkar
The Goa state Biodiversity Board (GSBB) by asking its 67 Biodiversity Management Committees across the state to note the visibility of the House Crow has once again brought into focus the anecdotal question raised by Akbar on the number of crows living in Delhi. In equal measure the witty reply given by his famous courtier Birbal, that there lived exactly 6387 crows in Delhi, and further that any variation in this count was attributable to the corvine residents visiting their relatives outside Delhi and vice versa best illustrates the limitations of such eccentric curiosity.
Why at all was the emperor interested in the bird count at that point of time in history is a matter of speculation.
The genesis of this apparently queer quest to enumerate the Corvine population of the state may be traced back to the Chief Minister’s written reply to a Legislative Assembly Question in 2017 that there was no study conducted to draw any confident conclusions on crow population trends in Goa, and that the bird was under Schedule V of the Indian Wildlife Protection Act 1972, their count would be high with no conservation threat.
The recent attempt by the GSBB to gather information on the visibility of what is presumed to be a common bird is a welcome step towards addressing a critical gap in our understanding. Uncompromisingly, there should be a scientific enumeration done at the scavenging , roosting and nesting sites of the Crow across the state for a confident count. But why would anyone be interested in knowing the number of House Crows in Goa, and what if they are actually declining, given the notoriety of their vermin status.
It is noteworthy that the UK based Centre for Agriculture and Bioscience International (CABI), includes the House Crow Corvus splendens in its Invasive Species Compendium, besides the bird appears in the Invasive Species Specialist Group’s (IUCN) ‘Alert List’ and is a regulated pest species at least in Australia!
As for the four reported subspecies of the House Crow in the Indian subcontinent, there is confusion regarding the affiliation of the Goan Crow.
Conventionally though in most bird lists, the Goan Crow is classified as Corvus splendens splendens; the neighbouring state of Kerala has presence of Corvus splendens protegatus, a Sri Lankan subspecies. Given the proximity of the two Indian states, flight prowess of the bird, and that the bird can effectively ride on boats to disperse along the coastline increase possibility of occurrence of both the subspecies in Goa.
However, to ascertain the subspecies of the crow in Goa, a meticulous investigation of their genome is necessary. This will require hand holding between a classical zoologist and the molecular biologist, with funding support from the State Biodiversity Board; if the latter is genuinely interested in understanding the status of the bird here.
In a rapidly urbanizing coastal state like Goa; with fast changing landscape dominated by high-rise structures, acute demographic pressure and increased per capita garbage, and loss of tree cover for infrastructure development, the corvine ecology takes a beating for sure. The implication therefore is that even the ubiquitous crow will not be spared from this habitat alteration and loss, despite its resilience and desperate attempt to adapt.
Exactly 18 years ago along with 3 of my students at the Biodiversity Research Cell of Carmel College for Women, I examined the impact of urbanization on the nest architecture of the Indian House Crow in Goa through a detailed study lasting for 6 months.
The study involved analysis of numerous in situ and 75 collected nests of the bird along the rural-urban gradient in 3 talukas of Goa. The findings were indeed interesting and revealing. The rural crow was clearly different from the urban counterpart in its nesting behaviour, choice of nesting material and the nest construct. The city nests were compact and had a preferential and often exclusive incorporation of metal wires in place of twigs used by the rural crows. To be precise, the number of metal wires used in the nest construction varied from 8 to 335 along the rural-urban gradient.
That the metal reinforced nests offered any advantage to the urban population of the House Crow was tested by controlled thermodynamic study of the nests exposed to sun, to compare heat gain and loss by the two types of nests.
Results clearly indicated urban metal nests had better aeration and insulation; which reduced the time parents spent for incubating the eggs and allowed more time for foraging. The house crow is very adaptable, a cunning opportunist, and demonstrates learning ability and use of tools; with clear advantage in this tug of war for survival against changing environment. Its obligatory association with humans flag some critical issues. This bird is a scavenger, commensal, pest, carrier of parasites and pathogens of poultry with chances of human transmission in certain cases. Crow droppings may deface facades of apartments and monuments causing civic embarrassment, pose public health risk as it contains a fungal pathogen that can affect humans with lowered immunity, besides viral particles that can cause ‘New castle disease’ in pigeons and poultry causing huge economic losses.
Its socio-cultural relevance in India is immense. For Hindus, posthumous rituals cannot be complete without the House Crow. If the crow population crashes; like the reformist Parsi Irani Zoroastrians who given the decline in population of the vultures that devoured the corpses, have opted for alternative of burial and cremation, the Hindus may have to look for an alternative avian beneficiary for their customary Pind daan!
