Kolkata has more deep cornices, ornate mouldings and boxed window heads than any other Indian city. That changes the job: here the problem is usually a sheltered corner or a cavity rather than an open parapet, and the enemy of an installation is damp rather than sun.
At a Glance
Most Indian cities are a bird control problem of flat parapets and balcony openings. Kolkata is not. Its older buildings — the North Kolkata houses, the Dalhousie and Park Street blocks, the institutional buildings — carry deep decorative cornices, heavy string courses, boxed shuttered window heads and generous chajjas.
Every one of those is a corner rather than a shelf: a horizontal surface with a wall behind it and an overhang above. Deep, dry and sheltered on two sides is a nest site, not a perch — which means a resident pair returning for years rather than passing visitors, and it changes both the urgency and the method.
Where the row actually goes
On a plain ledge or parapet you set the row toward the outer edge, because that is where birds land. On a Kolkata cornice they land there and then walk back into the corner, because the corner is the sheltered part.
A row fitted along the outer edge alone leaves the good part open and the birds simply step over it. The row belongs hard against the wall junction, with a second toward the outer edge on anything deeper than about 200 mm. Detail on cornices and beam junctions.
| Condition | What it attacks | What to specify |
|---|---|---|
| High humidity, most of the year | Adhesive fixings, and anything sealed into a damp cavity | Mechanical fixing; never close a cavity that has not dried |
| Heavy monsoon, June to September | Nothing bonds to wet masonry | Fit November to February |
| Cyclone-season wind | Exposed edge and roof runs | Mechanical fixing on all exposed edges |
| Old, soft lime plaster | Adhesive on a friable surface, and the plaster itself | Repair before fitting — nesting material holds water against the substrate and causes spalling |
| Airborne grime | Adhesion — the base bonds to the deposit | Clean and dry thoroughly first |
The lime plaster point is worth taking seriously on older buildings. Nesting material packed into a decorative profile holds moisture against the wall, and in Kolkata's humidity that causes spalling and loosens the moulding from the structure. On buildings of that age, pieces do eventually come down. Fitting a deterrent to already-failing plaster attaches it to material that is on its way off the wall — repair first.
Kolkata is one of the few Indian cities where a bird control brief has to account for crows seriously, not just pigeons. They behave differently and it affects the specification:
Practically: use the wider, taller profile on open high runs, and fix mechanically anywhere crows are the main species.
| Building type | Where | Usual job |
|---|---|---|
| Colonial and institutional | Dalhousie, Park Street, Esplanade, Chowringhee | Deep cornices, mouldings, portico columns |
| Old North Kolkata houses | Shyambazar, Bagbazar, Shobhabazar | Boxed window heads, cavities, courtyard ledges |
| New towers | Salt Lake, Rajarhat, New Town, EM Bypass | Balconies, parapets, terrace tanks |
| Markets and commercial | Burrabazar, Gariahat, New Market | Signage cavities, canopies, shopfront heads |
| Industrial | Howrah, Dankuni, Taratala, Kalyani | Warehouse netting, trusses, cable trays |
Each of these covers ordering, delivery and what is specific to that product in Kolkata. The full specification for any of them is on the product page it links out to.
Almost certainly because the row is on the outer edge and they are stepping over it into the sheltered corner behind. On a cornice the row belongs hard against the wall junction.
November to February. Humidity and monsoon between them mean nothing bonds reliably for much of the year, and cavities should never be closed while they are damp.
Repair first. Nesting material holds water against the wall and is part of why it is spalling, and anything fixed to failing plaster is attached to material that is already coming off.
Yes. Crows are heavier and will stand over a shallow row, so use the taller, wider profile on open runs. They also pull at loose ends, so fix mechanically.
Barely. The polycarbonate is transparent, so there is no colour to sit against the plaster, and set back from the front edge it is not picked out from street level.
That is a cavity rather than a surface. Spikes on the outside will not help — the opening has to be closed, and not while there are chicks inside.
Yes, including Dankuni, Taratala and Kalyani for warehouse and truss work.
A shot showing the corner where the band meets the wall, plus the depth and the total run, is enough for a quote. If there is nesting material in that corner, say so — on Kolkata's older buildings that changes the priority.