Avian Diversity In Lokhandwala Mangroves Biology Essay


ABSTRACT: Mangroves are areas of rich diversity. It also houses several species of migratory and resident birds and therefore, also adds up to a rich avian diversity. Researchers have recorded about 135 species of birds in the Mahim creek mangroves, an area close to my field of study. Some of the species recorded consisted of distant migrants, resident bird species, local migrants and resident migrants. Similarly, the Lokhandwala mangrove is home to several such species of birds and this contributes to the urban avian diversity. The Lokhandwala mangroves attract several ardent bird watchers each year. However, the current anthropogenic activities are constantly causing pressure on these natural habitats. The major reason causing deleterious effects on mangroves is the transit dumping station belonging to the Brihanmumbai Municipal Corporation (BMC). The dumping station was started in the year ___________ and thereafter enormous quantities of solid wastes have been dumped in the heart of this ecologically important area. Also, there have been other anthropogenic activities in the Lokhandwala Lake present along this area. Activities like washing, bathing and religious rituals are carried out on regular basis by slumdwellers and migrant populations in this lake. The lake also is an important part of this area and attracts many migratory aquatic birds. My focus for this essay is on the avian diversity, as the growing anthropogenic activities have altered the entire ecosystem and I assume the species diversity has also been altered. My study has shown that the feeding habits of some species have also been changed where these species have now become more dependent on the incoming garbage to suffice their daily nutrient requirements. Also the study highlights on the reduced probability of sitings of some species of birds and this may be contributed by the increased activities of dumping causing disturbance to the natural habitats of birds.

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Research Question: What are the effects of anthropogenic activities and the increase of invasive species of birds on the native avian biodiversity of the Lokhandwala Mangroves?

Rationale: Lokhandwala-Versova mangroves one of the oldest in Mumbai are under constant threat of being wiped off. This is primarily due to the anthropogenic activities in the area especially the transit point of the BMC waste ground which is affecting the avian diversity of the area adversely and also the domestic activities carried out around the lake. Recently, the lake was also used for immersion of Ganapathi Idols during the Ganesh festival. The mangroves are life savers and should be protected. The Lokhandwala-Versova mangroves played a major role in absorbing huge amounts of water during the 2005 Mumbai floods. This was why the Lokhandwala area wasn't affected as badly as the other adjoining areas. However, recently the Brihan Mumbai municipal corporation (BMC), have now started dumping waste in the heart of the Lokhandwala- Versova mangrove site. This seems to be affecting the avian diversity adversely which lies in that area.

Introduction: Mangroves are trees and shrubs that grow in saline coastal habitats in the tropics and subtropics . Mangroves form a characteristic saline woodland or shrub land habitat called mangrove swamp or mangrove forest. [1] Mangroves are tropical and subtropical swampy forests comprising of many unrelated genera that share the common ability to grow in saline, coastal habitat and interfaces where land and sea meet.] These systems usually act as a buffer ecotonal zone between land and oceans and are capable of tolerating violent seasonal winds. They play a very important role in maintaining high productivity and rich biotic diversity of coastal waters and are of interest from the economic, scientific as well as wildlife management point of view.

The evergreen, broad-leaved trees of the mangrove forests are highly adapted to the stresses of flooding and salinity. The adaptations include specialized root-cell membranes which prevent or reduce the entry of salts; elaborate tube-like breathing structures called pneumatophores which grow vertically upwards from the roots and viviparous seedlings that germinate on the parent tree and thereby decrease their mortality rates in the unfavorable environment.

Where do Mangroves occur?

Since mangroves are distributed in the tropical and sub tropical regions where temperatures and humidity are high, these ecosystems are absent in cooler areas like Europe, arctic and Antarctic. Asia has recorded the maximum luxuriant patches of rainforest, India and Bangladesh being a few of the most important areas. The Sunderbans which are distributed here comprise of large biodiversity and also covers a large area of the East coast of Indian and Bangladesh.

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7% of the world's total mangroves are located in India which covers a total area of about 6,740 sq. km. Out of this 80% of the mangroves are distributed along the East coast comprising of the Sunderbans and Bhitarkanika and the islands of Andaman and Nicobar in the South of India.

The west coast comprises of the remaining 20% of the mangroves which are scattered between Kutch and Kerala. The reason for such a restricted mangrove cover is the peculiar coastal structure and the nature of estuaries formed by the relatively small and non-perennial rivers except Narmada and Tapi.


Zonation in Mangroves

Mangroves along a tropical bay characteristically show Zonation. In India this Zonation may be very distinctive (east coast of India) or merging (west coast of India). A very broad and general distinction would be:-

1. Proximal Zone (Front mangroves)

This zone is towards water front, subject to regular tidal effect where intensity of soil accumulation and inundation is a continuous process. The mangrove species in this zone are specially adapted with stilt roots, prop roots for stability and anchorage.

2. Middle Zones (Mid mangroves)

Above the front mangroves the species develop a strong hold fast in the form of knee roots or bent roots as a special adoption for supporting the erect bole.

3. Distal Zone (Back mangroves)

Towards island area this species of mangroves produce buttresses. Generally the salinity is on lower side in this zone occurring towards hill sides where run off of fresh water is for a prolonged period. The duration of tidal submersion is low in this zone compared to front mangroves.

However, the Zonation in mangroves is more complex and varies from place to place. Every species has its own level of salinity tolerance. Estuaries on east coast show distinct Zonation as compared to that of the west coast. The high salinity range on the east coast estuaries may be the principal reason for distinct Zonation there. The range and force of tidal action also play a determinant role in creation and maintenance of zones as distribution of seeds or propagules is influenced by tidal action. Also, tides do influence the salinity in an estuary. [2] 

Distribution of Mangroves of the Mumbai Metropolitan region

Distribution of mangroves as per Survey of India Topsheets (1968): The area of about 350 sq. km i.e. 7% of the total measured area of the Mumbai Metropolitan Region of 4236 sq. km is mud-flat - which is coastal wet land. In these Topsheets the mangroves are not separately identified.

Distribution of mangroves in 1991: An area of about 95.43 sq. km i.e. 2.25% of the area of the Mumbai Metropolitan Region was under mangroves in 1991. Mangrove categories of sparse and dense were identified using the interpretations of satellite images.

Distribution of mangroves in 1997: Deforestation was stopped and programs to protect the mangroves and promote their growth were undertaken in the period between 1991 and 1997 leading to an increase in the area under mangroves.

Methods for data collection: The Lokhandwala Mangrove area has a fresh water body called the Lokhandwala lake. There are several species of birds sited here. For understanding the biodiversity of the Lokhandwala Mangroves and its adjoining lake, birds were directly identified using binoculars. The mangrove area being a harsh ecosystem, counting birds using different bird survey methods was not possible. Hence, with the help of an ornithologist I was able to identify species of birds that were seen in the mangroves, the lake and the transit dumping ground. The area thus has varied habitats for feeding and nesting of birds.


The 2005 rains in Mumbai and the deluge that followed manifested the consequence of tampering with the ecology of fragile ecosystems like mangroves. If only Mumbai's Mithi river and Mahim creek mangroves wouldn't have been destroyed by the builders fewer number of people would have died and property damage would have been considerably less as mangroves do have water retentive properties.

Builders, city planners, even some of our best known architects in the race for development and cash have been waging a quiet (sometimes not so quiet) war against mangroves and wetlands, not just in Mumbai but across the country. This battle was fought and won by the builders who almost closed out the mouth of the Mithi river and ended up reclaiming 700 acres of mangroves swamps in the Mahim creek which is the only outlet of the river which flows into the Arabian sea.

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Millions of Mumbaikars pass these mangroves some of them wondering what these dirty muddy weeds growing pointlessly along the shoreline are and the others not bothering to have a look at them. Mangroves are plucky survivors-They represent the spirit of Mumbai. Very few people understand the importance of these mangroves that they act as the buffer between land and sea.

Going by the stats mangrove diversity in Mumbai has decreased considerably over the last decade. Mumbai had over 37 sq. km of mangrove area in the 90's. Areas of the Thane creek, mahim, Versova, gorai were covered with huge chunks of mangroves. The decade just gone (2000-2010) by has seen a severe dip. Mumbai has lost perhaps 40 percent of what existed in the last decade or so largely due to reclamation of housing, slums, garbage dumps and sewage treatment.

Lakhs of Mumbai residents had to endure floods during the recent rains largely due to the builders obstinate war against the mangrove swamps in Mumbai. Following the path of the promoters of bandra kurla complex, they ruthlessly replaced these mangroves with buildings thus earning millions worth through real estate all under the safe roof of 'development'.

A vast patch of the mangrove ecosystem is found in areas of Versova, Seven Bungalows, Yari Road and Lokhandwala Back Road.

The coastal regulatory zone (CRZ) Notification of 1991, was given under the environment protection act 1986. Under the CRZ notification, the coastal areas were divided into four zones as per their importance for conservation and the degree of disturbance of these sensitive areas. The mangroves are classified under CRZ 1 which consists of all those coastal areas with fragile ecosystems and any disturbance caused by any anthropogenic activities in this area is completely prohibited. It was environmental activist Rishi Agarwal who anticipated that the mangroves were under threat from garbage by who other than the BMC. It was cleat to any careful observer that garbage was spilling over into the mangroves from the transit garbage dump for K/west ward due to the proximity of the two.

A recent study shows that the Lokhandwala mangroves are under constant threat from developers and the BMC dumping ground. However local action groups like the Save Andheri Versova Environment - SAVE group and Lokhandwala environment action group - LEAG are playing an important role in saving these mangroves and areas along it and also the bio-diversity of this area. The area has now become a site for birdwatchers and several migratory birds have been recorded in the past. However, the increasing anthropogenic activities may lead to the decline of these migratory populations and also of the native species.

Anthropogenic factors causing the deterioration of the Lokhandwala mangrove ecosystem:

The main anthropogenic factor that has lead to a change and deterioration of the ecosystem is the presence of the BMC transitional garbage landfill site in the heart of the mangroves.

Now, upon entering the mangroves more garbage was to be seen mainly because of the human activities inside this unsecured zone and also because birds like egrets, stray dogs and crows tend to pick up garbage, pilfer it for food and then drop it when they travel over these areas. This kind of garbage inside the mangroves disrupts the flow of water leading to a severely water-logged condition that is detrimental to the working of the ecosystem. The garbage just does not seem to stop! Even in the remote areas that are not very likely to have any human interference have tons of plastics and other garbage just strewn about.

From inside, the core mangrove zone a terrible site is visible - that of piles of garbage!

There is a small mandir near the lake that is used by the slum-dwellers of the area. Because of this garlands and other objects used in worship can be seen in the water. This leads to an increase in the metal contents of the water Ganpati immersions are also carried out in the water. The idols do not dissolve for a number of weeks and kill all the fauna in the water. Recent scientific analysis have shown that the concentration of lead and other metals also increased because of these immersions. There is also the problem of migrant workers that set up huts nearby to the water body and then use it for washing and bathing purposes. This leads to the accumulation of nitrates and phosphates in the water body leading to its eutrophication. All these factors have been contributing to the decline of the once - thriving ecosystem and therefore the birds thriving in this ecosystem.

Rishi agarwal, an environmental activist and co-founder of 'Mangrove Society of India' along with renowned bird watcher Sunjoy Monga and other colleagues carried out a bird watching session on 1st Feb 2009 at the Lokhandwala mangrove site and recorded the following species during the morning and evening session.



Spot-billed duck

Common Moorhen

Bronze-winged Jacana

Spotted Sandpiper

Green Sandpiper

Yellow Bittern

Cattle egret

At least six Spot-billed Duck

Little egret

Pond Heron

Little Cormorant

Purple Heron

Little Grebe

Brahminy Kite

Black Kite


Steppe Eagle - towards landfill site

White-throated Kingfisher

Common Kingfisher

Alexandrine Parakeet

Ring-necked Parakeet

Common Myna

House Sparrow

Large-billed Crow

House Crow

Red-whiskered Bulbul

Red-vented Bulbul

Blyth's Reed Warbler

Greenish Warbler

Purple-rumped Sunbird

Greater Coucal (Crow-pheasant)


Golden Oriole

White-throated Fantail (calling)

Ashy Prinia

Long-tailed Shrike

Based on this secondary data, a study was undertaken by me in two phases across a three day period to record the birds and then compare these sightings in and around the Lokhandwala mangroves. The first phase of recording these birds was undertaken in November 2009. The second phase was carried out a month later in December 2009 and both the recordings were compared with each other and also with the recordings carried out in February 2009.

Observation: It was observed that the birds recorded in February could not be spotted in November. However, a few species like…. Were spotted in January which matched the recordings of February 2009.

Day 1

Day 2

Day 3

White breasted kingfisher

White breasted kingfisher

White breasted kingfisher

White eared bulbul

White eared bulbul


Cattle egret


Cattle egret

Indian pond heron

Indian pond heron

Indian pond heron



Bar-headed goose

Purple-rumped sunbird

Purple-rumped sunbird

Purple-rumped sunbird




Little cormorant


Little cormorant




Birds identified:

White breasted kingfisher: A brilliant turquoise-blue kingfisher with deep chocolate-brown head, neck and underparts, a conspicuous white 'shirt front' and long, heavy, pointed red bill. A white wing-patch prominent in flight.

Distribution: Plains and lower hills throughout the Indian Union; Bangladesh; Pakistan; sri Lanka; Myanmar. Four races based on size and coloration differences.

Habits: the most familiar of our kingfishers and also the least dependent upon water. Seen at Ponds, puddles, rain filled ditches, inundated paddy fields and near the shore, but also in light forest at considerable distances from water.

White eared bulbul - Pycnonotus leucotis

Field characters - An earth-brown bulbul with black head, glistening white cheeks, and sulphur yellow under root of tail.

Distribution - the Himalayas, Pakistan, western and central India.

Habits -Tame and confiding. It will eat food scraps. It also eats insects and flower nectar.

Cattle egret - Bubulcus ibis

Field characters: in non-breeding pure white plumage distinguished from the little egret by color of bill which is yellow not black.

Distribution: Throughout the Indian union; Bangladesh; Pakistan; Sri Lanka; Myanmar.

Food: chiefly grasshoppers, bluebottle flies, cicadas and other insects: also frogs, lizards, fish etc. Banyan capsules avidly gulped down in season. Roosts at night in favorite trees and shares those with crows, mynas and other birds.

The bird is usually known to feed on ectoparasites of cattle or herbivores. However, these were seen foraging on garbage. Thus, it can be concluded that the alteration of the habitat has also resulted in an alteration of the feeding habits and those species of birds.

Indian pond heron - Ardeola grayii

Field characteristics - an egret-like marsh bird chiefly earthy brown when at rest, but with glistening white wings, tail and rump flashing into prominence immediately it flies.

Distribution - Found throughout the Indian union; Bangladesh; Pakistan; Sri Lanka; Myanmar; plains and up to about 1000m elevation.

Habits - Found wherever there is water, river, jheel, roadside ditch, kutcha well, or temple pond, often in the midst of populous towns. Also on the seacoast in the mangrove swamps, mudflats, etc.

Food - frogs, fish, crabs and insects. Flight typically heron - steady wing beats with neck pulled in. Roosts in large leafy trees in mixed congregations of crows and other birds

Bar-headed goose - Anser indicus

Field characteristics - a grey brownish white goose with white head and sides of neck.

Distribution - in winter throughout north and north-east India; rare in central India; Bangladesh; Pakistan; Myanmar.

Habits -Rather crepuscular and nocturnal.

Food - chiefly green shoots of winter such as wheat or gram.

Purple-rumped sunbird - Nectarinia zeylonica

Field characters - upperparts and breast glistening metallic crimson green and purple; lower parts yellow. Rump is metallic bluish purple.

Shikra - Accipiter badius

Field characters: a lightly bulky hawk ashy blue grey above and white below, cross-barred with rusty brown.

Distribution - throughout India, Bangladesh, Pakistan, Myanmar.

Habits - avoids heavy forest. From its lookout in a leafy branch it swoops down and carries off its prey before the victim is aware of any danger. Flight is swift, several rapid wing strokes followed by a glide.

Food - lizards, mice, squirrels, birds, etc.

Little cormorant - Phalacrocorax niger

A glistening black duck like water bird with a longish stiff tail, and slender, compressed bill hooked at the tip.

Distribution - Throughout India, Nepal Bangladesh, Pakistan, Myanmar, Sri Lanka

Habits - found on all the inland waters; also brackish lagoons and tidal creeks. Lives exclusively on fish which it chases and captures under water. When satiated it perches on a rock or stake near water and dries itself with outstretched wings.

Crow - Corvus splendens

Field characters - grey neck and smaller in size to distinguish it from the black jungle crow. Sexes are alike.

Distribution - throughout India, Bangladesh, Pakistan, Myanmar, Sri Lanka.

Habits - perhaps the most familiar bird of Indian towns and villages. They have no particular food preferences. Will eat almost anything - dead sewer rat, offal, carrion, kitchen scraps and refuse, locusts, termites, fruit grain and eggs.

A useful scavenger but also a serious menace to defenseless ornamental bird species in urban areas.

Discussion: Wetlands form a major type of ecosystem with distinct physical, climatic and biotic characteristics. Mangroves being wetlands too have peculiar physical and biotic characteristics. However, these areas have always been prone to destruction by human anthropogenic activities. This is severe in the case of a metropolitan city like Mumbai which is the economic capital, where development is at a constant rise, where employment is fairly easily achievable and space is always a cause of concern, such natural habitats like mangroves tend to make up for the scarcity of land by the process of reclamation.


Understudied, Mumbai mangroves can provide a large base for research opportunities. While macro flora is little studied, micro flora and fauna of Mumbai coastline remains understudied.

Mangroves are valuable for controlling pollution


Some species of mangrove flora and fauna act as bio indicators. The pollution of the water body can be determined by the presence or absence of these species.

Shelled mollusks cannot survive in acidic water - their shells are dissolved by such water

Indian skimmer - Rynchops albicollis is extremely sensitive to contaminated water and its disappearance is a distinct sign of surface-water pollution.

The black-winged stilt - Himantopus himantopus is known for its high level of tolerance to polluted waters and its dominance is an indicator of poor water quality.


Legislation- Mangroves are protected legally under the following Acts in Mumbai:

Maharashtra Tree Act of 1984.

Environment Protection Act 1986 (Coastal Regulatory Zone Notification of 1991)

Forest Conservation Act 1980


Survey and demarcation of mangrove area including mapping of degraded mangroves areas using remote sensing as well as ground survey.

Regular patrolling in creeks to check possible destruction of existing mangroves and protecting rare species of mangroves found in these islands.

Ecological restoration of degraded mangroves by raising nurseries and replenishing degraded mangrove areas through artificial regeneration.

Publicity and awareness campaign through film shows, organizing seminars, nature camps, distributing publicity materials etc.