Abstract: Mangroves are areas of rich avian diversity. It houses several bird species. 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.
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.
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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.  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.
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.
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Zonation in Mangroves
Mangal along a tropical bay characteristically shows 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)
Always on Time
Marked to Standard
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 not so simple and varies from place to place. Every species has its own level of salinity tolerance. Estuaries on east coast show distinct Zonation. 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. 
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. 8% 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.
Distribution of mangroves in the Mumbai Metropolitan Region:
Region Mangrove type Total area under mangroves Sparse Dense In 1991 Brihan Mumbai 16.67 14.10 30.77 Island city 0.17 0.25 0.42 Western suburbs 6.92 5.47 12.39 Eastern suburbs 9.58 8.38 17.96 Region Mangrove type Total area under mangroves Sparse Dense Above 3m Below 3m Total In 1997 Brihan Mumbai 11.25 20.77 20.25 41.02 52.27 Island city 0.84 0.55 0.24 0.79 1.63 Western suburbs 5.89 5.61 14.11 20.72 26.61 Eastern suburbs 4.52 13.61 5.9 19.51 24.03
Methods of 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.
NEED FOR STUDY
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. Had that been the case a 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.
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.
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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.
Cases of CRZ (Coastal Regulation Zone) violations have been rampant in various areas like seven bungalows, Janakidevi Public School near Versova creek and even Millat nagar. 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.
Although the area is in constant threat from land sharks and incidences of debris dumping are often reported, the place is a good example of how active residents (like the Save Andheri Versova Environment - SAVE group) can play an important role in protecting the remaining mangrove forests.
ANTHROPOGENIC FACTORS CAUSING THE DETERIORATION OF THE MANGROVE ECOSYSTEM:
The main anthropogenic factors that have lead to a change and deterioration of the eco system is the presence of a BMC transitional garbage separating site extremely close to the mangroves and the pollution of the water because of a sewage pipe leading to 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 and crows tend to pick up garbage, pilfer it for food and then drop it when they fly 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 people 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. 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.
Rishi agarwal, an environmental activist and a few of his colleagues on February 1st went for a bird watching session at the Lokhandwala mangrove site. The species that they recorded were:
Renowned Bird Watcher Sunjoy Monga joined in the morning and the evening proving to be a valuable resource at spotting and identifying the birds.
Below is the list of the birds compiled by Sunjoy -
Here is a list of birds seen during the morning (7:20 - 9:10 am) and evening (4:45 - 6:20 pm) sessions.
At least six Spot-billed Duck
Steppe Eagle - towards landfill site
Blyth's Reed Warbler
Greater Coucal (Crow-pheasant)
White-throated Fantail (calling)
Hence, a study was made (13th November 2009) across a three day period to look at the birds which are found in and around the Lokhandwala mangrove site. However, the same number of species could not be matched. This could be either due to the season or weather conditions or simply loss of bio-diversity.
White breasted kingfisher
White breasted kingfisher
White breasted kingfisher
White eared bulbul
White eared bulbul
Indian pond heron
Indian pond heron
Indian pond heron
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; Marathi name - gochandi khao
Field characters: in non-breeding pure white plumage distinguished from the little egret by color of bill which is yellow not black.
Distribution: throughtout 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.
Indian pond heron - ardeola grayii (sykes)
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 - local name - shakarkhora
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 amaller size to distinguish it from the all 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. Has 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.