Survey of Ecology and Plantation strategy for conservation of White Bellied Sea Eagle (Haliaeetus leucogaster)
Presentation by Mr.Premsagar Mestri, SEESCAP ,Mahad. Under the guidance of Dr.Madhuri Pejaver and Rupa Dawane. Photos by : Ankit Kerkal , Manashree Bapat.
Introduction
The White bellied sea eagle (Haliaeetus leucogaster) are recognised as an indicator species by which to measure biodiversity, environmental integrity and the general health of the ecosystem in a rapidly changing world (Newton 1979).
The selections of favoured habitat and nesting locations of White bellied sea eagle have been recorded.
A decline in the number of sea eagle nests was noticed in the northern part of Raigad.
Surveys have been carried out from 2006 to 2016 along the 106 Km costal stretch of Raigad district in the state of Maharashtra.
Two prominent estuaries located in the northern part of Raigad which acted as attractive nesting locations for the White bellied sea eagle.
These sites were severely affected by the recent industrialization and ship building projects.
Also, new investors increased the productivity of their land by coconut plantation.
This involved cutting down of trees like Tamarind, Banyan, Wild Almond, Mango, Sativa Terminalia, Arjuna, Beheda, Kalam, etc. which had been growing in these locations for many years.
These trees provide ideal locations for nesting since they provided an easy to access area between the coconut trees and were also close to the much needed hunting ground provided by the estuaries.
The Forest department has also been following a program of removing the natural habitat of mangroves and its accompanying undergrowth.
They are replacing it with Casuarina equisetifolia trees which are foreign to the ecosystem.
In the absence of its favoured nesting sites (indigenous tree species like Wild Almond, Palm, Mango, Banyan) ,the White bellied sea eagle has shifted nesting on these exotic trees.
The WBSE nesting requirements are not entirely compatible with this exotic tree.
The naturally occurring slow change that is observed in the habitat as we move from inland towards the coast (tall trees>shorter trees> shrubs and trees>Mangroves>undergrowth with creepers)
Study Area Raigad Coastal Area Coast line distance : 106km Average width of district : 60km We surveyed 5km wide coastal area Temperature range : 22oC to 30oC Mean relative humidity : 80% Geography: Uniformly rocky and shallow beaches Small sandy beaches Estuaries of the more important rivers The mouths of numerous minor streams
Aims and Objectives
To identify the trees on which nesting is preferred by the White bellied sea eagle in Raigad District in the state of Maharashtra. To study the population status of the White bellied sea eagle To collect data on the nesting site parameters on the basis of: Distance from sea shore Height of nest from ground level To identify threats to the White bellied sea eagle To use the collected data for the repair and restoration of the surrounding ecosystem.
Methodology
We collected information from available literature and other sources
We located nesting sites of the white bellied sea eagle by walking along coastal line of the district during the breeding season (October to January)
We also collected information from local people by showing photographs.
Materials
Camera (Nikon P510)
Binocular (Olympus 10*50)
GPS for location of nesting sites
Google Earth for mapping and measuring distance
Pole method for measuring height
Observation Table Place
Active/Inactive
Distance from Sea Coast (m)
Age (years)
Underi
Active
0
N.A.
Alibag
Active
200
1
Revdanda Sarve ( Old)
Active Inactive
250 5
100 22
Sarve (new)
Active
150
3
Murud (Old)
Inactive
100
N.A.
Murud (Incomplete)
Inactive
50
1
Velas
Active
300
6
Bharadkhol (Old N.L.)
Inactive
2
N.A.
Aaravi
Active
5
22
Valvati
Active
5
25
Shrivardhan (Koliwada) Shrivardhan (Vetal Pakhadi )
Active
5
N.A.
220
15
Harihareshwar
Active
5
N.A.
Active
Distance between two nests Place Underi to Alibag
Distance between 2 nest location(Aerial distance) 7kms
Alibag to Revdanda
13km
Revdanda to Sarve
14km
Sarve to Murud
9km
Murud to Velas
14km
Velas to Bharadkhol
6km
Bharadkhol to Aaravi
4km
Aaravi to Valavti
1km
Valvati to Shrivardhan (koliwada)
2.8km
Shrivardhan (koliwada) to Vetal Pakhadi
723m
Vetal Pakhadi to Harihareshwar
6.51km
Number of nests on tree species
Height of nest from ground level
Observations Mostly the nests along the sea coats Recorded nests: 13 Active nests: 10 Inactive nests: 3 Tree Species Preference: Casuarina (Casurina equistifolia) : 7 Wild almond tree (Sterculia foetida) :3 Mango tree (Mangifera indica) :1 Banyan tree ( Ficus bengalensis) :1 Asian Palm (Borassus flabellifer) : 1
Distance between two consecutive nest: Alibag & Murud Taluka : 10km Shrivardhan Taluka : 5km
Average territory area: 7km Minimum distance observed: 700m Maximum distance observed: 14km
Frequently preferred height for Nesting 40-60ft Minimum Height at Underi: 10ft Maximum Height at Valvati :100ft approximate
Branch preferred for nesting is facing opposite from sea shore
Nests
libag, Asian Palm tree (Borassus flabellifer)
Revdanda, Wild almond Tree (Sterculia foetida)
rve, Casuarina tree (Casuarina equisetifolia)
Sarve, Casuarina tree (Casuarina equisetifolia
Alternate Nesting site
urud(incomplete nest),Casuarina tree (Casuarina equisetifolia)
Velas, Wild Almond Tree (Sterculia foe
aravi, Casuarina tree (Casuarina quisetifolia)
Valvati, Casuarina tree (Casuarina equisetif
Shrivardhan,Wild almond tree (Sterculia foetida)
Result and Discussion Issues facing WBSE: The Northern stretch of the study area i.e. from Alibag to Murud is under the most stress with both the foraging grounds, Dighi and Salavi Creek, experiencing a lot of problems. Salavi Creek:- The creek sees by-products from a wide variety of processing and manufacturing plants being poured into it. Boats carrying chemicals are often seen over the creek which leave a lot of turbidity. Dighi Creek:- Construction of a port which started in 1999 has been extremely detrimental to the health of the ecosystem in and around the creek. The port building process involved mining and levelling the hills on both sides of the creek and building structures jutting out into the creek.
The effects that these have had on the ecosystem are clearly seen through the Nest distribution in these areas with the average distance between nests in sub-section one (Alibag to Murud) being 12.5Km with the rest of the study area having an average distance between nests of 3.5Km.
the resorts cropping up all along the sea coast, with resorts located in Alibag, Salav, Murud, Diveagar, Shrivardhan and Harihareshwar.
Casurina Estifolia trees were often the alternative that the WBSE selected simply because of the lack of other suitable nesting trees.
The WBSE is often seen taking a longer time to settle down when roosting on a Casurina tree and often change their nest when possible.
Conclusion
The data collected shows that habitat reduction is the most significant threat to the WBSE,this includes a sizable reduction in the number of indigenous tree species which were suitable for its nesting.
The WBSEs shy away from the first sub-section of the study area because of the heavy industrialization and pollution of its feeding grounds.
The palm plantations can reintroduce indigenous trees along the fence lines which wouldn’t affect the palm plantations productivity while also allowing eco-friendlier fences. Trees like Saliva Terminalia would be ideal as they grow vertically upwards. Also they don’t have a large canopy so it won’t affect the sunlight reaching the palm trees. Others that would be useful include wild almond and mango trees.
Absence of proper knowledge of trees and their effects on the habitat around them have led to a steady decline in the quality of nesting habitat. The forest department should start planting indigenous trees instead of Casurina equistifolia WBSE feels uneasy adopting the Casurina equistifolia trees for nesting purposes because the tree is flimsier and shakes a lot more when the bird lands on it or it experiences gales of wind. WBSEs are observed to prefer palm plantations for nesting purposes and use the nests for many years so the owners could be trained to protect the nest and keep tourists/workers away from it.
Thank you!
Thank You …!!