Archive for the ‘Dragonfly’ Category

Sri Lanka could be in path of world’s longest insect migration

October 21, 2012
Public asked to watch out for mass movement of dragonflies

Last year same period: Waves of Dragonflies were reported from the west coast and other areas. The world’s longest insect migration was documented from India-Maldives-Africa and this observation hints Sri Lanka too could be a hub in its path. Public support is sought this year to unravel this mystery�

On October 20 last year a large swarm of dragonflies were spotted in Sri Lanka’s west coast by a bird watcher Nashath Hafi. The insects had been seen heading south from areas including Moratuwa and Kollupitiya. Subsequent investigations confirmed this unusual influx of insects

A Globe Skimmer Dragonfly found last year soon after the wave of dragonflies

Speaking to the Sunday Times Sarath who lives by the coast in Dehiwela said, “the cloud of dragonflies took a few hours to pass our area. The insects were everywhere and some even ended up inside houses”. Members of the fishing community at Dehiwela helped to catch a few dragonflies that were still hovering around.

An investigation into the phenomenon by consulting biologists revealed a possibility of a mass migration of dragonflies spanning India – Maldives and all the way up to East Africa. The path covers a distance of around 14,000 kilometres and could be called the world’s longest insect migration.

Maldivian-based biologist Dr. Charles Anderson initially revealed the amazing phenomenon based onthe dates the dragonflies appear in the Maldives and India.

The Maldive Islands lack surface freshwater as the soil absorbs all rainwater. This indicated that dragonflies which spend their larvae stage in fresh water cannot breed in these tropical islands. Yet, every year millions of dragonflies appeared in the Maldives which the biologist who had been living in the islands for many years found puzzling. He also noted the insects appeared in the Maldives in October.

So Dr. Anderson investigated the concentration of dragonflies in other areas.�He noted the dates dragonflies arrived in the Maldives and India demonstrated that the insects travelled from southern India –a distance of some 500 – 1000 km. Subsequent investigations also revealed an increase of dragonflies in Seychelles islands in Africa and the arrival dates in the Seychelles matched with a possible mass migration.

Dr.Anderson based on his data calculated the Dragonflies first appear in the capital city of Maldives on 21st of October on average. Quite interestingly the wave of Dragonflies was observed in Sri Lanka on 20th October highlighting the possibility that the island too was part of the path of the India-Africa dragonfly mass migration.

Checking photos of the species of dragonflies found in Sri Lanka Dr.Anderson was able to confirm it was the same species known as Globe Skimmer, or Wandering Glider, scientifically categorised as Pantala flavescens.

A Dehiwala resident showing a dragonfly caught on the beach

The biologist also noted the dates of arrival of dragonflies and occurrence coincided with the southward passage of the Inter-tropical Convergence Zone (ITCZ) which creates certain wind patterns that could assist dragonflies in their journey across oceans.

The Meteorological department confirmed the ITCZ would cross Sri Lanka next week. So it is likely that this year’s mass movement of the dragonflies could occur in next few days.

Inspired by this mass movement of dragonflies, the Field Ornithology Group of Sri Lanka (FOGSL) that studies bird migration has launched a MigrantWATCH programme.

It calls on members of the public who may notice the mass movement of dragonflies, to note down the date and time of observation, the location, the direction they fly and the approximate number of dragonflies if possible.

All data should be sent to MigrantWATCH program via email at: fogsl@slt.lk, by post: MigrantWATCH, FOGSL, Department of Zoology, University of Colombo, Colombo-03 or by telephone via Nos: 2501332/ 0712543634.

New species of dragonfly found in Sri Lanka�

Sri Lanka is listed with having 118 species of dragonflies of which 43 are endemic to the country. Recently a new variety was discovered by Nancy van der Poorten – a well known researcher into dragonflies who made the discovery from Kudawa at the western edge of Sinharaja rain forest.

The new Dragonfly – Macromidia donaldi pethiyagodai

The variety belongs to a genus referred to as Macromidia. Genus is a categorization of species that has similar characteristics and this is the first time a dragonfly of this genus has been discovered from Sri Lanka.

The species similar to a species found in India’s Western Ghats is separated from its Indian cousin by a distance of 750 km and could therefore be endemic to Sri Lanka.

Researchers however point out, until certain aspects of the Indian dragonfly are studied in detail, it would not possible to confirm the differences scientifically.

Until such time the latest discovery of Dr. Nancy van der Poorten has been designated as a Sri Lankan subspecies and named Macromidia donaldi pethiyagodai, honouring Rohan Pethiyagoda who made several discoveries of new species.

Published on 14.10.2012 www.sundaytimes.lk/121014/news/sri-lanka-could-be-in-path-of-worlds-longest-insect-migration-16409.html

World’s longest dragonfly migration via Sri Lanka?

November 6, 2011
By Malaka Rodrigo
Last week, a large cloud of dragonflies was observed along the west coast near Colombo. Subsequently, an increase of dragonflies was sighted in many areas islandwide. This sudden appearance of dragonflies in large numbers raised the curiosity of the public.This wave of dragonflies was first reported moving southwards in large numbers on October 20 morning. One of the witnesses, Nashath Haffi of the Field Ornithology Group of Sri Lanka (FOGSL) says while travelling by train he observed this wave around 7 a.m., parallel to the coast, continuously from Moratuwa to Kollupitiya. It is not clear whether the swarm continued further southward.With the aim of investigating the phenomena, the Sunday Times visited the Dehiwala beach, which was in the middle of the recorded route of the dragonflies last Sunday. The residents, mostly fisher folk, when interviewed, confirmed sighting on October 20 a wave of dragonflies flying southwards at a height of about 10 feet. Some of them said it was the first time they had observed such a phenomenon, while others said it was an annual event.

The Dehiwala residents also assisted in catching a few dragonflies still hovering in the vicinity. This dragonfly is about 4.5 cm long, with a wingspan of about 5 cm. The body is a golden colour (dark yellow) with a dark line. The wings are clear and very broad at the base, with a tip near the end. The photos were shared with dragonfly experts and the species identified as Globe Skimmer, or Wandering Glider, scientifically categorised as Pantala flavescens.

Investigations also revealed an interesting fact that this dragonfly is migratory like birds. A Dragonfly migration is believed to be happening annually from India to Africa via the Maldives. Dr. Charles Anderson, who had researched this migration, confirms that, the dragonflies caught in Dehiwala, are the same species involved in the India-Africa migration. Living in the Maldives since 1983, Dr. Anderson continues to observe a sudden influx of dragonflies which raised his initial curiosity. Dragonflies need freshwater to raise their young, as their larvae stage is spent in freshwater.

However, the Maldives is a group of oceanic islands with sand that absorbs all the rainwater it gets. Hence, no freshwater pools are formed even after rain falls. So, apparently, the dragonflies recorded in the Maldives are from elsewhere.

Dr. Anderson started noting down dates of dragonflies seen for the first time in the Maldives, and then compared the data of dragonflies appearing in South India. He found a clear sequence of arrival dates from north to south. According to this data, dragonflies first arrive in Southern India and then in the Maldives. According to his research, each year, dragonflies first appear in the Maldive’s capital, Male, between October 4 and 23, with a mean arrival date of October 21. Quite interestingly, the sighting of the dragonfly wave along the west coast was reported on October 20, which is quite close to the dates they arrive in the Maldives. So, dragonflies seen in Sri Lanka, must also be those involved in this migration.

Dragonflies, though hardy, are small insects – so how can they fly such long distances? Dr. Anderson also attributes that wind patterns help them in this journey. In October, and continuing into November and December, a weather system called the Inter-Tropical Convergence Zone (ITCZ) moves southwards over the Maldives. Dr. Anderson suggests these dragonflies must be flying on these winds at altitudes above 1,000 metres.

Globe Skimmer (Pantala flavescens) caught from Dehiwala

“Ahead of the ITCZ, the wind blows towards India, but above and behind it, the winds blow from India. So, it seems that, the dragonflies are able to reach the Maldives by flying on these winds at altitudes above 1,000 metres” he said.

This could probably be assisting them to visit Sri Lanka too. Since last week, we are experiencing much rain, which could be a result of this weather pattern. Raising the importance of following traditional knowledge, many of the Dehiwala fishing community say these dragonfly waves appear with the change of wind, or ‘goda sulan’, which they are quite accustomed to identifying.

The researcher also found data of sudden appearances of dragonflies in Africa, and when collated, the analysis matches, indicating this migration continues all the way to Africa, more than 14,000 km away.

Migrant Watch – You too can support science

There is a need for extensive research to solve the mysteries of this migration. But the first step would be to monitor where the dragonflies have been sighted in large numbers, which will at least give the coordinates of a possible map. The FOGSL has initiated a programme called MIGRANT WATCH, and invites the general public to forward information on these dragonfly movements. If you have seen swarms of dragonflies recently, please forward location and related dates.

Migrant Watch mainly aims at observing Migrant Birds as a Citizen Science project. Prof. Sarath Kotagama also highlights the importance of observation even by non-experts, as being immensely helpful, as that of the dragonfly migration, which was triggered by Nashath sharing his sighting on October 20. So, he invites all to participate in MIGRANT WATCH, and email the data to fogsl@slt.lk or, post it to FOGSL, Dept. of Zoology, University of Colombo, Colombo 3. Further details can be obtained from 2 501 332 / 0712 543 634 / 0712 543 634.

published on sundayTimes on 06/11/2011 http://www.sundaytimes.lk/111106/News/nws_09.html