Dragonflies likely migrate across the Indian Ocean
Date:
October 4, 2021
Source:
Lund University
Summary:
Can dragonflies migrate thousands of miles across the Indian
Ocean, from India via the Maldives to Africa, and back again? An
international research team has used models and simulations to
find out if the hypothesis could be true.
FULL STORY ==========================================================================
Can dragonflies migrate thousands of miles across the Indian Ocean,
from India via the Maldives to Africa, and back again? An international research team led by Lund University in Sweden has used models and
simulations to find out if the hypothesis could be true.
==========================================================================
In 2009, marine biologist Charles Anderson put forward a hypothesis
after observing globe skimmer dragonflies(Pantala flavescens) on the
Maldives, that had flown in from what he assumed was India. When they
flew off again, it was towards East Africa. Now, 12 years later, a group
of researchers decided to investigate his claim.
Globe skimmer dragonflies are too small to be fitted with transmitters.
Instead, the researchers examined its physiological aspects and
calculated how long a globe skimmer dragonfly could stay airborne using
the energy that can be stored in its body. In addition, the researchers
used meteorological wind models to determine if there are winds that
can facilitate the migration in both directions.
"Our study shows that this migration from India to East Africa is actually possible. However, the globe skimmer dragonfly can't manage it using
only the fat it can store in its body. It also requires favourable winds
and these are present during certain periods of the year," says Johanna Hedlund, a biology researcher at Lund University.
According to the simulated migration experiments using wind models,
about 15 per cent of the dragonflies could manage the migration from
India to Africa in the spring. In the autumn, 40 per cent could make
the same journey in the opposite direction.
Johanna Hedlund and her colleagues consider it impressive that dragonflies
can do this at all. Even more impressive is the fact that the globe
skimmer dragonfly migration across the Indian Ocean is the longest in
the animal kingdom in relation to an animal's size.
"We have got a lot closer to solving the mystery of how a tiny dragonfly,
which only weighs 300 milligrams, can cross 2,000 kilometres of open sea,"
says Johanna Hedlund.
Other animals also rely on favourable wind conditions when they
migrate. Two examples are the amur falcon and the Jacobin cuckoo, which
also fly across the Indian Ocean. The researchers behind the study in
question warn that climate change may affect the chances of these birds
and the globe skimmer dragonfly in the future. There is a risk that wind patterns will change when the water surface gets warmer.
The researchers consider that the study is important in several ways. It creates an understanding of the distances that one of the animal kingdom's smallest migrants can cover, it increases knowledge about how migratory
animals can spread diseases, and it also contributes to ecosystem services
at widespread locations around the world.
========================================================================== Story Source: Materials provided by Lund_University. Note: Content may
be edited for style and length.
========================================================================== Journal Reference:
1. Johanna S. U. Hedlund, Hua Lv, Philipp Lehmann, Gao Hu, R. Charles
Anderson, Jason W. Chapman. Unraveling the World's Longest Non-stop
Migration: The Indian Ocean Crossing of the Globe Skimmer Dragonfly.
Frontiers in Ecology and Evolution, 2021; 9 DOI:
10.3389/fevo.2021.698128 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2021/10/211004104132.htm
--- up 4 weeks, 4 days, 8 hours, 25 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)