The Speed of a Moth
Which is faster? A small moth or a songbird? The answer does surprise. A study published in March 2011 in Proceedings of the Royal Society B by researchers at Rothamsted Research, and the universities of Lund (Sweden), Greenwich and York, reports the surprising finding that night-flying moths are able to match their songbird counterparts for travel speed and direction during their annual migrations but they use quite different strategies to do so - information that adds to our understanding of the lifestyle of such insects, which are important for maintaining biodiversity and food security. This new international study of moth migration over the UK, and songbird migration over Sweden, funded by the Biotechnology and Biological Sciences Research Council (BBSRC) and the Swedish Research Council, shows that songbirds (mainly Willow Warblers) and moths (Silver Y moths) have very similar migration speeds — between 30 kilometers and 65 kilometers per hour — and both travel approximately northwards in the spring and southwards in the autumn.
A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order. Most species of moth are nocturnal
A songbird is a bird belonging to the suborder Passeri of the perching birds. This group contains some 4000 species, in which the vocal organ typically is developed in such a way as to produce a diverse and elaborate bird song.
Dr Jason Chapman, Rothamsted Research, one of the lead authors on the paper said "Songbirds such as warblers and thrushes are able to fly unassisted about four times faster than migratory moths, which might appear to be largely at the mercy of the winds. So we had assumed that songbirds would travel much faster over the same distance. It was a great surprise when we found out the degree of overlap between the travel speeds - the mean values are almost identical, which is really remarkable."
The discovery gives fresh insight into exactly how moths are able to travel in their billions from summer breeding grounds in the UK and elsewhere in northern Europe to their winter quarters in the Mediterranean region and sub-Saharan Africa, thousands of miles away. This is important information in the context of declining moth populations and a critical need for pollinating insects to ensure maximum yields of food crops in the face of a potential food crisis — the more we understand about the life cycle and lifestyle of these insects, the better we can understand and mitigate the challenges they face for survival.
The team used specially-designed radars to track the travel speeds and directions of many thousands of individual Silver Y moths and songbirds on their night-time spring and autumn migrations.
The similarity in speed results from differing strategies: moths fly only when tailwinds are favorable, so gaining the maximum degree of wind assistance; whereas birds fly on winds from a variety of directions, and consequently receive less assistance.
Moths are therefore more efficient in their flight as opposed to the birds who fly when they want to.
The findings therefore demonstrate that moths and songbirds have evolved very different behavioral solutions to the challenge of moving great distances in a seasonally-beneficial direction in a short period of time.
Moths, and particularly their caterpillars, are a major agricultural pest in many parts of the world. Examples include corn borers and bollworms. The caterpillar of the gypsy moth causes severe damage to forests in the northeast United States, where it is an invasive species. In temperate climates, the codling moth causes extensive damage, especially to fruit farms.
Some moths are farmed. The most notable of these is the silkworm, the larva of the domesticated moth Bombyx mori. It is farmed for the silk with which it builds its cocoon.
Knowing how the moth moves about will lead to a better understanding of their world wide ecological role.
For further information: http://www.eurekalert.org/pub_releases/2011-03/babs-mma030811.php