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Resolving the heading-direction ambiguity in vertical-beam radar observations of migrating insects

Hao, Zhenhua LU ; Drake, Vincent Alistair and Taylor, John R. (2019) In Ecology and Evolution 9(10). p.6003-6013
Abstract

Each year, massive numbers of insects fly across the continents at heights of hundreds of meters, carried by the wind, bringing both environmental benefits and serious economic and social costs. To investigate the insects' flight behavior and their response to winds, entomological radar has proved to be a particularly valuable tool; however, its observations of insect orientation are ambiguous with regard to the head/tail direction, and this greatly hinders interpretation of the migrants' flight behavior. We have developed two related methods of using wind data to resolve the head/tail ambiguity, and we have compared their outputs with those from simply assigning the heading direction to be that which is closer to the track direction.... (More)

Each year, massive numbers of insects fly across the continents at heights of hundreds of meters, carried by the wind, bringing both environmental benefits and serious economic and social costs. To investigate the insects' flight behavior and their response to winds, entomological radar has proved to be a particularly valuable tool; however, its observations of insect orientation are ambiguous with regard to the head/tail direction, and this greatly hinders interpretation of the migrants' flight behavior. We have developed two related methods of using wind data to resolve the head/tail ambiguity, and we have compared their outputs with those from simply assigning the heading direction to be that which is closer to the track direction. We applied all three methods to observations of Australian plague locust migrations made with an insect monitoring radar. For the study dataset, some of the headings selected by the simpler method are shown to be clearly incorrect. The two new methods generally agree and reveal a significantly different, and presumably more accurate, relationship of heading direction to track direction. However, use of these methods leads to quite a large proportion of the sample being lost because the wind values, which derive from a regional-scale numerical model, are shown to be incompatible with the radar observations. This exploratory study has moreover demonstrated that locusts are frequently oriented at a large angle to their track and that quite often their movement is at least slightly tailfirst. Both new methods appear to be a significant improvement on the simpler method. As well as providing an accurate representation of migratory flight behavior, they allow occasions when the model wind values are unreliable to be eliminated from the data sample.

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author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Australian plague locust, heading direction, insect migration, orientation, radar entomology, selection method
in
Ecology and Evolution
volume
9
issue
10
pages
11 pages
publisher
Wiley-Blackwell
external identifiers
  • pmid:31161015
  • scopus:85066264383
ISSN
2045-7758
DOI
10.1002/ece3.5184
language
English
LU publication?
yes
id
85bc6d3e-e48a-4fbb-88da-80abeb3b8867
date added to LUP
2019-06-12 14:17:28
date last changed
2021-01-12 01:38:34
@article{85bc6d3e-e48a-4fbb-88da-80abeb3b8867,
  abstract     = {<p>Each year, massive numbers of insects fly across the continents at heights of hundreds of meters, carried by the wind, bringing both environmental benefits and serious economic and social costs. To investigate the insects' flight behavior and their response to winds, entomological radar has proved to be a particularly valuable tool; however, its observations of insect orientation are ambiguous with regard to the head/tail direction, and this greatly hinders interpretation of the migrants' flight behavior. We have developed two related methods of using wind data to resolve the head/tail ambiguity, and we have compared their outputs with those from simply assigning the heading direction to be that which is closer to the track direction. We applied all three methods to observations of Australian plague locust migrations made with an insect monitoring radar. For the study dataset, some of the headings selected by the simpler method are shown to be clearly incorrect. The two new methods generally agree and reveal a significantly different, and presumably more accurate, relationship of heading direction to track direction. However, use of these methods leads to quite a large proportion of the sample being lost because the wind values, which derive from a regional-scale numerical model, are shown to be incompatible with the radar observations. This exploratory study has moreover demonstrated that locusts are frequently oriented at a large angle to their track and that quite often their movement is at least slightly tailfirst. Both new methods appear to be a significant improvement on the simpler method. As well as providing an accurate representation of migratory flight behavior, they allow occasions when the model wind values are unreliable to be eliminated from the data sample.</p>},
  author       = {Hao, Zhenhua and Drake, Vincent Alistair and Taylor, John R.},
  issn         = {2045-7758},
  language     = {eng},
  number       = {10},
  pages        = {6003--6013},
  publisher    = {Wiley-Blackwell},
  series       = {Ecology and Evolution},
  title        = {Resolving the heading-direction ambiguity in vertical-beam radar observations of migrating insects},
  url          = {http://dx.doi.org/10.1002/ece3.5184},
  doi          = {10.1002/ece3.5184},
  volume       = {9},
  year         = {2019},
}