Visual counts, bioacoustics and RADAR: three methods to study waterfowl prenuptial migration in Southern France

This study comes from four years (2006–2009) of monitoring on two sites during the prenuptial migration. On each site, a monitoring of 24 hours per each 10–day period from the second 10–day period of January (J2), though February (F1–F3) and March (M1–M3), up to the first 10–day period of April (A1)...

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Main Authors: Beroud, T., Druais, J., Bay, Y., Ricci, J. C.
Format: Article
Language:English
Published: Museu de Ciències Naturals de Barcelona 2012-01-01
Series:Animal Biodiversity and Conservation
Subjects:
Online Access:http://abc.museucienciesjournals.cat/files/ABC_35-2_pp_175-188.pdf
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spelling doaj-b7087f99e12340a692916bdc2deeae5b2020-11-24T22:10:26ZengMuseu de Ciències Naturals de BarcelonaAnimal Biodiversity and Conservation1578-665X2012-01-01352175188Visual counts, bioacoustics and RADAR: three methods to study waterfowl prenuptial migration in Southern FranceBeroud, T.Druais, J.Bay, Y.Ricci, J. C.This study comes from four years (2006–2009) of monitoring on two sites during the prenuptial migration. On each site, a monitoring of 24 hours per each 10–day period from the second 10–day period of January (J2), though February (F1–F3) and March (M1–M3), up to the first 10–day period of April (A1). Monitoring was carried out by RADAR (FURUNO FAR2127), associated with nocturnal bioacoustics recordings, and visual censuses on the same areas. The monitoring effort was considerable: visual counts carried out represent 282 counts–sites (n = 262,030 ducks counted), bioacoustics detected 9,573 calls during 814 hours of nocturnal recording and RADAR recorded 67,368 echoes on a set of 2,128 hours of monitoring. Visual counts showed a decline in the number of birds from late January/early February. Two patterns were observed with the nocturnal recordings with a maximum or a minimum of the value of bioacoustics index on F2 and F3, depending on the years. RADAR, the most relevant method for tracking of bird movements at a population level, identified two different abundance peaks using variables ‘flight altitude > 400 m’ and ‘flight direction towards north–east/south–east’, considered as characteritics of the prenuptial migration. The first peak was detected during F1 on Site 1 only in 2007 (once every four years) and during F2 on Site 2 only in 2006 (once every four years). A second peak with a higher number of echoes was recorded on M1 (Site 1) and on M2 (Site 2). Although all methods may suffer from different biases, the combination of two new technologies complementary to visual counts provided reliable and updated data for waterfowl migration in the Mediterranean area.http://abc.museucienciesjournals.cat/files/ABC_35-2_pp_175-188.pdfPrenuptial migrationWaterfowlCountsBioacousticsRADAR
collection DOAJ
language English
format Article
sources DOAJ
author Beroud, T.
Druais, J.
Bay, Y.
Ricci, J. C.
spellingShingle Beroud, T.
Druais, J.
Bay, Y.
Ricci, J. C.
Visual counts, bioacoustics and RADAR: three methods to study waterfowl prenuptial migration in Southern France
Animal Biodiversity and Conservation
Prenuptial migration
Waterfowl
Counts
Bioacoustics
RADAR
author_facet Beroud, T.
Druais, J.
Bay, Y.
Ricci, J. C.
author_sort Beroud, T.
title Visual counts, bioacoustics and RADAR: three methods to study waterfowl prenuptial migration in Southern France
title_short Visual counts, bioacoustics and RADAR: three methods to study waterfowl prenuptial migration in Southern France
title_full Visual counts, bioacoustics and RADAR: three methods to study waterfowl prenuptial migration in Southern France
title_fullStr Visual counts, bioacoustics and RADAR: three methods to study waterfowl prenuptial migration in Southern France
title_full_unstemmed Visual counts, bioacoustics and RADAR: three methods to study waterfowl prenuptial migration in Southern France
title_sort visual counts, bioacoustics and radar: three methods to study waterfowl prenuptial migration in southern france
publisher Museu de Ciències Naturals de Barcelona
series Animal Biodiversity and Conservation
issn 1578-665X
publishDate 2012-01-01
description This study comes from four years (2006–2009) of monitoring on two sites during the prenuptial migration. On each site, a monitoring of 24 hours per each 10–day period from the second 10–day period of January (J2), though February (F1–F3) and March (M1–M3), up to the first 10–day period of April (A1). Monitoring was carried out by RADAR (FURUNO FAR2127), associated with nocturnal bioacoustics recordings, and visual censuses on the same areas. The monitoring effort was considerable: visual counts carried out represent 282 counts–sites (n = 262,030 ducks counted), bioacoustics detected 9,573 calls during 814 hours of nocturnal recording and RADAR recorded 67,368 echoes on a set of 2,128 hours of monitoring. Visual counts showed a decline in the number of birds from late January/early February. Two patterns were observed with the nocturnal recordings with a maximum or a minimum of the value of bioacoustics index on F2 and F3, depending on the years. RADAR, the most relevant method for tracking of bird movements at a population level, identified two different abundance peaks using variables ‘flight altitude > 400 m’ and ‘flight direction towards north–east/south–east’, considered as characteritics of the prenuptial migration. The first peak was detected during F1 on Site 1 only in 2007 (once every four years) and during F2 on Site 2 only in 2006 (once every four years). A second peak with a higher number of echoes was recorded on M1 (Site 1) and on M2 (Site 2). Although all methods may suffer from different biases, the combination of two new technologies complementary to visual counts provided reliable and updated data for waterfowl migration in the Mediterranean area.
topic Prenuptial migration
Waterfowl
Counts
Bioacoustics
RADAR
url http://abc.museucienciesjournals.cat/files/ABC_35-2_pp_175-188.pdf
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