Effect of group size on individual and collective vigilance in greater rheas

We studied the effect of group size on the proportion of time that greater rheas, Rhea americana, allocated to vigilance and feeding during the non-breeding season. We tested whether: (1) the proportion of time that one bird allocates to vigilance (individual vigilance) decreases with group size, an...

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Autores principales:	Fernandez, Gustavo Javier, Capurro, Angel Francisco, Reboreda, Juan Carlos
Publicado:	2003
Materias:	feeding behavior group size time allocation vigilance Aves Rhea Rhea americana Rheiformes
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01791613_v109_n5_p413_Fernandez http://hdl.handle.net/20.500.12110/paper_01791613_v109_n5_p413_Fernandez
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_01791613_v109_n5_p413_Fernandez
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spelling	paper:paper_01791613_v109_n5_p413_Fernandez2023-06-08T15:19:26Z Effect of group size on individual and collective vigilance in greater rheas Fernandez, Gustavo Javier Capurro, Angel Francisco Reboreda, Juan Carlos feeding behavior group size time allocation vigilance Aves Rhea Rhea americana Rheiformes We studied the effect of group size on the proportion of time that greater rheas, Rhea americana, allocated to vigilance and feeding during the non-breeding season. We tested whether: (1) the proportion of time that one bird allocates to vigilance (individual vigilance) decreases with group size, and (2) the proportion of time that at least one bird of the group is vigilant (collective vigilance) increases with group size. We analyzed video-recordings of birds that were foraging alone or in groups from two to 12 birds. The proportion of time allocated to individual vigilance decreased and the proportion of time spent feeding increased with group size. In both cases the main significant difference was between birds foraging alone and in groups. Collective vigilance did not vary with group size and it was lower than expected if vigilance bouts were random or sequential. Our results indicate that rheas foraging in large groups would not receive the benefit of an increase in collective vigilance, although they could still benefit from a reduction of predation risk by the dilution effect. Fil:Fernández, G.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Capurro, A.F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Reboreda, J.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2003 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01791613_v109_n5_p413_Fernandez http://hdl.handle.net/20.500.12110/paper_01791613_v109_n5_p413_Fernandez
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	feeding behavior group size time allocation vigilance Aves Rhea Rhea americana Rheiformes
spellingShingle	feeding behavior group size time allocation vigilance Aves Rhea Rhea americana Rheiformes Fernandez, Gustavo Javier Capurro, Angel Francisco Reboreda, Juan Carlos Effect of group size on individual and collective vigilance in greater rheas
topic_facet	feeding behavior group size time allocation vigilance Aves Rhea Rhea americana Rheiformes
description	We studied the effect of group size on the proportion of time that greater rheas, Rhea americana, allocated to vigilance and feeding during the non-breeding season. We tested whether: (1) the proportion of time that one bird allocates to vigilance (individual vigilance) decreases with group size, and (2) the proportion of time that at least one bird of the group is vigilant (collective vigilance) increases with group size. We analyzed video-recordings of birds that were foraging alone or in groups from two to 12 birds. The proportion of time allocated to individual vigilance decreased and the proportion of time spent feeding increased with group size. In both cases the main significant difference was between birds foraging alone and in groups. Collective vigilance did not vary with group size and it was lower than expected if vigilance bouts were random or sequential. Our results indicate that rheas foraging in large groups would not receive the benefit of an increase in collective vigilance, although they could still benefit from a reduction of predation risk by the dilution effect.
author	Fernandez, Gustavo Javier Capurro, Angel Francisco Reboreda, Juan Carlos
author_facet	Fernandez, Gustavo Javier Capurro, Angel Francisco Reboreda, Juan Carlos
author_sort	Fernandez, Gustavo Javier
title	Effect of group size on individual and collective vigilance in greater rheas
title_short	Effect of group size on individual and collective vigilance in greater rheas
title_full	Effect of group size on individual and collective vigilance in greater rheas
title_fullStr	Effect of group size on individual and collective vigilance in greater rheas
title_full_unstemmed	Effect of group size on individual and collective vigilance in greater rheas
title_sort	effect of group size on individual and collective vigilance in greater rheas
publishDate	2003
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01791613_v109_n5_p413_Fernandez http://hdl.handle.net/20.500.12110/paper_01791613_v109_n5_p413_Fernandez
work_keys_str_mv	AT fernandezgustavojavier effectofgroupsizeonindividualandcollectivevigilanceingreaterrheas AT capurroangelfrancisco effectofgroupsizeonindividualandcollectivevigilanceingreaterrheas AT reboredajuancarlos effectofgroupsizeonindividualandcollectivevigilanceingreaterrheas
_version_	1768546489464782848

Effect of group size on individual and collective vigilance in greater rheas

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