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Bangal P, Sridhar H. Revisiting the 'nuclear species' concept: do we really know what we think we know? Philos Trans R Soc Lond B Biol Sci 2023; 378:20220108. [PMID: 37066658 PMCID: PMC10107234 DOI: 10.1098/rstb.2022.0108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 01/31/2023] [Indexed: 04/18/2023] Open
Abstract
The idea of 'nuclear species' has received a lot of attention in mixed-species flock research. Our impression of this literature is that referenced statements tend to cite the same papers in support of a small set of ideas, and often there is a mismatch between what papers contain and what they're cited for. Motivated by these impressions, we built and quantitatively examined a database of referenced statements about nuclearity in flocks. This confirmed our impression quantitatively, but more strikingly, a single paper stood out in its influence on ideas around nuclearity in flocks. Moynihan's 1962 monograph on mixed-species flocks in Panama, 'The organization and probable evolution of some mixed-species flocks of neotropical birds' published in Smithsonian Miscellaneous Collections, was cited twice as much as the next most-cited paper and was the most-cited paper for 10 out of 15 most-discussed ideas related to nuclearity. Further, a number of other highly cited papers are strongly influenced by Moynihan's ideas, i.e. its influence is much greater than what a count of citations conveys. We also found that Moynihan was mis-cited frequently. We juxtapose what we found from the citation analysis with what the paper actually contains to better understand the nature of support that Moynihan provides, and discuss the implications of our findings for what we know about and how we research nuclearity in flocks. This article is part of the theme issue 'Mixed-species groups and aggregations: shaping ecological and behavioural patterns and processes'.
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Affiliation(s)
- Priti Bangal
- Nature Conservation Foundation, Mysore 570017, Karnataka, India
| | - Hari Sridhar
- Independent Researcher, Bengaluru 560003, Karnataka, India
- Konrad Lorenz Institute for Evolution and Cognition Research, A-3400 Klosterneuburg, Austria
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2
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Jiang D, Sieving KE, Meaux E, Goodale E. Seasonal changes in mixed-species bird flocks and antipredator information. Ecol Evol 2020; 10:5368-5382. [PMID: 32607159 PMCID: PMC7319245 DOI: 10.1002/ece3.6280] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 03/28/2020] [Accepted: 03/28/2020] [Indexed: 11/18/2022] Open
Abstract
Animals acquire information produced by other species to reduce uncertainty and avoid predators. Mixed-species flocks (MSFs) of birds are ubiquitous in forest ecosystems and structured, in part, around interspecific information transfer, with "nuclear" species providing information that other species eavesdrop on. We hypothesized that in a seasonal tropical forest, the amount of information produced by birds about predation would be dynamic and particularly would decrease inside MSFs when the nuclear species leave MSFs to breed. We obtained baseline information on MSF encounter rate and species composition along established sampling routes over 9 months near the Sino-Vietnamese border. We also conducted three experiments to quantify information produced by different species in response to typical predator encounters, including a moving predator stimulus presented inside of MSFs, and a stationary predator model presented both inside and outside of MSFs. MSFs were much less frequent in the breeding season with fewer individuals of the nuclear species, David's Fulvetta (Alcippe davidi), participating, though the diversity of other species remained stable. Fulvettas were the dominant producer of alarm-related information both to the moving and stationary stimuli in MSFs and were also among the most active mobbers to stimuli presented outside of MSFs. In the breeding season, they tended to call less to the moving stimulus, and substantially fewer individuals responded to the in-flock stationary stimulus. Other species increased their own information production at stationary predator stimuli (inside and outside of MSFs) during the breeding season, perhaps due to their increased investment in offspring during this time. Yet even during the breeding season, David's Fulvetta remained the highest producer of information about predators in MSFs. Hence, while we show that information production in MSFs can be somewhat dynamic, we describe a continually asymmetric communication system, in which a nuclear species is important to the whole community.
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Affiliation(s)
- Demeng Jiang
- Guangxi Key Laboratory of Forest Ecology and ConservationCollege of ForestryGuangxi UniversityNanningChina
| | - Kathryn E. Sieving
- Department of Wildlife Ecology & ConservationUniversity of FloridaGainesvilleFLUSA
| | - Estelle Meaux
- Guangxi Key Laboratory of Forest Ecology and ConservationCollege of ForestryGuangxi UniversityNanningChina
| | - Eben Goodale
- Guangxi Key Laboratory of Forest Ecology and ConservationCollege of ForestryGuangxi UniversityNanningChina
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3
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Goodale E, Sridhar H, Sieving KE, Bangal P, Colorado Z GJ, Farine DR, Heymann EW, Jones HH, Krams I, Martínez AE, Montaño-Centellas F, Muñoz J, Srinivasan U, Theo A, Shanker K. Mixed company: a framework for understanding the composition and organization of mixed-species animal groups. Biol Rev Camb Philos Soc 2020; 95:889-910. [PMID: 32097520 PMCID: PMC7383667 DOI: 10.1111/brv.12591] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 02/02/2020] [Accepted: 02/06/2020] [Indexed: 12/19/2022]
Abstract
Mixed-species animal groups (MSGs) are widely acknowledged to increase predator avoidance and foraging efficiency, among other benefits, and thereby increase participants' fitness. Diversity in MSG composition ranges from two to 70 species of very similar or completely different phenotypes. Yet consistency in organization is also observable in that one or a few species usually have disproportionate importance for MSG formation and/or maintenance. We propose a two-dimensional framework for understanding this diversity and consistency, concentrating on the types of interactions possible between two individuals, usually of different species. One axis represents the similarity of benefit types traded between the individuals, while the second axis expresses asymmetry in the relative amount of benefits/costs accrued. Considering benefit types, one extreme represents the case of single-species groups wherein all individuals obtain the same supplementary, group-size-related benefits, and the other extreme comprises associations of very different, but complementary species (e.g. one partner creates access to food while the other provides vigilance). The relevance of social information and the matching of activities (e.g. speed of movement) are highest for relationships on the supplementary side of this axis, but so is competition; relationships between species will occur at points along this gradient where the benefits outweigh the costs. Considering benefit amounts given or received, extreme asymmetry occurs when one species is exclusively a benefit provider and the other a benefit user. Within this parameter space, some MSG systems are constrained to one kind of interaction, such as shoals of fish of similar species or leader-follower interactions in fish and other taxa. Other MSGs, such as terrestrial bird flocks, can simultaneously include a variety of supplementary and complementary interactions. We review the benefits that species obtain across the diversity of MSG types, and argue that the degree and nature of asymmetry between benefit providers and users should be measured and not just assumed. We then discuss evolutionary shifts in MSG types, focusing on drivers towards similarity in group composition, and selection on benefit providers to enhance the benefits they can receive from other species. Finally, we conclude by considering how individual and collective behaviour in MSGs may influence both the structure and processes of communities.
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Affiliation(s)
- Eben Goodale
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, 530004, China
| | - Hari Sridhar
- Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, Karnataka, 560012, India.,National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka, 560012, India
| | - Kathryn E Sieving
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, 32611, U.S.A
| | - Priti Bangal
- Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, Karnataka, 560012, India
| | - Gabriel J Colorado Z
- Departamento de Ciencias Forestales, Universidad Nacional de Colombia, Medellín, 050034, Colombia
| | - Damien R Farine
- Department of Collective Behavior, Max Planck Institute of Animal Behavior, Universitätsstrasse 10, D-78464, Konstanz, Germany.,Centre for the Advanced Study of Collective Behaviour, University of Konstanz, D-78464, Konstanz, Germany.,Department of Biology, University of Konstanz, D-78464, Konstanz, Germany
| | - Eckhard W Heymann
- Deutsches Primatenzentrum, Leibniz-Institut für Primatenforschung, D-37077, Göttingen, Germany
| | - Harrison H Jones
- Department of Biology, University of Florida, Gainesville, FL, 32611, U.S.A.,Florida Museum of Natural History, Gainesville, FL, 32611, U.S.A
| | - Indrikis Krams
- Institute of Ecology and Earth Sciences, University of Tartu, Tartu, 51410, Estonia.,Department of Zoology and Animal Ecology, Faculty of Biology, University of Latvia, Rīga, 1004, Latvia
| | - Ari E Martínez
- Department of Biological Sciences, California State University, Long Beach, CA, 90840, U.S.A
| | - Flavia Montaño-Centellas
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, 32611, U.S.A.,Instituto de Ecologia, Universidad Mayor de San Andres, La Paz, 10077, Bolivia
| | - Jenny Muñoz
- Zoology Department and Biodiversity Research Center, University of British Columbia, Vancouver, BC, V6T 1ZA, Canada
| | - Umesh Srinivasan
- Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ, 08540, U.S.A
| | - Anne Theo
- Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, Karnataka, 560012, India
| | - Kartik Shanker
- Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, Karnataka, 560012, India.,Dakshin Foundation, Bengaluru, 560092, India
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Eierman LE, Laccetti K, Melillo-Sweeting K, Kaplan JD. Interspecies pectoral fin contact between bottlenose dolphins and Atlantic spotted dolphins off Bimini, The Bahamas. Anim Behav 2019. [DOI: 10.1016/j.anbehav.2019.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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5
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Nautiyal H, Huffman MA. Interspecific Feeding Association between Central Himalayan Langurs (Semnopithecus schistaceus) and Himalayan Black Bears (Ursus thibetanus), in a Temperate Forest of the Western Indian Himalayas. MAMMAL STUDY 2018. [DOI: 10.3106/ms2017-0033] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
| | - Michael A. Huffman
- Primate Research Institute, Kyoto University 41-2 Kanrin, Inuyama, Aichi 484-8506, Japan
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Nonlethal predator effects on the turn-over of wild bird flocks. Sci Rep 2016; 6:33476. [PMID: 27633495 PMCID: PMC5025840 DOI: 10.1038/srep33476] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 08/25/2016] [Indexed: 11/18/2022] Open
Abstract
Nonlethal predator effects arise when individuals of a prey species adjust their behaviour due to the presence of predators. Non-lethal predator effects have been shown to affect social group structure and social behaviour as well as individual fitness of the prey. In this experimental study, we used model sparrowhawks to launch attacks on flocks of wild great tits and blue tits whilst monitoring their social dynamics. We show that nonlethal attacks caused instantaneous turn-over and mixing of group composition within foraging flocks. A single experimental ‘attack’ lasting on average less than three seconds, caused the amount of turn-over expected over three hours (2.0–3.8 hours) of undisturbed foraging. This suggests that nonlethal predator effects can greatly alter group composition within populations, with potential implications for social behaviour by increasing the number of potential interaction partners, as well as longer-term consequences for pair formation and emergent effects determined by social structure such as information and disease transmission. We provide the first evidence, to our knowledge, based on in depth monitoring of a social network to comprehensively support the hypothesis that predators influence the social structure of groups, which offers new perspectives on the key drivers of social behaviour in wild populations.
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Brauze T, Zieliński J. Do forest birds take the risk of feeding in an open area in winter? Experiment with extra food gradually moved away from the edge of the forest into the open area. RUSS J ECOL+ 2016. [DOI: 10.1134/s1067413616020053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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8
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Sridhar H, Shanker K. Importance of intraspecifically gregarious species in a tropical bird community. Oecologia 2014; 176:763-70. [PMID: 25182930 DOI: 10.1007/s00442-014-3045-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 08/11/2014] [Indexed: 10/24/2022]
Abstract
In both single- and mixed-species social groups, certain participants are known to play important roles in providing benefits. Identifying these participants is critical for understanding group dynamics, but is often difficult with large roving social groups in the wild. Here, we develop a new approach to characterize roles in social groups and apply it to mixed-species bird flocks (flocks hereafter) in an Indian tropical evergreen forest. Two types of species, namely intraspecifically gregarious and sallying species, are thought to play important roles in flocks because studies have shown they attract other flock participants. However, it is unclear why these types are attractive and whether they are essential for flock formation. We address these questions by focusing on the composition of the subset of flocks containing only two species each. In two-species flocks, it is reasonable to assume that at least one species obtains some kind of benefit. Therefore, only those species combinations that result in benefit to at least one species should occur as two-species flocks. Using data from 540 flocks overall, of which 158 were two-species flocks, we find that intraspecifically gregarious species are disproportionately represented in two-species flocks and always lead flocks when present, and that flocks containing them are joined significantly more by other species. Our results suggest that intraspecifically gregarious species are likely to be the primary benefit providers in flocks and are important for tropical flock formation. Our study also provides a new approach to understanding importance in other mixed-species and single-species social groups.
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Affiliation(s)
- Hari Sridhar
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560012, India,
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9
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Heymann EW, Hsia SS. Unlike fellows - a review of primate-non-primate associations. Biol Rev Camb Philos Soc 2014; 90:142-56. [PMID: 24661546 DOI: 10.1111/brv.12101] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 02/11/2014] [Accepted: 02/23/2014] [Indexed: 11/27/2022]
Abstract
Throughout many regions of the tropics, non-primate animals - mainly birds and mammals - have been observed to follow primate groups and to exploit dropped food and flushed prey. The anecdotal nature of most of the numerous reports on these primate-non-primate associations (PNPAs) may obscure the biological significance of such associations. We review the existing literature and test predictions concerning the influence of primate traits (body size, activity patterns, dietary strategies, habitat, group size) on the occurrence of PNPAs. Furthermore, we examine the influence of non-primates' dietary strategies on the occurrence of PNPAs, and the distribution of benefits and costs. We detected a strong signal in the geographic distribution of PNPAs, with a larger number of such associations in the Neotropics compared to Africa and Asia. Madagascar lacks PNPAs altogether. Primate body size, activity patterns, habitat and dietary strategies as well as non-primate dietary strategies affect the occurrence of PNPAs, while primate group size did not play a role. Benefits are asymmetrically distributed and mainly accrue to non-primates. They consist of foraging benefits through the consumption of dropped leaves and fruits and flushed prey, and anti-predation benefits through eavesdropping on primate alarm calls and vigilance. Where quantitative information is available, it has been shown that benefits for non-primates can be substantial. The majority of PNPAs can thus be categorized as cases of commensalism, while mutualism is very rare. Our review provides evidence that the ecological function of primates extends beyond their manifold interactions with plants, but may remain underestimated.
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Affiliation(s)
- Eckhard W Heymann
- Abteilung Verhaltensökologie & Soziobiologie, Deutsches Primatenzentrum, Kellnerweg 4, D-37077, Göttingen, Germany
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10
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Using intra-flock association patterns to understand why birds participate in mixed-species foraging flocks in terrestrial habitats. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1633-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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11
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Farine DR, Milburn PJ. Social organisation of thornbill-dominated mixed-species flocks using social network analysis. Behav Ecol Sociobiol 2012. [DOI: 10.1007/s00265-012-1452-y] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Affiliation(s)
- Rachele Malavasi
- a Department of Basic Sciences and Foundations , University of Urbino , Urbino , Italy
| | - Almo Farina
- a Department of Basic Sciences and Foundations , University of Urbino , Urbino , Italy
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Jones EI, Bronstein JL, Ferrière R. The fundamental role of competition in the ecology and evolution of mutualisms. Ann N Y Acad Sci 2012; 1256:66-88. [PMID: 22583047 DOI: 10.1111/j.1749-6632.2012.06552.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mutualisms are interspecific interactions that yield reciprocal benefits. Here, by adopting a consumer-resource perspective, we show how considering competition is necessary in order to understand the evolutionary and ecological dynamics of mutualism. We first review the ways in which competition shapes the ecology of mutualisms, using a graphical framework based on resource flows rather than net effects to highlight the opportunities for competition. We then describe the known mechanisms of competition and show how it is a critical driver of the evolutionary dynamics, persistence, and diversification of mutualism. We argue that empirical and theoretical research on the ecology and evolution of mutualisms will jointly progress by addressing four key points: (i) the existence and shape of physiological trade-offs among cooperation, competition, and other life-history and functional traits; (ii) the capacity for individuals to express conditional responses to variation in their mutualistic and competitive environment; (iii) the existence of heritable variation for mutualistic and competitive traits and their potentially conditional expression; and (iv) the structure of the network of consumer-resource interactions in which individuals are embedded.
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Affiliation(s)
- Emily I Jones
- School of Biological Sciences, Washington State University, Pullman, Washington 99164, USA.
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Newson SE, Rexstad EA, Baillie SR, Buckland ST, Aebischer NJ. Population change of avian predators and grey squirrels in England: is there evidence for an impact on avian prey populations? J Appl Ecol 2010. [DOI: 10.1111/j.1365-2664.2010.01771.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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15
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Sridhar H, Beauchamp G, Shanker K. Why do birds participate in mixed-species foraging flocks? A large-scale synthesis. Anim Behav 2009. [DOI: 10.1016/j.anbehav.2009.05.008] [Citation(s) in RCA: 222] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Morgan T, Fernández-Juricic E. The Effects of Predation Risk, Food Abundance, and Population Size on Group Size of Brown-Headed Cowbirds (Molothrus ater). Ethology 2007. [DOI: 10.1111/j.1439-0310.2007.01419.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Affiliation(s)
- Alexander M. Mills
- Department of Zoology, University of Toronto, 25 Harbord Street, Toronto, Ontario, M5S 3G5 Canada
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18
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Abstract
Adaptive hypotheses for the evolution of flocking in birds have usually focused on predation avoidance or foraging enhancement. It still remains unclear to what extent each factor has contributed to the evolution of flocking. If predation avoidance were the sole factor involved, flocking should not be prevalent when predation is relaxed. I examined flocking tendencies along with mean and maximum flock size in species living on islands where predation risk is either absent or negligible and then compared these results with matched counterparts on the mainland. The dataset consisted of 46 pairs of species from 22 different islands across the world. The tendency to flock was retained on islands in most species, but in pairs with dissimilar flocking tendencies, island species were less likely to flock. Mean and maximum flock size were smaller on islands than on the mainland. Potential confounding factors such as population density, nest predation, habitat type, food type and body mass failed to account for the results. The results suggest that predation is a significant factor in the evolution of flocking in birds. Nevertheless, predation and other factors, such as foraging enhancement, probably act together to maintain the trait in most species.
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Affiliation(s)
- Guy Beauchamp
- Faculty of Veterinary Medicine, University of Montreal, PO Box 5000, St-Hyacinthe, Quebec 72S 7C6, Canada.
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Gibson RM, Aspbury AS, McDaniel LL. Active formation of mixed-species grouse leks: a role for predation in lek evolution? Proc Biol Sci 2002; 269:2503-7. [PMID: 12573063 PMCID: PMC1691199 DOI: 10.1098/rspb.2002.2187] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Behavioural ecologists have interpreted avian leks as products of sexual selection, in which males display socially to increase their opportunities to mate. However, without invoking reproductive queuing or kin selection, this paradigm does not necessarily explain why many males that fail to mate participate in leks. An alternative solution, that males also aggregate to reduce predation, has previously lacked compelling support. We show that mixed-species leks, comprising two congeneric grouse, form when single males or small groups of one species, the greater prairie chicken Tympanuchus cupido, join leks of another, the sharp-tailed grouse T. phasianellus. We documented the process by observing lek dynamics and comparing group sizes between mixed- and single-species leks. Joining implies that prairie chickens benefit from displaying with sharp-tailed grouse. The numbers of females of each species attending a lek increased with the number of conspecific, but not heterospecific, males. This suggests that the joining of heterospecifics is unlikely to increase mating opportunities, and leaves lowered predation risk as the most likely benefit of associating with heterospecifics. Active formation of mixed-species leks therefore suggests that predation may be sufficient to drive lek formation. The benefits of participation in mixed leks may be asymmetrical because prairie chickens display more and are less vigilant than sharp-tailed grouse.
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Affiliation(s)
- Robert M Gibson
- School of Biological Sciences, 348 Manter Hall, University of Nebraska-Lincoln, NE 68588-0118, USA.
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20
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Nakamura M, Shindo N. Effects of snow cover on the social and foraging behavior of the great tit Parus major. Ecol Res 2001. [DOI: 10.1046/j.1440-1703.2001.00397.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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22
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Ragusa-Netto J. Raptors and "campo-cerrado" bird mixed flock LED BY Cypsnagra hirundinacea (Emberizidae:Thraupinae). REVISTA BRASILEIRA DE BIOLOGIA 2000; 60:461-7. [PMID: 11188872 DOI: 10.1590/s0034-71082000000300011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bird mixed flocks including Cypsnagra hirundinacea and Neothraupis fasciata as species with sentinels were studied in "campo-cerrado" in order to investigate the possible relationship between alertness and the mixed flock leadership. This study was conducted from March to September 1996 and mixed flocks were observed on average for 2:30h. The time with sentinels were recorded for C. hirundinacea and N. fasciata. The sentinels of Cypsnagra hirundinacea performed most of the vigilance (time with sentinel was on average 42 +/- 17%, 41 +/- 17% of which by C. hirundinacea, whereas only 1.2% by N. fasciata) and gave all the alarm calls recorded (54% of the encounters with raptors stimulated alarm calls). A relationship was verified between time with sentinel and the rate of encounters with raptor (ANOVA, F = 3.0. P < 0.05). The results of this study are an evidence for the anti-predatory function of mixed flocks, in campo-cerrado, and the alertness as a major feature of a leader species, since C. hirundinacea always led those flocks.
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Barta Z, Giraldeau LA. Daily Patterns of Optimal Producer and Scrounger Use under Predation Hazard: A State-Dependent Dynamic Game Analysis. Am Nat 2000; 155:570-582. [PMID: 10753082 DOI: 10.1086/303342] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Feeding in groups often gives rise to joining: feeding from other's discoveries. The joining decision has been modeled as a producer-scrounger game where the producer strategy consists of searching for one's food and the scrounger strategy consists of searching for food discovered by others. Previous models revealed that the evolutionarily stable proportion of scrounging mostly depends on the fraction of each food patch available only to its producer. These early models are static and state independent and are therefore unable to explore whether the time of day, the animal's state, and the degree of predation hazard influence an individual's decision of whether to use the producer or scrounger strategy. To investigate these issues, we developed a state-dependent dynamic producer-scrounger game model. The model predicts that, early in the day, low reserves promote a preference for the scrounger strategy, while the same condition late in the day favors the use of the producer strategy. Under rich and clumped food, the availability of scrounging can improve the daily survival of any average group member. The model suggests only weak effects of predation hazard on the use of scrounging. Future developments should consider the effects of dominance asymmetries and allowing foragers a choice between foraging alone or in a group harboring an evolutionarily stable frequency of scrounger.
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Dolby AS. Benefits to satellite members in mixed-species foraging groups: an experimental analysis. Anim Behav 1998; 56:501-509. [PMID: 9787042 DOI: 10.1006/anbe.1998.0808] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypotheses proposed to explain the formation of mixed-species foraging groups have focused on both foraging and antipredation benefits. Mixed-species flocks of bark-foraging birds form during the winter in the eastern deciduous forests of North America. These flocks are composed of two parid nuclear species, tufted titmice, Baeolophus bicolor, and either Carolina or black-capped chickadees, Poecile carolinensis or P. atricapillus, and several satellite species including downy woodpeckers, Picoides pubescens, and white-breasted nuthatches, Sitta carolinensis. The parid nuclear species seem to act as flock leaders and are closely followed by the satellite species. To elucidate what advantages downy woodpeckers and white-breasted nuthatches gain by flocking with parids, we removed parids from eight Ohio woodlots isolated by surrounding agricultural fields and compared the woodpeckers and nuthatches in these woodlots to those in eight controls. We tested four predictions generated by group-foraging hypotheses: compared with controls, satellite birds in treatment woodlots should (1) forage more in microclimates that reduce metabolic costs, (2) increase their vigilance, (3) exhibit reduced nutritional condition and (4) exhibit higher mortality rates. As predicted, female downy woodpeckers in treatment woodlots tended to forage in locations that were more sheltered from wind, presumably thereby reducing metabolic costs. Treatment males and females of both species significantly increased their vigilance. Finally, in the absence of parids, male nuthatches showed significantly reduced nutritional condition according to ptilochronology analysis of feathers grown during the experimental manipulation, and tended to exhibit increased mortality Copyright 1998 The Association for the Study of Animal Behaviour
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Affiliation(s)
- AS Dolby
- Behavioral Ecology Group, Department of Zoology, The Ohio State University
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Beauchamp G, Giraldeau LA, Ennis N. Experimental evidence for the maintenance of foraging specializations by frequency-dependent choice in flocks of spice finches. ETHOL ECOL EVOL 1997. [DOI: 10.1080/08927014.1997.9522890] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Poulsen BO. Movements of single birds and mixed‐species flocks between isolated fragments of cloud forest in Ecuador. STUDIES ON NEOTROPICAL FAUNA AND ENVIRONMENT 1994. [DOI: 10.1080/01650529409360927] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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