The DOI matches its Crossref record; 106 of the 106 references it cites were found in a registry or an index.
Brain development, song learning and mate choice in birds: a review and experimental test of the "nutritional stress hypothesis"
Abstract
The nutritional stress hypothesis explains how learned features of song, such as complexity and local dialect structure, can serve as indicators of male quality of interest to females in mate choice. The link between song and quality comes about because the brain structures underlying song learning largely develop during the first few months post-hatching. During this same period, songbirds are likely to be subject to nutritional and other stresses. Only individuals faring well in the face of stress are able to invest the resources in brain development necessary to optimize song learning. Learned features of song thus become reliable indicators of male quality, with reliability maintained by the developmental costs of song. We review the background and assumptions of the nutritional stress hypothesis, and present new experimental data demonstrating an effect of nestling nutrition on nestling growth, brain development, and song learning, providing support for a key prediction of the hypothesis.
Overview
Integrity signals
Registry
Cites
Statistics
Verification
Claims the paper makes
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
In the citing paper
“Song output, finally, is perhaps the most energy-demanding trait, and thus particularly sensitive to environmental factors (e.g. food availability) [24,27].”
From ‘Out of tune’: consequences of inbreeding on bird song (2016) · cites this paper as [27]
Citations
Cites
Mate selection—A selection for a handicap
Zahavi, A. (1975) · Journal of Theoretical Biology · doi:10.1016/0022-5193(75)90111-3 · Cited by 5,251
Biological signals as handicaps
Grafen, A. (1990) · Journal of Theoretical Biology · doi:10.1016/s0022-5193(05)80088-8 · Cited by 2,462
Bird song: biological themes and variations
(1996) · Choice Reviews Online · doi:10.5860/choice.33-2735 · Cited by 2,170
Southern, H. N., & Lack, D. L. (1967) · Journal of Animal Ecology · doi:10.2307/2828 · Cited by 1,763
The evolution of mating preferences and the paradox of the lek
Kirkpatrick, M., & Ryan, M. J. (1991) · Nature · doi:10.1038/350033a0 · Cited by 1,315
Good genes, oxidative stress and condition–dependent sexual signals
von Schantz, T., Bensch, S., Grahn, M., Hasselquist, D., & Wittzell, H. (1999) · Proceedings of the Royal Society B Biological Sciences · doi:10.1098/rspb.1999.0597 · Cited by 885
Ricklefs, R. E. (1968) · Ibis · doi:10.1111/j.1474-919x.1968.tb00058.x · Cited by 878
Plumage coloration is a sexually selected indicator of male quality
Hill, G. E. (1991) · Nature · doi:10.1038/350337a0 · Cited by 839
THE EVOLUTION OF COSTLY MATE PREFERENCES II. THE “HANDICAP” PRINCIPLE
Iwasa, Y., Pomiankowski, A., & Nee, S. (1991) · Evolution · doi:10.1111/j.1558-5646.1991.tb02646.x · Cited by 757
A Brain for All Seasons: Cyclical Anatomical Changes in Song Control Nuclei of the Canary Brain
Nottebohm, F. (1981) · Science · doi:10.1126/science.7313697 · Cited by 753
Animal signals: information or manipulation?
Dawkins, R., & Krebs, J. R. (1978) · Cited by 751
The honesty of bird song: multiple constraints for multiple traits
Gil, D., & Gahr, M. L. (2002) · Trends in Ecology & Evolution · doi:10.1016/s0169-5347(02)02410-2 · Cited by 732
SEXUAL SELECTION AND THE EVOLUTION OF SONG
Searcy, W. A., & Andersson, M. (1986) · Annual Review of Ecology and Systematics · doi:10.1146/annurev.es.17.110186.002451 · Cited by 700
Hasselquist, D., Bensch, S., & von Schantz, T. (1996) · Nature · doi:10.1038/381229a0 · Cited by 694
Andersson, M. (1986) · Evolution · doi:10.1111/j.1558-5646.1986.tb00540.x · Cited by 638
Temporal Hierarchical Control of Singing in Birds
Yu, A. C., & Margoliash, D. (1996) · Science · doi:10.1126/science.273.5283.1871 · Cited by 600
Sexual selection unhandicapped by the fisher process
Grafen, A. (1990) · Journal of Theoretical Biology · doi:10.1016/s0022-5193(05)80087-6 · Cited by 593
Song "Dialects" in Three Populations of White-Crowned Sparrows
Marler, P., & Tamura, M. (1962) · Ornithological Applications · doi:10.2307/1365545 · Cited by 561
Song Learning, Early Nutrition and Sexual Selection in Songbirds
Nowicki, S., Peters, S. S., & Podos, J. (1998) · American Zoologist · doi:10.1093/icb/38.1.179 · Cited by 473
Female house finches prefer colourful males: sexual selection for a condition-dependent trait
Hill, G. E. (1990) · Animal Behaviour · doi:10.1016/s0003-3472(05)80537-8 · Cited by 470
Host-Parasite Evolution: General Principles and Avian Models
Lindholm, A. K., Clayton, D. H., & Moore, J. (1997) · Journal of Animal Ecology · doi:10.2307/6007 · Cited by 460
Nottebohm, F. (1972) · American Naturalist · doi:10.1086/282756 · Cited by 442
The good parent process of sexual selection
Hoelzer, G. A. (1989) · Animal Behaviour · doi:10.1016/s0003-3472(89)80146-0 · Cited by 415
The Growth and Development of Birds
Aebischer, N. J., & O’Connor, R. J. (1985) · Journal of Animal Ecology · doi:10.2307/4402 · Cited by 409
Kempenaers, B., Verheyen, G. R., & Dhondi, A. A. (1997) · Behavioral Ecology · doi:10.1093/beheco/8.5.481 · Cited by 390
The Biology of Bird-Song Dialects
Baker, M. C., & Cunningham, M. A. (1985) · Behavioral and Brain Sciences · doi:10.1017/s0140525x00019750 · Cited by 388
Malnutrition and the Brain: Changing Concepts, Changing Concerns
Levitsky, D. A., & Strupp, B. J. (1995) · Journal of Nutrition · doi:10.1093/jn/125.suppl_8.2212s · Cited by 387
Neuronal growth, atrophy and death in a sexually dimorphic song nucleus in the zebra finch brain
Konishi, M., & Akutagawa, E. (1985) · Nature · doi:10.1038/315145a0 · Cited by 382
Dishonesty and the handicap principle
Johnstone, R. A., & Grafen, A. (1993) · Animal Behaviour · doi:10.1006/anbe.1993.1253 · Cited by 377
Bird-parasite interactions: ecology, evolution, and behaviour
(1992) · Choice Reviews Online · doi:10.5860/choice.29-5685 · Cited by 369
Catchpole, C. K. (1980) · Behaviour · doi:10.1163/156853980x00366 · Cited by 360
Nottebohm, F., Nottebohm, M. E., & Crane, L. (1986) · Behavioral and Neural Biology · doi:10.1016/s0163-1047(86)90485-1 · Cited by 352
Identification of a forebrain motor programming network for the learned song of zebra finches
Vu, E. T., Mazurek, M. E., & Kuo, Y. (1994) · Journal of Neuroscience · doi:10.1523/jneurosci.14-11-06924.1994 · Cited by 341
Nottebohm, F. (1969) · Ornithological Applications · doi:10.2307/1366306 · Cited by 336
Proximate Basis of Variation in Carotenoid Pigmentation in Male House Finches
Hill, G. E. (1992) · The Auk · doi:10.2307/4088262 · Cited by 334
Ricklefs, R. E. (1983) · Elsevier eBooks · doi:10.1016/b978-0-12-249407-9.50010-7 · Cited by 334
Enquist, M. (1985) · Animal Behaviour · doi:10.1016/s0003-3472(85)80175-5 · Cited by 328
Energetic constraints on expression of carotenoid‐based plumage coloration
Hill, G. E. (2000) · Journal of Avian Biology · doi:10.1034/j.1600-048x.2000.310415.x · Cited by 301
A Test for Responsiveness to Song Structure and Programming in Female Sparrows
Searcy, W. A., & Marler, P. (1981) · Science · doi:10.1126/science.213.4510.926 · Cited by 287
Sexual selection: the handicap principle does work – sometimes
Pomiankowski, A. (1987) · Proceedings of the Royal Society B Biological Sciences · doi:10.1098/rspb.1987.0038 · Cited by 286
Smith, G. T., Brenowitz, E. A., Beecher, M. D., & Wingfield, J. C. (1997) · Journal of Neuroscience · doi:10.1523/jneurosci.17-15-06001.1997 · Cited by 282
(1993) · Proceedings of the Royal Society of London. Series B: Biological Sciences · doi:10.1098/rspb.1993.0129 · Cited by 280
Sexual selection when the female directly benefits
Price, T. D., Schluter, D., & Heckman, N. (1993) · Biological Journal of the Linnean Society · doi:10.1111/j.1095-8312.1993.tb00887.x · Cited by 264
Juvenile Foraging Proficiency, Parental Effort, and Avian Reproductive Success
Weathers, W. W., & Sullivan, K. A. (1989) · Ecological Monographs · doi:10.2307/1942600 · Cited by 261
Quantitative Analysis of Animal Vocal Phonology: an Application to Swamp Sparrow Song
Clark, C. W., Marler, P., & Beeman, K. (1987) · Ethology · doi:10.1111/j.1439-0310.1987.tb00676.x · Cited by 254
POLYGYNY IN GREAT REED WARBLERS: A LONG-TERM STUDY OF FACTORS CONTRIBUTING TO MALE FITNESS
Hasselquist, D. (1998) · Ecology · doi:10.1890/0012-9658(1998)079[2376:pigrwa]2.0.co;2 · Cited by 250
Male Song as a Cue for Mate Choice in the European Starling
Eens, M., Pinxten, R., & Verheyen, R. F. (1991) · Behaviour · doi:10.1163/156853991x00049 · Cited by 243
Ontogeny of brain nuclei controlling song learning and behavior in zebra finches
Bottjer, S., Glaessner, S., & Arnold, A. P. (1985) · Journal of Neuroscience · doi:10.1523/jneurosci.05-06-01556.1985 · Cited by 225
Song Learning in Zebra Finches (Taeniopygia guttata): Progress and Prospects
Slater, P. J. B., Eales, L. A., & Clayton, N. S. (1988) · Advances in the study of behavior · doi:10.1016/s0065-3454(08)60308-3 · Cited by 203
Song Repertoires and Lifetime Reproductive Success in the Great Tit (Parus major)
McGregor, P. K., Krebs, J. R., & Perrins, C. M. (1981) · The American Naturalist · doi:10.1086/283811 · Cited by 203
Male quality, reproduction, and survival in the great tit (Parus major)
Lambrechts, M. M., & Dhondt, A. A. (1986) · Behavioral Ecology and Sociobiology · doi:10.1007/bf00303843 · Cited by 193
Nowicki, S., Hasselquist, D., Bensch, S., & Peters, S. S. (2000) · Proceedings of the Royal Society B Biological Sciences · doi:10.1098/rspb.2000.1300 · Cited by 191
Song repertoires and sexual selection in the Red-winged Blackbird
Yasukawa, K., Blank, J. L., & Patterson, C. B. (1980) · Behavioral Ecology and Sociobiology · doi:10.1007/bf00299369 · Cited by 190
Bensch, S., Hasselquist, D., Nielsen, B., & Hansson, B. (1998) · Evolution · doi:10.1111/j.1558-5646.1998.tb03712.x · Cited by 188
SEXUAL SELECTION BY THE HANDICAP MECHANISM
Heywood, J. S. (1989) · Evolution · doi:10.1111/j.1558-5646.1989.tb02590.x · Cited by 183
Song repertoire size and female preferences in song sparrows
Searcy, W. A. (1984) · Behavioral Ecology and Sociobiology · doi:10.1007/bf00299499 · Cited by 180
Buchanan, K. L., & Catchpole, C. K. (1997) · Proceedings of the Royal Society B Biological Sciences · doi:10.1098/rspb.1997.0074 · Cited by 180
A critique of the neuroecology of learning and memory
Bolhuis, J. J., & Macphail, E. M. (2001) · Trends in Cognitive Sciences · doi:10.1016/s1364-6613(00)01753-8 · Cited by 173
Early Experience Determines Song Dialect Responsiveness of Female Sparrows
Baker, M. C., Spitler-Nabors, K. J., & Bradley, D. C. (1981) · Science · doi:10.1126/science.214.4522.819 · Cited by 173
Variation in the song rate of the male pied flycatcher Ficedula hypoleuca: causes and consequences
Gottlander, K. (1987) · Animal Behaviour · doi:10.1016/s0003-3472(87)80160-4 · Cited by 163
Differential responses to male song repertoires in female songbirds implanted with oestradiol
Catchpole, C. K., Dittami, J., & Leisler, B. (1984) · Nature · doi:10.1038/312563a0 · Cited by 162
Nordeen, E. J., & Nordeen, K. W. (1988) · Journal of Neuroscience · doi:10.1523/jneurosci.08-08-02869.1988 · Cited by 161
Repertoire size, territory acquisition and reproductive success in the song sparrow
Hiebert, S. M., Stoddard, P. K., & Arcese, P. (1989) · Animal Behaviour · doi:10.1016/0003-3472(89)90115-2 · Cited by 159
Categorical Perception of a Natural Stimulus Continuum: Birdsong
Nelson, D. A., & Marler, P. (1989) · Science · doi:10.1126/science.2727689 · Cited by 152
Female mate choice in the zebra finch ? the effect of male beak colour and male song
Collins, S. A., Hubbard, C., & Houtman, A. (1994) · Behavioral Ecology and Sociobiology · doi:10.1007/bf00167055 · Cited by 151
Singing rate and female attraction in the pied flycatcher: an experiment
Alatalo, R. V., Glynn, C., & Lundberg, A. (1990) · Animal Behaviour · doi:10.1016/s0003-3472(05)80430-0 · Cited by 148
Canady, R., Kroodsma, D. E., & Nottebohm, F. (1984) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.81.19.6232 · Cited by 144
Song as an indicator of parasitism in the sedge warbler
Buchanan, K. L., Catchpole, C. K., Lewis, J. W., & LODGE, A. (1999) · Animal Behaviour · doi:10.1006/anbe.1998.0969 · Cited by 144
Quality of song learning affects female response to male bird song
Nowicki, S., Searcy, W. A., & Peters, S. S. (2002) · Proceedings of the Royal Society B Biological Sciences · doi:10.1098/rspb.2002.2124 · Cited by 140
Lambrechts, M. M., & Dhondt, A. A. (1988) · Animal Behaviour · doi:10.1016/s0003-3472(88)80002-2 · Cited by 138
King, A. P., West, M. J., & Eastzer, D. H. (1980) · Journal of Comparative and Physiological Psychology · doi:10.1037/h0077737 · Cited by 138
Kirn, J. R., Clower, R. P., Kroodsma, D. E., & DeVoogd, T. J. (1989) · Journal of Neurobiology · doi:10.1002/neu.480200304 · Cited by 137
Sources of Variation in Growth of Tree Swallows
Quinney, T. E., Hussell, D. J. T., & Ankney, C. D. (1986) · The Auk · doi:10.1093/auk/103.2.389 · Cited by 134
Álvarez-Buylla, A., Ling, C., & Yu, W. (1994) · The Journal of Comparative Neurology · doi:10.1002/cne.903470207 · Cited by 132
Song Dialects in the Corn Bunting (Emberiza calandra)
McGregor, P. K. (2010) · Zeitschrift für Tierpsychologie · doi:10.1111/j.1439-0310.1980.tb01246.x · Cited by 125
Factors Affecting Juvenile Survival in House Sparrow Passer domesticus
Ringsby, T. H., Sæther, B., & Solberg, E. J. (1998) · Journal of Avian Biology · doi:10.2307/3677106 · Cited by 118
MOONEY, R. D., & Rao, M. S. R. (1994) · Journal of Neuroscience · doi:10.1523/jneurosci.14-11-06532.1994 · Cited by 115
Geographic Song Discrimination in Relation to Dispersal Distances in Song Sparrows
Searcy, W. A., Nowicki, S., Hughes, M., & Peters, S. S. (2002) · The American Naturalist · doi:10.1086/338509 · Cited by 114
Catchpole, C. K., Leisler, B., & Dittami, J. (1986) · Ethology · doi:10.1111/j.1439-0310.1986.tb01000.x · Cited by 111
Székely, T., Catchpole, C. K., Devoogd, A., Marchl, Z., & DeVoogd, T. J. (1996) · Proceedings of the Royal Society B Biological Sciences · doi:10.1098/rspb.1996.0091 · Cited by 107
Sexual Response of Female Great Tits to Variation in Size of Males' Song Repertoires
Baker, M. C., Bjerke, T. K., Lampe, H. U., & Espmark, Y. O. (1986) · The American Naturalist · doi:10.1086/284582 · Cited by 102
The Response of Male and Female Song Sparrows to Geographic Variation in Song
Searcy, W. A., Nowicki, S., & Hughes, M. (1997) · Ornithological Applications · doi:10.2307/1370477 · Cited by 101
Song learning in montane white-crowned sparrows: from whom and when
Baptista, L. F., & Morton, M. L. (1988) · Animal Behaviour · doi:10.1016/s0003-3472(88)80114-3 · Cited by 97
Baker, M. C., Bjerke, T. K., Lampe, H. U., & Espmark, Y. O. (1987) · Animal Behaviour · doi:10.1016/s0003-3472(87)80263-4 · Cited by 91
Song output and stimulation of the female in white-throated sparrows
Wasserman, F. E., & Cigliano, J. A. (1991) · Behavioral Ecology and Sociobiology · doi:10.1007/bf00164295 · Cited by 84
Behavioural Brain Research in Naturalistic and Semi-Naturalistic Settings
(1995) · Springer eBooks · doi:10.1007/978-94-011-0091-5 · Cited by 82
Growth and regression of thalamic efferents in the song‐control system of male zebra finches
Johnson, F., & Bottjer, S. W. (1992) · The Journal of Comparative Neurology · doi:10.1002/cne.903260309 · Cited by 81
Álvarez-Buylla, A., Ling, C., & Nottebohm, F. (1992) · Journal of Neurobiology · doi:10.1002/neu.480230406 · Cited by 81
Marler, P., & Peters, S. S. (1988) · Ethology · doi:10.1111/j.1439-0310.1988.tb00193.x · Cited by 79
Song and female choice: good genes and big brains?
Catchpole, C. K. (1996) · Trends in Ecology & Evolution · doi:10.1016/0169-5347(96)30042-6 · Cited by 79
Castro, C. A., & Rudy, J. W. (1987) · Developmental Psychobiology · doi:10.1002/dev.420200506 · Cited by 70
Blue Tit song repertoire size, male quality and interspecific competition
Doutrelant, C., Blondel, J., Perret, P., & Lambrechts, M. M. (2000) · Journal of Avian Biology · doi:10.1034/j.1600-048x.2000.310312.x · Cited by 68
Deficits in spatial memory performance induced by early undernutrition
Jordan, T. C., Cane, S., & Howells, K. F. (1981) · Developmental Psychobiology · doi:10.1002/dev.420140404 · Cited by 63
Cultural and Genetic Variation in Swamp Sparrows (Melospiza Georgiana)
Balaban, E. (1988) · Behaviour · doi:10.1163/156853988x00052 · Cited by 63
Song Repertoire Size and Male Quality in Song Sparrows
Searcy, W. A., McArthur, P. D., & Yasukawa, K. (1985) · Ornithological Applications · doi:10.2307/1366886 · Cited by 61
Spatial cue utilization in chronically malnourished rats: Task‐specific learning deficits
Goodlett, C. R., Valentino, M. L., Morgane, P. J., & Resnick, O. (1986) · Developmental Psychobiology · doi:10.1002/dev.420190102 · Cited by 58
Species recognition of song by female red-winged blackbirds
Searcy, W. A. (1990) · Animal Behaviour · doi:10.1016/s0003-3472(05)80178-2 · Cited by 55
Price, T. D. (1985) · Oecologia · doi:10.1007/bf00378307 · Cited by 55
Ricklefs, R. E. (1984) · The Auk · doi:10.1093/auk/101.2.319 · Cited by 52
Sensitive periods and circuits for learned birdsong.
Mooney, R. (1999) · Current Opinion in Neurobiology · doi:10.1016/s0959-4388(99)80015-4 · Cited by 48
Age-specific profitability and prey choice
Sullivan, K. A. (1988) · Animal Behaviour · doi:10.1016/s0003-3472(88)80038-1 · Cited by 41
Offspring number and quality in the blue tit: a quantitative genetic approach
Merilä, J., & Wiggins, D. A. (1995) · Journal of Zoology · doi:10.1111/j.1469-7998.1995.tb05018.x · Cited by 35
Nordeen, K. W., Marler, P., & Nordeen, E. J. (1989) · Journal of Neurobiology · doi:10.1002/neu.480200705 · Cited by 34
The neural basis for the acquisition and production of bird song
DeVoogd, T. J. (1994) · Cambridge University Press eBooks · doi:10.1017/cbo9780511565120.005 · Cited by 28
Free radical-induced elevation of ornithine decarboxylase activity in developing rat brain slices
Saito, K., Packianathan, S., & Longo, L. D. (1997) · Brain Research · doi:10.1016/s0006-8993(97)00414-9 · Cited by 27
Burek, M. J., Nordeen, K. W., & Nordeen, E. J. (1995) · Journal of Neurobiology · doi:10.1002/neu.480270109 · Cited by 25
Cited by
Sorted by citations
Early growth conditions, phenotypic development and environmental change
Monaghan, P. (2007) · Philosophical Transactions of the Royal Society B Biological Sciences · doi:10.1098/rstb.2007.0011 · Cited by 1,063
Boyer, P., & Liénard, P. (2006) · Behavioral and Brain Sciences · doi:10.1017/s0140525x06009332 · Cited by 601
Female mate choice based upon male motor performance
Byers, J., Hebets, E. A., & Podos, J. (2010) · Animal Behaviour · doi:10.1016/j.anbehav.2010.01.009 · Cited by 447
Vocal performance influences female response to male bird song: an experimental test
Ballentine, B. (2004) · Behavioral Ecology · doi:10.1093/beheco/arg090 · Cited by 370
The Evolution of Geographic Variation in Birdsong
Podos, J., & Warren, P. S. (2007) · Advances in the study of behavior · doi:10.1016/s0065-3454(07)37009-5 · Cited by 386
Metadata
- Authors
- S., N., W., S., & S., P.
- Venue
- Journal of Comparative Physiology A: Sensory, Neural, and Behavioral Physiology
- Published
- 2002-12-01
- Volume
- 188
- Issue
- 11-12
- Pages
- 1003-1014
- ISSN
- 0340-7594 (ISSN-L)
- 1432-1351
- OpenAlex
- W2117191589
- Cited by
- 481
- References
- 106
- Citations by year
- 2026: 7 · 2025: 8 · 2024: 12 · 2023: 5 · 2022: 16 · 2021: 15 · 2020: 13 · 2019: 23 · 2018: 29 · 2017: 26 · 2016: 29 · 2015: 60 · 2014: 29 · 2013: 28 · 2012: 21
- FWCI
- 9.72
- Type
- journal article
- Language
- en
- Open access
- closed
- Licence
- www.springer.com/tdm (tdm)
- Locations
- Journal of Comparative Physiology A (publishedVersion)
- PubMed (publishedVersion)
- Funders
- National Science Foundation
- National Institutes of Health
- Topics
- Life Sciences › Agricultural and Biological Sciences › Ecology, Evolution, Behavior and Systematics › Animal Vocal Communication and Behavior
- Life Sciences › Agricultural and Biological Sciences › Ecology, Evolution, Behavior and Systematics › Animal Behavior and Reproduction
- Physical Sciences › Environmental Science › Ecology › Avian ecology and behavior
- Keywords
- song learning, mate choice, song complexity, dialect structure, male quality, nestling growth, sexual selection
- MeSH terms
- Age Factors, Animals, Birds, Body Weight, Brain, Biological Evolution, Feathers, Female, Learning, Male, Nutritional Physiological Phenomena, Sex, Sound Spectrography, Stress, Physiological, Telencephalon, Vocalization, Animal, Voice, Prosencephalon, Statistics, Nonparametric
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review