Nest-site characteristics of Rufous Hornero (Furnarius rufus) across its distribution as reported by citizen scientists

Lucia Mentesana; Nico M. Adreani

doi:10.56178/eh.v41i1.1540

Articles Published 02 July 2026 https://doi.org/10.56178/eh.v41i1.1540

Nest-site characteristics of Rufous Hornero (Furnarius rufus) across its distribution as reported by citizen scientists

breeding domed nests Furnariidae nesting biology suboscine

Lucia Mentesana Facultad de Ciencias, Universidad de la República, Uruguay | Max Planck Institute of Animal Behavior, Konstanz, Germany

Nico M. Adreani Facultad de Ciencias, Universidad de la República, Uruguay | Max Planck Institute of Animal Behavior, Konstanz, Germany

Abstract

Nests provide a secure place for eggs and offspring, offer camouflage and defense against predators, and can also help moderate the microenvironment. Although most nests serve similar functions, nest traits can vary widely across and within species. While nest architecture is largely constrained by genetics, nest-site characteristics are more strongly shaped by external factors and are therefore expected to vary with environmental conditions. Yet most evidence for this pattern comes from comparative studies across species, while large-scale spatial variation within species remains understudied. Here, we described the nest-site characteristics of 13,325 Rufous Hornero nests (Furnarius rufus) reported by citizen scientists across the species’ entire distribution. We characterized nest height, nest substrate type (natural vs artificial), and nest cover (covered vs uncovered) across urban, rural, and natural areas. We also examined how nest height and nest cover varied along latitudinal and longitudinal gradients within each environment, as well as the relationship between nest cover and nest height across these three environmental contexts. We found that nest height tended to be similar in natural, rural, and urban areas; that horneros in rural and urban areas more frequently built nests on artificial substrates, whereas nests in natural areas were more often built on natural substrates; that uncovered nests were more common in urban and rural areas, while in natural areas covered and uncovered nests occurred in similar proportions; that nest height and cover varied geographically, especially for rural and urban populations; and that, regardless of environmental context, higher nests and nests built on artificial substrates were more likely to be uncovered than those closer to the ground or built on natural substrates. Overall, our results show that horneros exhibit substantial flexibility in nest-site characteristics across environments, raising questions about whether this variation reflects nest-site preferences, availability of breeding sites, or both.

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References

Adreani NM, Valcu M, Scientists C, Mentesana L (2022) Asymmetric architecture is non-random and repeatable in a bird’s nests. Current Biology 32:R412-R413. https://doi.org/10.1016/j.cub.2022.03.075
Adreani NM, Morales V, Mentesana L (2025) External structures at the nest site predict nest’s asymmetric architecture in mud- building birds. Ibis. https://doi.org/10.1111/ibi.70064
Bailey RL, Larson L, Bonter DN (2024) NestWatch: An open-access, long-term data set on avian reproductive success. Ecology 105:e4230. https://doi.org/10.1002/ecy.4230
Bates D, Mächler M, Bolker BM, Walker SC (2015) Fitting Linear Mixed-Effects Models using lme4. Journal of Statistical Software 67:1-48. https://doi.org/10.18637/jss.v067.i01
Becker ME, Weisberg PJ (2014) Synergistic effects of spring temperatures and land cover on nest survival of urban birds. Condor Ornithological Applications 117:18-30. https://doi.org/10.1650/CONDOR-14-1.1
Collias NE, Collias EC (1986) Nest Building and Bird Behavior. Princeton University Press, Princeton
Deeming DC, Reynolds SJ (2016) Nests, eggs, and incubation : new ideas about avian reproduction. Oxford: Oxford University Press, United Kingdom
Delhey K (2018) Nest webs beyond woodpeckers: the ecological role of other nest builders. Ecology 99:985-988. https://doi.org/10.1002/ecy.2108
Diniz P, Macedo RH, Webster MS (2019) Duetting correlates with territory quality and reproductive success in a suboscine bird with low extra-pair paternity. Auk 136(1):p.uky004. https://doi.org/10.1093/auk/uky004
Fang Y-T, Tuanmu M-N, Hung C-M (2018) Asynchronous evolution of interdependent nest characters across the avian phylogeny. Nature Communications 9:1863. https://doi.org/10.1038/s41467-018-04265-x
Fraga RM (1980) The breeding of Rufous Horneros (Furnarius rufus). Condor 82:58-68. https://doi.org/10.2307/1366785
Garreta L, Rivas-Ortiz N (2026) Primer registro de depredación de un nido de Hornero (Furnarius rufus) por un Carancho (Caracara plancus). Nuestras Aves 71. https://doi.org/10.56178/na.v71i.1186
Gelman A, Hill J (2007) Data analysis using regression and multilevel/hierarchical models. Cambridge University Press, Cambridge
Gelman A, Yu-Sung S (2015) arm: Data Analysis Using Regression and Multilevel/Hierarchical Models. R package version 1.8-5. [URL: https://cran.r-project.org/package=arm]
Guillette LM, Healy SD (2015) Nest building, the forgotten behaviour. Current Opinion in Behavioral Sciences 6:90-96. https://doi.org/10.1016/j.cobeha.2015.10.009
Hansell MH (2000) Bird nests and construction behaviour. Cambridge University Press, Cambridge
Hansell MH (2005) Animal architecture. Oxford University Press, Oxford
Hartig F (2024) DHARMa: Residual Diagnostics for Hierarchical (Multi-Level / Mixed) Regression Models_. R package version 0.4.7. [URL: http://florianhartig.github.io/DHARMa]
Healy SD, Tello-Ramos MC, Hébert M (2023) Bird nest building: visions for the future. Philosophical Transactions of the Royal Society B Biological Science 378(1884):20220157. https://doi.org/10.1098/rstb.2022.0157
INaturalist (2025) [URL: https://www.inaturalist.org] (10/10/2025)
Indykiewicz P (1991) Nests and nest-sites of the house sparrow Passer domesticus (Linnaeus, 1758) in urban, suburban and rural environments. Acta Zoologica Cracoviensia 34(2):475-495
Jara RF, Crego RD, Samuel MD, Rozzi R, Jiménez JE (2020) Nest-site selection and breeding success of passerines in the world’s southernmost forests. PeerJ 8:e9892. https://doi.org/10.7717/peerj.9892
Korner-Nievergelt F, Roth T, von Felten S, Guélat J, Almasi B, Korner-Nievergelt (2015) Bayesian data analysis in ecology using linear models with R, BUGS, and Stan. Academic Press, London
Loss SR, Li B V, Horn LC, et al (2023) Citizen science to address the global issue of bird–window collisions. Frontiers in Ecology and the Environment 21(9):418-427. https://doi.org/10.1002/fee.2614
Mainwaring MC, Hartley IR, Lambrechts MM, Deeming DC (2014) The design and function of birds’ nests. Ecology and Evolution 4(20):3909-3928. https://doi.org/10.1002/ece3.1054
Mainwaring MC, Barber I, Deeming DC, Pike DA, Roznik EA, Hartley IR (2016) Climate change and nesting behaviour in vertebrates : a review of the ecological threats and potential for adaptive responses. Biological Reviews 92(4):1991-2002. https://doi.org/10.1111/brv.12317
Mainwaring MC (2017) Causes and consequences of intraspecific variation in nesting behaviors: insights from blue tits and great tits. Frontiers in Ecology and Evolution 5:39. https://doi.org/10.3389/fevo.2017.00039
Mainwaring MC, Medina I, Tobalske BW, Hartley IR, Varricchio DJ, Hauber ME (2023) The evolution of nest site use and nest architecture in modern birds and their ancestors. Philosophical Transactions of the Royal Society B: Biological Science 378:20220143. https://doi.org/10.1098/rstb.2022.0143
Martin TE, Boyce AJ, Fierro-Calderón K, Mitchell AE, Armstad CE, Mouton JC, Bin Soudi EE (2017) Enclosed nests may provide greater thermal than nest predation benefits compared with open nests across latitudes. Functional Ecology 31(6):1231-1240. https://doi.org/10.1111/1365-2435.12819
Mason P (1985) The Nesting Biology of Some Passerines of Buenos Aires, Argentina. Ornithological Monographs 36:954-972. https://doi.org/10.2307/40168328
Massoni V, Reboreda JC, López GC, Aldatz MF (2012) High coordination| and equitable parental effort in the Rufous Hornero. Condor 114(3):564-570. https://doi.org/10.1525/cond.2012.110135
Mentesana L, Moiron M, Guedes E, Cavalli E, Tassino B, Adreani NM (2020) Defending as a unit: sex- and context-specific territorial defence in a duetting bird. Behavioral Ecology and Sociobiology 74:1–11. https://doi.org/10.1007/s00265-020-02891-4
Mentesana L, Amador A, Amorim P, Delhey K, Diniz P, Fraga R, Mindlin GB, Reboreda JC, Schaaf A, Tassino B, Adreani NM (2024) Biology of the Rufous Hornero, from mechanisms to behavioral ecology: a potential Neotropical model species? Journal of Field Ornithology 95(4):2. https://doi.org/10.5751/jfo-00544-950402
Mentesana L, Adreani NM (2026) Data and Code for “Nest-site characteristics of Rufous Hornero (Furnarius rufus) across its distribution as reported by citizen scientists”. In Hornero. Zenodo. https://doi.org/10.5281/zenodo.21100861
Perez DM, Manica LT, Medina I (2023) Variation in nest-building behaviour in birds: a multi-species approach. hilosophical Transactions of the Royal Society B: Biological Science 378(1884):20220145. https://doi.org/10.1098/rstb.2022.0145
R Core Team (2021) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. [URL: http://www.R-project.org/]
Remsen Jr JV., Bonan Barfull A (2020) Rufous Hornero (Furnarius rufus), version 1.0. In: del Hoyo J, Elliott A, Sargatal J, Christie DA, de Juana E (eds). Birds of the World. https://doi.org/10.2173/bow.rufhor2.01
Reynolds JS, Ibáñez-Álamo J, Sumasgutner P, Mainwaring MC (2019) Urbanisation and nest building in birds: a review of threats and opportunities. Journal of Ornithology 160:841-860. https://doi.org/10.1007/s10336-019-01657-8
Schaaf AA, García CG, Puechagut PB, et al. (2018) Effect of geographical latitude and sun exposure on Rufous Hornero (Furnarius rufus) nest orientation. Journal of Ornithology 159:967-974. https://doi.org/10.1007/s10336-018-1569-5
Sheard C, Street SE, Healy SD, et al (2024) Nest traits for the world’s birds. Global Ecology and Biogeography 33(2):206–214. https://doi.org/10.1111/geb.13783
Sullivan BL, Wood CL, Iliff MJ, Bonney RE, Fink D, Kelling S (2009) eBird: a citizen-based bird observation network in the biological sciences. Biological Conservation 142(10):2282-2292
Vincze E, Seress G, Lagisz M, Nakagawa S, Dingemanse NJ, Sprau (2017) Does urbanization affect predation of bird nests? A meta-analysis. Frontiers in Ecology and Evolution 5:29. https://doi.org/10.3389/fevo.2017.00029
Wang Y, Chen S, Jiang P, Ding P (2008) Black-billed Magpies (Pica pica) adjust nest characteristics to adapt to urbanization in Hangzhou, China. Canadian Journal of Zoology 86(7):676-684. https://doi.org/10.1139/Z08-045
WikiAves (2026) João-de-barro (Furnarius rufus). [URL: https://www.wikiaves.com.br/wiki/joao-de-barro] (10/10/2025)
Winkler DW, Billerman SM, Lovette IJ (2020) Ovenbirds and Woodcreepers (Furnariidae), version 1.0. In: Billerman SM, Keeney BK, Rodewald PG, Schulenberg TS (eds). Birds of the World. Cornell Lab of Ornithology, Ithaca. https://doi.org/10.2173/bow.furnar2.01

How to cite

Lucia Mentesana, Nico M. Adreani (2026). Nest-site characteristics of Rufous Hornero (Furnarius rufus) across its distribution as reported by citizen scientists. El Hornero, Vol. 41 No. 1 (2026), 131-142. https://doi.org/10.56178/eh.v41i1.1540

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[1] Adreani NM, Valcu M, Scientists C, Mentesana L (2022) Asymmetric architecture is non-random and repeatable in a bird’s nests. Current Biology 32:R412-R413. https://doi.org/10.1016/j.cub.2022.03.075

[2] Adreani NM, Morales V, Mentesana L (2025) External structures at the nest site predict nest’s asymmetric architecture in mud- building birds. Ibis. https://doi.org/10.1111/ibi.70064

[3] Bailey RL, Larson L, Bonter DN (2024) NestWatch: An open-access, long-term data set on avian reproductive success. Ecology 105:e4230. https://doi.org/10.1002/ecy.4230

[4] Bates D, Mächler M, Bolker BM, Walker SC (2015) Fitting Linear Mixed-Effects Models using lme4. Journal of Statistical Software 67:1-48. https://doi.org/10.18637/jss.v067.i01

[5] Becker ME, Weisberg PJ (2014) Synergistic effects of spring temperatures and land cover on nest survival of urban birds. Condor Ornithological Applications 117:18-30. https://doi.org/10.1650/CONDOR-14-1.1

[6] Collias NE, Collias EC (1986) Nest Building and Bird Behavior. Princeton University Press, Princeton

[7] Deeming DC, Reynolds SJ (2016) Nests, eggs, and incubation : new ideas about avian reproduction. Oxford: Oxford University Press, United Kingdom

[8] Delhey K (2018) Nest webs beyond woodpeckers: the ecological role of other nest builders. Ecology 99:985-988. https://doi.org/10.1002/ecy.2108

[9] Diniz P, Macedo RH, Webster MS (2019) Duetting correlates with territory quality and reproductive success in a suboscine bird with low extra-pair paternity. Auk 136(1):p.uky004. https://doi.org/10.1093/auk/uky004

[10] Fang Y-T, Tuanmu M-N, Hung C-M (2018) Asynchronous evolution of interdependent nest characters across the avian phylogeny. Nature Communications 9:1863. https://doi.org/10.1038/s41467-018-04265-x

[11] Fraga RM (1980) The breeding of Rufous Horneros (Furnarius rufus). Condor 82:58-68. https://doi.org/10.2307/1366785

[12] Garreta L, Rivas-Ortiz N (2026) Primer registro de depredación de un nido de Hornero (Furnarius rufus) por un Carancho (Caracara plancus). Nuestras Aves 71. https://doi.org/10.56178/na.v71i.1186

[13] Gelman A, Hill J (2007) Data analysis using regression and multilevel/hierarchical models. Cambridge University Press, Cambridge

[14] Gelman A, Yu-Sung S (2015) arm: Data Analysis Using Regression and Multilevel/Hierarchical Models. R package version 1.8-5. [URL: https://cran.r-project.org/package=arm]

[15] Guillette LM, Healy SD (2015) Nest building, the forgotten behaviour. Current Opinion in Behavioral Sciences 6:90-96. https://doi.org/10.1016/j.cobeha.2015.10.009

[16] Hansell MH (2000) Bird nests and construction behaviour. Cambridge University Press, Cambridge

[17] Hansell MH (2005) Animal architecture. Oxford University Press, Oxford

[18] Hartig F (2024) DHARMa: Residual Diagnostics for Hierarchical (Multi-Level / Mixed) Regression Models_. R package version 0.4.7. [URL: http://florianhartig.github.io/DHARMa]

[19] Healy SD, Tello-Ramos MC, Hébert M (2023) Bird nest building: visions for the future. Philosophical Transactions of the Royal Society B Biological Science 378(1884):20220157. https://doi.org/10.1098/rstb.2022.0157

[20] INaturalist (2025) [URL: https://www.inaturalist.org] (10/10/2025)

[21] Indykiewicz P (1991) Nests and nest-sites of the house sparrow Passer domesticus (Linnaeus, 1758) in urban, suburban and rural environments. Acta Zoologica Cracoviensia 34(2):475-495

[22] Jara RF, Crego RD, Samuel MD, Rozzi R, Jiménez JE (2020) Nest-site selection and breeding success of passerines in the world’s southernmost forests. PeerJ 8:e9892. https://doi.org/10.7717/peerj.9892

[23] Korner-Nievergelt F, Roth T, von Felten S, Guélat J, Almasi B, Korner-Nievergelt (2015) Bayesian data analysis in ecology using linear models with R, BUGS, and Stan. Academic Press, London

[24] Loss SR, Li B V, Horn LC, et al (2023) Citizen science to address the global issue of bird–window collisions. Frontiers in Ecology and the Environment 21(9):418-427. https://doi.org/10.1002/fee.2614

[25] Mainwaring MC, Hartley IR, Lambrechts MM, Deeming DC (2014) The design and function of birds’ nests. Ecology and Evolution 4(20):3909-3928. https://doi.org/10.1002/ece3.1054

[26] Mainwaring MC, Barber I, Deeming DC, Pike DA, Roznik EA, Hartley IR (2016) Climate change and nesting behaviour in vertebrates : a review of the ecological threats and potential for adaptive responses. Biological Reviews 92(4):1991-2002. https://doi.org/10.1111/brv.12317

[27] Mainwaring MC (2017) Causes and consequences of intraspecific variation in nesting behaviors: insights from blue tits and great tits. Frontiers in Ecology and Evolution 5:39. https://doi.org/10.3389/fevo.2017.00039

[28] Mainwaring MC, Medina I, Tobalske BW, Hartley IR, Varricchio DJ, Hauber ME (2023) The evolution of nest site use and nest architecture in modern birds and their ancestors. Philosophical Transactions of the Royal Society B: Biological Science 378:20220143. https://doi.org/10.1098/rstb.2022.0143

[29] Martin TE, Boyce AJ, Fierro-Calderón K, Mitchell AE, Armstad CE, Mouton JC, Bin Soudi EE (2017) Enclosed nests may provide greater thermal than nest predation benefits compared with open nests across latitudes. Functional Ecology 31(6):1231-1240. https://doi.org/10.1111/1365-2435.12819

[30] Mason P (1985) The Nesting Biology of Some Passerines of Buenos Aires, Argentina. Ornithological Monographs 36:954-972. https://doi.org/10.2307/40168328

[31] Massoni V, Reboreda JC, López GC, Aldatz MF (2012) High coordination| and equitable parental effort in the Rufous Hornero. Condor 114(3):564-570. https://doi.org/10.1525/cond.2012.110135

[32] Mentesana L, Moiron M, Guedes E, Cavalli E, Tassino B, Adreani NM (2020) Defending as a unit: sex- and context-specific territorial defence in a duetting bird. Behavioral Ecology and Sociobiology 74:1–11. https://doi.org/10.1007/s00265-020-02891-4

[33] Mentesana L, Amador A, Amorim P, Delhey K, Diniz P, Fraga R, Mindlin GB, Reboreda JC, Schaaf A, Tassino B, Adreani NM (2024) Biology of the Rufous Hornero, from mechanisms to behavioral ecology: a potential Neotropical model species? Journal of Field Ornithology 95(4):2. https://doi.org/10.5751/jfo-00544-950402

[34] Mentesana L, Adreani NM (2026) Data and Code for “Nest-site characteristics of Rufous Hornero (Furnarius rufus) across its distribution as reported by citizen scientists”. In Hornero. Zenodo. https://doi.org/10.5281/zenodo.21100861

[35] Perez DM, Manica LT, Medina I (2023) Variation in nest-building behaviour in birds: a multi-species approach. hilosophical Transactions of the Royal Society B: Biological Science 378(1884):20220145. https://doi.org/10.1098/rstb.2022.0145

[36] R Core Team (2021) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. [URL: http://www.R-project.org/]

[37] Remsen Jr JV., Bonan Barfull A (2020) Rufous Hornero (Furnarius rufus), version 1.0. In: del Hoyo J, Elliott A, Sargatal J, Christie DA, de Juana E (eds). Birds of the World. https://doi.org/10.2173/bow.rufhor2.01

[38] Reynolds JS, Ibáñez-Álamo J, Sumasgutner P, Mainwaring MC (2019) Urbanisation and nest building in birds: a review of threats and opportunities. Journal of Ornithology 160:841-860. https://doi.org/10.1007/s10336-019-01657-8

[39] Schaaf AA, García CG, Puechagut PB, et al. (2018) Effect of geographical latitude and sun exposure on Rufous Hornero (Furnarius rufus) nest orientation. Journal of Ornithology 159:967-974. https://doi.org/10.1007/s10336-018-1569-5

[40] Sheard C, Street SE, Healy SD, et al (2024) Nest traits for the world’s birds. Global Ecology and Biogeography 33(2):206–214. https://doi.org/10.1111/geb.13783

[41] Sullivan BL, Wood CL, Iliff MJ, Bonney RE, Fink D, Kelling S (2009) eBird: a citizen-based bird observation network in the biological sciences. Biological Conservation 142(10):2282-2292

[42] Vincze E, Seress G, Lagisz M, Nakagawa S, Dingemanse NJ, Sprau (2017) Does urbanization affect predation of bird nests? A meta-analysis. Frontiers in Ecology and Evolution 5:29. https://doi.org/10.3389/fevo.2017.00029

[43] Wang Y, Chen S, Jiang P, Ding P (2008) Black-billed Magpies (Pica pica) adjust nest characteristics to adapt to urbanization in Hangzhou, China. Canadian Journal of Zoology 86(7):676-684. https://doi.org/10.1139/Z08-045

[44] WikiAves (2026) João-de-barro (Furnarius rufus). [URL: https://www.wikiaves.com.br/wiki/joao-de-barro] (10/10/2025)

[45] Winkler DW, Billerman SM, Lovette IJ (2020) Ovenbirds and Woodcreepers (Furnariidae), version 1.0. In: Billerman SM, Keeney BK, Rodewald PG, Schulenberg TS (eds). Birds of the World. Cornell Lab of Ornithology, Ithaca. https://doi.org/10.2173/bow.furnar2.01