Tinbergen, J. M., Fokkema, R. W., Pen, I., & Ubels, R. (2019). Sea buckthorn berries Hippophae rhamnoides L. predict size and composition of a great tit population Parus major L. Journal of Avian Biology, 50(8), [02037]. https://doi.org/10.1111/jav.02037

Both, C., Ubels, R., & Ravussin, P-A. (2019). Life-history innovation to climate change: Can single-brooded migrant birds become multiple breeders? Journal of Avian Biology, 50(5), [01951]. https://doi.org/10.1111/jav.01951

Fokkema, R. W., Ubels, R., Both, C., de Felici, L., & Tinbergen, J. M. (2018). Reproductive effort and future parental competitive ability: A nest box removal experiment. Ecology and Evolution, 8(17), 8865-8879. https://doi.org/10.1002/ece3.4342

Fokkema, R. W., Ubels, R., & Tinbergen, J. M. (2018). Experimentally quantifying the effect of nest-site depth on the predation risk and breeding success of Blue Tits. The Auk, 135(4), 919-932. https://doi.org/10.1642/AUK-17-182.1

Lagendijk, D. D. G., Howison, R. A., Esselink, P., Ubels, R., & Smit, C. (2017). Rotation grazing as a conservation management tool: Vegetation changes after six years of application in a salt marsh ecosystem. Agriculture, Ecosystems and Environment, 246, 361-366. https://doi.org/10.1016/j.agee.2017.05.023

Both, C., Burger, C., Ouwehand, J., Samplonius, J. M., Ubels, R., & Bijlsma, R. G. (2017). Delayed age at first breeding and experimental removals show large non-breeding surplus in Pied Flycatchers. Ardea, 105(1), 43-60. https://doi.org/10.5253/arde.v105i1.a2

Fokkema, R. W., Ubels, R., & Tinbergen, J. M. (2017). Is parental competitive ability in winter negatively affected by previous springs' family size? Ecology and Evolution, 7(5), 1410-1420. https://doi.org/10.1002/ece3.2752

Nicolaus, M., Piault, R., Ubels, R., Dingemanse, N. J., & Tinbergen, J. (2016). The correlation between coloration and exploration behaviour varies across hierarchical levels in a wild passerine bird. Journal of Evolutionary Biology, 29(9), 1780-1792. https://doi.org/10.1111/jeb.12907

Lemoine, M., Lucek, K., Perrier, C., Saladin, V., Adriaensen, F., Barba, E., Belda, E. J., Charmantier, A., Cichon, M., Eeva, T., Gregoire, A., Hinde, C. A., Johnsen, A., Komdeur, J., Mand, R., Matthysen, E., Norte, A. C., Pitala, N., Sheldon, B. C., ... Richner, H. (2016). Low but contrasting neutral genetic differentiation shaped by winter temperature in European great tits. Biological Journal of the Linnean Society, 118(3), 668-685. https://doi.org/10.1111/bij.12745

Nicolaus, M., Tinbergen, J. M., Ubels, R., Both, C., & Dingemanse, N. J. (2016). Density fluctuations represent a key process maintaining personality variation in a wild passerine bird. Ecology Letters, 19(4), 478-486. https://doi.org/10.1111/ele.12584

Fokkema, R. W., Ubels, R., & Tinbergen, J. M. (2016). Great tits trade off future competitive advantage for current reproduction. Behavioral Ecology, 27(6), 1656-1664. https://doi.org/10.1093/beheco/arw097

de Jong, M. E., Fokkema, R. W., Ubels, R., van der Velde, M., & Tinbergen, J. M. (2014). No evidence for long-term effects of reproductive effort on parasite prevalence in great tits Parus major. Journal of Avian Biology, 45(2), 179-186. https://doi.org/10.1111/j.1600-048X.2013.00199.x

Tinbergen, J. M., Tinbergen, J., & Ubels, R. (2014). Is fitness affected by ring colour? Ardea, 101(2), 153-163. https://doi.org/10.5253/078.101.0210

Nicolaus, M., Brommer, J. E., Ubels, R., Tinbergen, J. M., & Dingemanse, N. J. (2013). Exploring patterns of variation in clutch size-density reaction norms in a wild passerine bird. Journal of Evolutionary Biology, 26(9), 2031-2043. https://doi.org/10.1111/jeb.12210

Michler, S. P. M., Nicolaus, M., van der Velde, M., Radersma, R., Ubels, R., Both, C., Komdeur, J., & Tinbergen, J. M. (2013). Local offspring density and sex ratio affect sex allocation in the great tit. Behavioral Ecology, 24(1), 169-181. https://doi.org/10.1093/beheco/ars151

Nicolaus, M., Tinbergen, J. M., Bouwman, K. M., Michler, S. P. M., Ubels, R., Both, C., Kempenaers, B., & Dingemanse, N. J. (2012). Experimental evidence for adaptive personalities in a wild passerine bird. Proceedings of the Royal Society of London. Series B, Biological Sciences, 279(1749), 4885-4892. https://doi.org/10.1098/rspb.2012.1936

Nicolaus, M., Michler, S. P. M., Jalvingh, K. M., Ubels, R., van der Velde, M., Komdeur, J., Both, C., & Tinbergen, J. M. (2012). Social environment affects juvenile dispersal in great tits (Parus major). Journal of Animal Ecology, 81(4), 827-837. https://doi.org/10.1111/j.1365-2656.2012.01959.x

Nicolaus, M., Michler, S. P. M., Ubels, R., van der Velde, M., Bouwman, K. M., Both, C., & Tinbergen, J. M. (2012). Local sex ratio affects the cost of reproduction. Journal of Animal Ecology, 81(3), 564-572. https://doi.org/10.1111/j.1365-2656.2011.01933.x

Prop, J., Ubels, R., Oudman, L., Gerdes, L., E., W., & de Boer, H. (2012). Wadvogels in de Dollard: Herstel van aantallen of aantasting van een natuurlijk systeem? Limosa, 85(1), 1.

Michler, S. P. M., Nicolaus, M., Ubels, R., van der Velde, M., Komdeur, J., Both, C., & Tinbergen, J. M. (2011). Sex-specific effects of the local social environment on juvenile post-fledging dispersal in great tits. Behavioral Ecology and Sociobiology, 65(10), 1975-1986. https://doi.org/10.1007/s00265-011-1207-1

Michler, S. P. M., Nicolaus, M., Ubels, R., van der Velde, M., Both, C., Tinbergen, J. M., & Komdeur, J. (2011). Do sex-specific densities affect local survival of free-ranging great tits? Behavioral Ecology, 22(4), 869-879. https://doi.org/10.1093/beheco/arr066

Kuijper, D. P. J., Ubels, R., & Loonen, M. J. J. E. (2009). Density-dependent switches in diet: a likely mechanism for negative feedbacks on goose population increase? Polar Biology, 32(12), 1789-1803. https://doi.org/10.1007/s00300-009-0678-2

Nicolaus, M., Both, C., Ubels, R., Edelaar, P., & Tinbergen, J. M. (2009). No experimental evidence for local competition in the nestling phase as a driving force for density-dependent avian clutch size. Journal of Animal Ecology, 78(4), 828-838. https://doi.org/10.1111/j.1365-2656.2009.01535.x

Nicolaus, M., Michler, S. P. M., Ubels, R., van der Velde, M., Komdeur, J., Both, C., & Tinbergen, J. M. (2009). Sex-specific effects of altered competition on nestling growth and survival: an experimental manipulation of brood size and sex ratio. Journal of Animal Ecology, 78(2), 414-426. https://doi.org/10.1111/j.1365-2656.2008.01505.x

de Heij, M. E., Ubels, R., Visser, G. H., & Tinbergen, J. M. (2008). Female great tits Parus major do not increase their daily energy expenditure when incubating enlarged clutches. Journal of Avian Biology, 39(2), 121-126. https://doi.org/10.1111/j.2008.0908-8857.04286.x

Kuijper, D. P. J., Bakker, J. P., Cooper, E. J., Ubels, R., Jónsdóttir, I. S., & Loonen, M. J. J. E. (2006). Intensive grazing by Barnacle geese depletes High Arctic seed bank. Canadian Journal of Botany, 84(6), 995-1004. https://doi.org/10.1139/B06-052

Hesse, C., Kruijer, H., Lutterop, D., Kasemir, G., Ubels, R., Corté, B., & van Gennip, B. (2004). De mossen van de Groninger waddeneilanden. 2. Rottumeroog, Vuurtorenduin en Zuiderduin. Buxbaumiella, 66, 27-38.

Ubels, R., Nienhuis, J., Beekman, J., Jager, T., & Dijkstra, A. (2003). Acht jaar (1994-2002) winter- en voorjaarstellingen van Knobbelzwanen Cygnus olor in de provincie Groningen. Grauwe Gors, 31(1), 33-40. http://natuurtijdschriften.nl/record/550661

Kruijer, H., Koops, K., Edelenbos, M., Ubels, R., Lutterop, D., Kasemir, G., & Corté, B. (2000). De mossen van de Groninger waddeneilanden. Buxbaumiella, 52, 17-37.

Ubels, R., & Edelenbos, M. (1999). De blauwe kiekendief Circus cyaneus op Rottumeroog. De Takkeling, 193-197.

Beekman, J., Ubels, R., & Koffijberg, K. (1991). Dispersie van onvolwassen Knobbelzwanen met halsbanden. Het Vogeljaar, 39(3), 121-144.