Tore Slagsvold

• Husby, Magne & Slagsvold, Tore (2023). The number of syllables per phrase in songs of Great Tits Parus major decreases with high levels of anthropogenic noise and at northern latitudes. Ornis Norvegica. ISSN 1892-9737. 46, p. 28–42. doi: 10.15845/on.v46.3854. Full text in Research Archive Show summary

  Birds often sing to defend a territory and to attract a mate. However, despite many studies, clear questions remain on how ecological conditions may affect the song, such as physical obstacles that may reduce the sound transmission, and anthropogenic noise that may mask the signal. The social environment of the local populations may also be important, such as breeding density and sex ratio, influencing the number of competing males with which to song match, and distances to neighbouring males and to prospecting females. During 2016-19, we counted the number of syllables (notes, elements) per phrase of singing male Great Tits Parus major by visiting seven countries in Europe and one country in North Africa. A total of 762 songs were observed by visiting 590 sampling points. We also recorded study year, levels of anthropogenic noise, calendar date, time of day, type of habitat and vegetation density, latitude, longitude and altitude. The most important explanatory variables for variation in songs were anthropogenic noise and the latitude of the sampling points; the number of syllables per phrase decreasing both with increasing levels of anthropogenic noise and with latitude. The latter result was also supported when listening to and analysing sonograms of Great Tits available at the Xeno-canto repository for sound recordings, with fewer syllables per phrase for birds in Norway than in Spain and Portugal. We suggest that repetition of a short phrase is quickly interpreted by conspecifics in noisy environments, and that such signals are more readily detected by conspecifics over a wider area where the density of the birds is low.

• Rydgren, Knut; Indreeide, Bendik; Slagsvold, Tore & Lampe, Helene M. (2023). Nest building in titmice Paridae: Selectivity in bryophyte use. Ecology and Evolution. ISSN 2045-7758. 13(3). doi: 10.1002/ece3.9852. Full text in Research Archive Show summary

  In many bird species, reproductive success is dependent on nest quality. However, detailed data on nest composition are scarce, and quantitative analyses have generally used only rough categories, without species identification. Bryophytes dominate the nests of many passerine bird species, but little is known about whether birds have preferences for certain species. In this study, we determined the bryophyte species composition in nests of blue tits Cyanistes caeruleus and great tits Parus major in a forest near Oslo, Norway. We also sampled the abundance of the bryophyte species in plots on the forest floor surrounding a subset of the great tit nests. Blue tits and great tits both used 15 bryophyte species as nest materials, mainly the same pleurocarpous species but in different proportions. The tits preferred highly branched bryophyte species, i.e., Pleurozium schreberi, Rhytidiadelphus squarrosus, and Sanionia uncinata but avoided common forest floor bryophyte species that are sparsely branched. Great tits clearly collected bryophyte species selectively. We also found that bryophyte species content in great tit nests in the same nest box in different years was very similar. Our results also indicated that the great tits collected bryophyte nest materials close to their nests, mostly within 5 m, supporting the view that collecting nest materials is costly. We review several hypotheses to explain why the tits prefer certain species of bryophytes as nest materials. These include handling costs and their suitability as structural materials. We recommend field experiments to test specific hypotheses and to study whether preferences are heritable.

• Engebretsen, Stein Ingolf & Slagsvold, Tore (2022). An experimental study of trade-offs between brood size and moult in the blue tit (Cyanistes caeruleus). IBIS. ISSN 0019-1019. doi: 10.1111/ibi.13172. Full text in Research Archive
• Walseng, Bjørn; Durant, Joël; Hessen, Dag Olav; Jerstad, Kurt; Nilsson, Anna & Røstad, Ole Wiggo [Show all 7 contributors for this article] (2022). Long-term annual and spatial variation of polygyny in the white-throated dipper (Cinclus cinclus). Ecology and Evolution. ISSN 2045-7758. 12(10). doi: 10.1002/ece3.9416. Full text in Research Archive Show summary

  Mating strategies are key components in the fitness of organisms, and notably in birds the occurrence of monogamy versus polygyny has attracted wide interest. We address this by a very comprehensive dataset (2899 breeding events spanning the years 1978–2019) of the white-throated dipper Cinclus cinclus. Though the mating system of this species has been regarded as generally monogamous, we find that 7% of all breeding events were performed by polygynous males (approximately 15% of all pairs). The fraction of polygyny has been stable over the entire study period irrespective of population size. The assumption that polygyny is most common at low population density was not supported. Surprisingly, there was no difference between polygynous and monogamous males with regard to the quality of the territories they inhabited, ranked according to their overall frequency of use. The most common age group, first-year breeders, dominated among monogamous males, while among polygynous males second-year breeders were most common, followed by third and first-year breeders. The primary females were in general older than females mated to monogamous males, also when controlled for their general frequency in the population. The majority of the two females mated to a polygynous male, bred in the vicinity of each other. The probability for a male to be involved in polygyny more than once, was significantly higher than by chance, suggesting phenotypic quality differences among males.

• Slagsvold, Tore & Wiebe, Karen (2021). Nest decoration: birds exploit a fear of feathers to guard their nest from usurpation. Royal Society Open Science. ISSN 2054-5703. 8(11), p. 1–11. doi: 10.1098/rsos.211579. Full text in Research Archive
• Slagsvold, Tore & Wiebe, Karen (2021). Egg covering in cavity nesting birds may prevent nest usurpation by other species. Behavioral Ecology and Sociobiology. ISSN 0340-5443. 75. doi: 10.1007/s00265-021-03045-w. Full text in Research Archive
• Slagsvold, Tore & Wiebe, Karen L. (2021). Use of landmarks for nest site choice and small-scale navigation to the nest in birds. Behaviour. ISSN 0005-7959. 158(8-9), p. 705–726. doi: 10.1163/1568539X-bja10091. Full text in Research Archive
• Slagsvold, Tore & Wiebe, Karen (2021). No evidence that nest site choice in Pied Flycatchers is mediated by assessing the clutch size of a heterospecific, the Great Tit. Journal of Ornithology = Journal fur Ornithologie. ISSN 0021-8375. 162, p. 997–1007. doi: 10.1007/s10336-021-01900-1. Full text in Research Archive
• Slagsvold, Tore & Wiebe, Karen (2020). Interspecific aggression and defence of extra nest sites in two species of songbirds. Ethology. ISSN 0179-1613. 127, p. 294–301. doi: 10.1111/eth.13127. Full text in Research Archive
• Pape Møller, Anders; Balbontin, Javier; Dhondt, André A.; Adriaensen, Frank; Artemyev, Alexandr & Banbura, Jerzy [Show all 71 contributors for this article] (2020). Interaction of climate change with effects of conspecific and heterospecific density on reproduction. Oikos. ISSN 0030-1299. 129, p. 1807–1819. doi: 10.1111/oik.07305.
• Loukola, Olli J.; Adamik, Peter; Adriaensen, Frank; Barba, Emilio; Doligez, Blandine & Flensted‐Jensen, Einar [Show all 21 contributors for this article] (2020). The roles of temperature, nest predators and information parasites for geographical variation in egg covering behaviour of tits (Paridae). Journal of Biogeography. ISSN 0305-0270. 47, p. 1482–1493. doi: 10.1111/jbi.13830. Full text in Research Archive
• Aasen, Maria & Slagsvold, Tore (2020). No cultural transmission of use of nest materials in titmice Paridae. Animal Behaviour. ISSN 0003-3472. 170, p. 27–32. doi: 10.1016/j.anbehav.2020.10.005. Full text in Research Archive
• Nilsson, Anna L. K.; Skaugen, Thomas; Reitan, Trond; L'Abee-Lund, Jan Henning; Gamelon, Marlène & Jerstad, Kurt [Show all 11 contributors for this article] (2020). Hydrology influences breeding time in the white-throated dipper. BMC Ecology. ISSN 1472-6785. 20(70). doi: 10.1186/s12898-020-00338-y. Full text in Research Archive Show summary

  Background: Earlier breeding is one of the strongest responses to global change in birds and is a key factor determining reproductive success. In most studies of climate effects, the focus has been on large-scale environmental indices or temperature averaged over large geographical areas, neglecting that animals are affected by the local conditions in their home ranges. In riverine ecosystems, climate change is altering the flow regime, in addition to changes resulting from the increasing demand for renewable and clean hydropower. Together with increasing temperatures, this can lead to shifts in the time window available for successful breeding of birds associated with the riverine habitat. Here, we investigated specifically how the environmental conditions at the territory level influence timing of breeding in a passerine bird with an aquatic lifestyle, the white-throated dipper Cinclus cinclus. We relate daily river discharge and other important hydrological parameters, to a long-term dataset of breeding phenology (1978–2015) in a natural river system. Results: Dippers bred earlier when winter river discharge and groundwater levels in the weeks prior to breeding were high, and when there was little snow in the catchment area. Breeding was also earlier at lower altitudes, although the effect dramatically declined over the period. This suggests that territories at higher altitudes had more open water in winter later in the study period, which permitted early breeding also here. Unexpectedly, the largest effect inducing earlier breeding time was territory river discharge during the winter months and not immediately prior to breeding. The territory river discharge also increased during the study period. Conclusions: The observed earlier breeding can thus be interpreted as a response to climate change. Measuring environmental variation at the scale of the territory thus provides detailed information about the interactions between organisms and the abiotic environment. Breeding phenology, Climate change, Environmental heterogeneity, Hydropower, Long-term study, Passerine bird, River discharge, Snow, Spatial scale, Stream

• Culina, Antica; Adriaensen, Frank; Bailey, Liam D.; Burgess, Malcolm; Charmantier, Anne & Cole, Ella F [Show all 54 contributors for this article] (2020). Connecting the data landscape of long‐term ecological studies: The SPI‐Birds data hub. Journal of Animal Ecology. ISSN 0021-8790. p. 1–14. doi: 10.1111/1365-2656.13388. Full text in Research Archive Show summary

  The integration and synthesis of the data in different areas of science is drastically slowed and hindered by a lack of standards and networking programmes. Long‐term studies of individually marked animals are not an exception. These studies are especially important as instrumental for understanding evolutionary and ecological processes in the wild. Furthermore, their number and global distribution provides a unique opportunity to assess the generality of patterns and to address broad‐scale global issues (e.g. climate change). To solve data integration issues and enable a new scale of ecological and evolutionary research based on long‐term studies of birds, we have created the SPI‐Birds Network and Database (www.spibirds.org)—a large‐scale initiative that connects data from, and researchers working on, studies of wild populations of individually recognizable (usually ringed) birds. Within year and a half since the establishment, SPI‐Birds has recruited over 120 members, and currently hosts data on almost 1.5 million individual birds collected in 80 populations over 2,000 cumulative years, and counting. SPI‐Birds acts as a data hub and a catalogue of studied populations. It prevents data loss, secures easy data finding, use and integration and thus facilitates collaboration and synthesis. We provide community‐derived data and meta‐data standards and improve data integrity guided by the principles of Findable, Accessible, Interoperable and Reusable (FAIR), and aligned with the existing met

• Nilsson, Anna L.K.; Reitan, Trond; Skaugen, Thomas; L'Abee-Lund, Jan Henning; Gamelon, Marlène & Jerstad, Kurt [Show all 11 contributors for this article] (2020). Location is everything, but climate gets a share: analyzing small-scale environmental influences on breeding success in the white-throated dipper. Frontiers in Ecology and Evolution. ISSN 2296-701X. 8. doi: 10.3389/fevo.2020.542846. Full text in Research Archive
• Slagsvold, Tore (2019). Social Learning in Birds Studied by Cross-Fostering in the Wild. Integrative Journal of Veterinary Biosciences (IJVB). ISSN 2577-4492. 3(2), p. 1–4. doi: 10.1098/rspb.2002.2045. Full text in Research Archive
• Nilsson, Anna; Slagsvold, Tore; Røstad, Ole Wiggo; Knudsen, Endre; Jerstad, Kurt & Cadahia, Luis [Show all 10 contributors for this article] (2019). Territory location and quality, together with climate, affect the timing of breeding in the white-throated dipper. Scientific Reports. ISSN 2045-2322. 9, p. 1–11. doi: 10.1038/s41598-019-43792-5. Full text in Research Archive Show summary

  Recent climate change has led to advanced spring phenology in many temperate regions. The phenological response to variation in the local environment, such as the habitat characteristics of the territories birds occupy, is less clear. The aim of this study is to understand how ecological conditions affect breeding time, and its consequences for reproduction, in a white-throated dipper Cinclus cinclus population in a river system in Norway during 34 years (1978–2011). Hatching date advanced almost nine days, indicating a response to higher temperatures and the advanced phenology in the area. Earlier breeding was found in warm springs and at lower altitudes. High population density facilitated earlier breeding close to the coast. Furthermore, when population density was low, breeding was early at territories that were rarely occupied, while in years with high density, breeding was early at territories that were frequently occupied. Also, when population density was low, earlier breeding occurred at territories that on average produced more offspring than other territories, while there was no difference in breeding time in high population years. Selection for early breeding was dependent on spring temperatures and high spring temperatures contributed to higher breeding success during the study period. We found that breeding phenology may have strong effects on fitness in the white-throated dipper, and thus that breeding time is an important ecological factor in a species that feeds mainly on aquatic rather than terrestrial prey.

• Hogstad, Olav & Slagsvold, Tore (2018). Survival of Willow tits Poecile montanus: the significance of flock membership, social rank and body size. Ornis Norvegica. ISSN 1892-9737. 41, p. 13–18. doi: 10.15845/on.v41i0.1540. Full text in Research Archive
• Slagsvold, Tore & Wiebe, Karen (2018). Immigrants and locally recruited birds differ in prey delivered to their offspring in blue tits and great tits. Animal Behaviour. ISSN 0003-3472. 139, p. 127–135. doi: 10.1016/j.anbehav.2018.01.007. Full text in Research Archive
• Slagsvold, Tore & Wiebe, Karen (2018). On heterospecifc learning in birds – comments on Samplonius and Forsman et al. Journal of Avian Biology. ISSN 0908-8857. 49(3). doi: 10.1111/jav.01706. Full text in Research Archive
• Slagsvold, Tore & Wiebe, Karen (2017). On the use of heterospecific information for nest site selection in birds. Journal of Avian Biology. ISSN 0908-8857. 48(7), p. 1035–1040. doi: 10.1111/jav.01398. Full text in Research Archive
• Cadahia, Luis; Labra, Antonieta; Knudsen, Endre; Nilsson, Anna; Lampe, Helene M. & Slagsvold, Tore [Show all 7 contributors for this article] (2017). Advancement of spring arrival in a long‑term study of a passerine bird: sex, age and environmental effects. Oecologia. ISSN 0029-8549. 184(4), p. 917–929. doi: 10.1007/s00442-017-3922-4. Full text in Research Archive
• Gamelon, Marlène; Grøtan, Vidar; Nilsson, Anna L. K.; Engen, Steinar; Hurrell, James W. & Jerstad, Kurt [Show all 12 contributors for this article] (2017). Interactions between demography and environmental effects are important determinants of population dynamics. Science Advances. ISSN 2375-2548. 3(2). doi: 10.1126/sciadv.1602298. Full text in Research Archive Show summary

  Climate change will affect the population dynamics of many species, yet the consequences for the long-term persistence of populations are poorly understood. A major reason for this is that density-dependent feedback effects caused by fluctuations in population size are considered independent of stochastic variation in the environment. We show that an interplay between winter temperature and population density can influence the persistence of a small passerine population under global warming. Although warmer winters favor an increased mean population size, density-dependent feedback can cause the local population to be less buffered against occasional poor environmental conditions (cold winters). This shows that it is essential to go beyond the population size and explore climate effects on the full dynamics to elaborate targeted management actions.

• Vaugoyeau, Marie; Adriaensen, Frank; Artemyev, Alexandr; Banbura, Jerzy; Barba, Emilio & Biard, Clotilde [Show all 77 contributors for this article] (2016). Interspecific variation in the relationship between clutch size, laying date and intensity of urbanization in four species of hole-nesting birds. Ecology and Evolution. ISSN 2045-7758. 6(16), p. 5907–5920. doi: 10.1002/ece3.2335.
• Lemoine, Melissa; Lucek, Kay; Perrier, Charles; Saladin, Verena; Adriaensen, Frank & Barba, Emilio [Show all 27 contributors for this article] (2016). Low but contrasting neutral genetic differentiation shaped by winter temperature in European great tits. Biological Journal of the Linnean Society. ISSN 0024-4066. 118(3), p. 668–685. doi: 10.1111/bij.12745.
• Laine, Veronika N.; Gossmann, Toni; Schachtschneider, Kyle M.; Garroway, Colin J.; Madsen, Ole & Verhoeven, Koen J.F. [Show all 46 contributors for this article] (2016). Evolutionary signals of selection on cognition from the great tit genome and methylome. Nature Communications. ISSN 2041-1723. 7. doi: 10.1038/ncomms10474. Full text in Research Archive
• Cramer, Emily Rebecca A; Stensrud, Even; Marthinsen, Gunnhild; Hogner, Silje; Johannessen, Lars Erik & Laskemoen, Terje [Show all 10 contributors for this article] (2016). Sperm performance in conspecific and heterospecific female fluid. Ecology and Evolution. ISSN 2045-7758. doi: 10.1002/ece3.1977. Full text in Research Archive
• Wiebe, Karen & Slagsvold, Tore (2015). Foraging trade-offs between prey size, delivery rate and prey type: How does niche breadth and early learning of the foraging niche affect food delivery? Ethology. ISSN 0179-1613. 121(10), p. 1010–1017. doi: 10.1111/eth.12411.
• Møller, Anders P.; Adriaensen, Frank; Artemyev, Alexandr; Banbura, Jerzy; Barba, Emilio & Biard, Clotilde [Show all 82 contributors for this article] (2014). Variation in clutch size in relation to nest size in birds. Ecology and Evolution. ISSN 2045-7758. 4(18), p. 3583–3595. doi: 10.1002/ece3.1189.
• Møller, Anders Pape; Adriaensen, Frank; Artemyev, Alexandr; Banbura, Jerzy; Barba, Emilio & Biard, Clotilde [Show all 86 contributors for this article] (2014). Clutch-size variation in Western Palaearctic secondary hole-nesting passerine birds in relation to nest box design. Methods in Ecology and Evolution. ISSN 2041-210X. 5(4), p. 353–362. doi: 10.1111/2041-210X.12160.
• Sonerud, Geir Andreas; Steen, Ronny; Selås, Vidar; Aanonsen, Ole Martin; Aasen, Gunn-Henny & Fagerland, Kristine L. [Show all 21 contributors for this article] (2014). Evolution of parental roles in provisioning birds: Diet determines role asymmetry in raptors. Behavioral Ecology. ISSN 1045-2249. 25(4), p. 762–772. doi: 10.1093/beheco/aru053.
• Sonerud, Geir Andreas; Steen, Ronny; Løw, Line Marie; Røed, Line T.; Skar, Kristin & Selås, Vidar [Show all 7 contributors for this article] (2014). Evolution of parental roles in raptors: Prey type determines role asymmetry in the Eurasian kestrel. Animal Behaviour. ISSN 0003-3472. 96, p. 31–38. doi: 10.1016/j.anbehav.2014.07.011.
• Wiebe, Karen L. & Slagsvold, Tore (2014). Prey size increases with nestling age: Are provisioning parents programmed or responding to cues from offspring? Behavioral Ecology and Sociobiology. ISSN 0340-5443. 68(5), p. 711–719. doi: 10.1007/s00265-014-1684-0.
• Slagsvold, Tore; Husek, Jan; Whittington, Jason & Wiebe, Karen (2014). Antipredator behavior: Escape flights on a landscape slope. Behavioral Ecology. ISSN 1045-2249. 25(2), p. 378–385. doi: 10.1093/beheco/aru003.
• Husek, Jan; Lampe, Helene M. & Slagsvold, Tore (2014). Natal dispersal based on past and present environmental phenology in the pied flycatcher (Ficedula hypoleuca). Oecologia. ISSN 0029-8549. 174(4), p. 1139–1149. doi: 10.1007/s00442-013-2842-1.
• Møller, Anders Pape; Merino, Santiago; Soler, Juan José; Antonov, Anton; Badás, Elisa P. & Calero-Torralbo, Miguel A. [Show all 37 contributors for this article] (2013). Assessing the effects of climate on host-parasite interactions: a comparative study of European birds and their parasites. PLOS ONE. ISSN 1932-6203. 8(12). doi: 10.1371/journal.pone.0082886. Full text in Research Archive Show summary

  Background: Climate change potentially has important effects on distribution, abundance, transmission and virulence of parasites in wild populations of animals. Methodology/Principal Finding: Here we analyzed paired information on 89 parasite populations for 24 species of bird hosts some years ago and again in 2010 with an average interval of 10 years. The parasite taxa included protozoa, feather parasites, diptera, ticks, mites and fleas. We investigated whether change in abundance and prevalence of parasites was related to change in body condition, reproduction and population size of hosts. We conducted analyses based on the entire dataset, but also on a restricted dataset with intervals between study years being 5–15 years. Parasite abundance increased over time when restricting the analyses to datasets with an interval of 5–15 years, with no significant effect of changes in temperature at the time of breeding among study sites. Changes in host body condition and clutch size were related to change in temperature between first and second study year. In addition, changes in clutch size, brood size and body condition of hosts were correlated with change in abundance of parasites. Finally, changes in population size of hosts were not significantly related to changes in abundance of parasites or their prevalence. Conclusions/Significance: Climate change is associated with a general increase in parasite abundance. Variation in laying date depended on locality and was associated with latitude while body condition of hosts was associated with a change in temperature. Because clutch size, brood size and body condition were associated with change in parasitism, these results suggest that parasites, perhaps mediated through the indirect effects of temperature, may affect fecundity and condition of their hosts. The conclusions were particularly in accordance with predictions when the restricted dataset with intervals of 5– 15 years was used, suggesting that short intervals may bias findings.

• Slagsvold, Tore; Eriksen, Ane; de Ayala, Rosa Mary; Husek, Jan & Wiebe, Karen (2013). POSTFLEDGING MOVEMENTS IN BIRDS: DO TIT FAMILIES TRACK ENVIRONMENTAL PHENOLOGY? The AUK: A Quarterly Journal of Ornithology. ISSN 0004-8038. 130(1), p. 36–45. doi: 10.1525/auk.2012.12122.
• Sonerud, Geir Andreas; Steen, Ronny; Løw, Line Marie; Røed, Line T.; Skar, Kristin & Selås, Vidar [Show all 7 contributors for this article] (2013). Size-biased allocation of prey from male to offspring via female: family conflicts, prey selection, and evolution of sexual size dimorphism in raptors. Oecologia. ISSN 0029-8549. 172(1), p. 93–107. doi: 10.1007/s00442-012-2491-9.
• Landys, Meta M.; Goymann, Wolfgang; Soma, Kiran K. & Slagsvold, Tore (2013). Year-round territorial aggression is independent of plasma DHEA in the European nuthatch Sitta europaea. Hormones and Behavior. ISSN 0018-506X. 63(1), p. 166–172. doi: 10.1016/j.yhbeh.2012.10.002.
• Slagsvold, Tore; Kleiven, Kari; Eriksen, Ane & Johannessen, Lars Erik (2013). Vertical and horizontal transmission of nest site preferences in titmice. Animal Behaviour. ISSN 0003-3472. 85(2), p. 323–328. doi: 10.1016/j.anbehav.2012.10.024.
• Steen, Ronny; Sonerud, Geir Andreas & Slagsvold, Tore (2012). Parents adjust feeding effort in relation to nestling age in the Eurasian Kestrel (Falco tinnunculus). Journal of Ornithology = Journal fur Ornithologie. ISSN 0021-8375. 153(4), p. 1087–1099. doi: 10.1007/s10336-012-0838-y.
• Husek, Jan; Weidinger, Karel; Adamik, Peter & Slagsvold, Tore (2012). Impact of Nesting Mortality on Avian Breeding Phenology: A Case Study on the Red-Backed Shrike (Lanius collurio). PLOS ONE. ISSN 1932-6203. 7(8:e43944). doi: 10.1371/journal.pone.0043944. Full text in Research Archive
• Lifjeld, Jan Terje; Laskemoen, Terje; Kleven, Oddmund; Pedersen, Anne Tiril Myhre; Lampe, Helene M. & Rudolfsen, Geir [Show all 8 contributors for this article] (2012). No Evidence for Pre-Copulatory Sexual Selection on Sperm Length in a Passerine Bird. PLOS ONE. ISSN 1932-6203. 7(2). doi: 10.1371/journal.pone.0032611. Full text in Research Archive
• Burger, Claudia; Belskii, E; Eeva, T; Laaksonen, T; Mägi, M & Mand, Raivo [Show all 14 contributors for this article] (2012). Climate change, breeding date and nestling diet: how temperature differentially affects seasonal changes in pied flycatcher diet depending on habitat variation. Journal of Animal Ecology. ISSN 0021-8790. 81(4), p. 926–936. doi: 10.1111/j.1365-2656.2012.01968.x.
• Wiebe, Karen & Slagsvold, Tore (2012). Brood parasites may use gape size constraints to exploit provisioning rules of smaller hosts: an experimental test of mechanisms of food allocation. Behavioral Ecology. ISSN 1045-2249. 23(2), p. 391–396. doi: 10.1093/beheco/arr202.
• Wiebe, Karen & Slagsvold, Tore (2012). Parents take both size and conspicuousness into account when feeding nestlings in dark cavity nests. Animal Behaviour. ISSN 0003-3472. 84(6), p. 1307–1312. doi: 10.1016/j.anbehav.2012.09.014.
• Landys, Meta M.; Goymann, Wolfgang & Slagsvold, Tore (2011). Rearing conditions have long-term consequences for stress responsiveness in free-living great tits. General and Comparative Endocrinology. ISSN 0016-6480. 174(2), p. 219–224. doi: 10.1016/j.ygcen.2011.08.022.
• Nilsson, Anna; Stige, Leif Christian; Jerstad, Kurt; Røstad, Ole Wiggo; Slagsvold, Tore & Knudsen, Endre [Show all 8 contributors for this article] (2011). To make the most of what we have: extracting phenological data from nestling measurements. International journal of biometeorology. ISSN 0020-7128. 55, p. 797–804. doi: 10.1007/s00484-011-0461-2.
• Størmer, Fredrik; Mysterud, Ivar & Slagsvold, Tore (2011). Evolution and possible storage of information in a magnetite system of significance for brain development. Medical Hypotheses. ISSN 0306-9877. 76(6), p. 901–904. doi: 10.1016/j.mehy.2011.03.004.
• Steen, Ronny; Løw, Line Marie; Sonerud, Geir Andreas; Selås, Vidar & Slagsvold, Tore (2011). Prey delivery rates as estimates of prey consumption by Eurasian Kestrel Falco tinnunculus nestlings. Ardea. ISSN 0373-2266. 99(1), p. 1–8. doi: 10.5253/078.099.0101.
• Johnsen, Arild; Vesterkjær, Kristin & Slagsvold, Tore (2011). Do Male Pied Flycatchers (Ficedula hypoleuca) Adjust Their Feeding Effort According to Egg Colour? Ethology. ISSN 0179-1613. 117(4), p. 309–317. doi: 10.1111/j.1439-0310.2011.01876.x.
• Saggese, Katja; Korner-Nievergelt, Fränzi; Slagsvold, Tore & Amrhein, Valentin (2011). Wild bird feeding delays start of dawn singing in the great tit. Animal Behaviour. ISSN 0003-3472. 81(2), p. 361–365. doi: 10.1016/j.anbehav.2010.11.008.
• Slagsvold, Tore & Wiebe, Karen (2011). Social learning in birds and its role in shaping a foraging niche. Philosophical Transactions of the Royal Society of London. Biological Sciences. ISSN 0962-8436. 366(1567), p. 969–977. doi: 10.1098/rstb.2010.0343.
• Eriksen, Ane; Slagsvold, Tore & Lampe, Helene M. (2011). Vocal Plasticity - are Pied Flycatchers, Ficedula Hypoleuca, Open-Ended Learners? Ethology. ISSN 0179-1613. 117(3), p. 188–198. doi: 10.1111/j.1439-0310.2010.01864.x.
• Nilsson, Anna; Knudsen, Endre; Jerstad, Kurt; Røstad, Ole Wiggo; Walseng, Bjørn & Slagsvold, Tore [Show all 7 contributors for this article] (2011). Climate effects on population fluctuations of the white-throated dipper Cinclus cinclus. Journal of Animal Ecology. ISSN 0021-8790. 80(1), p. 235–243. doi: 10.1111/j.1365-2656.2010.01755.x.
• Steen, Ronny; Løw, Line Marie; Sonerud, Geir Andreas; Selås, Vidar & Slagsvold, Tore (2010). The feeding constraint hypothesis: prey preparation as a function of nestling age and prey mass in the Eurasian kestrel. Animal Behaviour. ISSN 0003-3472. 80(1), p. 147–153. doi: 10.1016/j.anbehav.2010.04.015. Show summary

  The feeding constraint hypothesis states that an inability of young nestlings to ingest prey included in the diet of older nestlings and adult birds affects the evolution of parental behaviour, and predicts that the extent of prey preparation would increase with prey size and decrease with nestling age. In the Eurasian kestrel, Falco tinnunculus, a small raptor with a wide diet, parents often prepare prey prior to delivery at the nest, most notably by decapitation. We studied this behaviour by video monitoring prey deliveries at 29 nests for a total of about 200 days over 3 years. The probability of a prey item being decapitated prior to delivery differed between prey types and prey sizes; none of the insects or common lizards, Zootoca vivipara, and almost none of the shrews (Soricidae) were decapitated, whereas voles (Microtinae) and birds were commonly decapitated. For voles the probability of being decapitated decreased with nestling age, which supports the feeding constraint hypothesis because the nestlings' gape size limit and swallowing capacity would increase with age. For both voles and birds the probability of being decapitated increased with prey body mass, suggesting that kestrel nestlings may be unable to swallow, digest or egest skulls from larger prey. We suggest that the extent to which kestrel parents decapitate prey prior to delivery is an effect of their nestlings' age-dependent swallowing capacity and that the age of the nestlings therefore imposes constraints on the kestrel parents' foraging behaviour. (C) 2010 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

• Slagsvold, Tore; Sonerud, Geir Andreas; Grønlien, Helge E & Stige, Leif Christian (2010). Prey handling in raptors in relation to their morphology and feeding niches. Journal of Avian Biology. ISSN 0908-8857. 41(4), p. 488–497. doi: 10.1111/j.1600-048X.2010.05081.x.
• Turtumøygard, Tea & Slagsvold, Tore (2010). Evolution of brood parasitism in birds: constraints related to prey type. Behaviour. ISSN 0005-7959. 147(3), p. 299–317. doi: 10.1163/000579509X12529334990189.
• Lambrechts, M.; Adriaensen, Frank; Ardia, Daniel R.; Artemyev, AV; Atienzar, Francisco & Banbura, Jerzy [Show all 56 contributors for this article] (2010). The design of artificial nestboxes for the study of secondary hole-nesting birds: a review of methodological inconsistencies and potential biases. Acta Ornithologica. ISSN 0001-6454. 45(1), p. 1–26. doi: 10.3161/000164510X516047.
• Hansen, Bo Terning; Johannessen, Lars Erik & Slagsvold, Tore (2010). Interspecific cross-fostering of great tits (Parus major) by blue tits (Cyanistes caeruleus) affects inter- and intraspecific communication. Behaviour. ISSN 0005-7959. 147(3), p. 413–424. doi: 10.1163/000579509X12578482434926.
• Landys, Meta M.; Goymann, W.; Schwabl, Ingrid; Trapschuh, Monika & Slagsvold, Tore (2010). Impact of season and social challenge on testosterone and corticosterone levels in a year-round territorial bird. Hormones and Behavior. ISSN 0018-506X. 58(2), p. 317–325. doi: 10.1016/j.yhbeh.2010.02.013.
• Calhim, S; Lampe, Helene M.; Slagsvold, Tore & Birkhead, TR (2009). Selection on sperm morphology under relaxed sperm competition in a wild passerine bird. Biology Letters. ISSN 1744-9561. 5(1), p. 58–61. doi: 10.1098/rsbl.2008.0544.
• Wiebe, KL & Slagsvold, Tore (2009). Parental Sex Differences in Food Allocation to Junior Brood Members as Mediated by Prey Size. Ethology. ISSN 0179-1613. 115(1), p. 49–58. doi: 10.1111/j.1439-0310.2008.01580.x.
• Eriksen, Ane; Lampe, Helene M. & Slagsvold, Tore (2009). Interspecific cross-fostering affects song acquisition but not mate choice in pied flycatchers, Ficedula hypoleuca. Animal Behaviour. ISSN 0003-3472. 78(4), p. 857–863. doi: 10.1016/j.anbehav.2009.07.005. Show summary

  Laboratory studies suggest that young birds prefer to learn conspecific songs over songs from heterospecifics. However, field studies have shown that many species copy heterospecific song. We crossfostered pied flycatchers, Ficedula hypoleuca, to nests of blue tits, Cyanistes caeruleus, and great tits, Parus major, in the field. Recent studies have shown that species recognition is genetically determined in pied flycatchers. However, we found that most cross-fostered males included song types from the foster species in their repertoire, with an even stronger effect if reared with heterospecific nestmates. Furthermore, in cross-fostered males frequency range and syllable number per strophe were intermediate between control flycatchers and the foster species. The results contrast with those obtained when blue tits and great tits are cross-fostered in the field; the tits not only adopt songs from the foster species but, in contrast to the flycatchers, they also become sexually imprinted on it. Vocal mimicry may include a cost of reduced species recognition, but this cost may be minimized by also keeping a large proportion of conspecific song in the repertoire. Our finding highlights the importance of early experience for song acquisition, showing that altered social-rearing conditions may cause a mixed choice of song tutors. Depending on different proximate mechanisms, song used in mate choice may more readily respond to environmental change than mate choice itself. Changes in song by learning may thus serve as an essential first step in hybridization and speciation processes.

• Hansen, Bo Terning; Johannessen, Lars Erik & Slagsvold, Tore (2009). Interspecific cross-fostering affects mate guarding behaviour in great tits (Parus major). Behaviour. ISSN 0005-7959. 146, p. 1349–1361. doi: 10.1163/156853909X427713.
• Johannessen, Lars Erik; Kristiansen, Lena; Hansen, Bo Terning & Slagsvold, Tore (2009). Facultative Adjustment of Brood Sex Ratio in Response to Indirect Manipulation of Behaviour. Ethology. ISSN 0179-1613. 115(11), p. 1057–1065. doi: 10.1111/j.1439-0310.2009.01695.x.
• Wiebe, Karen L. & Slagsvold, Tore (2009). Mouth coloration in nestling birds: increasing detection or signalling quality? Animal Behaviour. ISSN 0003-3472. 78(6), p. 1413–1420. doi: 10.1016/j.anbehav.2009.09.013.
• Amrhein, Valentin; Johannessen, Lars Erik; Kristiansen, Lena & Slagsvold, Tore (2008). Reproductive strategy and singing activity: blue tit and great tit compared. Behavioral Ecology and Sociobiology. ISSN 0340-5443. 62, p. 1633–1641. doi: 10.1007/s00265-008-0592-6.

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• Lifjeld, Jan Terje & Slagsvold, Tore (2022). Female extra-pair copulation for direct fitness benefits: A cautionary note. Proceedings of the National Academy of Sciences of the United States of America. ISSN 0027-8424. 119(30). doi: 10.1073/pnas.2207108119.
• Hol, Kristiane E. & Slagsvold, Tore (2017). On the “silver-spoon” effect: Telomere length in relation to rearing conditions in blue tits.
• MacNeish, Avery & Slagsvold, Tore (2017). Variation in telomere length in blue tits in relation to age, sex, breeding success, and the telomere length of their parents.
• Aandstad, Kristian & Slagsvold, Tore (2017). Crystallization of song in the pied flycatcher (Ficedula hypoleuca).
• Fong, Lydia & Slagsvold, Tore (2017). Comparing the song variation of early and late arrivals of pied flycatchers (Ficedula hypoleuca).
• Slagsvold, Tore (2017). On the use of heterospecific information in birds.
• Aandstad, Kristian & Slagsvold, Tore (2016). Crystallization of song in the pied flycatcher (Ficedula hypoleuca).
• Fong, Lydia & Slagsvold, Tore (2016). Comparing the song variation of early and late arrivals of juvenile pied flycatchers (Ficedula hypoleuca).
• Hol, Kristiane E. & Slagsvold, Tore (2016). On the “silver-spoon” effect: telomere length in relation to rearing conditions in blue tits.
• MacNeish, Avery & Slagsvold, Tore (2016). Variation in telomere length in blue tits in relation to age, sex, breeding success, and the telomere length of their parents.
• Skaraas, Christine & Slagsvold, Tore (2015). Personality and natal dispersal in great tits Parus major.
• Slagsvold, Tore (2015). On the significance of early social learning in titmice.
• Hagelin, Jon Valbjørn; Ergon, Torbjørn & Slagsvold, Tore (2014). Change in distribution of Norwegian alpine breeding birds in response to global warming.
• Skaraas, Christine; Slagsvold, Tore & Lampe, Helene M. (2014). Personality and natal dispersal in great tits Parus major.
• Thorsteinsen, Camilla; Slagsvold, Tore & Lampe, Helene M. (2014). Reproductive success in great tits (Parus major) in relation to individual personality.
• Stræte, Tina Ø.; Slagsvold, Tore & Lampe, Helene M. (2014). Consistency between personality traits in wild great tits Parus major.
• Ivarsen, Anne E. & Slagsvold, Tore (2013). Does brain size affect survival and reproductive success in a wild population of great tits Parus major?
• Thorsteinsen, Camilla & Slagsvold, Tore (2013). Winter survival and reproductive success in great tits in relation to individual personality.
• Stræte, Tina Ø. & Slagsvold, Tore (2013). Significance of rearing conditions for personality later in life: a field study of great tits Parus major.
• Slagsvold, Tore (2012). Citizen science.
• Slagsvold, Tore (2012). Social learning in birds studied by cross-fostering in the wild.
• Slagsvold, Tore (2011). Feeding garden birds such as tits delays dawn chorus. [Newspaper]. BBC Earth News.
• Slagsvold, Tore (2011). Bird feeders delay great tits' dawn chorus. [Internet]. NewScientist.
• Slagsvold, Tore (2010). Feeding the birds can delay their dawn chorus. [Newspaper]. The Telegraph.
• Slagsvold, Tore (2010). El dilema de alimentar a las aves silvestres. [Internet]. BBC Mundo.
• Slagsvold, Tore (2010). Don't feed the birds. [Newspaper]. The Economist.
• Husek, Jan; Slagsvold, Tore; Weidinger, Karel & Adamik, Peter (2010). Impact of nest predation on breeding phenology in birds.
• Slagsvold, Tore (2010). Det biologiske mennesket – individer og samfunn i lys av evolusjon. [Internet]. Nina.no.
• Eriksen, Ane & Slagsvold, Tore (2010). Are mothers models for song learning - an experimental study on great tits. Show summary

  In songbirds, it is assumed that males learn songs from their father and conspecific male neighbours. We studied if the mother may play a role as well. Great tits Parus major were experimentally cross-fostered to blue tits Cyanistes caeruleus in the wild, and vice versa. In both species, cross-fostered males sang a combination of conspecific and heterospecific song, demonstrating an effect of early learning. Due to sexual misimprinting, cross-fostering resulted in pairings between the two species, providing an opportunity to see how species and gender of parent influence song learning. Great tit males reared by a great tit male and a blue tit female included blue tit song in their repertoires. To control for the possibility that they had learned blue tit songs from their cross-fostered great tit fathers, males reared by great tit pairs in which the father had been cross-fostered served as controls. None of these sang blue tit song, revealing an effect of the social mother on song acquisition. In great tits, the female rarely sings, and so it is possible that the juveniles select the male neighbours to be used as song tutors based on the neighbours’ resemblance to their (foster) mother as well as father.

• Amundsen, Trond; Folstad, Ivar; Giske, Jarl; Slagsvold, Tore & Stenseth, Nils Christian (2009). "Ida" er oversolgt. Aftenposten (morgenutg. : trykt utg.). ISSN 0804-3116. Show summary

  Kritikk av Jørn Hurum's formidling av "Ida-fossilet", skrevet av fem biologiprofessorer fra Oslo, Bergen, Trondheim og Tromsø. Hovedpoeng: Hurum's formidling til allmennheten "overselger" det vitenskapelige funnet; dette bryter med grunleggende kjøreregler for nøkternhet og troverdiget i vitenskapelig formidling.

• Eriksen, Ane; Slagsvold, Tore & Lampe, Helene M. (2009). Adult song learning – are pied flycatchers open-ended learners?
• Eriksen, Ane; Slagsvold, Tore & Lampe, Helene M. (2011). Song learning in oscine songbirds: tutor choice, timing, and the relationship with sexual imprinting. Faculty of Mathematics and Natural Sciences, University of Oslo. ISSN 1501-7710.

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