Data from: Contagious fear: escape behaviour increases with flock size in European gregarious birds

  • Federico Morelli (Contributor)
  • Yanina Benedetti (Contributor)
  • Mario Diaz (Contributor)
  • Tomas Grim (Contributor)
  • Juan Diego Ibáñez-Álamo (Contributor)
  • Jukka Jokimäki (Contributor)
  • Marja-Liisa Kaisanlahti-Jokimäki (Contributor)
  • Kunter Tätte (Contributor)
  • Gabor Marko (Contributor)
  • Yiting Jiang (Contributor)
  • Piotr Tryjanowski (Contributor)
  • Anders Pape Møller (Contributor)



Flight initiation distance (FID), the distance at which individuals take flight when approached by a potential (human) predator, is a tool for understanding predator-prey interactions. Among the factors affecting FID, tests of effects of group size (i.e. number of potential prey) on FID have yielded contrasting results. Group size or flock size could either affect FID negatively (i.e. the dilution effect caused by the presence of many individuals) or positively (i.e. increased vigilance due to more eyes scanning for predators). These effects may be associated with gregarious species, because such species should be better adapted to exploiting information from other individuals in the group than non-gregarious species. Sociality may explain why earlier findings on group size vs. FID have yielded different conclusions. Here, we analyzed how flock size affected bird FID in eight European countries. A phylogenetic generalized least square regression model was used to investigate changes in escape behavior of bird species in relation to number of individuals in the flock, starting distance, diet, latitude and type of habitat. Flock size of different bird species influenced how species responded to perceived threats. We found that gregarious birds reacted to a potential predator earlier (longer flight initiation distance) when aggregated in large flocks. These results support a higher vigilance arising from many eyes scanning in birds, suggesting that sociality may be a key factor in the evolution of anti-predator behavior both in urban and rural areas. Finally, future studies comparing FID must pay explicit attention to the number of individuals in flocks of gregarious species.,dataset.fid.gregarious.2019Dataset associated to the article "Contagious fear: Escape behaviour increases with flock size in European gregarious birds" by Morelli et al. 2019. Metadata: Variable Details Species Species latin name FID_mean Flight initiation distance measured in meters (mean value) n No. observations of FID initiation Starting distance species Scientific name diet.specific Type of diet gregariousness gregarious bdm.quant body mass quartile latitude Latitude in decimel degrees habitat Type of habitat: Rural or urban flock Flock size (individuals) bodymass body mass (g),
Date made available2-May-2019
PublisherUniversity of Groningen

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