Despite growing evidence for the recognition of conspecifics, studies on heterospecific recognition are still scarce. There is some evidence that birds living in urban habitats are able to distinguish between specific humans, depending on their previous experience with them. Nonetheless, the features by which the birds actually discriminated among humans remain unclear. This study investigated whether pigeons are capable of performing such a sophisticated categorisation and the features relevant to making this discrimination. The results revealed that pigeons are able to discriminate reliably between familiar and unfamiliar humans and provide evidence that facial features are important for this recognition. Furthermore, our results suggest that the ability to discriminate between individual heterospecifics is not restricted to bird species that are considered highly cognitive.
AustU., and HuberL. (2006) Picture-object recognition in pigeons: Evidence of representational insight in a visual discrimination task using a complementary information procedure. J. Exp. Psychol. - Anim. Behav. Process., 32, 190–195.
2.
BelguermiA., BovetD., PascalA., Prévot-JulliardA.C., Saint JalmeM., Rat-FischerL., and LeboucherG. (2011) Pigeons discriminate between human feeders. Anim. Cogn., 14, 6, 909–914.
3.
BogaleB.A., AoyamabM., and SugitaaS. (2011) Categorical learning between ‘male’ and ‘female’ photographic human faces in jungle crows (Corvus macrorhynchos). Behav. Proc., 86, 109–118.
4.
CookR.G., WrightA.A., and KendrickD.F. (1990) Visual categorisation by pigeons. In: CommonsM. L., and HerrnsteinR. J. (eds), Quantitative analyses of behavior: Vol. 8. Behavioral approaches to pattern recognition and concept formation, pp. 187–214. Hillsdale, NJ: Erlbaum.
5.
DittrichL., AdamR., ÜnverE., and GüntürkünO. (2010) Pigeons identify individual humans but show no sign of recognizing them in photographs. Behav. Proc., 83, 82–89.
6.
FerrariM.C.O., MessierF., and ChiversD.P. (2008) Can prey exhibit threat sensitive generalization of predator recognition? Extending the predator recognition continuum hypothesis. Proc. R. Soc. Lond. Ser. B Biol. Sci., 275, 1811–1816.
7.
GriffinA.S. (2004) Social learning about predators: A review and prospectus. Learn. Behav., 32, 1, 131–140.
8.
HuberL., TrojeN.F., LoidoltM., AustU., and GrassD. (2000) Natural categorisation through multiple feature learning in pigeons. Q. J. Exp. Psychol. B, 53, 4, 341–357.
9.
LeeW.Y., LeeS. I., ChoeJ.C., and JablonskiP.G. (2011) Wild birds recognise individual humans: experiments on magpies, Pica pica. Anim. Cogn., 14, 6, 817–825.
10.
LeveyD.J., LondonoG.A., Ungvari-MartinJ., HiersouxM.R., JankowskiJ.E., PoulsenJ.R., StraceyC.M., and RobinsonS.K. (2009) Urban mockingbirds quickly learn to identify individual humans. Proc. Natl. Acad. Sci. USA, 106, 22, 8959–8962.
11.
MarzluffJ.M., WallsJ., CornellH.N., WitheyJ.C., and CraigD.P. (2010) Lasting recognition of threatening people by wild American crows. Anim. Behav., 79, 699–707.
12.
MunksgaardL., de PassilleA.M., RushenJ., ThodbergK., and JensenM.B. (1997) Discrimination of people by dairy cows based on handling. J. Dairy. Sci., 80, 1106–1112.
13.
NakamuraT., CroftD.B., and WestbrookR.F. (2003) Domestic pigeons (Columba livia) discriminate between photographs of individual pigeons. Learn. Behav., 31, 307–317.
14.
RyanC. M. E., and LeaS. E. G. (1994) Images of conspecifics as categories to be discriminated by pigeons and chickens: slides, video tapes, stuffed birds and live birds. Behav. Process., 33, 155–176.
15.
SliwaJ., DuhamelJ.R., PascalisO., and WirthS. (2011) Spontaneous voice-face identity matching by rhesus monkeys for familiar conspecifics and humans. Proc. Natl. Acad. Sci. USA, 108, 4, 1735–1740.
16.
SlobodchikoffC.N., KiriazisJ., FischerC., and CreefE. (1991) Semantic information distinguishing individual predators in the alarm calls of Gunnison prairie dogs. Anim. Behav., 42, 713–719.
17.
StephanC., WilkinsonA., and HuberL. (submitted to Anim. Cogn.) Individual recognition in the non-social domain – Pigeons recognize individual objects that are ecologically relevant for them.
18.
StoneS.M. (2010) Human facial discrimination in horses: can they tell us apart?Anim. Cogn., 13, 51–61.
19.
TaylorA.A., and DavisH. (1998) Individual humans as discriminative stimuli for cattle (Bos taurus). Appl. Anim. Behav. Sci., 58, 13–21.
20.
TricaricoE., BorrelliL., GherardiF., and FioritoG. (2011) I know my neighbour: individual recognition in Octopus vulgaris. PLoS ONE, 6, 4, e18710. doi:10.1371/journal.pone.0018710.
21.
WascherC.A.F., SziplG., BoeckleM., and WilkinsonA. (2012) You sound familiar – Carrion crows can differentiate between the calls of known and unknown heterospecifics. Anim. Cogn., In press.
22.
WilkinsonA., SpechtH.L., and HuberL. (2010) Pigeons can discriminate group mates from strangers using the concept of familiarity. Anim. Behav., 80, 109–115.
