The ability of ravens (Corvus corax Linnaeus, 1758) to evaluate human behavior from a bystander perspective

master's thesis

• Title (croatian): Sposobnost gavrana (Corvus corax Linnaeus, 1758) za procjenu ponašanja ljudi iz perspektive promatrača
• Author: Ana Tomašić
• Mentor: Thomas Bugnyar (mentor)
• Mentor: Zoran Tadić (sumentor)
• Committee member: Zoran Tadić (predsjednik povjerenstva)
• Committee member: Ivana Buj (član povjerenstva)
• Committee member: Sven Jelaska (član povjerenstva)
• Committee member: Zoran Marčić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2021-09-28, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Ravens (Corvus corax) have a complex social structure with various interaction between
individuals. Predicting the behavior of others based on observation would be advantageous for
future interactions. While previous studies showed that ravens can discriminate between human
experimenters after direct interaction, I was interested to see if they would be able to do so when
put in a bystander position. In this study, individual ravens could observe two experimenters
engaging in the retrieval of their food previously cached or in the pilfering of the other’s cache.
Two experimenters (pilferer or retriever versus a neutral person) offered food and each raven had
the choice to take the food from one of them. Contrary to expectation, the ravens did not choose
one experimenter significantly over the other. Yet, when comparing their choices made before and
after the observation, I found a tendency to discriminate. Furthermore, the ravens changed their
visual behavior (head turns) across the phase types of a trial, but not between the conditions. This
study produced equivocal results, which might be caused by small sample size. Further
investigation is needed to confirm whether ravens are capable to understand displayed human
interaction and what behavioral actions ravens are paying attention to.

Abstract (croatian)

Gavrani (Corvus corax) imaju složenu socijalnu strukturu u kojoj su jedinke izložene različitim
situacijama u interakciji s drugim jedinkama. Stoga, predviđanje ponašanja drugih, pomoću
informacija dobivenih opažanjem, može biti korisno u budućim interakcijama. Kako su u
prijašnjim studijama gavrani razlikovali ljude nakon direktne interakcije s njima, zanimalo me
mogu li razlikovati ljude i iz pozicije promatrača. U ovom eksperimentu, svaki je gavran promatrao
dva izvođača pokusa koji su ili uzeli hranu koju su sami prethodno sakrili ili su ukrali hranu iz
skrovišta drugog izvođača pokusa. Naknadno, dva izvođača pokusa (kradljivac ili osoba koja je
uzela svoju hranu natrag i neutralna osoba) ponudili su hranu gavranu, koji je potom odabrao od
koga uzeti hranu. Suprotno predviđanjima, gavrani nisu odabrali niti jednog izvođača pokusa
značajno više od drugih. Ipak, analiza njihovih odabira prije i nakon promatranja pokazuje da imaju
sklonost razlikovanju osoba. Također, gavrani su promijenili svoje ponašanje (okretaji glavom)
kroz pojedine faze pokusa, ali ne i kroz tip pokusa. U konačnici, ovo istraživanje je dalo
dvosmislene rezultate, vjerojatno zbog male veličine uzorka. Potrebna su dodatna istraživanje kako
bi se potvrdilo jesu li gavrani sposobni razumjeti prikazanu ljudsku interakciju i na koje njene
elemente obraćaju pozornost.

• Keywords: animal cognition; third-party evaluation
• Keywords (croatian): kognicija životninja; indirektna recipročnost; gavran
• Language: english
• URN:NBN: urn:nbn:hr:217:873086
• Study programme: Title: Ecology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra ekologije i zaštite prirode (magistar/magistra ekologije i zaštite prirode)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2023-09-28
• Created on: 2021-10-14 13:20:49