Unlearned visual preferences for the head region in domestic chicks.

Orsola Rosa-Salva,Giorgio Vallortigara,Uwe Mayer,Lesley Joy Rogers

doi:10.1371/journal.pone.0222079

Abstract

Unlearned tendencies to approach animate creatures are of great adaptive value, especially for nidifugous social birds that need to react to the presence of potential social companions shortly after hatching. Domestic chicks’ preferences for taxidermized hens provided the first evidence of social predispositions. However, the nature of the stimuli eliciting this predisposition is not completely understood. Here we explore the unlearned preferences of visually naïve domestic chicks for taxidermized animals. Visually naive chicks were tested for their approach preferences between a target stimulus (an intact stuffed animal whose head region was clearly visible) and a control stimulus. After confirming the predisposition for the intact stuffed fowl hen (Exp. 1), we found an analogous preference for a taxidermized, young domestic chick over a severely scrambled version of the same stimulus, whose body structure was completely disrupted, extending to same-age individuals the results that had been obtained with taxidermized hens (Exp. 2). We also directly tested preferences for specimens whose head region is visible compared to ones whose head region was occluded. To clarify whether chicks are sensitive to species-specific information, we employed specimens of female mallard ducks and of a mammalian predator, the polecat. Chicks showed a preference for the duck stimulus whose wings have been covered over a similar stimulus whose head region has been covered, providing direct evidence that the visibility of the head region of taxidermized models drive chicks’ behaviour in this test, and that the attraction for the head region indeed extends to females of other bird species (Exp. 3). However, no similar preference was obtained with the polecat stimuli (Exp. 4). We thus confirmed the presence of unlearned visual preferences for the head region in newly-hatched chicks, though other factors can limit the species-generality of the phenomenon.

Highlights

The ability to detect animate creatures is of great adaptive value for most animals, since it allows the identification of potential preys or predators, as well as conspecifics, i.e. potential social companions and competitors [1,2]
The aim of this study was to investigate the early emerging preferences that visually naïve domestic chicks display for taxidermized animals
By demonstrating that the duck stimulus whose wings have been covered is preferred over a similar stimulus whose head region has been covered (Exp. 3), we provide the first direct evidence that the visibility of the head region of taxidermized models drive chicks’ approach preference in this classical test

Summary

Introduction

The ability to detect animate creatures is of great adaptive value for most animals, since it allows the identification of potential preys or predators, as well as conspecifics, i.e. potential social companions and competitors [1,2]. Typical and atypical development of the brain) to GV. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

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