The development of caching and object permanence in western scrub-jays (Aphelocoma californica): Which emerges first?

Abstract

Recent studies on the food-caching behavior of corvids have revealed complex physical and social skills, yet little is known about the ontogeny of food caching in relation to the development of cognitive capacities. Piagetian object permanence is the understanding that objects continue to exist even when they are no longer visible. Here, the authors focus on Piagetian Stages 3 and 4, because they are hallmarks in the cognitive development of both young children and animals. Our aim is to determine in a food-caching corvid, the Western scrub-jay, whether (1) Piagetian Stage 4 competence and tentative caching (i.e., hiding an item invisibly and retrieving it without delay), emerge concomitantly or consecutively; (2) whether experiencing the reappearance of hidden objects enhances the timing of the appearance of object permanence; and (3) discuss how the development of object permanence is related to behavioral development and sensorimotor intelligence. Our findings suggest that object permanence Stage 4 emerges before tentative caching, and independent of environmental influences, but that once the birds have developed simple object-permanence, then social learning might advance the interval after which tentative caching commences.

The development of support intuitions and object causality in juvenile Eurasian jays (Garrulus glandarius)

“…Juvenile scrub-jays develop stage four object permanence (i.e. mental representations of hidden objects) before the emergence of tentative caching (hiding an object and immediately retrieving it)40. In the present study, the finding that birds without experience of string support (the nail group) looked longer at ‘impossible’ string support suggests that the development of support intuitions may be independent of experience, and perhaps due to fixed developmental milestones.…”

Problems faced by food-caching corvids and the evolution of cognitive solutions

“…Until young ravens and scrub-jays finally develop their full caching behaviour, placing items out of sight for later consumption, food and time are probably wasted and such tentative caching behaviours do not fulfil any obvious function except for the caching experience they may provide. This, together with their structured, sequential development, suggests that the propensity to cache may be pre-programmed (Pollok et al 2000;Bugnyar et al 2007a;Salwiczek et al 2009). …”

“…Young ravens, Corvus corax, have a predisposition to move objects around with their beaks, press them visibly towards large objects and then also to insert them into crevices and ultimately to cover them (Bugnyar et al 2007a). Similarly, young western scrub-jays, Aphelocoma californica, start manipulating objects in a structured sequence: picking up objects from the ground, moving them around, placing them elsewhere, pecking an object into the ground and later hiding and immediately retrieving objects (Salwiczek et al 2009). Until young ravens and scrub-jays finally develop their full caching behaviour, placing items out of sight for later consumption, food and time are probably wasted and such tentative caching behaviours do not fulfil any obvious function except for the caching experience they may provide.…”

Eurasian jays do not copy the choices of conspecifics, but they do show evidence of stimulus enhancement

“…To our knowledge, no corvid studies have compared juvenile and adult social information use. However, object permanence in Eurasian jays, which relates to caching development, develops at a similar stage as in other corvids (ravens: Bugnyar, Stowe & Heinrich, 2007; California scrub-jays: Salwiczek et al, 2009). Specifically, jays reach a full (i.e., stage six Piagetian) understanding of object permanence within their first few months of life (Zucca, Milos & Vallortigara, 2007).…”