Cautious Crows: Neophobia in Torresian Crows (Corvus orru) Compared with Three Other Corvoids in Suburban Australia

Abstract

Corvids (Family: CORVIDAE) are a clade of some 120 species widespread throughout much of the world that have attracted the interest of researchers due to their impressive cognitive abilities. The group is, however, also generally described as neophobic, a trait that increases the difficulty of undertaking such research. In Australia, Torresian crows (Corvus orru) have, like corvid species worldwide, thrived in urban environments, sharing this habitat with a number of other corvoid (Superfamily: CORVOIDEA) species. While each of these species has successfully colonised urban areas, the extent to which neophobia is present is not known. This study empirically tested the extent to which neophobia is exhibited in wild urban Torresian crows by measuring the delaying effect of a novel object to obtaining food and any changes in neophobic behaviours displayed. This was then compared with the other urban corvoid species that inhabit similar niches. This study confirmed that Torresian crows are significantly wary of a novel objects, displaying more neophobic behaviours and taking longer to attain the food. Crow behaviour provided evidence in support of both the dangerous niche hypothesis and the two‐factor model of neophobia and neophilia. Crows also displayed these behaviours to a significantly greater extent than the three other corvoids studied. However, the individual variation in crow behaviours when exposed to a novel object was extensive. This variation may be attributed to differing behavioural types between individuals, or different experiences with novel objects or humans in the bird's past.

Individual exploratory responses are not repeatable across time or context for four species of food-storing corvid

“…Species comparisons provide opportunities to examine the variability of behavioural responses at the level of a species 4 . Comparative studies of variability in individual's behavioural responses across species are limited 33,34,[64][65][66][67][68][69] , even though this approach is necessary to identify potential factors contributing to individual-level variability of behavioural responses among closely-related species. Previous comparative studies that focused on identifying factors influencing exploratory behaviour at a species level have identified three main factors: the www.nature.com/scientificreports www.nature.com/scientificreports/ relative sociality of the species (e.g., Social Niche Hypothesis 70,71 ), the foraging ecology and habitat complexity of the species 10,33,34,72 , and the migratory patterns of the species 67,73 .…”

Finding food in a human-dominated environment: Exploring the foraging behaviour of urban Torresian Crows Corvus orru

“…Corvids have become among the most abundant avian taxa found in urban environments throughout the world (Marzluff et al 2001). This abundance is despite millennia of active persecution and antipathy in both rural and urban areas (Knight 1984) and, unlike many other urban exploiters (Blair 1996), innate behavioural characteristics that include neophobia and a persistent lack of habituation (Brown & Jones 2016). Nonetheless, urbanised corvids can demonstrate clear evidence of tolerance of human presence; Vines & Lill (2015) showed that Little Ravens in urban Melbourne allowed humans to approach far closer than conspecifics in exurban areas.…”

“…The remarkable range of foods consumed by urban Torresian Crows demonstrates clearly a highly versatile diet and a willingness to try thoroughly unfamiliar items. Although Brown & Jones (2016) recently found this species to be strongly neophobic, being reluctant to approach a familiar food item when a novel object was nearby, it appears that this characteristic is overcome with time. For example, the various forms of packaging (foil, paper bags, packets etc.)…”

“…These items Queensland (Sinden 2002). Although numerous aspects of the behaviour of this species have been investigated in Brisbane (Sinden 2002;Everding & Jones 2006;Brown & Jones 2016), foraging ecology has been neglected. The aims of the present study were to investigate the foraging ecology of the Torresian Crow in the suburbs of Brisbane by determining its diet, whether foraging activities changed throughout the day, and how proximity to people influenced its behaviour.…”

“…One of the greatest of these opportunities is the increased availability of a wide range of anthropogenic foraging resources, although exploiting these requires the ability to adapt to both the different forms of food and to the presence of humans. Despite being naturally cautious and wary of new objects (Brown & Jones 2016), corvids (family Corvidae: crows, ravens and jays) have become proficient exploiters of the urban environment throughout the world (Marzluff et al 2001). In many cases, urban corvid populations have increased dramatically, a phenomenon often attributed to their exploitation of anthropogenic foods (Everding 1995;Marzluff & Neatherlin 2006;Webb et al 2011; but see Lill & Hales 2015).…”