Fear and Exploration in European Starlings (Sturnus vulgaris): A Comparison of Hand-Reared and Wild-Caught Birds

Abstract

The revision of EU legislation will ban the use of wild-caught animals in scientific procedures. This change is partially predicated on the assumption that captive-rearing produces animals with reduced fearfulness. Previously, we have shown that hand-reared starlings (Sturnus vulgaris) indeed exhibit reduced fear of humans compared to wild-caught conspecifics. Here, we asked whether this reduction in fear in hand-reared birds is limited to fear of humans or extends more generally to fear of novel environments and novel objects. Comparing 6–8 month old birds hand-reared in the lab with age-matched birds caught from the wild as fledged juveniles a minimum of 1 month previously, we examined the birds' initial reactions in a novel environment (a small cage) and found that wild-caught starlings were faster to initiate movement compared to the hand-reared birds. We interpret this difference as evidence for greater escape motivation in the wild-caught birds. In contrast, we found no differences between hand-reared and wild-caught birds when tested in novel object tests assumed to measure neophobia and exploratory behaviour. Moreover, we found no correlations between individual bird's responses in the different tests, supporting the idea that these measure different traits (e.g. fear and exploration). In summary, our data show that developmental origin affects one measure of response to novelty in young starlings, indicative of a difference in either fear or coping style in a stressful situation. Our data contribute to a growing literature demonstrating effects of early-life experience on later behaviour in a range of species. However, since we did not find consistent evidence for reduced fearfulness in hand-reared birds, we remain agnostic about the welfare benefits of hand-rearing as a method for sourcing wild birds for behavioural and physiological research.

Hand rearing affects emotional responses but not basic cognitive performance in European starlings

“…The cages were identical with the exception that four were environmentally enriched with a small hide, a tray of sawdust for foraging and a water bath, while the other four had no hide and an empty foraging tray and bath (the bath was filled twice a week for 1 h to allow basic hygiene). Previous data from this group of birds (Feenders & Bateson 2011; Feenders et al. 2011) and preliminary analyses of the current data set did not reveal any effect of current housing condition (enriched versus nonenriched); thus, we decided to exclude housing as a between-subjects factor in the current experiment to maximize power.…”

“…by the U.K. Home Office) as a strategy that will address the welfare objective of the law. We have been concerned that there has been insufficient attention paid to the potential welfare and scientific problems associated with a widespread switch to the use of hand-reared birds (Feenders & Bateson 2011; Feenders et al. 2011; Jayne et al.…”

“…In support of the practice, there is evidence that early handling reduces fear of humans and the stress reaction to restraint in parrots (Aengus & Millam 1999; Collette et al. 2000), and recent experimental studies have confirmed that hand-reared starlings are less fearful of humans and novel environments compared to birds caught from the wild as adults (Feenders & Bateson 2011; Feenders et al. 2011; Jayne et al.…”

Developmental programming: Cumulative effects of increased pre-hatching corticosterone levels and post-hatching unpredictable food availability on physiology and behaviour in adulthood

“…In rats, post-natal maternal separation resulted in increased object exploration compared to controls (Hensleigh et al, 2011; Roy and Chapillon, 2004). However, rearing environment had no effect on neophobia in starlings (Feenders et al, 2011). It has been proposed that differences in neophobia due to developmental history might only be evident when individuals experience intense fear (Feenders et al, 2011).…”

Olfactory cues and the value of information: voles interpret cues based on recent predator encounters

“…In many instances, animals born in the lab, even first generation, exhibit weakened responses to predators which they would encounter on a day-to-day basis in nature (e.g., Burns et al 2009; Feenders et al 2011; Troxell-Smith et al 2015). Similarly, but on a larger scale, ecologists have been puzzling over the inability of prey to recognize risk from unfamiliar, invasive, predators (Carthey and Banks 2014).…”