Nutritional Stress Causes Heterogeneous Relationships with Multi-Trait FA in Lesser Black-Backed Gull Chicks: An Aviary Experiment

Abstract

Abstract:Environmental stressors have the potential to induce perturbations in the development of young individuals, leading to aberrant and unstable development. This may manifest as fluctuating asymmetry (FA; small, non-directional changes in the bilateral symmetry of morphological traits). Although widely regarded as a proxy for stress effects, the use of FA as a biomarker is still a topic of much debate. We investigated the applicability of FA as an indicator of nutritional stress (brought about by energetic constraints) by experimental manipulation of the diet composition and quantity during the growth of Lesser Black-backed Gull (Larus fuscus) chicks. FA as an endpoint was measured across the tarsus, wing and 10th primary feather when chicks reached 30 days of age. Although levels of asymmetry were found to increase with stress in the feather, relationships with tarsus and wing FA were mixed and mostly non-significant. Furthermore, we did not find any correlations in unsigned FA between traits, indicating the absence of organism-wide asymmetry. Our study was therefore unable to find unequivocal evidence in support of the application of FA as a reliable estimator of nutritional stress.

Early-life diet does not affect preference for fish in herring gulls (Larus argentatus)

“…S1 and S2 ). Our findings differ from studies on captive lesser black-backed gull chicks, where those reared on chicken breast grew faster and were larger in mass at 30 days old than those that ate more fish ( Gupta et al, 2016 ; Sotillo et al, 2019 ). Anthropogenic foods of terrestrial origin, like household food waste ( e.g ., animal remains), can be high in calories and protein, which would meet chick requirements for growth and development ( Gupta et al, 2016 ; Sotillo et al, 2019 ; van Donk et al, 2017 ; van der Meer et al, 2020 ).…”

“…Our findings differ from studies on captive lesser black-backed gull chicks, where those reared on chicken breast grew faster and were larger in mass at 30 days old than those that ate more fish ( Gupta et al, 2016 ; Sotillo et al, 2019 ). Anthropogenic foods of terrestrial origin, like household food waste ( e.g ., animal remains), can be high in calories and protein, which would meet chick requirements for growth and development ( Gupta et al, 2016 ; Sotillo et al, 2019 ; van Donk et al, 2017 ; van der Meer et al, 2020 ). Our terrestrial diet group chicks may have been lighter because, once they were >25 days old, they started to refuse the terrestrial foods provided for the majority of the time (with time available used to create the experimental diet ratios).…”