Does melanin-based plumage coloration reflect health status of free-living birds in urban environments?

Hani Amir Aouissi,Zihad Bouslama,Mostefa Ababsa,Yassine Farhi,Haroun Chenchouni,Aissam Gaagai

doi:10.1186/s40657-021-00280-7

Abstract

BackgroundEcological functions and processes in urban ecosystems are governed by various human activities. City-adapted and city-exploiting animal species are expected to present certain specific behavioral and physiological traits in comparison to city-avoiders or conspecific individual frequenting less urbanized or rural environments. A trait of high importance, the plumage color polymorphism has been selected as the main study model and was correlated with different morphological and physiological parameters to highlight its importance in determining the possible health status of urban Feral Pigeons (Columba livia) in North African urban habitats.MethodsDifferent body morphometrics, hematological and hemoparasitic parameters were quantified on free-living Feral Pigeons in urban environments of northern Algeria. Moreover, plumage melanin-based coloration (MBC) was measured and the data collected at the individual scale was correlated with the previous parameters using linear and non-linear modeling approaches.ResultsPlumage MBC scores of the sampled Feral Pigeons ranged between 0.3% and 74.8%. Among the 12 morphological traits measured, body weight, tail length and total length were deemed to be positively correlated with MBC. Darker morphs appeared to have more hemoparasites compared to lighter pigeons. Quite the same observation goes with the immunity but with non-linear trends. The number of monocytes and granulocytes increased with the increase in MBC levels in lighter morphs, while pigeons with high MBC scores exhibited negative relationships between MBC levels and the number of white blood cells.ConclusionsDespite the existence of a number of studies demonstrating phenotypic directional selection, further studies are undoubtedly necessary to understand in detail the underlying mechanisms in species life-history strategies between differently colored individuals. Findings of this correlative study open exciting perspectives revealing that MBC can be considered a good indicator of and health status and adaptation strategies to changes in urban environments.

Highlights

Ecological functions and processes in urban ecosystems are governed by various human activities
The generalized linear models testing the effects of body morphometrics on the variation of melanin-based coloration (MBC) demonstrated that body weight (P = 0.003), tail length (P = 0.023) and body total length (P = 0.040) had significant positive effects at a 5% probability threshold (Table 2; Fig. 2)
These 3 body measurements, in the same order stated above, expressed the best fit for explaining the variation of MBC data based on Akaike’s information criterion (AIC) and R2 scores

Summary

Introduction

Ecological functions and processes in urban ecosystems are governed by various human activities. City-adapted and city-exploiting animal species are expected to present certain specific behavioral and physiological traits in comparison to city-avoiders or conspecific individual frequenting less urbanized or rural environments. Urbanization expansion caused the replacement of rural habitats by urban, industrial and Aouissi et al Avian Res (2021) 12:45 other manmade sites ecosystems (Berry 1990). There are two kinds of species in urban environments: specialists and generalists. Hanson et al (2020) claimed that epigenetic potential may play a role in House Sparrow (Passer domesticus) range expansions, even though it remains very difficult to understand how epigenetic potential affects the gene’s expression, which is identical to the phenotypic plasticity at the individual, population, and species levels

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