Work

Physiological biomarkers and hemoparasites in two gull species from human-altered landscapes

Year: 2026

Type: article

Abstract: Human-altered landscapes expose wildlife to interacting stressors, including contamination, habitat modification, and altered food resources, potentially causing sublethal and often overlooked effects on health, immune function, and parasite dynamics. We assessed these effects by evaluating the physiological condition and hemoparasite prevalence and intensity of two gull species breeding in contrasting anthropogenic contexts in eastern Spain: yellow-legged gull ( Larus michahellis , YLG) and Audouin’s gull ( Ichthyaetus audouinii , AG). We quantified hematological parameters, plasma B-esterase activities, and hemoparasite occurrence and metrics. Principal component analyses revealed species-specific multivariate responses. YLG showed weak inter-colony differentiation in hematological variables and similar B-esterase activities across sites. In contrast, AG exhibited clear habitat-associated differences. Individuals from the highly agriculture-modified Ebro Delta, where rice fields made up much of the habitat used, had elevated total leukocyte counts, eosinophils, and monocytes, consistent with innate immune activation potentially related to parasite exposure. They also showed consistently lower activities of all six B-esterases measured compared with other colonies. Erythrocyte abnormalities did not vary among sites within species but were higher in AG than in YLG. Both species hosted Haemoproteus sp., while Babesia sp. was detected only in AG. Hemoparasite prevalence was similar between species, whereas infection intensity was positively associated with monocytes and immature erythrocytes. Integrative blood biomarkers revealed subtle, species-specific physiological responses to human-altered environments, with greater inter-colony physiological and hemoparasite variation in AG than in YLG. Combining physiological biomarkers with hemoparasite analyses provides sensitive early-warning indicators of environmental stress, supporting wildlife health assessments and evidence-based urban planning.

Source: Urban Ecosystems

DOI: 10.1007/s11252-026-02166-2