Adrenal response to competitive singing: glucocorticoid metabolites in male Saltator similis (Aves, Thraupidae)

Author(s)

Lorieri-Vanin, Carolina ; Barbosa-Moyano, Heriberto ; Alvarenga, Claudio de Oliveira ; Silveira, Luis Fabio

• Document type: Journal article
• Source: CONSERVATION PHYSIOLOGY; v. 13, n. 1, p. 11-pg., 2025-02-13.

Abstract

Song competitions involving passerines, such as the Green-winged Saltator (Saltator similis), are legally permitted in Brazil and attract widespread participation. This study aimed to assess the adrenal response in male S. similis by comparing glucocorticoid metabolite (GCM) levels in uro-faecal extract samples collected during three competitions with those from a rest day (3 days before the competition, D-3), a day before the competition (D-1), the day of the competition (D0) and a day after the competition (D1). Simultaneously, we examined the potential variation in GCM levels among other males not engaged in song competitions but subjected to ex situ conditions much like those of participating males. GCM levels were measured using a direct enzyme immunoassay (EIA, CJM006), which was physiologically (ACTH challenge) and analytically validated (parallelism, accuracy and precision tests) for the species under study. The results indicated that the average GCM concentration was lower in the competition group (33.43 +/- 22.09 ng/g) as compared to the control group (70.09 +/- 29.45 ng/g; P = 0.01). However, concentrations spiked significantly on competition day (D0: 38.29 +/- 26.12 ng/g) as compared to the rest day (D-3: 28.64 +/- 17.86 ng/g; P = 0.02), suggesting acute stress response. Given the elevated GCM levels observed during competitions, further research is necessary to confirm the welfare of these birds under competition conditions and to explore the long-term effects of such stressors. This research examines the adrenal response of male Green-winged Saltators (Saltator similis) during song competitions by measuring glucocorticoid metabolites. Results show elevated levels of these hormones on competition days, indicating an acute stress response and highlighting the need for further investigation into the long-term impacts on avian welfare. (AU)

• FAPESP's process: 17/23548-2 - Evaluation, recovering and conservation of endangered animal species from the Pernambuco Centre of Endemism
• Grantee: Luís Fábio Silveira
• Support Opportunities: BIOTA-FAPESP Program - Thematic Grants
• FAPESP's process: 21/08898-2 - Seasonal gonadal, endocrine, and genetic changes during the reproductive and non-reproductive phases in nocturnal birds of prey
• Grantee: Claudio Alvarenga de Oliveira
• Support Opportunities: Regular Research Grants